github.com/cellofellow/gopkg@v0.0.0-20140722061823-eec0544a62ad/database/sqlite3/sqlite3.h (about)

     1  /*
     2  ** 2001 September 15
     3  **
     4  ** The author disclaims copyright to this source code.  In place of
     5  ** a legal notice, here is a blessing:
     6  **
     7  **    May you do good and not evil.
     8  **    May you find forgiveness for yourself and forgive others.
     9  **    May you share freely, never taking more than you give.
    10  **
    11  *************************************************************************
    12  ** This header file defines the interface that the SQLite library
    13  ** presents to client programs.  If a C-function, structure, datatype,
    14  ** or constant definition does not appear in this file, then it is
    15  ** not a published API of SQLite, is subject to change without
    16  ** notice, and should not be referenced by programs that use SQLite.
    17  **
    18  ** Some of the definitions that are in this file are marked as
    19  ** "experimental".  Experimental interfaces are normally new
    20  ** features recently added to SQLite.  We do not anticipate changes
    21  ** to experimental interfaces but reserve the right to make minor changes
    22  ** if experience from use "in the wild" suggest such changes are prudent.
    23  **
    24  ** The official C-language API documentation for SQLite is derived
    25  ** from comments in this file.  This file is the authoritative source
    26  ** on how SQLite interfaces are suppose to operate.
    27  **
    28  ** The name of this file under configuration management is "sqlite.h.in".
    29  ** The makefile makes some minor changes to this file (such as inserting
    30  ** the version number) and changes its name to "sqlite3.h" as
    31  ** part of the build process.
    32  */
    33  #ifndef _SQLITE3_H_
    34  #define _SQLITE3_H_
    35  #include <stdarg.h>     /* Needed for the definition of va_list */
    36  
    37  /*
    38  ** Make sure we can call this stuff from C++.
    39  */
    40  #ifdef __cplusplus
    41  extern "C" {
    42  #endif
    43  
    44  
    45  /*
    46  ** Add the ability to override 'extern'
    47  */
    48  #ifndef SQLITE_EXTERN
    49  # define SQLITE_EXTERN extern
    50  #endif
    51  
    52  #ifndef SQLITE_API
    53  # define SQLITE_API
    54  #endif
    55  
    56  
    57  /*
    58  ** These no-op macros are used in front of interfaces to mark those
    59  ** interfaces as either deprecated or experimental.  New applications
    60  ** should not use deprecated interfaces - they are support for backwards
    61  ** compatibility only.  Application writers should be aware that
    62  ** experimental interfaces are subject to change in point releases.
    63  **
    64  ** These macros used to resolve to various kinds of compiler magic that
    65  ** would generate warning messages when they were used.  But that
    66  ** compiler magic ended up generating such a flurry of bug reports
    67  ** that we have taken it all out and gone back to using simple
    68  ** noop macros.
    69  */
    70  #define SQLITE_DEPRECATED
    71  #define SQLITE_EXPERIMENTAL
    72  
    73  /*
    74  ** Ensure these symbols were not defined by some previous header file.
    75  */
    76  #ifdef SQLITE_VERSION
    77  # undef SQLITE_VERSION
    78  #endif
    79  #ifdef SQLITE_VERSION_NUMBER
    80  # undef SQLITE_VERSION_NUMBER
    81  #endif
    82  
    83  /*
    84  ** CAPI3REF: Compile-Time Library Version Numbers
    85  **
    86  ** ^(The [SQLITE_VERSION] C preprocessor macro in the sqlite3.h header
    87  ** evaluates to a string literal that is the SQLite version in the
    88  ** format "X.Y.Z" where X is the major version number (always 3 for
    89  ** SQLite3) and Y is the minor version number and Z is the release number.)^
    90  ** ^(The [SQLITE_VERSION_NUMBER] C preprocessor macro resolves to an integer
    91  ** with the value (X*1000000 + Y*1000 + Z) where X, Y, and Z are the same
    92  ** numbers used in [SQLITE_VERSION].)^
    93  ** The SQLITE_VERSION_NUMBER for any given release of SQLite will also
    94  ** be larger than the release from which it is derived.  Either Y will
    95  ** be held constant and Z will be incremented or else Y will be incremented
    96  ** and Z will be reset to zero.
    97  **
    98  ** Since version 3.6.18, SQLite source code has been stored in the
    99  ** <a href="http://www.fossil-scm.org/">Fossil configuration management
   100  ** system</a>.  ^The SQLITE_SOURCE_ID macro evaluates to
   101  ** a string which identifies a particular check-in of SQLite
   102  ** within its configuration management system.  ^The SQLITE_SOURCE_ID
   103  ** string contains the date and time of the check-in (UTC) and an SHA1
   104  ** hash of the entire source tree.
   105  **
   106  ** See also: [sqlite3_libversion()],
   107  ** [sqlite3_libversion_number()], [sqlite3_sourceid()],
   108  ** [sqlite_version()] and [sqlite_source_id()].
   109  */
   110  #define SQLITE_VERSION        "3.8.0"
   111  #define SQLITE_VERSION_NUMBER 3008000
   112  #define SQLITE_SOURCE_ID      "2013-08-07 23:15:52 3adb6c1bfda897859dc9cf9ae7f1e6719855ee68"
   113  
   114  /*
   115  ** CAPI3REF: Run-Time Library Version Numbers
   116  ** KEYWORDS: sqlite3_version, sqlite3_sourceid
   117  **
   118  ** These interfaces provide the same information as the [SQLITE_VERSION],
   119  ** [SQLITE_VERSION_NUMBER], and [SQLITE_SOURCE_ID] C preprocessor macros
   120  ** but are associated with the library instead of the header file.  ^(Cautious
   121  ** programmers might include assert() statements in their application to
   122  ** verify that values returned by these interfaces match the macros in
   123  ** the header, and thus insure that the application is
   124  ** compiled with matching library and header files.
   125  **
   126  ** <blockquote><pre>
   127  ** assert( sqlite3_libversion_number()==SQLITE_VERSION_NUMBER );
   128  ** assert( strcmp(sqlite3_sourceid(),SQLITE_SOURCE_ID)==0 );
   129  ** assert( strcmp(sqlite3_libversion(),SQLITE_VERSION)==0 );
   130  ** </pre></blockquote>)^
   131  **
   132  ** ^The sqlite3_version[] string constant contains the text of [SQLITE_VERSION]
   133  ** macro.  ^The sqlite3_libversion() function returns a pointer to the
   134  ** to the sqlite3_version[] string constant.  The sqlite3_libversion()
   135  ** function is provided for use in DLLs since DLL users usually do not have
   136  ** direct access to string constants within the DLL.  ^The
   137  ** sqlite3_libversion_number() function returns an integer equal to
   138  ** [SQLITE_VERSION_NUMBER].  ^The sqlite3_sourceid() function returns 
   139  ** a pointer to a string constant whose value is the same as the 
   140  ** [SQLITE_SOURCE_ID] C preprocessor macro.
   141  **
   142  ** See also: [sqlite_version()] and [sqlite_source_id()].
   143  */
   144  SQLITE_API SQLITE_EXTERN const char sqlite3_version[];
   145  SQLITE_API const char *sqlite3_libversion(void);
   146  SQLITE_API const char *sqlite3_sourceid(void);
   147  SQLITE_API int sqlite3_libversion_number(void);
   148  
   149  /*
   150  ** CAPI3REF: Run-Time Library Compilation Options Diagnostics
   151  **
   152  ** ^The sqlite3_compileoption_used() function returns 0 or 1 
   153  ** indicating whether the specified option was defined at 
   154  ** compile time.  ^The SQLITE_ prefix may be omitted from the 
   155  ** option name passed to sqlite3_compileoption_used().  
   156  **
   157  ** ^The sqlite3_compileoption_get() function allows iterating
   158  ** over the list of options that were defined at compile time by
   159  ** returning the N-th compile time option string.  ^If N is out of range,
   160  ** sqlite3_compileoption_get() returns a NULL pointer.  ^The SQLITE_ 
   161  ** prefix is omitted from any strings returned by 
   162  ** sqlite3_compileoption_get().
   163  **
   164  ** ^Support for the diagnostic functions sqlite3_compileoption_used()
   165  ** and sqlite3_compileoption_get() may be omitted by specifying the 
   166  ** [SQLITE_OMIT_COMPILEOPTION_DIAGS] option at compile time.
   167  **
   168  ** See also: SQL functions [sqlite_compileoption_used()] and
   169  ** [sqlite_compileoption_get()] and the [compile_options pragma].
   170  */
   171  #ifndef SQLITE_OMIT_COMPILEOPTION_DIAGS
   172  SQLITE_API int sqlite3_compileoption_used(const char *zOptName);
   173  SQLITE_API const char *sqlite3_compileoption_get(int N);
   174  #endif
   175  
   176  /*
   177  ** CAPI3REF: Test To See If The Library Is Threadsafe
   178  **
   179  ** ^The sqlite3_threadsafe() function returns zero if and only if
   180  ** SQLite was compiled with mutexing code omitted due to the
   181  ** [SQLITE_THREADSAFE] compile-time option being set to 0.
   182  **
   183  ** SQLite can be compiled with or without mutexes.  When
   184  ** the [SQLITE_THREADSAFE] C preprocessor macro is 1 or 2, mutexes
   185  ** are enabled and SQLite is threadsafe.  When the
   186  ** [SQLITE_THREADSAFE] macro is 0, 
   187  ** the mutexes are omitted.  Without the mutexes, it is not safe
   188  ** to use SQLite concurrently from more than one thread.
   189  **
   190  ** Enabling mutexes incurs a measurable performance penalty.
   191  ** So if speed is of utmost importance, it makes sense to disable
   192  ** the mutexes.  But for maximum safety, mutexes should be enabled.
   193  ** ^The default behavior is for mutexes to be enabled.
   194  **
   195  ** This interface can be used by an application to make sure that the
   196  ** version of SQLite that it is linking against was compiled with
   197  ** the desired setting of the [SQLITE_THREADSAFE] macro.
   198  **
   199  ** This interface only reports on the compile-time mutex setting
   200  ** of the [SQLITE_THREADSAFE] flag.  If SQLite is compiled with
   201  ** SQLITE_THREADSAFE=1 or =2 then mutexes are enabled by default but
   202  ** can be fully or partially disabled using a call to [sqlite3_config()]
   203  ** with the verbs [SQLITE_CONFIG_SINGLETHREAD], [SQLITE_CONFIG_MULTITHREAD],
   204  ** or [SQLITE_CONFIG_MUTEX].  ^(The return value of the
   205  ** sqlite3_threadsafe() function shows only the compile-time setting of
   206  ** thread safety, not any run-time changes to that setting made by
   207  ** sqlite3_config(). In other words, the return value from sqlite3_threadsafe()
   208  ** is unchanged by calls to sqlite3_config().)^
   209  **
   210  ** See the [threading mode] documentation for additional information.
   211  */
   212  SQLITE_API int sqlite3_threadsafe(void);
   213  
   214  /*
   215  ** CAPI3REF: Database Connection Handle
   216  ** KEYWORDS: {database connection} {database connections}
   217  **
   218  ** Each open SQLite database is represented by a pointer to an instance of
   219  ** the opaque structure named "sqlite3".  It is useful to think of an sqlite3
   220  ** pointer as an object.  The [sqlite3_open()], [sqlite3_open16()], and
   221  ** [sqlite3_open_v2()] interfaces are its constructors, and [sqlite3_close()]
   222  ** and [sqlite3_close_v2()] are its destructors.  There are many other
   223  ** interfaces (such as
   224  ** [sqlite3_prepare_v2()], [sqlite3_create_function()], and
   225  ** [sqlite3_busy_timeout()] to name but three) that are methods on an
   226  ** sqlite3 object.
   227  */
   228  typedef struct sqlite3 sqlite3;
   229  
   230  /*
   231  ** CAPI3REF: 64-Bit Integer Types
   232  ** KEYWORDS: sqlite_int64 sqlite_uint64
   233  **
   234  ** Because there is no cross-platform way to specify 64-bit integer types
   235  ** SQLite includes typedefs for 64-bit signed and unsigned integers.
   236  **
   237  ** The sqlite3_int64 and sqlite3_uint64 are the preferred type definitions.
   238  ** The sqlite_int64 and sqlite_uint64 types are supported for backwards
   239  ** compatibility only.
   240  **
   241  ** ^The sqlite3_int64 and sqlite_int64 types can store integer values
   242  ** between -9223372036854775808 and +9223372036854775807 inclusive.  ^The
   243  ** sqlite3_uint64 and sqlite_uint64 types can store integer values 
   244  ** between 0 and +18446744073709551615 inclusive.
   245  */
   246  #ifdef SQLITE_INT64_TYPE
   247    typedef SQLITE_INT64_TYPE sqlite_int64;
   248    typedef unsigned SQLITE_INT64_TYPE sqlite_uint64;
   249  #elif defined(_MSC_VER) || defined(__BORLANDC__)
   250    typedef __int64 sqlite_int64;
   251    typedef unsigned __int64 sqlite_uint64;
   252  #else
   253    typedef long long int sqlite_int64;
   254    typedef unsigned long long int sqlite_uint64;
   255  #endif
   256  typedef sqlite_int64 sqlite3_int64;
   257  typedef sqlite_uint64 sqlite3_uint64;
   258  
   259  /*
   260  ** If compiling for a processor that lacks floating point support,
   261  ** substitute integer for floating-point.
   262  */
   263  #ifdef SQLITE_OMIT_FLOATING_POINT
   264  # define double sqlite3_int64
   265  #endif
   266  
   267  /*
   268  ** CAPI3REF: Closing A Database Connection
   269  **
   270  ** ^The sqlite3_close() and sqlite3_close_v2() routines are destructors
   271  ** for the [sqlite3] object.
   272  ** ^Calls to sqlite3_close() and sqlite3_close_v2() return SQLITE_OK if
   273  ** the [sqlite3] object is successfully destroyed and all associated
   274  ** resources are deallocated.
   275  **
   276  ** ^If the database connection is associated with unfinalized prepared
   277  ** statements or unfinished sqlite3_backup objects then sqlite3_close()
   278  ** will leave the database connection open and return [SQLITE_BUSY].
   279  ** ^If sqlite3_close_v2() is called with unfinalized prepared statements
   280  ** and unfinished sqlite3_backups, then the database connection becomes
   281  ** an unusable "zombie" which will automatically be deallocated when the
   282  ** last prepared statement is finalized or the last sqlite3_backup is
   283  ** finished.  The sqlite3_close_v2() interface is intended for use with
   284  ** host languages that are garbage collected, and where the order in which
   285  ** destructors are called is arbitrary.
   286  **
   287  ** Applications should [sqlite3_finalize | finalize] all [prepared statements],
   288  ** [sqlite3_blob_close | close] all [BLOB handles], and 
   289  ** [sqlite3_backup_finish | finish] all [sqlite3_backup] objects associated
   290  ** with the [sqlite3] object prior to attempting to close the object.  ^If
   291  ** sqlite3_close_v2() is called on a [database connection] that still has
   292  ** outstanding [prepared statements], [BLOB handles], and/or
   293  ** [sqlite3_backup] objects then it returns SQLITE_OK but the deallocation
   294  ** of resources is deferred until all [prepared statements], [BLOB handles],
   295  ** and [sqlite3_backup] objects are also destroyed.
   296  **
   297  ** ^If an [sqlite3] object is destroyed while a transaction is open,
   298  ** the transaction is automatically rolled back.
   299  **
   300  ** The C parameter to [sqlite3_close(C)] and [sqlite3_close_v2(C)]
   301  ** must be either a NULL
   302  ** pointer or an [sqlite3] object pointer obtained
   303  ** from [sqlite3_open()], [sqlite3_open16()], or
   304  ** [sqlite3_open_v2()], and not previously closed.
   305  ** ^Calling sqlite3_close() or sqlite3_close_v2() with a NULL pointer
   306  ** argument is a harmless no-op.
   307  */
   308  SQLITE_API int sqlite3_close(sqlite3*);
   309  SQLITE_API int sqlite3_close_v2(sqlite3*);
   310  
   311  /*
   312  ** The type for a callback function.
   313  ** This is legacy and deprecated.  It is included for historical
   314  ** compatibility and is not documented.
   315  */
   316  typedef int (*sqlite3_callback)(void*,int,char**, char**);
   317  
   318  /*
   319  ** CAPI3REF: One-Step Query Execution Interface
   320  **
   321  ** The sqlite3_exec() interface is a convenience wrapper around
   322  ** [sqlite3_prepare_v2()], [sqlite3_step()], and [sqlite3_finalize()],
   323  ** that allows an application to run multiple statements of SQL
   324  ** without having to use a lot of C code. 
   325  **
   326  ** ^The sqlite3_exec() interface runs zero or more UTF-8 encoded,
   327  ** semicolon-separate SQL statements passed into its 2nd argument,
   328  ** in the context of the [database connection] passed in as its 1st
   329  ** argument.  ^If the callback function of the 3rd argument to
   330  ** sqlite3_exec() is not NULL, then it is invoked for each result row
   331  ** coming out of the evaluated SQL statements.  ^The 4th argument to
   332  ** sqlite3_exec() is relayed through to the 1st argument of each
   333  ** callback invocation.  ^If the callback pointer to sqlite3_exec()
   334  ** is NULL, then no callback is ever invoked and result rows are
   335  ** ignored.
   336  **
   337  ** ^If an error occurs while evaluating the SQL statements passed into
   338  ** sqlite3_exec(), then execution of the current statement stops and
   339  ** subsequent statements are skipped.  ^If the 5th parameter to sqlite3_exec()
   340  ** is not NULL then any error message is written into memory obtained
   341  ** from [sqlite3_malloc()] and passed back through the 5th parameter.
   342  ** To avoid memory leaks, the application should invoke [sqlite3_free()]
   343  ** on error message strings returned through the 5th parameter of
   344  ** of sqlite3_exec() after the error message string is no longer needed.
   345  ** ^If the 5th parameter to sqlite3_exec() is not NULL and no errors
   346  ** occur, then sqlite3_exec() sets the pointer in its 5th parameter to
   347  ** NULL before returning.
   348  **
   349  ** ^If an sqlite3_exec() callback returns non-zero, the sqlite3_exec()
   350  ** routine returns SQLITE_ABORT without invoking the callback again and
   351  ** without running any subsequent SQL statements.
   352  **
   353  ** ^The 2nd argument to the sqlite3_exec() callback function is the
   354  ** number of columns in the result.  ^The 3rd argument to the sqlite3_exec()
   355  ** callback is an array of pointers to strings obtained as if from
   356  ** [sqlite3_column_text()], one for each column.  ^If an element of a
   357  ** result row is NULL then the corresponding string pointer for the
   358  ** sqlite3_exec() callback is a NULL pointer.  ^The 4th argument to the
   359  ** sqlite3_exec() callback is an array of pointers to strings where each
   360  ** entry represents the name of corresponding result column as obtained
   361  ** from [sqlite3_column_name()].
   362  **
   363  ** ^If the 2nd parameter to sqlite3_exec() is a NULL pointer, a pointer
   364  ** to an empty string, or a pointer that contains only whitespace and/or 
   365  ** SQL comments, then no SQL statements are evaluated and the database
   366  ** is not changed.
   367  **
   368  ** Restrictions:
   369  **
   370  ** <ul>
   371  ** <li> The application must insure that the 1st parameter to sqlite3_exec()
   372  **      is a valid and open [database connection].
   373  ** <li> The application must not close [database connection] specified by
   374  **      the 1st parameter to sqlite3_exec() while sqlite3_exec() is running.
   375  ** <li> The application must not modify the SQL statement text passed into
   376  **      the 2nd parameter of sqlite3_exec() while sqlite3_exec() is running.
   377  ** </ul>
   378  */
   379  SQLITE_API int sqlite3_exec(
   380    sqlite3*,                                  /* An open database */
   381    const char *sql,                           /* SQL to be evaluated */
   382    int (*callback)(void*,int,char**,char**),  /* Callback function */
   383    void *,                                    /* 1st argument to callback */
   384    char **errmsg                              /* Error msg written here */
   385  );
   386  
   387  /*
   388  ** CAPI3REF: Result Codes
   389  ** KEYWORDS: SQLITE_OK {error code} {error codes}
   390  ** KEYWORDS: {result code} {result codes}
   391  **
   392  ** Many SQLite functions return an integer result code from the set shown
   393  ** here in order to indicate success or failure.
   394  **
   395  ** New error codes may be added in future versions of SQLite.
   396  **
   397  ** See also: [SQLITE_IOERR_READ | extended result codes],
   398  ** [sqlite3_vtab_on_conflict()] [SQLITE_ROLLBACK | result codes].
   399  */
   400  #define SQLITE_OK           0   /* Successful result */
   401  /* beginning-of-error-codes */
   402  #define SQLITE_ERROR        1   /* SQL error or missing database */
   403  #define SQLITE_INTERNAL     2   /* Internal logic error in SQLite */
   404  #define SQLITE_PERM         3   /* Access permission denied */
   405  #define SQLITE_ABORT        4   /* Callback routine requested an abort */
   406  #define SQLITE_BUSY         5   /* The database file is locked */
   407  #define SQLITE_LOCKED       6   /* A table in the database is locked */
   408  #define SQLITE_NOMEM        7   /* A malloc() failed */
   409  #define SQLITE_READONLY     8   /* Attempt to write a readonly database */
   410  #define SQLITE_INTERRUPT    9   /* Operation terminated by sqlite3_interrupt()*/
   411  #define SQLITE_IOERR       10   /* Some kind of disk I/O error occurred */
   412  #define SQLITE_CORRUPT     11   /* The database disk image is malformed */
   413  #define SQLITE_NOTFOUND    12   /* Unknown opcode in sqlite3_file_control() */
   414  #define SQLITE_FULL        13   /* Insertion failed because database is full */
   415  #define SQLITE_CANTOPEN    14   /* Unable to open the database file */
   416  #define SQLITE_PROTOCOL    15   /* Database lock protocol error */
   417  #define SQLITE_EMPTY       16   /* Database is empty */
   418  #define SQLITE_SCHEMA      17   /* The database schema changed */
   419  #define SQLITE_TOOBIG      18   /* String or BLOB exceeds size limit */
   420  #define SQLITE_CONSTRAINT  19   /* Abort due to constraint violation */
   421  #define SQLITE_MISMATCH    20   /* Data type mismatch */
   422  #define SQLITE_MISUSE      21   /* Library used incorrectly */
   423  #define SQLITE_NOLFS       22   /* Uses OS features not supported on host */
   424  #define SQLITE_AUTH        23   /* Authorization denied */
   425  #define SQLITE_FORMAT      24   /* Auxiliary database format error */
   426  #define SQLITE_RANGE       25   /* 2nd parameter to sqlite3_bind out of range */
   427  #define SQLITE_NOTADB      26   /* File opened that is not a database file */
   428  #define SQLITE_NOTICE      27   /* Notifications from sqlite3_log() */
   429  #define SQLITE_WARNING     28   /* Warnings from sqlite3_log() */
   430  #define SQLITE_ROW         100  /* sqlite3_step() has another row ready */
   431  #define SQLITE_DONE        101  /* sqlite3_step() has finished executing */
   432  /* end-of-error-codes */
   433  
   434  /*
   435  ** CAPI3REF: Extended Result Codes
   436  ** KEYWORDS: {extended error code} {extended error codes}
   437  ** KEYWORDS: {extended result code} {extended result codes}
   438  **
   439  ** In its default configuration, SQLite API routines return one of 26 integer
   440  ** [SQLITE_OK | result codes].  However, experience has shown that many of
   441  ** these result codes are too coarse-grained.  They do not provide as
   442  ** much information about problems as programmers might like.  In an effort to
   443  ** address this, newer versions of SQLite (version 3.3.8 and later) include
   444  ** support for additional result codes that provide more detailed information
   445  ** about errors. The extended result codes are enabled or disabled
   446  ** on a per database connection basis using the
   447  ** [sqlite3_extended_result_codes()] API.
   448  **
   449  ** Some of the available extended result codes are listed here.
   450  ** One may expect the number of extended result codes will be expand
   451  ** over time.  Software that uses extended result codes should expect
   452  ** to see new result codes in future releases of SQLite.
   453  **
   454  ** The SQLITE_OK result code will never be extended.  It will always
   455  ** be exactly zero.
   456  */
   457  #define SQLITE_IOERR_READ              (SQLITE_IOERR | (1<<8))
   458  #define SQLITE_IOERR_SHORT_READ        (SQLITE_IOERR | (2<<8))
   459  #define SQLITE_IOERR_WRITE             (SQLITE_IOERR | (3<<8))
   460  #define SQLITE_IOERR_FSYNC             (SQLITE_IOERR | (4<<8))
   461  #define SQLITE_IOERR_DIR_FSYNC         (SQLITE_IOERR | (5<<8))
   462  #define SQLITE_IOERR_TRUNCATE          (SQLITE_IOERR | (6<<8))
   463  #define SQLITE_IOERR_FSTAT             (SQLITE_IOERR | (7<<8))
   464  #define SQLITE_IOERR_UNLOCK            (SQLITE_IOERR | (8<<8))
   465  #define SQLITE_IOERR_RDLOCK            (SQLITE_IOERR | (9<<8))
   466  #define SQLITE_IOERR_DELETE            (SQLITE_IOERR | (10<<8))
   467  #define SQLITE_IOERR_BLOCKED           (SQLITE_IOERR | (11<<8))
   468  #define SQLITE_IOERR_NOMEM             (SQLITE_IOERR | (12<<8))
   469  #define SQLITE_IOERR_ACCESS            (SQLITE_IOERR | (13<<8))
   470  #define SQLITE_IOERR_CHECKRESERVEDLOCK (SQLITE_IOERR | (14<<8))
   471  #define SQLITE_IOERR_LOCK              (SQLITE_IOERR | (15<<8))
   472  #define SQLITE_IOERR_CLOSE             (SQLITE_IOERR | (16<<8))
   473  #define SQLITE_IOERR_DIR_CLOSE         (SQLITE_IOERR | (17<<8))
   474  #define SQLITE_IOERR_SHMOPEN           (SQLITE_IOERR | (18<<8))
   475  #define SQLITE_IOERR_SHMSIZE           (SQLITE_IOERR | (19<<8))
   476  #define SQLITE_IOERR_SHMLOCK           (SQLITE_IOERR | (20<<8))
   477  #define SQLITE_IOERR_SHMMAP            (SQLITE_IOERR | (21<<8))
   478  #define SQLITE_IOERR_SEEK              (SQLITE_IOERR | (22<<8))
   479  #define SQLITE_IOERR_DELETE_NOENT      (SQLITE_IOERR | (23<<8))
   480  #define SQLITE_IOERR_MMAP              (SQLITE_IOERR | (24<<8))
   481  #define SQLITE_IOERR_GETTEMPPATH       (SQLITE_IOERR | (25<<8))
   482  #define SQLITE_LOCKED_SHAREDCACHE      (SQLITE_LOCKED |  (1<<8))
   483  #define SQLITE_BUSY_RECOVERY           (SQLITE_BUSY   |  (1<<8))
   484  #define SQLITE_BUSY_SNAPSHOT           (SQLITE_BUSY   |  (2<<8))
   485  #define SQLITE_CANTOPEN_NOTEMPDIR      (SQLITE_CANTOPEN | (1<<8))
   486  #define SQLITE_CANTOPEN_ISDIR          (SQLITE_CANTOPEN | (2<<8))
   487  #define SQLITE_CANTOPEN_FULLPATH       (SQLITE_CANTOPEN | (3<<8))
   488  #define SQLITE_CORRUPT_VTAB            (SQLITE_CORRUPT | (1<<8))
   489  #define SQLITE_READONLY_RECOVERY       (SQLITE_READONLY | (1<<8))
   490  #define SQLITE_READONLY_CANTLOCK       (SQLITE_READONLY | (2<<8))
   491  #define SQLITE_READONLY_ROLLBACK       (SQLITE_READONLY | (3<<8))
   492  #define SQLITE_ABORT_ROLLBACK          (SQLITE_ABORT | (2<<8))
   493  #define SQLITE_CONSTRAINT_CHECK        (SQLITE_CONSTRAINT | (1<<8))
   494  #define SQLITE_CONSTRAINT_COMMITHOOK   (SQLITE_CONSTRAINT | (2<<8))
   495  #define SQLITE_CONSTRAINT_FOREIGNKEY   (SQLITE_CONSTRAINT | (3<<8))
   496  #define SQLITE_CONSTRAINT_FUNCTION     (SQLITE_CONSTRAINT | (4<<8))
   497  #define SQLITE_CONSTRAINT_NOTNULL      (SQLITE_CONSTRAINT | (5<<8))
   498  #define SQLITE_CONSTRAINT_PRIMARYKEY   (SQLITE_CONSTRAINT | (6<<8))
   499  #define SQLITE_CONSTRAINT_TRIGGER      (SQLITE_CONSTRAINT | (7<<8))
   500  #define SQLITE_CONSTRAINT_UNIQUE       (SQLITE_CONSTRAINT | (8<<8))
   501  #define SQLITE_CONSTRAINT_VTAB         (SQLITE_CONSTRAINT | (9<<8))
   502  #define SQLITE_NOTICE_RECOVER_WAL      (SQLITE_NOTICE | (1<<8))
   503  #define SQLITE_NOTICE_RECOVER_ROLLBACK (SQLITE_NOTICE | (2<<8))
   504  #define SQLITE_WARNING_AUTOINDEX       (SQLITE_WARNING | (1<<8))
   505  
   506  /*
   507  ** CAPI3REF: Flags For File Open Operations
   508  **
   509  ** These bit values are intended for use in the
   510  ** 3rd parameter to the [sqlite3_open_v2()] interface and
   511  ** in the 4th parameter to the [sqlite3_vfs.xOpen] method.
   512  */
   513  #define SQLITE_OPEN_READONLY         0x00000001  /* Ok for sqlite3_open_v2() */
   514  #define SQLITE_OPEN_READWRITE        0x00000002  /* Ok for sqlite3_open_v2() */
   515  #define SQLITE_OPEN_CREATE           0x00000004  /* Ok for sqlite3_open_v2() */
   516  #define SQLITE_OPEN_DELETEONCLOSE    0x00000008  /* VFS only */
   517  #define SQLITE_OPEN_EXCLUSIVE        0x00000010  /* VFS only */
   518  #define SQLITE_OPEN_AUTOPROXY        0x00000020  /* VFS only */
   519  #define SQLITE_OPEN_URI              0x00000040  /* Ok for sqlite3_open_v2() */
   520  #define SQLITE_OPEN_MEMORY           0x00000080  /* Ok for sqlite3_open_v2() */
   521  #define SQLITE_OPEN_MAIN_DB          0x00000100  /* VFS only */
   522  #define SQLITE_OPEN_TEMP_DB          0x00000200  /* VFS only */
   523  #define SQLITE_OPEN_TRANSIENT_DB     0x00000400  /* VFS only */
   524  #define SQLITE_OPEN_MAIN_JOURNAL     0x00000800  /* VFS only */
   525  #define SQLITE_OPEN_TEMP_JOURNAL     0x00001000  /* VFS only */
   526  #define SQLITE_OPEN_SUBJOURNAL       0x00002000  /* VFS only */
   527  #define SQLITE_OPEN_MASTER_JOURNAL   0x00004000  /* VFS only */
   528  #define SQLITE_OPEN_NOMUTEX          0x00008000  /* Ok for sqlite3_open_v2() */
   529  #define SQLITE_OPEN_FULLMUTEX        0x00010000  /* Ok for sqlite3_open_v2() */
   530  #define SQLITE_OPEN_SHAREDCACHE      0x00020000  /* Ok for sqlite3_open_v2() */
   531  #define SQLITE_OPEN_PRIVATECACHE     0x00040000  /* Ok for sqlite3_open_v2() */
   532  #define SQLITE_OPEN_WAL              0x00080000  /* VFS only */
   533  
   534  /* Reserved:                         0x00F00000 */
   535  
   536  /*
   537  ** CAPI3REF: Device Characteristics
   538  **
   539  ** The xDeviceCharacteristics method of the [sqlite3_io_methods]
   540  ** object returns an integer which is a vector of these
   541  ** bit values expressing I/O characteristics of the mass storage
   542  ** device that holds the file that the [sqlite3_io_methods]
   543  ** refers to.
   544  **
   545  ** The SQLITE_IOCAP_ATOMIC property means that all writes of
   546  ** any size are atomic.  The SQLITE_IOCAP_ATOMICnnn values
   547  ** mean that writes of blocks that are nnn bytes in size and
   548  ** are aligned to an address which is an integer multiple of
   549  ** nnn are atomic.  The SQLITE_IOCAP_SAFE_APPEND value means
   550  ** that when data is appended to a file, the data is appended
   551  ** first then the size of the file is extended, never the other
   552  ** way around.  The SQLITE_IOCAP_SEQUENTIAL property means that
   553  ** information is written to disk in the same order as calls
   554  ** to xWrite().  The SQLITE_IOCAP_POWERSAFE_OVERWRITE property means that
   555  ** after reboot following a crash or power loss, the only bytes in a
   556  ** file that were written at the application level might have changed
   557  ** and that adjacent bytes, even bytes within the same sector are
   558  ** guaranteed to be unchanged.
   559  */
   560  #define SQLITE_IOCAP_ATOMIC                 0x00000001
   561  #define SQLITE_IOCAP_ATOMIC512              0x00000002
   562  #define SQLITE_IOCAP_ATOMIC1K               0x00000004
   563  #define SQLITE_IOCAP_ATOMIC2K               0x00000008
   564  #define SQLITE_IOCAP_ATOMIC4K               0x00000010
   565  #define SQLITE_IOCAP_ATOMIC8K               0x00000020
   566  #define SQLITE_IOCAP_ATOMIC16K              0x00000040
   567  #define SQLITE_IOCAP_ATOMIC32K              0x00000080
   568  #define SQLITE_IOCAP_ATOMIC64K              0x00000100
   569  #define SQLITE_IOCAP_SAFE_APPEND            0x00000200
   570  #define SQLITE_IOCAP_SEQUENTIAL             0x00000400
   571  #define SQLITE_IOCAP_UNDELETABLE_WHEN_OPEN  0x00000800
   572  #define SQLITE_IOCAP_POWERSAFE_OVERWRITE    0x00001000
   573  
   574  /*
   575  ** CAPI3REF: File Locking Levels
   576  **
   577  ** SQLite uses one of these integer values as the second
   578  ** argument to calls it makes to the xLock() and xUnlock() methods
   579  ** of an [sqlite3_io_methods] object.
   580  */
   581  #define SQLITE_LOCK_NONE          0
   582  #define SQLITE_LOCK_SHARED        1
   583  #define SQLITE_LOCK_RESERVED      2
   584  #define SQLITE_LOCK_PENDING       3
   585  #define SQLITE_LOCK_EXCLUSIVE     4
   586  
   587  /*
   588  ** CAPI3REF: Synchronization Type Flags
   589  **
   590  ** When SQLite invokes the xSync() method of an
   591  ** [sqlite3_io_methods] object it uses a combination of
   592  ** these integer values as the second argument.
   593  **
   594  ** When the SQLITE_SYNC_DATAONLY flag is used, it means that the
   595  ** sync operation only needs to flush data to mass storage.  Inode
   596  ** information need not be flushed. If the lower four bits of the flag
   597  ** equal SQLITE_SYNC_NORMAL, that means to use normal fsync() semantics.
   598  ** If the lower four bits equal SQLITE_SYNC_FULL, that means
   599  ** to use Mac OS X style fullsync instead of fsync().
   600  **
   601  ** Do not confuse the SQLITE_SYNC_NORMAL and SQLITE_SYNC_FULL flags
   602  ** with the [PRAGMA synchronous]=NORMAL and [PRAGMA synchronous]=FULL
   603  ** settings.  The [synchronous pragma] determines when calls to the
   604  ** xSync VFS method occur and applies uniformly across all platforms.
   605  ** The SQLITE_SYNC_NORMAL and SQLITE_SYNC_FULL flags determine how
   606  ** energetic or rigorous or forceful the sync operations are and
   607  ** only make a difference on Mac OSX for the default SQLite code.
   608  ** (Third-party VFS implementations might also make the distinction
   609  ** between SQLITE_SYNC_NORMAL and SQLITE_SYNC_FULL, but among the
   610  ** operating systems natively supported by SQLite, only Mac OSX
   611  ** cares about the difference.)
   612  */
   613  #define SQLITE_SYNC_NORMAL        0x00002
   614  #define SQLITE_SYNC_FULL          0x00003
   615  #define SQLITE_SYNC_DATAONLY      0x00010
   616  
   617  /*
   618  ** CAPI3REF: OS Interface Open File Handle
   619  **
   620  ** An [sqlite3_file] object represents an open file in the 
   621  ** [sqlite3_vfs | OS interface layer].  Individual OS interface
   622  ** implementations will
   623  ** want to subclass this object by appending additional fields
   624  ** for their own use.  The pMethods entry is a pointer to an
   625  ** [sqlite3_io_methods] object that defines methods for performing
   626  ** I/O operations on the open file.
   627  */
   628  typedef struct sqlite3_file sqlite3_file;
   629  struct sqlite3_file {
   630    const struct sqlite3_io_methods *pMethods;  /* Methods for an open file */
   631  };
   632  
   633  /*
   634  ** CAPI3REF: OS Interface File Virtual Methods Object
   635  **
   636  ** Every file opened by the [sqlite3_vfs.xOpen] method populates an
   637  ** [sqlite3_file] object (or, more commonly, a subclass of the
   638  ** [sqlite3_file] object) with a pointer to an instance of this object.
   639  ** This object defines the methods used to perform various operations
   640  ** against the open file represented by the [sqlite3_file] object.
   641  **
   642  ** If the [sqlite3_vfs.xOpen] method sets the sqlite3_file.pMethods element 
   643  ** to a non-NULL pointer, then the sqlite3_io_methods.xClose method
   644  ** may be invoked even if the [sqlite3_vfs.xOpen] reported that it failed.  The
   645  ** only way to prevent a call to xClose following a failed [sqlite3_vfs.xOpen]
   646  ** is for the [sqlite3_vfs.xOpen] to set the sqlite3_file.pMethods element
   647  ** to NULL.
   648  **
   649  ** The flags argument to xSync may be one of [SQLITE_SYNC_NORMAL] or
   650  ** [SQLITE_SYNC_FULL].  The first choice is the normal fsync().
   651  ** The second choice is a Mac OS X style fullsync.  The [SQLITE_SYNC_DATAONLY]
   652  ** flag may be ORed in to indicate that only the data of the file
   653  ** and not its inode needs to be synced.
   654  **
   655  ** The integer values to xLock() and xUnlock() are one of
   656  ** <ul>
   657  ** <li> [SQLITE_LOCK_NONE],
   658  ** <li> [SQLITE_LOCK_SHARED],
   659  ** <li> [SQLITE_LOCK_RESERVED],
   660  ** <li> [SQLITE_LOCK_PENDING], or
   661  ** <li> [SQLITE_LOCK_EXCLUSIVE].
   662  ** </ul>
   663  ** xLock() increases the lock. xUnlock() decreases the lock.
   664  ** The xCheckReservedLock() method checks whether any database connection,
   665  ** either in this process or in some other process, is holding a RESERVED,
   666  ** PENDING, or EXCLUSIVE lock on the file.  It returns true
   667  ** if such a lock exists and false otherwise.
   668  **
   669  ** The xFileControl() method is a generic interface that allows custom
   670  ** VFS implementations to directly control an open file using the
   671  ** [sqlite3_file_control()] interface.  The second "op" argument is an
   672  ** integer opcode.  The third argument is a generic pointer intended to
   673  ** point to a structure that may contain arguments or space in which to
   674  ** write return values.  Potential uses for xFileControl() might be
   675  ** functions to enable blocking locks with timeouts, to change the
   676  ** locking strategy (for example to use dot-file locks), to inquire
   677  ** about the status of a lock, or to break stale locks.  The SQLite
   678  ** core reserves all opcodes less than 100 for its own use.
   679  ** A [SQLITE_FCNTL_LOCKSTATE | list of opcodes] less than 100 is available.
   680  ** Applications that define a custom xFileControl method should use opcodes
   681  ** greater than 100 to avoid conflicts.  VFS implementations should
   682  ** return [SQLITE_NOTFOUND] for file control opcodes that they do not
   683  ** recognize.
   684  **
   685  ** The xSectorSize() method returns the sector size of the
   686  ** device that underlies the file.  The sector size is the
   687  ** minimum write that can be performed without disturbing
   688  ** other bytes in the file.  The xDeviceCharacteristics()
   689  ** method returns a bit vector describing behaviors of the
   690  ** underlying device:
   691  **
   692  ** <ul>
   693  ** <li> [SQLITE_IOCAP_ATOMIC]
   694  ** <li> [SQLITE_IOCAP_ATOMIC512]
   695  ** <li> [SQLITE_IOCAP_ATOMIC1K]
   696  ** <li> [SQLITE_IOCAP_ATOMIC2K]
   697  ** <li> [SQLITE_IOCAP_ATOMIC4K]
   698  ** <li> [SQLITE_IOCAP_ATOMIC8K]
   699  ** <li> [SQLITE_IOCAP_ATOMIC16K]
   700  ** <li> [SQLITE_IOCAP_ATOMIC32K]
   701  ** <li> [SQLITE_IOCAP_ATOMIC64K]
   702  ** <li> [SQLITE_IOCAP_SAFE_APPEND]
   703  ** <li> [SQLITE_IOCAP_SEQUENTIAL]
   704  ** </ul>
   705  **
   706  ** The SQLITE_IOCAP_ATOMIC property means that all writes of
   707  ** any size are atomic.  The SQLITE_IOCAP_ATOMICnnn values
   708  ** mean that writes of blocks that are nnn bytes in size and
   709  ** are aligned to an address which is an integer multiple of
   710  ** nnn are atomic.  The SQLITE_IOCAP_SAFE_APPEND value means
   711  ** that when data is appended to a file, the data is appended
   712  ** first then the size of the file is extended, never the other
   713  ** way around.  The SQLITE_IOCAP_SEQUENTIAL property means that
   714  ** information is written to disk in the same order as calls
   715  ** to xWrite().
   716  **
   717  ** If xRead() returns SQLITE_IOERR_SHORT_READ it must also fill
   718  ** in the unread portions of the buffer with zeros.  A VFS that
   719  ** fails to zero-fill short reads might seem to work.  However,
   720  ** failure to zero-fill short reads will eventually lead to
   721  ** database corruption.
   722  */
   723  typedef struct sqlite3_io_methods sqlite3_io_methods;
   724  struct sqlite3_io_methods {
   725    int iVersion;
   726    int (*xClose)(sqlite3_file*);
   727    int (*xRead)(sqlite3_file*, void*, int iAmt, sqlite3_int64 iOfst);
   728    int (*xWrite)(sqlite3_file*, const void*, int iAmt, sqlite3_int64 iOfst);
   729    int (*xTruncate)(sqlite3_file*, sqlite3_int64 size);
   730    int (*xSync)(sqlite3_file*, int flags);
   731    int (*xFileSize)(sqlite3_file*, sqlite3_int64 *pSize);
   732    int (*xLock)(sqlite3_file*, int);
   733    int (*xUnlock)(sqlite3_file*, int);
   734    int (*xCheckReservedLock)(sqlite3_file*, int *pResOut);
   735    int (*xFileControl)(sqlite3_file*, int op, void *pArg);
   736    int (*xSectorSize)(sqlite3_file*);
   737    int (*xDeviceCharacteristics)(sqlite3_file*);
   738    /* Methods above are valid for version 1 */
   739    int (*xShmMap)(sqlite3_file*, int iPg, int pgsz, int, void volatile**);
   740    int (*xShmLock)(sqlite3_file*, int offset, int n, int flags);
   741    void (*xShmBarrier)(sqlite3_file*);
   742    int (*xShmUnmap)(sqlite3_file*, int deleteFlag);
   743    /* Methods above are valid for version 2 */
   744    int (*xFetch)(sqlite3_file*, sqlite3_int64 iOfst, int iAmt, void **pp);
   745    int (*xUnfetch)(sqlite3_file*, sqlite3_int64 iOfst, void *p);
   746    /* Methods above are valid for version 3 */
   747    /* Additional methods may be added in future releases */
   748  };
   749  
   750  /*
   751  ** CAPI3REF: Standard File Control Opcodes
   752  **
   753  ** These integer constants are opcodes for the xFileControl method
   754  ** of the [sqlite3_io_methods] object and for the [sqlite3_file_control()]
   755  ** interface.
   756  **
   757  ** The [SQLITE_FCNTL_LOCKSTATE] opcode is used for debugging.  This
   758  ** opcode causes the xFileControl method to write the current state of
   759  ** the lock (one of [SQLITE_LOCK_NONE], [SQLITE_LOCK_SHARED],
   760  ** [SQLITE_LOCK_RESERVED], [SQLITE_LOCK_PENDING], or [SQLITE_LOCK_EXCLUSIVE])
   761  ** into an integer that the pArg argument points to. This capability
   762  ** is used during testing and only needs to be supported when SQLITE_TEST
   763  ** is defined.
   764  ** <ul>
   765  ** <li>[[SQLITE_FCNTL_SIZE_HINT]]
   766  ** The [SQLITE_FCNTL_SIZE_HINT] opcode is used by SQLite to give the VFS
   767  ** layer a hint of how large the database file will grow to be during the
   768  ** current transaction.  This hint is not guaranteed to be accurate but it
   769  ** is often close.  The underlying VFS might choose to preallocate database
   770  ** file space based on this hint in order to help writes to the database
   771  ** file run faster.
   772  **
   773  ** <li>[[SQLITE_FCNTL_CHUNK_SIZE]]
   774  ** The [SQLITE_FCNTL_CHUNK_SIZE] opcode is used to request that the VFS
   775  ** extends and truncates the database file in chunks of a size specified
   776  ** by the user. The fourth argument to [sqlite3_file_control()] should 
   777  ** point to an integer (type int) containing the new chunk-size to use
   778  ** for the nominated database. Allocating database file space in large
   779  ** chunks (say 1MB at a time), may reduce file-system fragmentation and
   780  ** improve performance on some systems.
   781  **
   782  ** <li>[[SQLITE_FCNTL_FILE_POINTER]]
   783  ** The [SQLITE_FCNTL_FILE_POINTER] opcode is used to obtain a pointer
   784  ** to the [sqlite3_file] object associated with a particular database
   785  ** connection.  See the [sqlite3_file_control()] documentation for
   786  ** additional information.
   787  **
   788  ** <li>[[SQLITE_FCNTL_SYNC_OMITTED]]
   789  ** ^(The [SQLITE_FCNTL_SYNC_OMITTED] opcode is generated internally by
   790  ** SQLite and sent to all VFSes in place of a call to the xSync method
   791  ** when the database connection has [PRAGMA synchronous] set to OFF.)^
   792  ** Some specialized VFSes need this signal in order to operate correctly
   793  ** when [PRAGMA synchronous | PRAGMA synchronous=OFF] is set, but most 
   794  ** VFSes do not need this signal and should silently ignore this opcode.
   795  ** Applications should not call [sqlite3_file_control()] with this
   796  ** opcode as doing so may disrupt the operation of the specialized VFSes
   797  ** that do require it.  
   798  **
   799  ** <li>[[SQLITE_FCNTL_WIN32_AV_RETRY]]
   800  ** ^The [SQLITE_FCNTL_WIN32_AV_RETRY] opcode is used to configure automatic
   801  ** retry counts and intervals for certain disk I/O operations for the
   802  ** windows [VFS] in order to provide robustness in the presence of
   803  ** anti-virus programs.  By default, the windows VFS will retry file read,
   804  ** file write, and file delete operations up to 10 times, with a delay
   805  ** of 25 milliseconds before the first retry and with the delay increasing
   806  ** by an additional 25 milliseconds with each subsequent retry.  This
   807  ** opcode allows these two values (10 retries and 25 milliseconds of delay)
   808  ** to be adjusted.  The values are changed for all database connections
   809  ** within the same process.  The argument is a pointer to an array of two
   810  ** integers where the first integer i the new retry count and the second
   811  ** integer is the delay.  If either integer is negative, then the setting
   812  ** is not changed but instead the prior value of that setting is written
   813  ** into the array entry, allowing the current retry settings to be
   814  ** interrogated.  The zDbName parameter is ignored.
   815  **
   816  ** <li>[[SQLITE_FCNTL_PERSIST_WAL]]
   817  ** ^The [SQLITE_FCNTL_PERSIST_WAL] opcode is used to set or query the
   818  ** persistent [WAL | Write Ahead Log] setting.  By default, the auxiliary
   819  ** write ahead log and shared memory files used for transaction control
   820  ** are automatically deleted when the latest connection to the database
   821  ** closes.  Setting persistent WAL mode causes those files to persist after
   822  ** close.  Persisting the files is useful when other processes that do not
   823  ** have write permission on the directory containing the database file want
   824  ** to read the database file, as the WAL and shared memory files must exist
   825  ** in order for the database to be readable.  The fourth parameter to
   826  ** [sqlite3_file_control()] for this opcode should be a pointer to an integer.
   827  ** That integer is 0 to disable persistent WAL mode or 1 to enable persistent
   828  ** WAL mode.  If the integer is -1, then it is overwritten with the current
   829  ** WAL persistence setting.
   830  **
   831  ** <li>[[SQLITE_FCNTL_POWERSAFE_OVERWRITE]]
   832  ** ^The [SQLITE_FCNTL_POWERSAFE_OVERWRITE] opcode is used to set or query the
   833  ** persistent "powersafe-overwrite" or "PSOW" setting.  The PSOW setting
   834  ** determines the [SQLITE_IOCAP_POWERSAFE_OVERWRITE] bit of the
   835  ** xDeviceCharacteristics methods. The fourth parameter to
   836  ** [sqlite3_file_control()] for this opcode should be a pointer to an integer.
   837  ** That integer is 0 to disable zero-damage mode or 1 to enable zero-damage
   838  ** mode.  If the integer is -1, then it is overwritten with the current
   839  ** zero-damage mode setting.
   840  **
   841  ** <li>[[SQLITE_FCNTL_OVERWRITE]]
   842  ** ^The [SQLITE_FCNTL_OVERWRITE] opcode is invoked by SQLite after opening
   843  ** a write transaction to indicate that, unless it is rolled back for some
   844  ** reason, the entire database file will be overwritten by the current 
   845  ** transaction. This is used by VACUUM operations.
   846  **
   847  ** <li>[[SQLITE_FCNTL_VFSNAME]]
   848  ** ^The [SQLITE_FCNTL_VFSNAME] opcode can be used to obtain the names of
   849  ** all [VFSes] in the VFS stack.  The names are of all VFS shims and the
   850  ** final bottom-level VFS are written into memory obtained from 
   851  ** [sqlite3_malloc()] and the result is stored in the char* variable
   852  ** that the fourth parameter of [sqlite3_file_control()] points to.
   853  ** The caller is responsible for freeing the memory when done.  As with
   854  ** all file-control actions, there is no guarantee that this will actually
   855  ** do anything.  Callers should initialize the char* variable to a NULL
   856  ** pointer in case this file-control is not implemented.  This file-control
   857  ** is intended for diagnostic use only.
   858  **
   859  ** <li>[[SQLITE_FCNTL_PRAGMA]]
   860  ** ^Whenever a [PRAGMA] statement is parsed, an [SQLITE_FCNTL_PRAGMA] 
   861  ** file control is sent to the open [sqlite3_file] object corresponding
   862  ** to the database file to which the pragma statement refers. ^The argument
   863  ** to the [SQLITE_FCNTL_PRAGMA] file control is an array of
   864  ** pointers to strings (char**) in which the second element of the array
   865  ** is the name of the pragma and the third element is the argument to the
   866  ** pragma or NULL if the pragma has no argument.  ^The handler for an
   867  ** [SQLITE_FCNTL_PRAGMA] file control can optionally make the first element
   868  ** of the char** argument point to a string obtained from [sqlite3_mprintf()]
   869  ** or the equivalent and that string will become the result of the pragma or
   870  ** the error message if the pragma fails. ^If the
   871  ** [SQLITE_FCNTL_PRAGMA] file control returns [SQLITE_NOTFOUND], then normal 
   872  ** [PRAGMA] processing continues.  ^If the [SQLITE_FCNTL_PRAGMA]
   873  ** file control returns [SQLITE_OK], then the parser assumes that the
   874  ** VFS has handled the PRAGMA itself and the parser generates a no-op
   875  ** prepared statement.  ^If the [SQLITE_FCNTL_PRAGMA] file control returns
   876  ** any result code other than [SQLITE_OK] or [SQLITE_NOTFOUND], that means
   877  ** that the VFS encountered an error while handling the [PRAGMA] and the
   878  ** compilation of the PRAGMA fails with an error.  ^The [SQLITE_FCNTL_PRAGMA]
   879  ** file control occurs at the beginning of pragma statement analysis and so
   880  ** it is able to override built-in [PRAGMA] statements.
   881  **
   882  ** <li>[[SQLITE_FCNTL_BUSYHANDLER]]
   883  ** ^The [SQLITE_FCNTL_BUSYHANDLER]
   884  ** file-control may be invoked by SQLite on the database file handle
   885  ** shortly after it is opened in order to provide a custom VFS with access
   886  ** to the connections busy-handler callback. The argument is of type (void **)
   887  ** - an array of two (void *) values. The first (void *) actually points
   888  ** to a function of type (int (*)(void *)). In order to invoke the connections
   889  ** busy-handler, this function should be invoked with the second (void *) in
   890  ** the array as the only argument. If it returns non-zero, then the operation
   891  ** should be retried. If it returns zero, the custom VFS should abandon the
   892  ** current operation.
   893  **
   894  ** <li>[[SQLITE_FCNTL_TEMPFILENAME]]
   895  ** ^Application can invoke the [SQLITE_FCNTL_TEMPFILENAME] file-control
   896  ** to have SQLite generate a
   897  ** temporary filename using the same algorithm that is followed to generate
   898  ** temporary filenames for TEMP tables and other internal uses.  The
   899  ** argument should be a char** which will be filled with the filename
   900  ** written into memory obtained from [sqlite3_malloc()].  The caller should
   901  ** invoke [sqlite3_free()] on the result to avoid a memory leak.
   902  **
   903  ** <li>[[SQLITE_FCNTL_MMAP_SIZE]]
   904  ** The [SQLITE_FCNTL_MMAP_SIZE] file control is used to query or set the
   905  ** maximum number of bytes that will be used for memory-mapped I/O.
   906  ** The argument is a pointer to a value of type sqlite3_int64 that
   907  ** is an advisory maximum number of bytes in the file to memory map.  The
   908  ** pointer is overwritten with the old value.  The limit is not changed if
   909  ** the value originally pointed to is negative, and so the current limit 
   910  ** can be queried by passing in a pointer to a negative number.  This
   911  ** file-control is used internally to implement [PRAGMA mmap_size].
   912  **
   913  ** </ul>
   914  */
   915  #define SQLITE_FCNTL_LOCKSTATE               1
   916  #define SQLITE_GET_LOCKPROXYFILE             2
   917  #define SQLITE_SET_LOCKPROXYFILE             3
   918  #define SQLITE_LAST_ERRNO                    4
   919  #define SQLITE_FCNTL_SIZE_HINT               5
   920  #define SQLITE_FCNTL_CHUNK_SIZE              6
   921  #define SQLITE_FCNTL_FILE_POINTER            7
   922  #define SQLITE_FCNTL_SYNC_OMITTED            8
   923  #define SQLITE_FCNTL_WIN32_AV_RETRY          9
   924  #define SQLITE_FCNTL_PERSIST_WAL            10
   925  #define SQLITE_FCNTL_OVERWRITE              11
   926  #define SQLITE_FCNTL_VFSNAME                12
   927  #define SQLITE_FCNTL_POWERSAFE_OVERWRITE    13
   928  #define SQLITE_FCNTL_PRAGMA                 14
   929  #define SQLITE_FCNTL_BUSYHANDLER            15
   930  #define SQLITE_FCNTL_TEMPFILENAME           16
   931  #define SQLITE_FCNTL_MMAP_SIZE              18
   932  
   933  /*
   934  ** CAPI3REF: Mutex Handle
   935  **
   936  ** The mutex module within SQLite defines [sqlite3_mutex] to be an
   937  ** abstract type for a mutex object.  The SQLite core never looks
   938  ** at the internal representation of an [sqlite3_mutex].  It only
   939  ** deals with pointers to the [sqlite3_mutex] object.
   940  **
   941  ** Mutexes are created using [sqlite3_mutex_alloc()].
   942  */
   943  typedef struct sqlite3_mutex sqlite3_mutex;
   944  
   945  /*
   946  ** CAPI3REF: OS Interface Object
   947  **
   948  ** An instance of the sqlite3_vfs object defines the interface between
   949  ** the SQLite core and the underlying operating system.  The "vfs"
   950  ** in the name of the object stands for "virtual file system".  See
   951  ** the [VFS | VFS documentation] for further information.
   952  **
   953  ** The value of the iVersion field is initially 1 but may be larger in
   954  ** future versions of SQLite.  Additional fields may be appended to this
   955  ** object when the iVersion value is increased.  Note that the structure
   956  ** of the sqlite3_vfs object changes in the transaction between
   957  ** SQLite version 3.5.9 and 3.6.0 and yet the iVersion field was not
   958  ** modified.
   959  **
   960  ** The szOsFile field is the size of the subclassed [sqlite3_file]
   961  ** structure used by this VFS.  mxPathname is the maximum length of
   962  ** a pathname in this VFS.
   963  **
   964  ** Registered sqlite3_vfs objects are kept on a linked list formed by
   965  ** the pNext pointer.  The [sqlite3_vfs_register()]
   966  ** and [sqlite3_vfs_unregister()] interfaces manage this list
   967  ** in a thread-safe way.  The [sqlite3_vfs_find()] interface
   968  ** searches the list.  Neither the application code nor the VFS
   969  ** implementation should use the pNext pointer.
   970  **
   971  ** The pNext field is the only field in the sqlite3_vfs
   972  ** structure that SQLite will ever modify.  SQLite will only access
   973  ** or modify this field while holding a particular static mutex.
   974  ** The application should never modify anything within the sqlite3_vfs
   975  ** object once the object has been registered.
   976  **
   977  ** The zName field holds the name of the VFS module.  The name must
   978  ** be unique across all VFS modules.
   979  **
   980  ** [[sqlite3_vfs.xOpen]]
   981  ** ^SQLite guarantees that the zFilename parameter to xOpen
   982  ** is either a NULL pointer or string obtained
   983  ** from xFullPathname() with an optional suffix added.
   984  ** ^If a suffix is added to the zFilename parameter, it will
   985  ** consist of a single "-" character followed by no more than
   986  ** 11 alphanumeric and/or "-" characters.
   987  ** ^SQLite further guarantees that
   988  ** the string will be valid and unchanged until xClose() is
   989  ** called. Because of the previous sentence,
   990  ** the [sqlite3_file] can safely store a pointer to the
   991  ** filename if it needs to remember the filename for some reason.
   992  ** If the zFilename parameter to xOpen is a NULL pointer then xOpen
   993  ** must invent its own temporary name for the file.  ^Whenever the 
   994  ** xFilename parameter is NULL it will also be the case that the
   995  ** flags parameter will include [SQLITE_OPEN_DELETEONCLOSE].
   996  **
   997  ** The flags argument to xOpen() includes all bits set in
   998  ** the flags argument to [sqlite3_open_v2()].  Or if [sqlite3_open()]
   999  ** or [sqlite3_open16()] is used, then flags includes at least
  1000  ** [SQLITE_OPEN_READWRITE] | [SQLITE_OPEN_CREATE]. 
  1001  ** If xOpen() opens a file read-only then it sets *pOutFlags to
  1002  ** include [SQLITE_OPEN_READONLY].  Other bits in *pOutFlags may be set.
  1003  **
  1004  ** ^(SQLite will also add one of the following flags to the xOpen()
  1005  ** call, depending on the object being opened:
  1006  **
  1007  ** <ul>
  1008  ** <li>  [SQLITE_OPEN_MAIN_DB]
  1009  ** <li>  [SQLITE_OPEN_MAIN_JOURNAL]
  1010  ** <li>  [SQLITE_OPEN_TEMP_DB]
  1011  ** <li>  [SQLITE_OPEN_TEMP_JOURNAL]
  1012  ** <li>  [SQLITE_OPEN_TRANSIENT_DB]
  1013  ** <li>  [SQLITE_OPEN_SUBJOURNAL]
  1014  ** <li>  [SQLITE_OPEN_MASTER_JOURNAL]
  1015  ** <li>  [SQLITE_OPEN_WAL]
  1016  ** </ul>)^
  1017  **
  1018  ** The file I/O implementation can use the object type flags to
  1019  ** change the way it deals with files.  For example, an application
  1020  ** that does not care about crash recovery or rollback might make
  1021  ** the open of a journal file a no-op.  Writes to this journal would
  1022  ** also be no-ops, and any attempt to read the journal would return
  1023  ** SQLITE_IOERR.  Or the implementation might recognize that a database
  1024  ** file will be doing page-aligned sector reads and writes in a random
  1025  ** order and set up its I/O subsystem accordingly.
  1026  **
  1027  ** SQLite might also add one of the following flags to the xOpen method:
  1028  **
  1029  ** <ul>
  1030  ** <li> [SQLITE_OPEN_DELETEONCLOSE]
  1031  ** <li> [SQLITE_OPEN_EXCLUSIVE]
  1032  ** </ul>
  1033  **
  1034  ** The [SQLITE_OPEN_DELETEONCLOSE] flag means the file should be
  1035  ** deleted when it is closed.  ^The [SQLITE_OPEN_DELETEONCLOSE]
  1036  ** will be set for TEMP databases and their journals, transient
  1037  ** databases, and subjournals.
  1038  **
  1039  ** ^The [SQLITE_OPEN_EXCLUSIVE] flag is always used in conjunction
  1040  ** with the [SQLITE_OPEN_CREATE] flag, which are both directly
  1041  ** analogous to the O_EXCL and O_CREAT flags of the POSIX open()
  1042  ** API.  The SQLITE_OPEN_EXCLUSIVE flag, when paired with the 
  1043  ** SQLITE_OPEN_CREATE, is used to indicate that file should always
  1044  ** be created, and that it is an error if it already exists.
  1045  ** It is <i>not</i> used to indicate the file should be opened 
  1046  ** for exclusive access.
  1047  **
  1048  ** ^At least szOsFile bytes of memory are allocated by SQLite
  1049  ** to hold the  [sqlite3_file] structure passed as the third
  1050  ** argument to xOpen.  The xOpen method does not have to
  1051  ** allocate the structure; it should just fill it in.  Note that
  1052  ** the xOpen method must set the sqlite3_file.pMethods to either
  1053  ** a valid [sqlite3_io_methods] object or to NULL.  xOpen must do
  1054  ** this even if the open fails.  SQLite expects that the sqlite3_file.pMethods
  1055  ** element will be valid after xOpen returns regardless of the success
  1056  ** or failure of the xOpen call.
  1057  **
  1058  ** [[sqlite3_vfs.xAccess]]
  1059  ** ^The flags argument to xAccess() may be [SQLITE_ACCESS_EXISTS]
  1060  ** to test for the existence of a file, or [SQLITE_ACCESS_READWRITE] to
  1061  ** test whether a file is readable and writable, or [SQLITE_ACCESS_READ]
  1062  ** to test whether a file is at least readable.   The file can be a
  1063  ** directory.
  1064  **
  1065  ** ^SQLite will always allocate at least mxPathname+1 bytes for the
  1066  ** output buffer xFullPathname.  The exact size of the output buffer
  1067  ** is also passed as a parameter to both  methods. If the output buffer
  1068  ** is not large enough, [SQLITE_CANTOPEN] should be returned. Since this is
  1069  ** handled as a fatal error by SQLite, vfs implementations should endeavor
  1070  ** to prevent this by setting mxPathname to a sufficiently large value.
  1071  **
  1072  ** The xRandomness(), xSleep(), xCurrentTime(), and xCurrentTimeInt64()
  1073  ** interfaces are not strictly a part of the filesystem, but they are
  1074  ** included in the VFS structure for completeness.
  1075  ** The xRandomness() function attempts to return nBytes bytes
  1076  ** of good-quality randomness into zOut.  The return value is
  1077  ** the actual number of bytes of randomness obtained.
  1078  ** The xSleep() method causes the calling thread to sleep for at
  1079  ** least the number of microseconds given.  ^The xCurrentTime()
  1080  ** method returns a Julian Day Number for the current date and time as
  1081  ** a floating point value.
  1082  ** ^The xCurrentTimeInt64() method returns, as an integer, the Julian
  1083  ** Day Number multiplied by 86400000 (the number of milliseconds in 
  1084  ** a 24-hour day).  
  1085  ** ^SQLite will use the xCurrentTimeInt64() method to get the current
  1086  ** date and time if that method is available (if iVersion is 2 or 
  1087  ** greater and the function pointer is not NULL) and will fall back
  1088  ** to xCurrentTime() if xCurrentTimeInt64() is unavailable.
  1089  **
  1090  ** ^The xSetSystemCall(), xGetSystemCall(), and xNestSystemCall() interfaces
  1091  ** are not used by the SQLite core.  These optional interfaces are provided
  1092  ** by some VFSes to facilitate testing of the VFS code. By overriding 
  1093  ** system calls with functions under its control, a test program can
  1094  ** simulate faults and error conditions that would otherwise be difficult
  1095  ** or impossible to induce.  The set of system calls that can be overridden
  1096  ** varies from one VFS to another, and from one version of the same VFS to the
  1097  ** next.  Applications that use these interfaces must be prepared for any
  1098  ** or all of these interfaces to be NULL or for their behavior to change
  1099  ** from one release to the next.  Applications must not attempt to access
  1100  ** any of these methods if the iVersion of the VFS is less than 3.
  1101  */
  1102  typedef struct sqlite3_vfs sqlite3_vfs;
  1103  typedef void (*sqlite3_syscall_ptr)(void);
  1104  struct sqlite3_vfs {
  1105    int iVersion;            /* Structure version number (currently 3) */
  1106    int szOsFile;            /* Size of subclassed sqlite3_file */
  1107    int mxPathname;          /* Maximum file pathname length */
  1108    sqlite3_vfs *pNext;      /* Next registered VFS */
  1109    const char *zName;       /* Name of this virtual file system */
  1110    void *pAppData;          /* Pointer to application-specific data */
  1111    int (*xOpen)(sqlite3_vfs*, const char *zName, sqlite3_file*,
  1112                 int flags, int *pOutFlags);
  1113    int (*xDelete)(sqlite3_vfs*, const char *zName, int syncDir);
  1114    int (*xAccess)(sqlite3_vfs*, const char *zName, int flags, int *pResOut);
  1115    int (*xFullPathname)(sqlite3_vfs*, const char *zName, int nOut, char *zOut);
  1116    void *(*xDlOpen)(sqlite3_vfs*, const char *zFilename);
  1117    void (*xDlError)(sqlite3_vfs*, int nByte, char *zErrMsg);
  1118    void (*(*xDlSym)(sqlite3_vfs*,void*, const char *zSymbol))(void);
  1119    void (*xDlClose)(sqlite3_vfs*, void*);
  1120    int (*xRandomness)(sqlite3_vfs*, int nByte, char *zOut);
  1121    int (*xSleep)(sqlite3_vfs*, int microseconds);
  1122    int (*xCurrentTime)(sqlite3_vfs*, double*);
  1123    int (*xGetLastError)(sqlite3_vfs*, int, char *);
  1124    /*
  1125    ** The methods above are in version 1 of the sqlite_vfs object
  1126    ** definition.  Those that follow are added in version 2 or later
  1127    */
  1128    int (*xCurrentTimeInt64)(sqlite3_vfs*, sqlite3_int64*);
  1129    /*
  1130    ** The methods above are in versions 1 and 2 of the sqlite_vfs object.
  1131    ** Those below are for version 3 and greater.
  1132    */
  1133    int (*xSetSystemCall)(sqlite3_vfs*, const char *zName, sqlite3_syscall_ptr);
  1134    sqlite3_syscall_ptr (*xGetSystemCall)(sqlite3_vfs*, const char *zName);
  1135    const char *(*xNextSystemCall)(sqlite3_vfs*, const char *zName);
  1136    /*
  1137    ** The methods above are in versions 1 through 3 of the sqlite_vfs object.
  1138    ** New fields may be appended in figure versions.  The iVersion
  1139    ** value will increment whenever this happens. 
  1140    */
  1141  };
  1142  
  1143  /*
  1144  ** CAPI3REF: Flags for the xAccess VFS method
  1145  **
  1146  ** These integer constants can be used as the third parameter to
  1147  ** the xAccess method of an [sqlite3_vfs] object.  They determine
  1148  ** what kind of permissions the xAccess method is looking for.
  1149  ** With SQLITE_ACCESS_EXISTS, the xAccess method
  1150  ** simply checks whether the file exists.
  1151  ** With SQLITE_ACCESS_READWRITE, the xAccess method
  1152  ** checks whether the named directory is both readable and writable
  1153  ** (in other words, if files can be added, removed, and renamed within
  1154  ** the directory).
  1155  ** The SQLITE_ACCESS_READWRITE constant is currently used only by the
  1156  ** [temp_store_directory pragma], though this could change in a future
  1157  ** release of SQLite.
  1158  ** With SQLITE_ACCESS_READ, the xAccess method
  1159  ** checks whether the file is readable.  The SQLITE_ACCESS_READ constant is
  1160  ** currently unused, though it might be used in a future release of
  1161  ** SQLite.
  1162  */
  1163  #define SQLITE_ACCESS_EXISTS    0
  1164  #define SQLITE_ACCESS_READWRITE 1   /* Used by PRAGMA temp_store_directory */
  1165  #define SQLITE_ACCESS_READ      2   /* Unused */
  1166  
  1167  /*
  1168  ** CAPI3REF: Flags for the xShmLock VFS method
  1169  **
  1170  ** These integer constants define the various locking operations
  1171  ** allowed by the xShmLock method of [sqlite3_io_methods].  The
  1172  ** following are the only legal combinations of flags to the
  1173  ** xShmLock method:
  1174  **
  1175  ** <ul>
  1176  ** <li>  SQLITE_SHM_LOCK | SQLITE_SHM_SHARED
  1177  ** <li>  SQLITE_SHM_LOCK | SQLITE_SHM_EXCLUSIVE
  1178  ** <li>  SQLITE_SHM_UNLOCK | SQLITE_SHM_SHARED
  1179  ** <li>  SQLITE_SHM_UNLOCK | SQLITE_SHM_EXCLUSIVE
  1180  ** </ul>
  1181  **
  1182  ** When unlocking, the same SHARED or EXCLUSIVE flag must be supplied as
  1183  ** was given no the corresponding lock.  
  1184  **
  1185  ** The xShmLock method can transition between unlocked and SHARED or
  1186  ** between unlocked and EXCLUSIVE.  It cannot transition between SHARED
  1187  ** and EXCLUSIVE.
  1188  */
  1189  #define SQLITE_SHM_UNLOCK       1
  1190  #define SQLITE_SHM_LOCK         2
  1191  #define SQLITE_SHM_SHARED       4
  1192  #define SQLITE_SHM_EXCLUSIVE    8
  1193  
  1194  /*
  1195  ** CAPI3REF: Maximum xShmLock index
  1196  **
  1197  ** The xShmLock method on [sqlite3_io_methods] may use values
  1198  ** between 0 and this upper bound as its "offset" argument.
  1199  ** The SQLite core will never attempt to acquire or release a
  1200  ** lock outside of this range
  1201  */
  1202  #define SQLITE_SHM_NLOCK        8
  1203  
  1204  
  1205  /*
  1206  ** CAPI3REF: Initialize The SQLite Library
  1207  **
  1208  ** ^The sqlite3_initialize() routine initializes the
  1209  ** SQLite library.  ^The sqlite3_shutdown() routine
  1210  ** deallocates any resources that were allocated by sqlite3_initialize().
  1211  ** These routines are designed to aid in process initialization and
  1212  ** shutdown on embedded systems.  Workstation applications using
  1213  ** SQLite normally do not need to invoke either of these routines.
  1214  **
  1215  ** A call to sqlite3_initialize() is an "effective" call if it is
  1216  ** the first time sqlite3_initialize() is invoked during the lifetime of
  1217  ** the process, or if it is the first time sqlite3_initialize() is invoked
  1218  ** following a call to sqlite3_shutdown().  ^(Only an effective call
  1219  ** of sqlite3_initialize() does any initialization.  All other calls
  1220  ** are harmless no-ops.)^
  1221  **
  1222  ** A call to sqlite3_shutdown() is an "effective" call if it is the first
  1223  ** call to sqlite3_shutdown() since the last sqlite3_initialize().  ^(Only
  1224  ** an effective call to sqlite3_shutdown() does any deinitialization.
  1225  ** All other valid calls to sqlite3_shutdown() are harmless no-ops.)^
  1226  **
  1227  ** The sqlite3_initialize() interface is threadsafe, but sqlite3_shutdown()
  1228  ** is not.  The sqlite3_shutdown() interface must only be called from a
  1229  ** single thread.  All open [database connections] must be closed and all
  1230  ** other SQLite resources must be deallocated prior to invoking
  1231  ** sqlite3_shutdown().
  1232  **
  1233  ** Among other things, ^sqlite3_initialize() will invoke
  1234  ** sqlite3_os_init().  Similarly, ^sqlite3_shutdown()
  1235  ** will invoke sqlite3_os_end().
  1236  **
  1237  ** ^The sqlite3_initialize() routine returns [SQLITE_OK] on success.
  1238  ** ^If for some reason, sqlite3_initialize() is unable to initialize
  1239  ** the library (perhaps it is unable to allocate a needed resource such
  1240  ** as a mutex) it returns an [error code] other than [SQLITE_OK].
  1241  **
  1242  ** ^The sqlite3_initialize() routine is called internally by many other
  1243  ** SQLite interfaces so that an application usually does not need to
  1244  ** invoke sqlite3_initialize() directly.  For example, [sqlite3_open()]
  1245  ** calls sqlite3_initialize() so the SQLite library will be automatically
  1246  ** initialized when [sqlite3_open()] is called if it has not be initialized
  1247  ** already.  ^However, if SQLite is compiled with the [SQLITE_OMIT_AUTOINIT]
  1248  ** compile-time option, then the automatic calls to sqlite3_initialize()
  1249  ** are omitted and the application must call sqlite3_initialize() directly
  1250  ** prior to using any other SQLite interface.  For maximum portability,
  1251  ** it is recommended that applications always invoke sqlite3_initialize()
  1252  ** directly prior to using any other SQLite interface.  Future releases
  1253  ** of SQLite may require this.  In other words, the behavior exhibited
  1254  ** when SQLite is compiled with [SQLITE_OMIT_AUTOINIT] might become the
  1255  ** default behavior in some future release of SQLite.
  1256  **
  1257  ** The sqlite3_os_init() routine does operating-system specific
  1258  ** initialization of the SQLite library.  The sqlite3_os_end()
  1259  ** routine undoes the effect of sqlite3_os_init().  Typical tasks
  1260  ** performed by these routines include allocation or deallocation
  1261  ** of static resources, initialization of global variables,
  1262  ** setting up a default [sqlite3_vfs] module, or setting up
  1263  ** a default configuration using [sqlite3_config()].
  1264  **
  1265  ** The application should never invoke either sqlite3_os_init()
  1266  ** or sqlite3_os_end() directly.  The application should only invoke
  1267  ** sqlite3_initialize() and sqlite3_shutdown().  The sqlite3_os_init()
  1268  ** interface is called automatically by sqlite3_initialize() and
  1269  ** sqlite3_os_end() is called by sqlite3_shutdown().  Appropriate
  1270  ** implementations for sqlite3_os_init() and sqlite3_os_end()
  1271  ** are built into SQLite when it is compiled for Unix, Windows, or OS/2.
  1272  ** When [custom builds | built for other platforms]
  1273  ** (using the [SQLITE_OS_OTHER=1] compile-time
  1274  ** option) the application must supply a suitable implementation for
  1275  ** sqlite3_os_init() and sqlite3_os_end().  An application-supplied
  1276  ** implementation of sqlite3_os_init() or sqlite3_os_end()
  1277  ** must return [SQLITE_OK] on success and some other [error code] upon
  1278  ** failure.
  1279  */
  1280  SQLITE_API int sqlite3_initialize(void);
  1281  SQLITE_API int sqlite3_shutdown(void);
  1282  SQLITE_API int sqlite3_os_init(void);
  1283  SQLITE_API int sqlite3_os_end(void);
  1284  
  1285  /*
  1286  ** CAPI3REF: Configuring The SQLite Library
  1287  **
  1288  ** The sqlite3_config() interface is used to make global configuration
  1289  ** changes to SQLite in order to tune SQLite to the specific needs of
  1290  ** the application.  The default configuration is recommended for most
  1291  ** applications and so this routine is usually not necessary.  It is
  1292  ** provided to support rare applications with unusual needs.
  1293  **
  1294  ** The sqlite3_config() interface is not threadsafe.  The application
  1295  ** must insure that no other SQLite interfaces are invoked by other
  1296  ** threads while sqlite3_config() is running.  Furthermore, sqlite3_config()
  1297  ** may only be invoked prior to library initialization using
  1298  ** [sqlite3_initialize()] or after shutdown by [sqlite3_shutdown()].
  1299  ** ^If sqlite3_config() is called after [sqlite3_initialize()] and before
  1300  ** [sqlite3_shutdown()] then it will return SQLITE_MISUSE.
  1301  ** Note, however, that ^sqlite3_config() can be called as part of the
  1302  ** implementation of an application-defined [sqlite3_os_init()].
  1303  **
  1304  ** The first argument to sqlite3_config() is an integer
  1305  ** [configuration option] that determines
  1306  ** what property of SQLite is to be configured.  Subsequent arguments
  1307  ** vary depending on the [configuration option]
  1308  ** in the first argument.
  1309  **
  1310  ** ^When a configuration option is set, sqlite3_config() returns [SQLITE_OK].
  1311  ** ^If the option is unknown or SQLite is unable to set the option
  1312  ** then this routine returns a non-zero [error code].
  1313  */
  1314  SQLITE_API int sqlite3_config(int, ...);
  1315  
  1316  /*
  1317  ** CAPI3REF: Configure database connections
  1318  **
  1319  ** The sqlite3_db_config() interface is used to make configuration
  1320  ** changes to a [database connection].  The interface is similar to
  1321  ** [sqlite3_config()] except that the changes apply to a single
  1322  ** [database connection] (specified in the first argument).
  1323  **
  1324  ** The second argument to sqlite3_db_config(D,V,...)  is the
  1325  ** [SQLITE_DBCONFIG_LOOKASIDE | configuration verb] - an integer code 
  1326  ** that indicates what aspect of the [database connection] is being configured.
  1327  ** Subsequent arguments vary depending on the configuration verb.
  1328  **
  1329  ** ^Calls to sqlite3_db_config() return SQLITE_OK if and only if
  1330  ** the call is considered successful.
  1331  */
  1332  SQLITE_API int sqlite3_db_config(sqlite3*, int op, ...);
  1333  
  1334  /*
  1335  ** CAPI3REF: Memory Allocation Routines
  1336  **
  1337  ** An instance of this object defines the interface between SQLite
  1338  ** and low-level memory allocation routines.
  1339  **
  1340  ** This object is used in only one place in the SQLite interface.
  1341  ** A pointer to an instance of this object is the argument to
  1342  ** [sqlite3_config()] when the configuration option is
  1343  ** [SQLITE_CONFIG_MALLOC] or [SQLITE_CONFIG_GETMALLOC].  
  1344  ** By creating an instance of this object
  1345  ** and passing it to [sqlite3_config]([SQLITE_CONFIG_MALLOC])
  1346  ** during configuration, an application can specify an alternative
  1347  ** memory allocation subsystem for SQLite to use for all of its
  1348  ** dynamic memory needs.
  1349  **
  1350  ** Note that SQLite comes with several [built-in memory allocators]
  1351  ** that are perfectly adequate for the overwhelming majority of applications
  1352  ** and that this object is only useful to a tiny minority of applications
  1353  ** with specialized memory allocation requirements.  This object is
  1354  ** also used during testing of SQLite in order to specify an alternative
  1355  ** memory allocator that simulates memory out-of-memory conditions in
  1356  ** order to verify that SQLite recovers gracefully from such
  1357  ** conditions.
  1358  **
  1359  ** The xMalloc, xRealloc, and xFree methods must work like the
  1360  ** malloc(), realloc() and free() functions from the standard C library.
  1361  ** ^SQLite guarantees that the second argument to
  1362  ** xRealloc is always a value returned by a prior call to xRoundup.
  1363  **
  1364  ** xSize should return the allocated size of a memory allocation
  1365  ** previously obtained from xMalloc or xRealloc.  The allocated size
  1366  ** is always at least as big as the requested size but may be larger.
  1367  **
  1368  ** The xRoundup method returns what would be the allocated size of
  1369  ** a memory allocation given a particular requested size.  Most memory
  1370  ** allocators round up memory allocations at least to the next multiple
  1371  ** of 8.  Some allocators round up to a larger multiple or to a power of 2.
  1372  ** Every memory allocation request coming in through [sqlite3_malloc()]
  1373  ** or [sqlite3_realloc()] first calls xRoundup.  If xRoundup returns 0, 
  1374  ** that causes the corresponding memory allocation to fail.
  1375  **
  1376  ** The xInit method initializes the memory allocator.  (For example,
  1377  ** it might allocate any require mutexes or initialize internal data
  1378  ** structures.  The xShutdown method is invoked (indirectly) by
  1379  ** [sqlite3_shutdown()] and should deallocate any resources acquired
  1380  ** by xInit.  The pAppData pointer is used as the only parameter to
  1381  ** xInit and xShutdown.
  1382  **
  1383  ** SQLite holds the [SQLITE_MUTEX_STATIC_MASTER] mutex when it invokes
  1384  ** the xInit method, so the xInit method need not be threadsafe.  The
  1385  ** xShutdown method is only called from [sqlite3_shutdown()] so it does
  1386  ** not need to be threadsafe either.  For all other methods, SQLite
  1387  ** holds the [SQLITE_MUTEX_STATIC_MEM] mutex as long as the
  1388  ** [SQLITE_CONFIG_MEMSTATUS] configuration option is turned on (which
  1389  ** it is by default) and so the methods are automatically serialized.
  1390  ** However, if [SQLITE_CONFIG_MEMSTATUS] is disabled, then the other
  1391  ** methods must be threadsafe or else make their own arrangements for
  1392  ** serialization.
  1393  **
  1394  ** SQLite will never invoke xInit() more than once without an intervening
  1395  ** call to xShutdown().
  1396  */
  1397  typedef struct sqlite3_mem_methods sqlite3_mem_methods;
  1398  struct sqlite3_mem_methods {
  1399    void *(*xMalloc)(int);         /* Memory allocation function */
  1400    void (*xFree)(void*);          /* Free a prior allocation */
  1401    void *(*xRealloc)(void*,int);  /* Resize an allocation */
  1402    int (*xSize)(void*);           /* Return the size of an allocation */
  1403    int (*xRoundup)(int);          /* Round up request size to allocation size */
  1404    int (*xInit)(void*);           /* Initialize the memory allocator */
  1405    void (*xShutdown)(void*);      /* Deinitialize the memory allocator */
  1406    void *pAppData;                /* Argument to xInit() and xShutdown() */
  1407  };
  1408  
  1409  /*
  1410  ** CAPI3REF: Configuration Options
  1411  ** KEYWORDS: {configuration option}
  1412  **
  1413  ** These constants are the available integer configuration options that
  1414  ** can be passed as the first argument to the [sqlite3_config()] interface.
  1415  **
  1416  ** New configuration options may be added in future releases of SQLite.
  1417  ** Existing configuration options might be discontinued.  Applications
  1418  ** should check the return code from [sqlite3_config()] to make sure that
  1419  ** the call worked.  The [sqlite3_config()] interface will return a
  1420  ** non-zero [error code] if a discontinued or unsupported configuration option
  1421  ** is invoked.
  1422  **
  1423  ** <dl>
  1424  ** [[SQLITE_CONFIG_SINGLETHREAD]] <dt>SQLITE_CONFIG_SINGLETHREAD</dt>
  1425  ** <dd>There are no arguments to this option.  ^This option sets the
  1426  ** [threading mode] to Single-thread.  In other words, it disables
  1427  ** all mutexing and puts SQLite into a mode where it can only be used
  1428  ** by a single thread.   ^If SQLite is compiled with
  1429  ** the [SQLITE_THREADSAFE | SQLITE_THREADSAFE=0] compile-time option then
  1430  ** it is not possible to change the [threading mode] from its default
  1431  ** value of Single-thread and so [sqlite3_config()] will return 
  1432  ** [SQLITE_ERROR] if called with the SQLITE_CONFIG_SINGLETHREAD
  1433  ** configuration option.</dd>
  1434  **
  1435  ** [[SQLITE_CONFIG_MULTITHREAD]] <dt>SQLITE_CONFIG_MULTITHREAD</dt>
  1436  ** <dd>There are no arguments to this option.  ^This option sets the
  1437  ** [threading mode] to Multi-thread.  In other words, it disables
  1438  ** mutexing on [database connection] and [prepared statement] objects.
  1439  ** The application is responsible for serializing access to
  1440  ** [database connections] and [prepared statements].  But other mutexes
  1441  ** are enabled so that SQLite will be safe to use in a multi-threaded
  1442  ** environment as long as no two threads attempt to use the same
  1443  ** [database connection] at the same time.  ^If SQLite is compiled with
  1444  ** the [SQLITE_THREADSAFE | SQLITE_THREADSAFE=0] compile-time option then
  1445  ** it is not possible to set the Multi-thread [threading mode] and
  1446  ** [sqlite3_config()] will return [SQLITE_ERROR] if called with the
  1447  ** SQLITE_CONFIG_MULTITHREAD configuration option.</dd>
  1448  **
  1449  ** [[SQLITE_CONFIG_SERIALIZED]] <dt>SQLITE_CONFIG_SERIALIZED</dt>
  1450  ** <dd>There are no arguments to this option.  ^This option sets the
  1451  ** [threading mode] to Serialized. In other words, this option enables
  1452  ** all mutexes including the recursive
  1453  ** mutexes on [database connection] and [prepared statement] objects.
  1454  ** In this mode (which is the default when SQLite is compiled with
  1455  ** [SQLITE_THREADSAFE=1]) the SQLite library will itself serialize access
  1456  ** to [database connections] and [prepared statements] so that the
  1457  ** application is free to use the same [database connection] or the
  1458  ** same [prepared statement] in different threads at the same time.
  1459  ** ^If SQLite is compiled with
  1460  ** the [SQLITE_THREADSAFE | SQLITE_THREADSAFE=0] compile-time option then
  1461  ** it is not possible to set the Serialized [threading mode] and
  1462  ** [sqlite3_config()] will return [SQLITE_ERROR] if called with the
  1463  ** SQLITE_CONFIG_SERIALIZED configuration option.</dd>
  1464  **
  1465  ** [[SQLITE_CONFIG_MALLOC]] <dt>SQLITE_CONFIG_MALLOC</dt>
  1466  ** <dd> ^(This option takes a single argument which is a pointer to an
  1467  ** instance of the [sqlite3_mem_methods] structure.  The argument specifies
  1468  ** alternative low-level memory allocation routines to be used in place of
  1469  ** the memory allocation routines built into SQLite.)^ ^SQLite makes
  1470  ** its own private copy of the content of the [sqlite3_mem_methods] structure
  1471  ** before the [sqlite3_config()] call returns.</dd>
  1472  **
  1473  ** [[SQLITE_CONFIG_GETMALLOC]] <dt>SQLITE_CONFIG_GETMALLOC</dt>
  1474  ** <dd> ^(This option takes a single argument which is a pointer to an
  1475  ** instance of the [sqlite3_mem_methods] structure.  The [sqlite3_mem_methods]
  1476  ** structure is filled with the currently defined memory allocation routines.)^
  1477  ** This option can be used to overload the default memory allocation
  1478  ** routines with a wrapper that simulations memory allocation failure or
  1479  ** tracks memory usage, for example. </dd>
  1480  **
  1481  ** [[SQLITE_CONFIG_MEMSTATUS]] <dt>SQLITE_CONFIG_MEMSTATUS</dt>
  1482  ** <dd> ^This option takes single argument of type int, interpreted as a 
  1483  ** boolean, which enables or disables the collection of memory allocation 
  1484  ** statistics. ^(When memory allocation statistics are disabled, the 
  1485  ** following SQLite interfaces become non-operational:
  1486  **   <ul>
  1487  **   <li> [sqlite3_memory_used()]
  1488  **   <li> [sqlite3_memory_highwater()]
  1489  **   <li> [sqlite3_soft_heap_limit64()]
  1490  **   <li> [sqlite3_status()]
  1491  **   </ul>)^
  1492  ** ^Memory allocation statistics are enabled by default unless SQLite is
  1493  ** compiled with [SQLITE_DEFAULT_MEMSTATUS]=0 in which case memory
  1494  ** allocation statistics are disabled by default.
  1495  ** </dd>
  1496  **
  1497  ** [[SQLITE_CONFIG_SCRATCH]] <dt>SQLITE_CONFIG_SCRATCH</dt>
  1498  ** <dd> ^This option specifies a static memory buffer that SQLite can use for
  1499  ** scratch memory.  There are three arguments:  A pointer an 8-byte
  1500  ** aligned memory buffer from which the scratch allocations will be
  1501  ** drawn, the size of each scratch allocation (sz),
  1502  ** and the maximum number of scratch allocations (N).  The sz
  1503  ** argument must be a multiple of 16.
  1504  ** The first argument must be a pointer to an 8-byte aligned buffer
  1505  ** of at least sz*N bytes of memory.
  1506  ** ^SQLite will use no more than two scratch buffers per thread.  So
  1507  ** N should be set to twice the expected maximum number of threads.
  1508  ** ^SQLite will never require a scratch buffer that is more than 6
  1509  ** times the database page size. ^If SQLite needs needs additional
  1510  ** scratch memory beyond what is provided by this configuration option, then 
  1511  ** [sqlite3_malloc()] will be used to obtain the memory needed.</dd>
  1512  **
  1513  ** [[SQLITE_CONFIG_PAGECACHE]] <dt>SQLITE_CONFIG_PAGECACHE</dt>
  1514  ** <dd> ^This option specifies a static memory buffer that SQLite can use for
  1515  ** the database page cache with the default page cache implementation.  
  1516  ** This configuration should not be used if an application-define page
  1517  ** cache implementation is loaded using the SQLITE_CONFIG_PCACHE2 option.
  1518  ** There are three arguments to this option: A pointer to 8-byte aligned
  1519  ** memory, the size of each page buffer (sz), and the number of pages (N).
  1520  ** The sz argument should be the size of the largest database page
  1521  ** (a power of two between 512 and 32768) plus a little extra for each
  1522  ** page header.  ^The page header size is 20 to 40 bytes depending on
  1523  ** the host architecture.  ^It is harmless, apart from the wasted memory,
  1524  ** to make sz a little too large.  The first
  1525  ** argument should point to an allocation of at least sz*N bytes of memory.
  1526  ** ^SQLite will use the memory provided by the first argument to satisfy its
  1527  ** memory needs for the first N pages that it adds to cache.  ^If additional
  1528  ** page cache memory is needed beyond what is provided by this option, then
  1529  ** SQLite goes to [sqlite3_malloc()] for the additional storage space.
  1530  ** The pointer in the first argument must
  1531  ** be aligned to an 8-byte boundary or subsequent behavior of SQLite
  1532  ** will be undefined.</dd>
  1533  **
  1534  ** [[SQLITE_CONFIG_HEAP]] <dt>SQLITE_CONFIG_HEAP</dt>
  1535  ** <dd> ^This option specifies a static memory buffer that SQLite will use
  1536  ** for all of its dynamic memory allocation needs beyond those provided
  1537  ** for by [SQLITE_CONFIG_SCRATCH] and [SQLITE_CONFIG_PAGECACHE].
  1538  ** There are three arguments: An 8-byte aligned pointer to the memory,
  1539  ** the number of bytes in the memory buffer, and the minimum allocation size.
  1540  ** ^If the first pointer (the memory pointer) is NULL, then SQLite reverts
  1541  ** to using its default memory allocator (the system malloc() implementation),
  1542  ** undoing any prior invocation of [SQLITE_CONFIG_MALLOC].  ^If the
  1543  ** memory pointer is not NULL and either [SQLITE_ENABLE_MEMSYS3] or
  1544  ** [SQLITE_ENABLE_MEMSYS5] are defined, then the alternative memory
  1545  ** allocator is engaged to handle all of SQLites memory allocation needs.
  1546  ** The first pointer (the memory pointer) must be aligned to an 8-byte
  1547  ** boundary or subsequent behavior of SQLite will be undefined.
  1548  ** The minimum allocation size is capped at 2**12. Reasonable values
  1549  ** for the minimum allocation size are 2**5 through 2**8.</dd>
  1550  **
  1551  ** [[SQLITE_CONFIG_MUTEX]] <dt>SQLITE_CONFIG_MUTEX</dt>
  1552  ** <dd> ^(This option takes a single argument which is a pointer to an
  1553  ** instance of the [sqlite3_mutex_methods] structure.  The argument specifies
  1554  ** alternative low-level mutex routines to be used in place
  1555  ** the mutex routines built into SQLite.)^  ^SQLite makes a copy of the
  1556  ** content of the [sqlite3_mutex_methods] structure before the call to
  1557  ** [sqlite3_config()] returns. ^If SQLite is compiled with
  1558  ** the [SQLITE_THREADSAFE | SQLITE_THREADSAFE=0] compile-time option then
  1559  ** the entire mutexing subsystem is omitted from the build and hence calls to
  1560  ** [sqlite3_config()] with the SQLITE_CONFIG_MUTEX configuration option will
  1561  ** return [SQLITE_ERROR].</dd>
  1562  **
  1563  ** [[SQLITE_CONFIG_GETMUTEX]] <dt>SQLITE_CONFIG_GETMUTEX</dt>
  1564  ** <dd> ^(This option takes a single argument which is a pointer to an
  1565  ** instance of the [sqlite3_mutex_methods] structure.  The
  1566  ** [sqlite3_mutex_methods]
  1567  ** structure is filled with the currently defined mutex routines.)^
  1568  ** This option can be used to overload the default mutex allocation
  1569  ** routines with a wrapper used to track mutex usage for performance
  1570  ** profiling or testing, for example.   ^If SQLite is compiled with
  1571  ** the [SQLITE_THREADSAFE | SQLITE_THREADSAFE=0] compile-time option then
  1572  ** the entire mutexing subsystem is omitted from the build and hence calls to
  1573  ** [sqlite3_config()] with the SQLITE_CONFIG_GETMUTEX configuration option will
  1574  ** return [SQLITE_ERROR].</dd>
  1575  **
  1576  ** [[SQLITE_CONFIG_LOOKASIDE]] <dt>SQLITE_CONFIG_LOOKASIDE</dt>
  1577  ** <dd> ^(This option takes two arguments that determine the default
  1578  ** memory allocation for the lookaside memory allocator on each
  1579  ** [database connection].  The first argument is the
  1580  ** size of each lookaside buffer slot and the second is the number of
  1581  ** slots allocated to each database connection.)^  ^(This option sets the
  1582  ** <i>default</i> lookaside size. The [SQLITE_DBCONFIG_LOOKASIDE]
  1583  ** verb to [sqlite3_db_config()] can be used to change the lookaside
  1584  ** configuration on individual connections.)^ </dd>
  1585  **
  1586  ** [[SQLITE_CONFIG_PCACHE2]] <dt>SQLITE_CONFIG_PCACHE2</dt>
  1587  ** <dd> ^(This option takes a single argument which is a pointer to
  1588  ** an [sqlite3_pcache_methods2] object.  This object specifies the interface
  1589  ** to a custom page cache implementation.)^  ^SQLite makes a copy of the
  1590  ** object and uses it for page cache memory allocations.</dd>
  1591  **
  1592  ** [[SQLITE_CONFIG_GETPCACHE2]] <dt>SQLITE_CONFIG_GETPCACHE2</dt>
  1593  ** <dd> ^(This option takes a single argument which is a pointer to an
  1594  ** [sqlite3_pcache_methods2] object.  SQLite copies of the current
  1595  ** page cache implementation into that object.)^ </dd>
  1596  **
  1597  ** [[SQLITE_CONFIG_LOG]] <dt>SQLITE_CONFIG_LOG</dt>
  1598  ** <dd> The SQLITE_CONFIG_LOG option is used to configure the SQLite
  1599  ** global [error log].
  1600  ** (^The SQLITE_CONFIG_LOG option takes two arguments: a pointer to a
  1601  ** function with a call signature of void(*)(void*,int,const char*), 
  1602  ** and a pointer to void. ^If the function pointer is not NULL, it is
  1603  ** invoked by [sqlite3_log()] to process each logging event.  ^If the
  1604  ** function pointer is NULL, the [sqlite3_log()] interface becomes a no-op.
  1605  ** ^The void pointer that is the second argument to SQLITE_CONFIG_LOG is
  1606  ** passed through as the first parameter to the application-defined logger
  1607  ** function whenever that function is invoked.  ^The second parameter to
  1608  ** the logger function is a copy of the first parameter to the corresponding
  1609  ** [sqlite3_log()] call and is intended to be a [result code] or an
  1610  ** [extended result code].  ^The third parameter passed to the logger is
  1611  ** log message after formatting via [sqlite3_snprintf()].
  1612  ** The SQLite logging interface is not reentrant; the logger function
  1613  ** supplied by the application must not invoke any SQLite interface.
  1614  ** In a multi-threaded application, the application-defined logger
  1615  ** function must be threadsafe. </dd>
  1616  **
  1617  ** [[SQLITE_CONFIG_URI]] <dt>SQLITE_CONFIG_URI
  1618  ** <dd> This option takes a single argument of type int. If non-zero, then
  1619  ** URI handling is globally enabled. If the parameter is zero, then URI handling
  1620  ** is globally disabled. If URI handling is globally enabled, all filenames
  1621  ** passed to [sqlite3_open()], [sqlite3_open_v2()], [sqlite3_open16()] or
  1622  ** specified as part of [ATTACH] commands are interpreted as URIs, regardless
  1623  ** of whether or not the [SQLITE_OPEN_URI] flag is set when the database
  1624  ** connection is opened. If it is globally disabled, filenames are
  1625  ** only interpreted as URIs if the SQLITE_OPEN_URI flag is set when the
  1626  ** database connection is opened. By default, URI handling is globally
  1627  ** disabled. The default value may be changed by compiling with the
  1628  ** [SQLITE_USE_URI] symbol defined.
  1629  **
  1630  ** [[SQLITE_CONFIG_COVERING_INDEX_SCAN]] <dt>SQLITE_CONFIG_COVERING_INDEX_SCAN
  1631  ** <dd> This option takes a single integer argument which is interpreted as
  1632  ** a boolean in order to enable or disable the use of covering indices for
  1633  ** full table scans in the query optimizer.  The default setting is determined
  1634  ** by the [SQLITE_ALLOW_COVERING_INDEX_SCAN] compile-time option, or is "on"
  1635  ** if that compile-time option is omitted.
  1636  ** The ability to disable the use of covering indices for full table scans
  1637  ** is because some incorrectly coded legacy applications might malfunction
  1638  ** malfunction when the optimization is enabled.  Providing the ability to
  1639  ** disable the optimization allows the older, buggy application code to work
  1640  ** without change even with newer versions of SQLite.
  1641  **
  1642  ** [[SQLITE_CONFIG_PCACHE]] [[SQLITE_CONFIG_GETPCACHE]]
  1643  ** <dt>SQLITE_CONFIG_PCACHE and SQLITE_CONFIG_GETPCACHE
  1644  ** <dd> These options are obsolete and should not be used by new code.
  1645  ** They are retained for backwards compatibility but are now no-ops.
  1646  ** </dd>
  1647  **
  1648  ** [[SQLITE_CONFIG_SQLLOG]]
  1649  ** <dt>SQLITE_CONFIG_SQLLOG
  1650  ** <dd>This option is only available if sqlite is compiled with the
  1651  ** [SQLITE_ENABLE_SQLLOG] pre-processor macro defined. The first argument should
  1652  ** be a pointer to a function of type void(*)(void*,sqlite3*,const char*, int).
  1653  ** The second should be of type (void*). The callback is invoked by the library
  1654  ** in three separate circumstances, identified by the value passed as the
  1655  ** fourth parameter. If the fourth parameter is 0, then the database connection
  1656  ** passed as the second argument has just been opened. The third argument
  1657  ** points to a buffer containing the name of the main database file. If the
  1658  ** fourth parameter is 1, then the SQL statement that the third parameter
  1659  ** points to has just been executed. Or, if the fourth parameter is 2, then
  1660  ** the connection being passed as the second parameter is being closed. The
  1661  ** third parameter is passed NULL In this case.  An example of using this
  1662  ** configuration option can be seen in the "test_sqllog.c" source file in
  1663  ** the canonical SQLite source tree.</dd>
  1664  **
  1665  ** [[SQLITE_CONFIG_MMAP_SIZE]]
  1666  ** <dt>SQLITE_CONFIG_MMAP_SIZE
  1667  ** <dd>SQLITE_CONFIG_MMAP_SIZE takes two 64-bit integer (sqlite3_int64) values
  1668  ** that are the default mmap size limit (the default setting for
  1669  ** [PRAGMA mmap_size]) and the maximum allowed mmap size limit.
  1670  ** The default setting can be overridden by each database connection using
  1671  ** either the [PRAGMA mmap_size] command, or by using the
  1672  ** [SQLITE_FCNTL_MMAP_SIZE] file control.  The maximum allowed mmap size
  1673  ** cannot be changed at run-time.  Nor may the maximum allowed mmap size
  1674  ** exceed the compile-time maximum mmap size set by the
  1675  ** [SQLITE_MAX_MMAP_SIZE] compile-time option.  
  1676  ** If either argument to this option is negative, then that argument is
  1677  ** changed to its compile-time default.
  1678  ** </dl>
  1679  */
  1680  #define SQLITE_CONFIG_SINGLETHREAD  1  /* nil */
  1681  #define SQLITE_CONFIG_MULTITHREAD   2  /* nil */
  1682  #define SQLITE_CONFIG_SERIALIZED    3  /* nil */
  1683  #define SQLITE_CONFIG_MALLOC        4  /* sqlite3_mem_methods* */
  1684  #define SQLITE_CONFIG_GETMALLOC     5  /* sqlite3_mem_methods* */
  1685  #define SQLITE_CONFIG_SCRATCH       6  /* void*, int sz, int N */
  1686  #define SQLITE_CONFIG_PAGECACHE     7  /* void*, int sz, int N */
  1687  #define SQLITE_CONFIG_HEAP          8  /* void*, int nByte, int min */
  1688  #define SQLITE_CONFIG_MEMSTATUS     9  /* boolean */
  1689  #define SQLITE_CONFIG_MUTEX        10  /* sqlite3_mutex_methods* */
  1690  #define SQLITE_CONFIG_GETMUTEX     11  /* sqlite3_mutex_methods* */
  1691  /* previously SQLITE_CONFIG_CHUNKALLOC 12 which is now unused. */ 
  1692  #define SQLITE_CONFIG_LOOKASIDE    13  /* int int */
  1693  #define SQLITE_CONFIG_PCACHE       14  /* no-op */
  1694  #define SQLITE_CONFIG_GETPCACHE    15  /* no-op */
  1695  #define SQLITE_CONFIG_LOG          16  /* xFunc, void* */
  1696  #define SQLITE_CONFIG_URI          17  /* int */
  1697  #define SQLITE_CONFIG_PCACHE2      18  /* sqlite3_pcache_methods2* */
  1698  #define SQLITE_CONFIG_GETPCACHE2   19  /* sqlite3_pcache_methods2* */
  1699  #define SQLITE_CONFIG_COVERING_INDEX_SCAN 20  /* int */
  1700  #define SQLITE_CONFIG_SQLLOG       21  /* xSqllog, void* */
  1701  #define SQLITE_CONFIG_MMAP_SIZE    22  /* sqlite3_int64, sqlite3_int64 */
  1702  
  1703  /*
  1704  ** CAPI3REF: Database Connection Configuration Options
  1705  **
  1706  ** These constants are the available integer configuration options that
  1707  ** can be passed as the second argument to the [sqlite3_db_config()] interface.
  1708  **
  1709  ** New configuration options may be added in future releases of SQLite.
  1710  ** Existing configuration options might be discontinued.  Applications
  1711  ** should check the return code from [sqlite3_db_config()] to make sure that
  1712  ** the call worked.  ^The [sqlite3_db_config()] interface will return a
  1713  ** non-zero [error code] if a discontinued or unsupported configuration option
  1714  ** is invoked.
  1715  **
  1716  ** <dl>
  1717  ** <dt>SQLITE_DBCONFIG_LOOKASIDE</dt>
  1718  ** <dd> ^This option takes three additional arguments that determine the 
  1719  ** [lookaside memory allocator] configuration for the [database connection].
  1720  ** ^The first argument (the third parameter to [sqlite3_db_config()] is a
  1721  ** pointer to a memory buffer to use for lookaside memory.
  1722  ** ^The first argument after the SQLITE_DBCONFIG_LOOKASIDE verb
  1723  ** may be NULL in which case SQLite will allocate the
  1724  ** lookaside buffer itself using [sqlite3_malloc()]. ^The second argument is the
  1725  ** size of each lookaside buffer slot.  ^The third argument is the number of
  1726  ** slots.  The size of the buffer in the first argument must be greater than
  1727  ** or equal to the product of the second and third arguments.  The buffer
  1728  ** must be aligned to an 8-byte boundary.  ^If the second argument to
  1729  ** SQLITE_DBCONFIG_LOOKASIDE is not a multiple of 8, it is internally
  1730  ** rounded down to the next smaller multiple of 8.  ^(The lookaside memory
  1731  ** configuration for a database connection can only be changed when that
  1732  ** connection is not currently using lookaside memory, or in other words
  1733  ** when the "current value" returned by
  1734  ** [sqlite3_db_status](D,[SQLITE_CONFIG_LOOKASIDE],...) is zero.
  1735  ** Any attempt to change the lookaside memory configuration when lookaside
  1736  ** memory is in use leaves the configuration unchanged and returns 
  1737  ** [SQLITE_BUSY].)^</dd>
  1738  **
  1739  ** <dt>SQLITE_DBCONFIG_ENABLE_FKEY</dt>
  1740  ** <dd> ^This option is used to enable or disable the enforcement of
  1741  ** [foreign key constraints].  There should be two additional arguments.
  1742  ** The first argument is an integer which is 0 to disable FK enforcement,
  1743  ** positive to enable FK enforcement or negative to leave FK enforcement
  1744  ** unchanged.  The second parameter is a pointer to an integer into which
  1745  ** is written 0 or 1 to indicate whether FK enforcement is off or on
  1746  ** following this call.  The second parameter may be a NULL pointer, in
  1747  ** which case the FK enforcement setting is not reported back. </dd>
  1748  **
  1749  ** <dt>SQLITE_DBCONFIG_ENABLE_TRIGGER</dt>
  1750  ** <dd> ^This option is used to enable or disable [CREATE TRIGGER | triggers].
  1751  ** There should be two additional arguments.
  1752  ** The first argument is an integer which is 0 to disable triggers,
  1753  ** positive to enable triggers or negative to leave the setting unchanged.
  1754  ** The second parameter is a pointer to an integer into which
  1755  ** is written 0 or 1 to indicate whether triggers are disabled or enabled
  1756  ** following this call.  The second parameter may be a NULL pointer, in
  1757  ** which case the trigger setting is not reported back. </dd>
  1758  **
  1759  ** </dl>
  1760  */
  1761  #define SQLITE_DBCONFIG_LOOKASIDE       1001  /* void* int int */
  1762  #define SQLITE_DBCONFIG_ENABLE_FKEY     1002  /* int int* */
  1763  #define SQLITE_DBCONFIG_ENABLE_TRIGGER  1003  /* int int* */
  1764  
  1765  
  1766  /*
  1767  ** CAPI3REF: Enable Or Disable Extended Result Codes
  1768  **
  1769  ** ^The sqlite3_extended_result_codes() routine enables or disables the
  1770  ** [extended result codes] feature of SQLite. ^The extended result
  1771  ** codes are disabled by default for historical compatibility.
  1772  */
  1773  SQLITE_API int sqlite3_extended_result_codes(sqlite3*, int onoff);
  1774  
  1775  /*
  1776  ** CAPI3REF: Last Insert Rowid
  1777  **
  1778  ** ^Each entry in an SQLite table has a unique 64-bit signed
  1779  ** integer key called the [ROWID | "rowid"]. ^The rowid is always available
  1780  ** as an undeclared column named ROWID, OID, or _ROWID_ as long as those
  1781  ** names are not also used by explicitly declared columns. ^If
  1782  ** the table has a column of type [INTEGER PRIMARY KEY] then that column
  1783  ** is another alias for the rowid.
  1784  **
  1785  ** ^This routine returns the [rowid] of the most recent
  1786  ** successful [INSERT] into the database from the [database connection]
  1787  ** in the first argument.  ^As of SQLite version 3.7.7, this routines
  1788  ** records the last insert rowid of both ordinary tables and [virtual tables].
  1789  ** ^If no successful [INSERT]s
  1790  ** have ever occurred on that database connection, zero is returned.
  1791  **
  1792  ** ^(If an [INSERT] occurs within a trigger or within a [virtual table]
  1793  ** method, then this routine will return the [rowid] of the inserted
  1794  ** row as long as the trigger or virtual table method is running.
  1795  ** But once the trigger or virtual table method ends, the value returned 
  1796  ** by this routine reverts to what it was before the trigger or virtual
  1797  ** table method began.)^
  1798  **
  1799  ** ^An [INSERT] that fails due to a constraint violation is not a
  1800  ** successful [INSERT] and does not change the value returned by this
  1801  ** routine.  ^Thus INSERT OR FAIL, INSERT OR IGNORE, INSERT OR ROLLBACK,
  1802  ** and INSERT OR ABORT make no changes to the return value of this
  1803  ** routine when their insertion fails.  ^(When INSERT OR REPLACE
  1804  ** encounters a constraint violation, it does not fail.  The
  1805  ** INSERT continues to completion after deleting rows that caused
  1806  ** the constraint problem so INSERT OR REPLACE will always change
  1807  ** the return value of this interface.)^
  1808  **
  1809  ** ^For the purposes of this routine, an [INSERT] is considered to
  1810  ** be successful even if it is subsequently rolled back.
  1811  **
  1812  ** This function is accessible to SQL statements via the
  1813  ** [last_insert_rowid() SQL function].
  1814  **
  1815  ** If a separate thread performs a new [INSERT] on the same
  1816  ** database connection while the [sqlite3_last_insert_rowid()]
  1817  ** function is running and thus changes the last insert [rowid],
  1818  ** then the value returned by [sqlite3_last_insert_rowid()] is
  1819  ** unpredictable and might not equal either the old or the new
  1820  ** last insert [rowid].
  1821  */
  1822  SQLITE_API sqlite3_int64 sqlite3_last_insert_rowid(sqlite3*);
  1823  
  1824  /*
  1825  ** CAPI3REF: Count The Number Of Rows Modified
  1826  **
  1827  ** ^This function returns the number of database rows that were changed
  1828  ** or inserted or deleted by the most recently completed SQL statement
  1829  ** on the [database connection] specified by the first parameter.
  1830  ** ^(Only changes that are directly specified by the [INSERT], [UPDATE],
  1831  ** or [DELETE] statement are counted.  Auxiliary changes caused by
  1832  ** triggers or [foreign key actions] are not counted.)^ Use the
  1833  ** [sqlite3_total_changes()] function to find the total number of changes
  1834  ** including changes caused by triggers and foreign key actions.
  1835  **
  1836  ** ^Changes to a view that are simulated by an [INSTEAD OF trigger]
  1837  ** are not counted.  Only real table changes are counted.
  1838  **
  1839  ** ^(A "row change" is a change to a single row of a single table
  1840  ** caused by an INSERT, DELETE, or UPDATE statement.  Rows that
  1841  ** are changed as side effects of [REPLACE] constraint resolution,
  1842  ** rollback, ABORT processing, [DROP TABLE], or by any other
  1843  ** mechanisms do not count as direct row changes.)^
  1844  **
  1845  ** A "trigger context" is a scope of execution that begins and
  1846  ** ends with the script of a [CREATE TRIGGER | trigger]. 
  1847  ** Most SQL statements are
  1848  ** evaluated outside of any trigger.  This is the "top level"
  1849  ** trigger context.  If a trigger fires from the top level, a
  1850  ** new trigger context is entered for the duration of that one
  1851  ** trigger.  Subtriggers create subcontexts for their duration.
  1852  **
  1853  ** ^Calling [sqlite3_exec()] or [sqlite3_step()] recursively does
  1854  ** not create a new trigger context.
  1855  **
  1856  ** ^This function returns the number of direct row changes in the
  1857  ** most recent INSERT, UPDATE, or DELETE statement within the same
  1858  ** trigger context.
  1859  **
  1860  ** ^Thus, when called from the top level, this function returns the
  1861  ** number of changes in the most recent INSERT, UPDATE, or DELETE
  1862  ** that also occurred at the top level.  ^(Within the body of a trigger,
  1863  ** the sqlite3_changes() interface can be called to find the number of
  1864  ** changes in the most recently completed INSERT, UPDATE, or DELETE
  1865  ** statement within the body of the same trigger.
  1866  ** However, the number returned does not include changes
  1867  ** caused by subtriggers since those have their own context.)^
  1868  **
  1869  ** See also the [sqlite3_total_changes()] interface, the
  1870  ** [count_changes pragma], and the [changes() SQL function].
  1871  **
  1872  ** If a separate thread makes changes on the same database connection
  1873  ** while [sqlite3_changes()] is running then the value returned
  1874  ** is unpredictable and not meaningful.
  1875  */
  1876  SQLITE_API int sqlite3_changes(sqlite3*);
  1877  
  1878  /*
  1879  ** CAPI3REF: Total Number Of Rows Modified
  1880  **
  1881  ** ^This function returns the number of row changes caused by [INSERT],
  1882  ** [UPDATE] or [DELETE] statements since the [database connection] was opened.
  1883  ** ^(The count returned by sqlite3_total_changes() includes all changes
  1884  ** from all [CREATE TRIGGER | trigger] contexts and changes made by
  1885  ** [foreign key actions]. However,
  1886  ** the count does not include changes used to implement [REPLACE] constraints,
  1887  ** do rollbacks or ABORT processing, or [DROP TABLE] processing.  The
  1888  ** count does not include rows of views that fire an [INSTEAD OF trigger],
  1889  ** though if the INSTEAD OF trigger makes changes of its own, those changes 
  1890  ** are counted.)^
  1891  ** ^The sqlite3_total_changes() function counts the changes as soon as
  1892  ** the statement that makes them is completed (when the statement handle
  1893  ** is passed to [sqlite3_reset()] or [sqlite3_finalize()]).
  1894  **
  1895  ** See also the [sqlite3_changes()] interface, the
  1896  ** [count_changes pragma], and the [total_changes() SQL function].
  1897  **
  1898  ** If a separate thread makes changes on the same database connection
  1899  ** while [sqlite3_total_changes()] is running then the value
  1900  ** returned is unpredictable and not meaningful.
  1901  */
  1902  SQLITE_API int sqlite3_total_changes(sqlite3*);
  1903  
  1904  /*
  1905  ** CAPI3REF: Interrupt A Long-Running Query
  1906  **
  1907  ** ^This function causes any pending database operation to abort and
  1908  ** return at its earliest opportunity. This routine is typically
  1909  ** called in response to a user action such as pressing "Cancel"
  1910  ** or Ctrl-C where the user wants a long query operation to halt
  1911  ** immediately.
  1912  **
  1913  ** ^It is safe to call this routine from a thread different from the
  1914  ** thread that is currently running the database operation.  But it
  1915  ** is not safe to call this routine with a [database connection] that
  1916  ** is closed or might close before sqlite3_interrupt() returns.
  1917  **
  1918  ** ^If an SQL operation is very nearly finished at the time when
  1919  ** sqlite3_interrupt() is called, then it might not have an opportunity
  1920  ** to be interrupted and might continue to completion.
  1921  **
  1922  ** ^An SQL operation that is interrupted will return [SQLITE_INTERRUPT].
  1923  ** ^If the interrupted SQL operation is an INSERT, UPDATE, or DELETE
  1924  ** that is inside an explicit transaction, then the entire transaction
  1925  ** will be rolled back automatically.
  1926  **
  1927  ** ^The sqlite3_interrupt(D) call is in effect until all currently running
  1928  ** SQL statements on [database connection] D complete.  ^Any new SQL statements
  1929  ** that are started after the sqlite3_interrupt() call and before the 
  1930  ** running statements reaches zero are interrupted as if they had been
  1931  ** running prior to the sqlite3_interrupt() call.  ^New SQL statements
  1932  ** that are started after the running statement count reaches zero are
  1933  ** not effected by the sqlite3_interrupt().
  1934  ** ^A call to sqlite3_interrupt(D) that occurs when there are no running
  1935  ** SQL statements is a no-op and has no effect on SQL statements
  1936  ** that are started after the sqlite3_interrupt() call returns.
  1937  **
  1938  ** If the database connection closes while [sqlite3_interrupt()]
  1939  ** is running then bad things will likely happen.
  1940  */
  1941  SQLITE_API void sqlite3_interrupt(sqlite3*);
  1942  
  1943  /*
  1944  ** CAPI3REF: Determine If An SQL Statement Is Complete
  1945  **
  1946  ** These routines are useful during command-line input to determine if the
  1947  ** currently entered text seems to form a complete SQL statement or
  1948  ** if additional input is needed before sending the text into
  1949  ** SQLite for parsing.  ^These routines return 1 if the input string
  1950  ** appears to be a complete SQL statement.  ^A statement is judged to be
  1951  ** complete if it ends with a semicolon token and is not a prefix of a
  1952  ** well-formed CREATE TRIGGER statement.  ^Semicolons that are embedded within
  1953  ** string literals or quoted identifier names or comments are not
  1954  ** independent tokens (they are part of the token in which they are
  1955  ** embedded) and thus do not count as a statement terminator.  ^Whitespace
  1956  ** and comments that follow the final semicolon are ignored.
  1957  **
  1958  ** ^These routines return 0 if the statement is incomplete.  ^If a
  1959  ** memory allocation fails, then SQLITE_NOMEM is returned.
  1960  **
  1961  ** ^These routines do not parse the SQL statements thus
  1962  ** will not detect syntactically incorrect SQL.
  1963  **
  1964  ** ^(If SQLite has not been initialized using [sqlite3_initialize()] prior 
  1965  ** to invoking sqlite3_complete16() then sqlite3_initialize() is invoked
  1966  ** automatically by sqlite3_complete16().  If that initialization fails,
  1967  ** then the return value from sqlite3_complete16() will be non-zero
  1968  ** regardless of whether or not the input SQL is complete.)^
  1969  **
  1970  ** The input to [sqlite3_complete()] must be a zero-terminated
  1971  ** UTF-8 string.
  1972  **
  1973  ** The input to [sqlite3_complete16()] must be a zero-terminated
  1974  ** UTF-16 string in native byte order.
  1975  */
  1976  SQLITE_API int sqlite3_complete(const char *sql);
  1977  SQLITE_API int sqlite3_complete16(const void *sql);
  1978  
  1979  /*
  1980  ** CAPI3REF: Register A Callback To Handle SQLITE_BUSY Errors
  1981  **
  1982  ** ^This routine sets a callback function that might be invoked whenever
  1983  ** an attempt is made to open a database table that another thread
  1984  ** or process has locked.
  1985  **
  1986  ** ^If the busy callback is NULL, then [SQLITE_BUSY] or [SQLITE_IOERR_BLOCKED]
  1987  ** is returned immediately upon encountering the lock.  ^If the busy callback
  1988  ** is not NULL, then the callback might be invoked with two arguments.
  1989  **
  1990  ** ^The first argument to the busy handler is a copy of the void* pointer which
  1991  ** is the third argument to sqlite3_busy_handler().  ^The second argument to
  1992  ** the busy handler callback is the number of times that the busy handler has
  1993  ** been invoked for this locking event.  ^If the
  1994  ** busy callback returns 0, then no additional attempts are made to
  1995  ** access the database and [SQLITE_BUSY] or [SQLITE_IOERR_BLOCKED] is returned.
  1996  ** ^If the callback returns non-zero, then another attempt
  1997  ** is made to open the database for reading and the cycle repeats.
  1998  **
  1999  ** The presence of a busy handler does not guarantee that it will be invoked
  2000  ** when there is lock contention. ^If SQLite determines that invoking the busy
  2001  ** handler could result in a deadlock, it will go ahead and return [SQLITE_BUSY]
  2002  ** or [SQLITE_IOERR_BLOCKED] instead of invoking the busy handler.
  2003  ** Consider a scenario where one process is holding a read lock that
  2004  ** it is trying to promote to a reserved lock and
  2005  ** a second process is holding a reserved lock that it is trying
  2006  ** to promote to an exclusive lock.  The first process cannot proceed
  2007  ** because it is blocked by the second and the second process cannot
  2008  ** proceed because it is blocked by the first.  If both processes
  2009  ** invoke the busy handlers, neither will make any progress.  Therefore,
  2010  ** SQLite returns [SQLITE_BUSY] for the first process, hoping that this
  2011  ** will induce the first process to release its read lock and allow
  2012  ** the second process to proceed.
  2013  **
  2014  ** ^The default busy callback is NULL.
  2015  **
  2016  ** ^The [SQLITE_BUSY] error is converted to [SQLITE_IOERR_BLOCKED]
  2017  ** when SQLite is in the middle of a large transaction where all the
  2018  ** changes will not fit into the in-memory cache.  SQLite will
  2019  ** already hold a RESERVED lock on the database file, but it needs
  2020  ** to promote this lock to EXCLUSIVE so that it can spill cache
  2021  ** pages into the database file without harm to concurrent
  2022  ** readers.  ^If it is unable to promote the lock, then the in-memory
  2023  ** cache will be left in an inconsistent state and so the error
  2024  ** code is promoted from the relatively benign [SQLITE_BUSY] to
  2025  ** the more severe [SQLITE_IOERR_BLOCKED].  ^This error code promotion
  2026  ** forces an automatic rollback of the changes.  See the
  2027  ** <a href="/cvstrac/wiki?p=CorruptionFollowingBusyError">
  2028  ** CorruptionFollowingBusyError</a> wiki page for a discussion of why
  2029  ** this is important.
  2030  **
  2031  ** ^(There can only be a single busy handler defined for each
  2032  ** [database connection].  Setting a new busy handler clears any
  2033  ** previously set handler.)^  ^Note that calling [sqlite3_busy_timeout()]
  2034  ** will also set or clear the busy handler.
  2035  **
  2036  ** The busy callback should not take any actions which modify the
  2037  ** database connection that invoked the busy handler.  Any such actions
  2038  ** result in undefined behavior.
  2039  ** 
  2040  ** A busy handler must not close the database connection
  2041  ** or [prepared statement] that invoked the busy handler.
  2042  */
  2043  SQLITE_API int sqlite3_busy_handler(sqlite3*, int(*)(void*,int), void*);
  2044  
  2045  /*
  2046  ** CAPI3REF: Set A Busy Timeout
  2047  **
  2048  ** ^This routine sets a [sqlite3_busy_handler | busy handler] that sleeps
  2049  ** for a specified amount of time when a table is locked.  ^The handler
  2050  ** will sleep multiple times until at least "ms" milliseconds of sleeping
  2051  ** have accumulated.  ^After at least "ms" milliseconds of sleeping,
  2052  ** the handler returns 0 which causes [sqlite3_step()] to return
  2053  ** [SQLITE_BUSY] or [SQLITE_IOERR_BLOCKED].
  2054  **
  2055  ** ^Calling this routine with an argument less than or equal to zero
  2056  ** turns off all busy handlers.
  2057  **
  2058  ** ^(There can only be a single busy handler for a particular
  2059  ** [database connection] any any given moment.  If another busy handler
  2060  ** was defined  (using [sqlite3_busy_handler()]) prior to calling
  2061  ** this routine, that other busy handler is cleared.)^
  2062  */
  2063  SQLITE_API int sqlite3_busy_timeout(sqlite3*, int ms);
  2064  
  2065  /*
  2066  ** CAPI3REF: Convenience Routines For Running Queries
  2067  **
  2068  ** This is a legacy interface that is preserved for backwards compatibility.
  2069  ** Use of this interface is not recommended.
  2070  **
  2071  ** Definition: A <b>result table</b> is memory data structure created by the
  2072  ** [sqlite3_get_table()] interface.  A result table records the
  2073  ** complete query results from one or more queries.
  2074  **
  2075  ** The table conceptually has a number of rows and columns.  But
  2076  ** these numbers are not part of the result table itself.  These
  2077  ** numbers are obtained separately.  Let N be the number of rows
  2078  ** and M be the number of columns.
  2079  **
  2080  ** A result table is an array of pointers to zero-terminated UTF-8 strings.
  2081  ** There are (N+1)*M elements in the array.  The first M pointers point
  2082  ** to zero-terminated strings that  contain the names of the columns.
  2083  ** The remaining entries all point to query results.  NULL values result
  2084  ** in NULL pointers.  All other values are in their UTF-8 zero-terminated
  2085  ** string representation as returned by [sqlite3_column_text()].
  2086  **
  2087  ** A result table might consist of one or more memory allocations.
  2088  ** It is not safe to pass a result table directly to [sqlite3_free()].
  2089  ** A result table should be deallocated using [sqlite3_free_table()].
  2090  **
  2091  ** ^(As an example of the result table format, suppose a query result
  2092  ** is as follows:
  2093  **
  2094  ** <blockquote><pre>
  2095  **        Name        | Age
  2096  **        -----------------------
  2097  **        Alice       | 43
  2098  **        Bob         | 28
  2099  **        Cindy       | 21
  2100  ** </pre></blockquote>
  2101  **
  2102  ** There are two column (M==2) and three rows (N==3).  Thus the
  2103  ** result table has 8 entries.  Suppose the result table is stored
  2104  ** in an array names azResult.  Then azResult holds this content:
  2105  **
  2106  ** <blockquote><pre>
  2107  **        azResult&#91;0] = "Name";
  2108  **        azResult&#91;1] = "Age";
  2109  **        azResult&#91;2] = "Alice";
  2110  **        azResult&#91;3] = "43";
  2111  **        azResult&#91;4] = "Bob";
  2112  **        azResult&#91;5] = "28";
  2113  **        azResult&#91;6] = "Cindy";
  2114  **        azResult&#91;7] = "21";
  2115  ** </pre></blockquote>)^
  2116  **
  2117  ** ^The sqlite3_get_table() function evaluates one or more
  2118  ** semicolon-separated SQL statements in the zero-terminated UTF-8
  2119  ** string of its 2nd parameter and returns a result table to the
  2120  ** pointer given in its 3rd parameter.
  2121  **
  2122  ** After the application has finished with the result from sqlite3_get_table(),
  2123  ** it must pass the result table pointer to sqlite3_free_table() in order to
  2124  ** release the memory that was malloced.  Because of the way the
  2125  ** [sqlite3_malloc()] happens within sqlite3_get_table(), the calling
  2126  ** function must not try to call [sqlite3_free()] directly.  Only
  2127  ** [sqlite3_free_table()] is able to release the memory properly and safely.
  2128  **
  2129  ** The sqlite3_get_table() interface is implemented as a wrapper around
  2130  ** [sqlite3_exec()].  The sqlite3_get_table() routine does not have access
  2131  ** to any internal data structures of SQLite.  It uses only the public
  2132  ** interface defined here.  As a consequence, errors that occur in the
  2133  ** wrapper layer outside of the internal [sqlite3_exec()] call are not
  2134  ** reflected in subsequent calls to [sqlite3_errcode()] or
  2135  ** [sqlite3_errmsg()].
  2136  */
  2137  SQLITE_API int sqlite3_get_table(
  2138    sqlite3 *db,          /* An open database */
  2139    const char *zSql,     /* SQL to be evaluated */
  2140    char ***pazResult,    /* Results of the query */
  2141    int *pnRow,           /* Number of result rows written here */
  2142    int *pnColumn,        /* Number of result columns written here */
  2143    char **pzErrmsg       /* Error msg written here */
  2144  );
  2145  SQLITE_API void sqlite3_free_table(char **result);
  2146  
  2147  /*
  2148  ** CAPI3REF: Formatted String Printing Functions
  2149  **
  2150  ** These routines are work-alikes of the "printf()" family of functions
  2151  ** from the standard C library.
  2152  **
  2153  ** ^The sqlite3_mprintf() and sqlite3_vmprintf() routines write their
  2154  ** results into memory obtained from [sqlite3_malloc()].
  2155  ** The strings returned by these two routines should be
  2156  ** released by [sqlite3_free()].  ^Both routines return a
  2157  ** NULL pointer if [sqlite3_malloc()] is unable to allocate enough
  2158  ** memory to hold the resulting string.
  2159  **
  2160  ** ^(The sqlite3_snprintf() routine is similar to "snprintf()" from
  2161  ** the standard C library.  The result is written into the
  2162  ** buffer supplied as the second parameter whose size is given by
  2163  ** the first parameter. Note that the order of the
  2164  ** first two parameters is reversed from snprintf().)^  This is an
  2165  ** historical accident that cannot be fixed without breaking
  2166  ** backwards compatibility.  ^(Note also that sqlite3_snprintf()
  2167  ** returns a pointer to its buffer instead of the number of
  2168  ** characters actually written into the buffer.)^  We admit that
  2169  ** the number of characters written would be a more useful return
  2170  ** value but we cannot change the implementation of sqlite3_snprintf()
  2171  ** now without breaking compatibility.
  2172  **
  2173  ** ^As long as the buffer size is greater than zero, sqlite3_snprintf()
  2174  ** guarantees that the buffer is always zero-terminated.  ^The first
  2175  ** parameter "n" is the total size of the buffer, including space for
  2176  ** the zero terminator.  So the longest string that can be completely
  2177  ** written will be n-1 characters.
  2178  **
  2179  ** ^The sqlite3_vsnprintf() routine is a varargs version of sqlite3_snprintf().
  2180  **
  2181  ** These routines all implement some additional formatting
  2182  ** options that are useful for constructing SQL statements.
  2183  ** All of the usual printf() formatting options apply.  In addition, there
  2184  ** is are "%q", "%Q", and "%z" options.
  2185  **
  2186  ** ^(The %q option works like %s in that it substitutes a nul-terminated
  2187  ** string from the argument list.  But %q also doubles every '\'' character.
  2188  ** %q is designed for use inside a string literal.)^  By doubling each '\''
  2189  ** character it escapes that character and allows it to be inserted into
  2190  ** the string.
  2191  **
  2192  ** For example, assume the string variable zText contains text as follows:
  2193  **
  2194  ** <blockquote><pre>
  2195  **  char *zText = "It's a happy day!";
  2196  ** </pre></blockquote>
  2197  **
  2198  ** One can use this text in an SQL statement as follows:
  2199  **
  2200  ** <blockquote><pre>
  2201  **  char *zSQL = sqlite3_mprintf("INSERT INTO table VALUES('%q')", zText);
  2202  **  sqlite3_exec(db, zSQL, 0, 0, 0);
  2203  **  sqlite3_free(zSQL);
  2204  ** </pre></blockquote>
  2205  **
  2206  ** Because the %q format string is used, the '\'' character in zText
  2207  ** is escaped and the SQL generated is as follows:
  2208  **
  2209  ** <blockquote><pre>
  2210  **  INSERT INTO table1 VALUES('It''s a happy day!')
  2211  ** </pre></blockquote>
  2212  **
  2213  ** This is correct.  Had we used %s instead of %q, the generated SQL
  2214  ** would have looked like this:
  2215  **
  2216  ** <blockquote><pre>
  2217  **  INSERT INTO table1 VALUES('It's a happy day!');
  2218  ** </pre></blockquote>
  2219  **
  2220  ** This second example is an SQL syntax error.  As a general rule you should
  2221  ** always use %q instead of %s when inserting text into a string literal.
  2222  **
  2223  ** ^(The %Q option works like %q except it also adds single quotes around
  2224  ** the outside of the total string.  Additionally, if the parameter in the
  2225  ** argument list is a NULL pointer, %Q substitutes the text "NULL" (without
  2226  ** single quotes).)^  So, for example, one could say:
  2227  **
  2228  ** <blockquote><pre>
  2229  **  char *zSQL = sqlite3_mprintf("INSERT INTO table VALUES(%Q)", zText);
  2230  **  sqlite3_exec(db, zSQL, 0, 0, 0);
  2231  **  sqlite3_free(zSQL);
  2232  ** </pre></blockquote>
  2233  **
  2234  ** The code above will render a correct SQL statement in the zSQL
  2235  ** variable even if the zText variable is a NULL pointer.
  2236  **
  2237  ** ^(The "%z" formatting option works like "%s" but with the
  2238  ** addition that after the string has been read and copied into
  2239  ** the result, [sqlite3_free()] is called on the input string.)^
  2240  */
  2241  SQLITE_API char *sqlite3_mprintf(const char*,...);
  2242  SQLITE_API char *sqlite3_vmprintf(const char*, va_list);
  2243  SQLITE_API char *sqlite3_snprintf(int,char*,const char*, ...);
  2244  SQLITE_API char *sqlite3_vsnprintf(int,char*,const char*, va_list);
  2245  
  2246  /*
  2247  ** CAPI3REF: Memory Allocation Subsystem
  2248  **
  2249  ** The SQLite core uses these three routines for all of its own
  2250  ** internal memory allocation needs. "Core" in the previous sentence
  2251  ** does not include operating-system specific VFS implementation.  The
  2252  ** Windows VFS uses native malloc() and free() for some operations.
  2253  **
  2254  ** ^The sqlite3_malloc() routine returns a pointer to a block
  2255  ** of memory at least N bytes in length, where N is the parameter.
  2256  ** ^If sqlite3_malloc() is unable to obtain sufficient free
  2257  ** memory, it returns a NULL pointer.  ^If the parameter N to
  2258  ** sqlite3_malloc() is zero or negative then sqlite3_malloc() returns
  2259  ** a NULL pointer.
  2260  **
  2261  ** ^Calling sqlite3_free() with a pointer previously returned
  2262  ** by sqlite3_malloc() or sqlite3_realloc() releases that memory so
  2263  ** that it might be reused.  ^The sqlite3_free() routine is
  2264  ** a no-op if is called with a NULL pointer.  Passing a NULL pointer
  2265  ** to sqlite3_free() is harmless.  After being freed, memory
  2266  ** should neither be read nor written.  Even reading previously freed
  2267  ** memory might result in a segmentation fault or other severe error.
  2268  ** Memory corruption, a segmentation fault, or other severe error
  2269  ** might result if sqlite3_free() is called with a non-NULL pointer that
  2270  ** was not obtained from sqlite3_malloc() or sqlite3_realloc().
  2271  **
  2272  ** ^(The sqlite3_realloc() interface attempts to resize a
  2273  ** prior memory allocation to be at least N bytes, where N is the
  2274  ** second parameter.  The memory allocation to be resized is the first
  2275  ** parameter.)^ ^ If the first parameter to sqlite3_realloc()
  2276  ** is a NULL pointer then its behavior is identical to calling
  2277  ** sqlite3_malloc(N) where N is the second parameter to sqlite3_realloc().
  2278  ** ^If the second parameter to sqlite3_realloc() is zero or
  2279  ** negative then the behavior is exactly the same as calling
  2280  ** sqlite3_free(P) where P is the first parameter to sqlite3_realloc().
  2281  ** ^sqlite3_realloc() returns a pointer to a memory allocation
  2282  ** of at least N bytes in size or NULL if sufficient memory is unavailable.
  2283  ** ^If M is the size of the prior allocation, then min(N,M) bytes
  2284  ** of the prior allocation are copied into the beginning of buffer returned
  2285  ** by sqlite3_realloc() and the prior allocation is freed.
  2286  ** ^If sqlite3_realloc() returns NULL, then the prior allocation
  2287  ** is not freed.
  2288  **
  2289  ** ^The memory returned by sqlite3_malloc() and sqlite3_realloc()
  2290  ** is always aligned to at least an 8 byte boundary, or to a
  2291  ** 4 byte boundary if the [SQLITE_4_BYTE_ALIGNED_MALLOC] compile-time
  2292  ** option is used.
  2293  **
  2294  ** In SQLite version 3.5.0 and 3.5.1, it was possible to define
  2295  ** the SQLITE_OMIT_MEMORY_ALLOCATION which would cause the built-in
  2296  ** implementation of these routines to be omitted.  That capability
  2297  ** is no longer provided.  Only built-in memory allocators can be used.
  2298  **
  2299  ** Prior to SQLite version 3.7.10, the Windows OS interface layer called
  2300  ** the system malloc() and free() directly when converting
  2301  ** filenames between the UTF-8 encoding used by SQLite
  2302  ** and whatever filename encoding is used by the particular Windows
  2303  ** installation.  Memory allocation errors were detected, but
  2304  ** they were reported back as [SQLITE_CANTOPEN] or
  2305  ** [SQLITE_IOERR] rather than [SQLITE_NOMEM].
  2306  **
  2307  ** The pointer arguments to [sqlite3_free()] and [sqlite3_realloc()]
  2308  ** must be either NULL or else pointers obtained from a prior
  2309  ** invocation of [sqlite3_malloc()] or [sqlite3_realloc()] that have
  2310  ** not yet been released.
  2311  **
  2312  ** The application must not read or write any part of
  2313  ** a block of memory after it has been released using
  2314  ** [sqlite3_free()] or [sqlite3_realloc()].
  2315  */
  2316  SQLITE_API void *sqlite3_malloc(int);
  2317  SQLITE_API void *sqlite3_realloc(void*, int);
  2318  SQLITE_API void sqlite3_free(void*);
  2319  
  2320  /*
  2321  ** CAPI3REF: Memory Allocator Statistics
  2322  **
  2323  ** SQLite provides these two interfaces for reporting on the status
  2324  ** of the [sqlite3_malloc()], [sqlite3_free()], and [sqlite3_realloc()]
  2325  ** routines, which form the built-in memory allocation subsystem.
  2326  **
  2327  ** ^The [sqlite3_memory_used()] routine returns the number of bytes
  2328  ** of memory currently outstanding (malloced but not freed).
  2329  ** ^The [sqlite3_memory_highwater()] routine returns the maximum
  2330  ** value of [sqlite3_memory_used()] since the high-water mark
  2331  ** was last reset.  ^The values returned by [sqlite3_memory_used()] and
  2332  ** [sqlite3_memory_highwater()] include any overhead
  2333  ** added by SQLite in its implementation of [sqlite3_malloc()],
  2334  ** but not overhead added by the any underlying system library
  2335  ** routines that [sqlite3_malloc()] may call.
  2336  **
  2337  ** ^The memory high-water mark is reset to the current value of
  2338  ** [sqlite3_memory_used()] if and only if the parameter to
  2339  ** [sqlite3_memory_highwater()] is true.  ^The value returned
  2340  ** by [sqlite3_memory_highwater(1)] is the high-water mark
  2341  ** prior to the reset.
  2342  */
  2343  SQLITE_API sqlite3_int64 sqlite3_memory_used(void);
  2344  SQLITE_API sqlite3_int64 sqlite3_memory_highwater(int resetFlag);
  2345  
  2346  /*
  2347  ** CAPI3REF: Pseudo-Random Number Generator
  2348  **
  2349  ** SQLite contains a high-quality pseudo-random number generator (PRNG) used to
  2350  ** select random [ROWID | ROWIDs] when inserting new records into a table that
  2351  ** already uses the largest possible [ROWID].  The PRNG is also used for
  2352  ** the build-in random() and randomblob() SQL functions.  This interface allows
  2353  ** applications to access the same PRNG for other purposes.
  2354  **
  2355  ** ^A call to this routine stores N bytes of randomness into buffer P.
  2356  **
  2357  ** ^The first time this routine is invoked (either internally or by
  2358  ** the application) the PRNG is seeded using randomness obtained
  2359  ** from the xRandomness method of the default [sqlite3_vfs] object.
  2360  ** ^On all subsequent invocations, the pseudo-randomness is generated
  2361  ** internally and without recourse to the [sqlite3_vfs] xRandomness
  2362  ** method.
  2363  */
  2364  SQLITE_API void sqlite3_randomness(int N, void *P);
  2365  
  2366  /*
  2367  ** CAPI3REF: Compile-Time Authorization Callbacks
  2368  **
  2369  ** ^This routine registers an authorizer callback with a particular
  2370  ** [database connection], supplied in the first argument.
  2371  ** ^The authorizer callback is invoked as SQL statements are being compiled
  2372  ** by [sqlite3_prepare()] or its variants [sqlite3_prepare_v2()],
  2373  ** [sqlite3_prepare16()] and [sqlite3_prepare16_v2()].  ^At various
  2374  ** points during the compilation process, as logic is being created
  2375  ** to perform various actions, the authorizer callback is invoked to
  2376  ** see if those actions are allowed.  ^The authorizer callback should
  2377  ** return [SQLITE_OK] to allow the action, [SQLITE_IGNORE] to disallow the
  2378  ** specific action but allow the SQL statement to continue to be
  2379  ** compiled, or [SQLITE_DENY] to cause the entire SQL statement to be
  2380  ** rejected with an error.  ^If the authorizer callback returns
  2381  ** any value other than [SQLITE_IGNORE], [SQLITE_OK], or [SQLITE_DENY]
  2382  ** then the [sqlite3_prepare_v2()] or equivalent call that triggered
  2383  ** the authorizer will fail with an error message.
  2384  **
  2385  ** When the callback returns [SQLITE_OK], that means the operation
  2386  ** requested is ok.  ^When the callback returns [SQLITE_DENY], the
  2387  ** [sqlite3_prepare_v2()] or equivalent call that triggered the
  2388  ** authorizer will fail with an error message explaining that
  2389  ** access is denied. 
  2390  **
  2391  ** ^The first parameter to the authorizer callback is a copy of the third
  2392  ** parameter to the sqlite3_set_authorizer() interface. ^The second parameter
  2393  ** to the callback is an integer [SQLITE_COPY | action code] that specifies
  2394  ** the particular action to be authorized. ^The third through sixth parameters
  2395  ** to the callback are zero-terminated strings that contain additional
  2396  ** details about the action to be authorized.
  2397  **
  2398  ** ^If the action code is [SQLITE_READ]
  2399  ** and the callback returns [SQLITE_IGNORE] then the
  2400  ** [prepared statement] statement is constructed to substitute
  2401  ** a NULL value in place of the table column that would have
  2402  ** been read if [SQLITE_OK] had been returned.  The [SQLITE_IGNORE]
  2403  ** return can be used to deny an untrusted user access to individual
  2404  ** columns of a table.
  2405  ** ^If the action code is [SQLITE_DELETE] and the callback returns
  2406  ** [SQLITE_IGNORE] then the [DELETE] operation proceeds but the
  2407  ** [truncate optimization] is disabled and all rows are deleted individually.
  2408  **
  2409  ** An authorizer is used when [sqlite3_prepare | preparing]
  2410  ** SQL statements from an untrusted source, to ensure that the SQL statements
  2411  ** do not try to access data they are not allowed to see, or that they do not
  2412  ** try to execute malicious statements that damage the database.  For
  2413  ** example, an application may allow a user to enter arbitrary
  2414  ** SQL queries for evaluation by a database.  But the application does
  2415  ** not want the user to be able to make arbitrary changes to the
  2416  ** database.  An authorizer could then be put in place while the
  2417  ** user-entered SQL is being [sqlite3_prepare | prepared] that
  2418  ** disallows everything except [SELECT] statements.
  2419  **
  2420  ** Applications that need to process SQL from untrusted sources
  2421  ** might also consider lowering resource limits using [sqlite3_limit()]
  2422  ** and limiting database size using the [max_page_count] [PRAGMA]
  2423  ** in addition to using an authorizer.
  2424  **
  2425  ** ^(Only a single authorizer can be in place on a database connection
  2426  ** at a time.  Each call to sqlite3_set_authorizer overrides the
  2427  ** previous call.)^  ^Disable the authorizer by installing a NULL callback.
  2428  ** The authorizer is disabled by default.
  2429  **
  2430  ** The authorizer callback must not do anything that will modify
  2431  ** the database connection that invoked the authorizer callback.
  2432  ** Note that [sqlite3_prepare_v2()] and [sqlite3_step()] both modify their
  2433  ** database connections for the meaning of "modify" in this paragraph.
  2434  **
  2435  ** ^When [sqlite3_prepare_v2()] is used to prepare a statement, the
  2436  ** statement might be re-prepared during [sqlite3_step()] due to a 
  2437  ** schema change.  Hence, the application should ensure that the
  2438  ** correct authorizer callback remains in place during the [sqlite3_step()].
  2439  **
  2440  ** ^Note that the authorizer callback is invoked only during
  2441  ** [sqlite3_prepare()] or its variants.  Authorization is not
  2442  ** performed during statement evaluation in [sqlite3_step()], unless
  2443  ** as stated in the previous paragraph, sqlite3_step() invokes
  2444  ** sqlite3_prepare_v2() to reprepare a statement after a schema change.
  2445  */
  2446  SQLITE_API int sqlite3_set_authorizer(
  2447    sqlite3*,
  2448    int (*xAuth)(void*,int,const char*,const char*,const char*,const char*),
  2449    void *pUserData
  2450  );
  2451  
  2452  /*
  2453  ** CAPI3REF: Authorizer Return Codes
  2454  **
  2455  ** The [sqlite3_set_authorizer | authorizer callback function] must
  2456  ** return either [SQLITE_OK] or one of these two constants in order
  2457  ** to signal SQLite whether or not the action is permitted.  See the
  2458  ** [sqlite3_set_authorizer | authorizer documentation] for additional
  2459  ** information.
  2460  **
  2461  ** Note that SQLITE_IGNORE is also used as a [SQLITE_ROLLBACK | return code]
  2462  ** from the [sqlite3_vtab_on_conflict()] interface.
  2463  */
  2464  #define SQLITE_DENY   1   /* Abort the SQL statement with an error */
  2465  #define SQLITE_IGNORE 2   /* Don't allow access, but don't generate an error */
  2466  
  2467  /*
  2468  ** CAPI3REF: Authorizer Action Codes
  2469  **
  2470  ** The [sqlite3_set_authorizer()] interface registers a callback function
  2471  ** that is invoked to authorize certain SQL statement actions.  The
  2472  ** second parameter to the callback is an integer code that specifies
  2473  ** what action is being authorized.  These are the integer action codes that
  2474  ** the authorizer callback may be passed.
  2475  **
  2476  ** These action code values signify what kind of operation is to be
  2477  ** authorized.  The 3rd and 4th parameters to the authorization
  2478  ** callback function will be parameters or NULL depending on which of these
  2479  ** codes is used as the second parameter.  ^(The 5th parameter to the
  2480  ** authorizer callback is the name of the database ("main", "temp",
  2481  ** etc.) if applicable.)^  ^The 6th parameter to the authorizer callback
  2482  ** is the name of the inner-most trigger or view that is responsible for
  2483  ** the access attempt or NULL if this access attempt is directly from
  2484  ** top-level SQL code.
  2485  */
  2486  /******************************************* 3rd ************ 4th ***********/
  2487  #define SQLITE_CREATE_INDEX          1   /* Index Name      Table Name      */
  2488  #define SQLITE_CREATE_TABLE          2   /* Table Name      NULL            */
  2489  #define SQLITE_CREATE_TEMP_INDEX     3   /* Index Name      Table Name      */
  2490  #define SQLITE_CREATE_TEMP_TABLE     4   /* Table Name      NULL            */
  2491  #define SQLITE_CREATE_TEMP_TRIGGER   5   /* Trigger Name    Table Name      */
  2492  #define SQLITE_CREATE_TEMP_VIEW      6   /* View Name       NULL            */
  2493  #define SQLITE_CREATE_TRIGGER        7   /* Trigger Name    Table Name      */
  2494  #define SQLITE_CREATE_VIEW           8   /* View Name       NULL            */
  2495  #define SQLITE_DELETE                9   /* Table Name      NULL            */
  2496  #define SQLITE_DROP_INDEX           10   /* Index Name      Table Name      */
  2497  #define SQLITE_DROP_TABLE           11   /* Table Name      NULL            */
  2498  #define SQLITE_DROP_TEMP_INDEX      12   /* Index Name      Table Name      */
  2499  #define SQLITE_DROP_TEMP_TABLE      13   /* Table Name      NULL            */
  2500  #define SQLITE_DROP_TEMP_TRIGGER    14   /* Trigger Name    Table Name      */
  2501  #define SQLITE_DROP_TEMP_VIEW       15   /* View Name       NULL            */
  2502  #define SQLITE_DROP_TRIGGER         16   /* Trigger Name    Table Name      */
  2503  #define SQLITE_DROP_VIEW            17   /* View Name       NULL            */
  2504  #define SQLITE_INSERT               18   /* Table Name      NULL            */
  2505  #define SQLITE_PRAGMA               19   /* Pragma Name     1st arg or NULL */
  2506  #define SQLITE_READ                 20   /* Table Name      Column Name     */
  2507  #define SQLITE_SELECT               21   /* NULL            NULL            */
  2508  #define SQLITE_TRANSACTION          22   /* Operation       NULL            */
  2509  #define SQLITE_UPDATE               23   /* Table Name      Column Name     */
  2510  #define SQLITE_ATTACH               24   /* Filename        NULL            */
  2511  #define SQLITE_DETACH               25   /* Database Name   NULL            */
  2512  #define SQLITE_ALTER_TABLE          26   /* Database Name   Table Name      */
  2513  #define SQLITE_REINDEX              27   /* Index Name      NULL            */
  2514  #define SQLITE_ANALYZE              28   /* Table Name      NULL            */
  2515  #define SQLITE_CREATE_VTABLE        29   /* Table Name      Module Name     */
  2516  #define SQLITE_DROP_VTABLE          30   /* Table Name      Module Name     */
  2517  #define SQLITE_FUNCTION             31   /* NULL            Function Name   */
  2518  #define SQLITE_SAVEPOINT            32   /* Operation       Savepoint Name  */
  2519  #define SQLITE_COPY                  0   /* No longer used */
  2520  
  2521  /*
  2522  ** CAPI3REF: Tracing And Profiling Functions
  2523  **
  2524  ** These routines register callback functions that can be used for
  2525  ** tracing and profiling the execution of SQL statements.
  2526  **
  2527  ** ^The callback function registered by sqlite3_trace() is invoked at
  2528  ** various times when an SQL statement is being run by [sqlite3_step()].
  2529  ** ^The sqlite3_trace() callback is invoked with a UTF-8 rendering of the
  2530  ** SQL statement text as the statement first begins executing.
  2531  ** ^(Additional sqlite3_trace() callbacks might occur
  2532  ** as each triggered subprogram is entered.  The callbacks for triggers
  2533  ** contain a UTF-8 SQL comment that identifies the trigger.)^
  2534  **
  2535  ** The [SQLITE_TRACE_SIZE_LIMIT] compile-time option can be used to limit
  2536  ** the length of [bound parameter] expansion in the output of sqlite3_trace().
  2537  **
  2538  ** ^The callback function registered by sqlite3_profile() is invoked
  2539  ** as each SQL statement finishes.  ^The profile callback contains
  2540  ** the original statement text and an estimate of wall-clock time
  2541  ** of how long that statement took to run.  ^The profile callback
  2542  ** time is in units of nanoseconds, however the current implementation
  2543  ** is only capable of millisecond resolution so the six least significant
  2544  ** digits in the time are meaningless.  Future versions of SQLite
  2545  ** might provide greater resolution on the profiler callback.  The
  2546  ** sqlite3_profile() function is considered experimental and is
  2547  ** subject to change in future versions of SQLite.
  2548  */
  2549  SQLITE_API void *sqlite3_trace(sqlite3*, void(*xTrace)(void*,const char*), void*);
  2550  SQLITE_API SQLITE_EXPERIMENTAL void *sqlite3_profile(sqlite3*,
  2551     void(*xProfile)(void*,const char*,sqlite3_uint64), void*);
  2552  
  2553  /*
  2554  ** CAPI3REF: Query Progress Callbacks
  2555  **
  2556  ** ^The sqlite3_progress_handler(D,N,X,P) interface causes the callback
  2557  ** function X to be invoked periodically during long running calls to
  2558  ** [sqlite3_exec()], [sqlite3_step()] and [sqlite3_get_table()] for
  2559  ** database connection D.  An example use for this
  2560  ** interface is to keep a GUI updated during a large query.
  2561  **
  2562  ** ^The parameter P is passed through as the only parameter to the 
  2563  ** callback function X.  ^The parameter N is the approximate number of 
  2564  ** [virtual machine instructions] that are evaluated between successive
  2565  ** invocations of the callback X.  ^If N is less than one then the progress
  2566  ** handler is disabled.
  2567  **
  2568  ** ^Only a single progress handler may be defined at one time per
  2569  ** [database connection]; setting a new progress handler cancels the
  2570  ** old one.  ^Setting parameter X to NULL disables the progress handler.
  2571  ** ^The progress handler is also disabled by setting N to a value less
  2572  ** than 1.
  2573  **
  2574  ** ^If the progress callback returns non-zero, the operation is
  2575  ** interrupted.  This feature can be used to implement a
  2576  ** "Cancel" button on a GUI progress dialog box.
  2577  **
  2578  ** The progress handler callback must not do anything that will modify
  2579  ** the database connection that invoked the progress handler.
  2580  ** Note that [sqlite3_prepare_v2()] and [sqlite3_step()] both modify their
  2581  ** database connections for the meaning of "modify" in this paragraph.
  2582  **
  2583  */
  2584  SQLITE_API void sqlite3_progress_handler(sqlite3*, int, int(*)(void*), void*);
  2585  
  2586  /*
  2587  ** CAPI3REF: Opening A New Database Connection
  2588  **
  2589  ** ^These routines open an SQLite database file as specified by the 
  2590  ** filename argument. ^The filename argument is interpreted as UTF-8 for
  2591  ** sqlite3_open() and sqlite3_open_v2() and as UTF-16 in the native byte
  2592  ** order for sqlite3_open16(). ^(A [database connection] handle is usually
  2593  ** returned in *ppDb, even if an error occurs.  The only exception is that
  2594  ** if SQLite is unable to allocate memory to hold the [sqlite3] object,
  2595  ** a NULL will be written into *ppDb instead of a pointer to the [sqlite3]
  2596  ** object.)^ ^(If the database is opened (and/or created) successfully, then
  2597  ** [SQLITE_OK] is returned.  Otherwise an [error code] is returned.)^ ^The
  2598  ** [sqlite3_errmsg()] or [sqlite3_errmsg16()] routines can be used to obtain
  2599  ** an English language description of the error following a failure of any
  2600  ** of the sqlite3_open() routines.
  2601  **
  2602  ** ^The default encoding for the database will be UTF-8 if
  2603  ** sqlite3_open() or sqlite3_open_v2() is called and
  2604  ** UTF-16 in the native byte order if sqlite3_open16() is used.
  2605  **
  2606  ** Whether or not an error occurs when it is opened, resources
  2607  ** associated with the [database connection] handle should be released by
  2608  ** passing it to [sqlite3_close()] when it is no longer required.
  2609  **
  2610  ** The sqlite3_open_v2() interface works like sqlite3_open()
  2611  ** except that it accepts two additional parameters for additional control
  2612  ** over the new database connection.  ^(The flags parameter to
  2613  ** sqlite3_open_v2() can take one of
  2614  ** the following three values, optionally combined with the 
  2615  ** [SQLITE_OPEN_NOMUTEX], [SQLITE_OPEN_FULLMUTEX], [SQLITE_OPEN_SHAREDCACHE],
  2616  ** [SQLITE_OPEN_PRIVATECACHE], and/or [SQLITE_OPEN_URI] flags:)^
  2617  **
  2618  ** <dl>
  2619  ** ^(<dt>[SQLITE_OPEN_READONLY]</dt>
  2620  ** <dd>The database is opened in read-only mode.  If the database does not
  2621  ** already exist, an error is returned.</dd>)^
  2622  **
  2623  ** ^(<dt>[SQLITE_OPEN_READWRITE]</dt>
  2624  ** <dd>The database is opened for reading and writing if possible, or reading
  2625  ** only if the file is write protected by the operating system.  In either
  2626  ** case the database must already exist, otherwise an error is returned.</dd>)^
  2627  **
  2628  ** ^(<dt>[SQLITE_OPEN_READWRITE] | [SQLITE_OPEN_CREATE]</dt>
  2629  ** <dd>The database is opened for reading and writing, and is created if
  2630  ** it does not already exist. This is the behavior that is always used for
  2631  ** sqlite3_open() and sqlite3_open16().</dd>)^
  2632  ** </dl>
  2633  **
  2634  ** If the 3rd parameter to sqlite3_open_v2() is not one of the
  2635  ** combinations shown above optionally combined with other
  2636  ** [SQLITE_OPEN_READONLY | SQLITE_OPEN_* bits]
  2637  ** then the behavior is undefined.
  2638  **
  2639  ** ^If the [SQLITE_OPEN_NOMUTEX] flag is set, then the database connection
  2640  ** opens in the multi-thread [threading mode] as long as the single-thread
  2641  ** mode has not been set at compile-time or start-time.  ^If the
  2642  ** [SQLITE_OPEN_FULLMUTEX] flag is set then the database connection opens
  2643  ** in the serialized [threading mode] unless single-thread was
  2644  ** previously selected at compile-time or start-time.
  2645  ** ^The [SQLITE_OPEN_SHAREDCACHE] flag causes the database connection to be
  2646  ** eligible to use [shared cache mode], regardless of whether or not shared
  2647  ** cache is enabled using [sqlite3_enable_shared_cache()].  ^The
  2648  ** [SQLITE_OPEN_PRIVATECACHE] flag causes the database connection to not
  2649  ** participate in [shared cache mode] even if it is enabled.
  2650  **
  2651  ** ^The fourth parameter to sqlite3_open_v2() is the name of the
  2652  ** [sqlite3_vfs] object that defines the operating system interface that
  2653  ** the new database connection should use.  ^If the fourth parameter is
  2654  ** a NULL pointer then the default [sqlite3_vfs] object is used.
  2655  **
  2656  ** ^If the filename is ":memory:", then a private, temporary in-memory database
  2657  ** is created for the connection.  ^This in-memory database will vanish when
  2658  ** the database connection is closed.  Future versions of SQLite might
  2659  ** make use of additional special filenames that begin with the ":" character.
  2660  ** It is recommended that when a database filename actually does begin with
  2661  ** a ":" character you should prefix the filename with a pathname such as
  2662  ** "./" to avoid ambiguity.
  2663  **
  2664  ** ^If the filename is an empty string, then a private, temporary
  2665  ** on-disk database will be created.  ^This private database will be
  2666  ** automatically deleted as soon as the database connection is closed.
  2667  **
  2668  ** [[URI filenames in sqlite3_open()]] <h3>URI Filenames</h3>
  2669  **
  2670  ** ^If [URI filename] interpretation is enabled, and the filename argument
  2671  ** begins with "file:", then the filename is interpreted as a URI. ^URI
  2672  ** filename interpretation is enabled if the [SQLITE_OPEN_URI] flag is
  2673  ** set in the fourth argument to sqlite3_open_v2(), or if it has
  2674  ** been enabled globally using the [SQLITE_CONFIG_URI] option with the
  2675  ** [sqlite3_config()] method or by the [SQLITE_USE_URI] compile-time option.
  2676  ** As of SQLite version 3.7.7, URI filename interpretation is turned off
  2677  ** by default, but future releases of SQLite might enable URI filename
  2678  ** interpretation by default.  See "[URI filenames]" for additional
  2679  ** information.
  2680  **
  2681  ** URI filenames are parsed according to RFC 3986. ^If the URI contains an
  2682  ** authority, then it must be either an empty string or the string 
  2683  ** "localhost". ^If the authority is not an empty string or "localhost", an 
  2684  ** error is returned to the caller. ^The fragment component of a URI, if 
  2685  ** present, is ignored.
  2686  **
  2687  ** ^SQLite uses the path component of the URI as the name of the disk file
  2688  ** which contains the database. ^If the path begins with a '/' character, 
  2689  ** then it is interpreted as an absolute path. ^If the path does not begin 
  2690  ** with a '/' (meaning that the authority section is omitted from the URI)
  2691  ** then the path is interpreted as a relative path. 
  2692  ** ^On windows, the first component of an absolute path 
  2693  ** is a drive specification (e.g. "C:").
  2694  **
  2695  ** [[core URI query parameters]]
  2696  ** The query component of a URI may contain parameters that are interpreted
  2697  ** either by SQLite itself, or by a [VFS | custom VFS implementation].
  2698  ** SQLite interprets the following three query parameters:
  2699  **
  2700  ** <ul>
  2701  **   <li> <b>vfs</b>: ^The "vfs" parameter may be used to specify the name of
  2702  **     a VFS object that provides the operating system interface that should
  2703  **     be used to access the database file on disk. ^If this option is set to
  2704  **     an empty string the default VFS object is used. ^Specifying an unknown
  2705  **     VFS is an error. ^If sqlite3_open_v2() is used and the vfs option is
  2706  **     present, then the VFS specified by the option takes precedence over
  2707  **     the value passed as the fourth parameter to sqlite3_open_v2().
  2708  **
  2709  **   <li> <b>mode</b>: ^(The mode parameter may be set to either "ro", "rw",
  2710  **     "rwc", or "memory". Attempting to set it to any other value is
  2711  **     an error)^. 
  2712  **     ^If "ro" is specified, then the database is opened for read-only 
  2713  **     access, just as if the [SQLITE_OPEN_READONLY] flag had been set in the 
  2714  **     third argument to sqlite3_open_v2(). ^If the mode option is set to 
  2715  **     "rw", then the database is opened for read-write (but not create) 
  2716  **     access, as if SQLITE_OPEN_READWRITE (but not SQLITE_OPEN_CREATE) had 
  2717  **     been set. ^Value "rwc" is equivalent to setting both 
  2718  **     SQLITE_OPEN_READWRITE and SQLITE_OPEN_CREATE.  ^If the mode option is
  2719  **     set to "memory" then a pure [in-memory database] that never reads
  2720  **     or writes from disk is used. ^It is an error to specify a value for
  2721  **     the mode parameter that is less restrictive than that specified by
  2722  **     the flags passed in the third parameter to sqlite3_open_v2().
  2723  **
  2724  **   <li> <b>cache</b>: ^The cache parameter may be set to either "shared" or
  2725  **     "private". ^Setting it to "shared" is equivalent to setting the
  2726  **     SQLITE_OPEN_SHAREDCACHE bit in the flags argument passed to
  2727  **     sqlite3_open_v2(). ^Setting the cache parameter to "private" is 
  2728  **     equivalent to setting the SQLITE_OPEN_PRIVATECACHE bit.
  2729  **     ^If sqlite3_open_v2() is used and the "cache" parameter is present in
  2730  **     a URI filename, its value overrides any behavior requested by setting
  2731  **     SQLITE_OPEN_PRIVATECACHE or SQLITE_OPEN_SHAREDCACHE flag.
  2732  ** </ul>
  2733  **
  2734  ** ^Specifying an unknown parameter in the query component of a URI is not an
  2735  ** error.  Future versions of SQLite might understand additional query
  2736  ** parameters.  See "[query parameters with special meaning to SQLite]" for
  2737  ** additional information.
  2738  **
  2739  ** [[URI filename examples]] <h3>URI filename examples</h3>
  2740  **
  2741  ** <table border="1" align=center cellpadding=5>
  2742  ** <tr><th> URI filenames <th> Results
  2743  ** <tr><td> file:data.db <td> 
  2744  **          Open the file "data.db" in the current directory.
  2745  ** <tr><td> file:/home/fred/data.db<br>
  2746  **          file:///home/fred/data.db <br> 
  2747  **          file://localhost/home/fred/data.db <br> <td> 
  2748  **          Open the database file "/home/fred/data.db".
  2749  ** <tr><td> file://darkstar/home/fred/data.db <td> 
  2750  **          An error. "darkstar" is not a recognized authority.
  2751  ** <tr><td style="white-space:nowrap"> 
  2752  **          file:///C:/Documents%20and%20Settings/fred/Desktop/data.db
  2753  **     <td> Windows only: Open the file "data.db" on fred's desktop on drive
  2754  **          C:. Note that the %20 escaping in this example is not strictly 
  2755  **          necessary - space characters can be used literally
  2756  **          in URI filenames.
  2757  ** <tr><td> file:data.db?mode=ro&cache=private <td> 
  2758  **          Open file "data.db" in the current directory for read-only access.
  2759  **          Regardless of whether or not shared-cache mode is enabled by
  2760  **          default, use a private cache.
  2761  ** <tr><td> file:/home/fred/data.db?vfs=unix-nolock <td>
  2762  **          Open file "/home/fred/data.db". Use the special VFS "unix-nolock".
  2763  ** <tr><td> file:data.db?mode=readonly <td> 
  2764  **          An error. "readonly" is not a valid option for the "mode" parameter.
  2765  ** </table>
  2766  **
  2767  ** ^URI hexadecimal escape sequences (%HH) are supported within the path and
  2768  ** query components of a URI. A hexadecimal escape sequence consists of a
  2769  ** percent sign - "%" - followed by exactly two hexadecimal digits 
  2770  ** specifying an octet value. ^Before the path or query components of a
  2771  ** URI filename are interpreted, they are encoded using UTF-8 and all 
  2772  ** hexadecimal escape sequences replaced by a single byte containing the
  2773  ** corresponding octet. If this process generates an invalid UTF-8 encoding,
  2774  ** the results are undefined.
  2775  **
  2776  ** <b>Note to Windows users:</b>  The encoding used for the filename argument
  2777  ** of sqlite3_open() and sqlite3_open_v2() must be UTF-8, not whatever
  2778  ** codepage is currently defined.  Filenames containing international
  2779  ** characters must be converted to UTF-8 prior to passing them into
  2780  ** sqlite3_open() or sqlite3_open_v2().
  2781  **
  2782  ** <b>Note to Windows Runtime users:</b>  The temporary directory must be set
  2783  ** prior to calling sqlite3_open() or sqlite3_open_v2().  Otherwise, various
  2784  ** features that require the use of temporary files may fail.
  2785  **
  2786  ** See also: [sqlite3_temp_directory]
  2787  */
  2788  SQLITE_API int sqlite3_open(
  2789    const char *filename,   /* Database filename (UTF-8) */
  2790    sqlite3 **ppDb          /* OUT: SQLite db handle */
  2791  );
  2792  SQLITE_API int sqlite3_open16(
  2793    const void *filename,   /* Database filename (UTF-16) */
  2794    sqlite3 **ppDb          /* OUT: SQLite db handle */
  2795  );
  2796  SQLITE_API int sqlite3_open_v2(
  2797    const char *filename,   /* Database filename (UTF-8) */
  2798    sqlite3 **ppDb,         /* OUT: SQLite db handle */
  2799    int flags,              /* Flags */
  2800    const char *zVfs        /* Name of VFS module to use */
  2801  );
  2802  
  2803  /*
  2804  ** CAPI3REF: Obtain Values For URI Parameters
  2805  **
  2806  ** These are utility routines, useful to VFS implementations, that check
  2807  ** to see if a database file was a URI that contained a specific query 
  2808  ** parameter, and if so obtains the value of that query parameter.
  2809  **
  2810  ** If F is the database filename pointer passed into the xOpen() method of 
  2811  ** a VFS implementation when the flags parameter to xOpen() has one or 
  2812  ** more of the [SQLITE_OPEN_URI] or [SQLITE_OPEN_MAIN_DB] bits set and
  2813  ** P is the name of the query parameter, then
  2814  ** sqlite3_uri_parameter(F,P) returns the value of the P
  2815  ** parameter if it exists or a NULL pointer if P does not appear as a 
  2816  ** query parameter on F.  If P is a query parameter of F
  2817  ** has no explicit value, then sqlite3_uri_parameter(F,P) returns
  2818  ** a pointer to an empty string.
  2819  **
  2820  ** The sqlite3_uri_boolean(F,P,B) routine assumes that P is a boolean
  2821  ** parameter and returns true (1) or false (0) according to the value
  2822  ** of P.  The sqlite3_uri_boolean(F,P,B) routine returns true (1) if the
  2823  ** value of query parameter P is one of "yes", "true", or "on" in any
  2824  ** case or if the value begins with a non-zero number.  The 
  2825  ** sqlite3_uri_boolean(F,P,B) routines returns false (0) if the value of
  2826  ** query parameter P is one of "no", "false", or "off" in any case or
  2827  ** if the value begins with a numeric zero.  If P is not a query
  2828  ** parameter on F or if the value of P is does not match any of the
  2829  ** above, then sqlite3_uri_boolean(F,P,B) returns (B!=0).
  2830  **
  2831  ** The sqlite3_uri_int64(F,P,D) routine converts the value of P into a
  2832  ** 64-bit signed integer and returns that integer, or D if P does not
  2833  ** exist.  If the value of P is something other than an integer, then
  2834  ** zero is returned.
  2835  ** 
  2836  ** If F is a NULL pointer, then sqlite3_uri_parameter(F,P) returns NULL and
  2837  ** sqlite3_uri_boolean(F,P,B) returns B.  If F is not a NULL pointer and
  2838  ** is not a database file pathname pointer that SQLite passed into the xOpen
  2839  ** VFS method, then the behavior of this routine is undefined and probably
  2840  ** undesirable.
  2841  */
  2842  SQLITE_API const char *sqlite3_uri_parameter(const char *zFilename, const char *zParam);
  2843  SQLITE_API int sqlite3_uri_boolean(const char *zFile, const char *zParam, int bDefault);
  2844  SQLITE_API sqlite3_int64 sqlite3_uri_int64(const char*, const char*, sqlite3_int64);
  2845  
  2846  
  2847  /*
  2848  ** CAPI3REF: Error Codes And Messages
  2849  **
  2850  ** ^The sqlite3_errcode() interface returns the numeric [result code] or
  2851  ** [extended result code] for the most recent failed sqlite3_* API call
  2852  ** associated with a [database connection]. If a prior API call failed
  2853  ** but the most recent API call succeeded, the return value from
  2854  ** sqlite3_errcode() is undefined.  ^The sqlite3_extended_errcode()
  2855  ** interface is the same except that it always returns the 
  2856  ** [extended result code] even when extended result codes are
  2857  ** disabled.
  2858  **
  2859  ** ^The sqlite3_errmsg() and sqlite3_errmsg16() return English-language
  2860  ** text that describes the error, as either UTF-8 or UTF-16 respectively.
  2861  ** ^(Memory to hold the error message string is managed internally.
  2862  ** The application does not need to worry about freeing the result.
  2863  ** However, the error string might be overwritten or deallocated by
  2864  ** subsequent calls to other SQLite interface functions.)^
  2865  **
  2866  ** ^The sqlite3_errstr() interface returns the English-language text
  2867  ** that describes the [result code], as UTF-8.
  2868  ** ^(Memory to hold the error message string is managed internally
  2869  ** and must not be freed by the application)^.
  2870  **
  2871  ** When the serialized [threading mode] is in use, it might be the
  2872  ** case that a second error occurs on a separate thread in between
  2873  ** the time of the first error and the call to these interfaces.
  2874  ** When that happens, the second error will be reported since these
  2875  ** interfaces always report the most recent result.  To avoid
  2876  ** this, each thread can obtain exclusive use of the [database connection] D
  2877  ** by invoking [sqlite3_mutex_enter]([sqlite3_db_mutex](D)) before beginning
  2878  ** to use D and invoking [sqlite3_mutex_leave]([sqlite3_db_mutex](D)) after
  2879  ** all calls to the interfaces listed here are completed.
  2880  **
  2881  ** If an interface fails with SQLITE_MISUSE, that means the interface
  2882  ** was invoked incorrectly by the application.  In that case, the
  2883  ** error code and message may or may not be set.
  2884  */
  2885  SQLITE_API int sqlite3_errcode(sqlite3 *db);
  2886  SQLITE_API int sqlite3_extended_errcode(sqlite3 *db);
  2887  SQLITE_API const char *sqlite3_errmsg(sqlite3*);
  2888  SQLITE_API const void *sqlite3_errmsg16(sqlite3*);
  2889  SQLITE_API const char *sqlite3_errstr(int);
  2890  
  2891  /*
  2892  ** CAPI3REF: SQL Statement Object
  2893  ** KEYWORDS: {prepared statement} {prepared statements}
  2894  **
  2895  ** An instance of this object represents a single SQL statement.
  2896  ** This object is variously known as a "prepared statement" or a
  2897  ** "compiled SQL statement" or simply as a "statement".
  2898  **
  2899  ** The life of a statement object goes something like this:
  2900  **
  2901  ** <ol>
  2902  ** <li> Create the object using [sqlite3_prepare_v2()] or a related
  2903  **      function.
  2904  ** <li> Bind values to [host parameters] using the sqlite3_bind_*()
  2905  **      interfaces.
  2906  ** <li> Run the SQL by calling [sqlite3_step()] one or more times.
  2907  ** <li> Reset the statement using [sqlite3_reset()] then go back
  2908  **      to step 2.  Do this zero or more times.
  2909  ** <li> Destroy the object using [sqlite3_finalize()].
  2910  ** </ol>
  2911  **
  2912  ** Refer to documentation on individual methods above for additional
  2913  ** information.
  2914  */
  2915  typedef struct sqlite3_stmt sqlite3_stmt;
  2916  
  2917  /*
  2918  ** CAPI3REF: Run-time Limits
  2919  **
  2920  ** ^(This interface allows the size of various constructs to be limited
  2921  ** on a connection by connection basis.  The first parameter is the
  2922  ** [database connection] whose limit is to be set or queried.  The
  2923  ** second parameter is one of the [limit categories] that define a
  2924  ** class of constructs to be size limited.  The third parameter is the
  2925  ** new limit for that construct.)^
  2926  **
  2927  ** ^If the new limit is a negative number, the limit is unchanged.
  2928  ** ^(For each limit category SQLITE_LIMIT_<i>NAME</i> there is a 
  2929  ** [limits | hard upper bound]
  2930  ** set at compile-time by a C preprocessor macro called
  2931  ** [limits | SQLITE_MAX_<i>NAME</i>].
  2932  ** (The "_LIMIT_" in the name is changed to "_MAX_".))^
  2933  ** ^Attempts to increase a limit above its hard upper bound are
  2934  ** silently truncated to the hard upper bound.
  2935  **
  2936  ** ^Regardless of whether or not the limit was changed, the 
  2937  ** [sqlite3_limit()] interface returns the prior value of the limit.
  2938  ** ^Hence, to find the current value of a limit without changing it,
  2939  ** simply invoke this interface with the third parameter set to -1.
  2940  **
  2941  ** Run-time limits are intended for use in applications that manage
  2942  ** both their own internal database and also databases that are controlled
  2943  ** by untrusted external sources.  An example application might be a
  2944  ** web browser that has its own databases for storing history and
  2945  ** separate databases controlled by JavaScript applications downloaded
  2946  ** off the Internet.  The internal databases can be given the
  2947  ** large, default limits.  Databases managed by external sources can
  2948  ** be given much smaller limits designed to prevent a denial of service
  2949  ** attack.  Developers might also want to use the [sqlite3_set_authorizer()]
  2950  ** interface to further control untrusted SQL.  The size of the database
  2951  ** created by an untrusted script can be contained using the
  2952  ** [max_page_count] [PRAGMA].
  2953  **
  2954  ** New run-time limit categories may be added in future releases.
  2955  */
  2956  SQLITE_API int sqlite3_limit(sqlite3*, int id, int newVal);
  2957  
  2958  /*
  2959  ** CAPI3REF: Run-Time Limit Categories
  2960  ** KEYWORDS: {limit category} {*limit categories}
  2961  **
  2962  ** These constants define various performance limits
  2963  ** that can be lowered at run-time using [sqlite3_limit()].
  2964  ** The synopsis of the meanings of the various limits is shown below.
  2965  ** Additional information is available at [limits | Limits in SQLite].
  2966  **
  2967  ** <dl>
  2968  ** [[SQLITE_LIMIT_LENGTH]] ^(<dt>SQLITE_LIMIT_LENGTH</dt>
  2969  ** <dd>The maximum size of any string or BLOB or table row, in bytes.<dd>)^
  2970  **
  2971  ** [[SQLITE_LIMIT_SQL_LENGTH]] ^(<dt>SQLITE_LIMIT_SQL_LENGTH</dt>
  2972  ** <dd>The maximum length of an SQL statement, in bytes.</dd>)^
  2973  **
  2974  ** [[SQLITE_LIMIT_COLUMN]] ^(<dt>SQLITE_LIMIT_COLUMN</dt>
  2975  ** <dd>The maximum number of columns in a table definition or in the
  2976  ** result set of a [SELECT] or the maximum number of columns in an index
  2977  ** or in an ORDER BY or GROUP BY clause.</dd>)^
  2978  **
  2979  ** [[SQLITE_LIMIT_EXPR_DEPTH]] ^(<dt>SQLITE_LIMIT_EXPR_DEPTH</dt>
  2980  ** <dd>The maximum depth of the parse tree on any expression.</dd>)^
  2981  **
  2982  ** [[SQLITE_LIMIT_COMPOUND_SELECT]] ^(<dt>SQLITE_LIMIT_COMPOUND_SELECT</dt>
  2983  ** <dd>The maximum number of terms in a compound SELECT statement.</dd>)^
  2984  **
  2985  ** [[SQLITE_LIMIT_VDBE_OP]] ^(<dt>SQLITE_LIMIT_VDBE_OP</dt>
  2986  ** <dd>The maximum number of instructions in a virtual machine program
  2987  ** used to implement an SQL statement.  This limit is not currently
  2988  ** enforced, though that might be added in some future release of
  2989  ** SQLite.</dd>)^
  2990  **
  2991  ** [[SQLITE_LIMIT_FUNCTION_ARG]] ^(<dt>SQLITE_LIMIT_FUNCTION_ARG</dt>
  2992  ** <dd>The maximum number of arguments on a function.</dd>)^
  2993  **
  2994  ** [[SQLITE_LIMIT_ATTACHED]] ^(<dt>SQLITE_LIMIT_ATTACHED</dt>
  2995  ** <dd>The maximum number of [ATTACH | attached databases].)^</dd>
  2996  **
  2997  ** [[SQLITE_LIMIT_LIKE_PATTERN_LENGTH]]
  2998  ** ^(<dt>SQLITE_LIMIT_LIKE_PATTERN_LENGTH</dt>
  2999  ** <dd>The maximum length of the pattern argument to the [LIKE] or
  3000  ** [GLOB] operators.</dd>)^
  3001  **
  3002  ** [[SQLITE_LIMIT_VARIABLE_NUMBER]]
  3003  ** ^(<dt>SQLITE_LIMIT_VARIABLE_NUMBER</dt>
  3004  ** <dd>The maximum index number of any [parameter] in an SQL statement.)^
  3005  **
  3006  ** [[SQLITE_LIMIT_TRIGGER_DEPTH]] ^(<dt>SQLITE_LIMIT_TRIGGER_DEPTH</dt>
  3007  ** <dd>The maximum depth of recursion for triggers.</dd>)^
  3008  ** </dl>
  3009  */
  3010  #define SQLITE_LIMIT_LENGTH                    0
  3011  #define SQLITE_LIMIT_SQL_LENGTH                1
  3012  #define SQLITE_LIMIT_COLUMN                    2
  3013  #define SQLITE_LIMIT_EXPR_DEPTH                3
  3014  #define SQLITE_LIMIT_COMPOUND_SELECT           4
  3015  #define SQLITE_LIMIT_VDBE_OP                   5
  3016  #define SQLITE_LIMIT_FUNCTION_ARG              6
  3017  #define SQLITE_LIMIT_ATTACHED                  7
  3018  #define SQLITE_LIMIT_LIKE_PATTERN_LENGTH       8
  3019  #define SQLITE_LIMIT_VARIABLE_NUMBER           9
  3020  #define SQLITE_LIMIT_TRIGGER_DEPTH            10
  3021  
  3022  /*
  3023  ** CAPI3REF: Compiling An SQL Statement
  3024  ** KEYWORDS: {SQL statement compiler}
  3025  **
  3026  ** To execute an SQL query, it must first be compiled into a byte-code
  3027  ** program using one of these routines.
  3028  **
  3029  ** The first argument, "db", is a [database connection] obtained from a
  3030  ** prior successful call to [sqlite3_open()], [sqlite3_open_v2()] or
  3031  ** [sqlite3_open16()].  The database connection must not have been closed.
  3032  **
  3033  ** The second argument, "zSql", is the statement to be compiled, encoded
  3034  ** as either UTF-8 or UTF-16.  The sqlite3_prepare() and sqlite3_prepare_v2()
  3035  ** interfaces use UTF-8, and sqlite3_prepare16() and sqlite3_prepare16_v2()
  3036  ** use UTF-16.
  3037  **
  3038  ** ^If the nByte argument is less than zero, then zSql is read up to the
  3039  ** first zero terminator. ^If nByte is non-negative, then it is the maximum
  3040  ** number of  bytes read from zSql.  ^When nByte is non-negative, the
  3041  ** zSql string ends at either the first '\000' or '\u0000' character or
  3042  ** the nByte-th byte, whichever comes first. If the caller knows
  3043  ** that the supplied string is nul-terminated, then there is a small
  3044  ** performance advantage to be gained by passing an nByte parameter that
  3045  ** is equal to the number of bytes in the input string <i>including</i>
  3046  ** the nul-terminator bytes as this saves SQLite from having to
  3047  ** make a copy of the input string.
  3048  **
  3049  ** ^If pzTail is not NULL then *pzTail is made to point to the first byte
  3050  ** past the end of the first SQL statement in zSql.  These routines only
  3051  ** compile the first statement in zSql, so *pzTail is left pointing to
  3052  ** what remains uncompiled.
  3053  **
  3054  ** ^*ppStmt is left pointing to a compiled [prepared statement] that can be
  3055  ** executed using [sqlite3_step()].  ^If there is an error, *ppStmt is set
  3056  ** to NULL.  ^If the input text contains no SQL (if the input is an empty
  3057  ** string or a comment) then *ppStmt is set to NULL.
  3058  ** The calling procedure is responsible for deleting the compiled
  3059  ** SQL statement using [sqlite3_finalize()] after it has finished with it.
  3060  ** ppStmt may not be NULL.
  3061  **
  3062  ** ^On success, the sqlite3_prepare() family of routines return [SQLITE_OK];
  3063  ** otherwise an [error code] is returned.
  3064  **
  3065  ** The sqlite3_prepare_v2() and sqlite3_prepare16_v2() interfaces are
  3066  ** recommended for all new programs. The two older interfaces are retained
  3067  ** for backwards compatibility, but their use is discouraged.
  3068  ** ^In the "v2" interfaces, the prepared statement
  3069  ** that is returned (the [sqlite3_stmt] object) contains a copy of the
  3070  ** original SQL text. This causes the [sqlite3_step()] interface to
  3071  ** behave differently in three ways:
  3072  **
  3073  ** <ol>
  3074  ** <li>
  3075  ** ^If the database schema changes, instead of returning [SQLITE_SCHEMA] as it
  3076  ** always used to do, [sqlite3_step()] will automatically recompile the SQL
  3077  ** statement and try to run it again. As many as [SQLITE_MAX_SCHEMA_RETRY]
  3078  ** retries will occur before sqlite3_step() gives up and returns an error.
  3079  ** </li>
  3080  **
  3081  ** <li>
  3082  ** ^When an error occurs, [sqlite3_step()] will return one of the detailed
  3083  ** [error codes] or [extended error codes].  ^The legacy behavior was that
  3084  ** [sqlite3_step()] would only return a generic [SQLITE_ERROR] result code
  3085  ** and the application would have to make a second call to [sqlite3_reset()]
  3086  ** in order to find the underlying cause of the problem. With the "v2" prepare
  3087  ** interfaces, the underlying reason for the error is returned immediately.
  3088  ** </li>
  3089  **
  3090  ** <li>
  3091  ** ^If the specific value bound to [parameter | host parameter] in the 
  3092  ** WHERE clause might influence the choice of query plan for a statement,
  3093  ** then the statement will be automatically recompiled, as if there had been 
  3094  ** a schema change, on the first  [sqlite3_step()] call following any change
  3095  ** to the [sqlite3_bind_text | bindings] of that [parameter]. 
  3096  ** ^The specific value of WHERE-clause [parameter] might influence the 
  3097  ** choice of query plan if the parameter is the left-hand side of a [LIKE]
  3098  ** or [GLOB] operator or if the parameter is compared to an indexed column
  3099  ** and the [SQLITE_ENABLE_STAT3] compile-time option is enabled.
  3100  ** the 
  3101  ** </li>
  3102  ** </ol>
  3103  */
  3104  SQLITE_API int sqlite3_prepare(
  3105    sqlite3 *db,            /* Database handle */
  3106    const char *zSql,       /* SQL statement, UTF-8 encoded */
  3107    int nByte,              /* Maximum length of zSql in bytes. */
  3108    sqlite3_stmt **ppStmt,  /* OUT: Statement handle */
  3109    const char **pzTail     /* OUT: Pointer to unused portion of zSql */
  3110  );
  3111  SQLITE_API int sqlite3_prepare_v2(
  3112    sqlite3 *db,            /* Database handle */
  3113    const char *zSql,       /* SQL statement, UTF-8 encoded */
  3114    int nByte,              /* Maximum length of zSql in bytes. */
  3115    sqlite3_stmt **ppStmt,  /* OUT: Statement handle */
  3116    const char **pzTail     /* OUT: Pointer to unused portion of zSql */
  3117  );
  3118  SQLITE_API int sqlite3_prepare16(
  3119    sqlite3 *db,            /* Database handle */
  3120    const void *zSql,       /* SQL statement, UTF-16 encoded */
  3121    int nByte,              /* Maximum length of zSql in bytes. */
  3122    sqlite3_stmt **ppStmt,  /* OUT: Statement handle */
  3123    const void **pzTail     /* OUT: Pointer to unused portion of zSql */
  3124  );
  3125  SQLITE_API int sqlite3_prepare16_v2(
  3126    sqlite3 *db,            /* Database handle */
  3127    const void *zSql,       /* SQL statement, UTF-16 encoded */
  3128    int nByte,              /* Maximum length of zSql in bytes. */
  3129    sqlite3_stmt **ppStmt,  /* OUT: Statement handle */
  3130    const void **pzTail     /* OUT: Pointer to unused portion of zSql */
  3131  );
  3132  
  3133  /*
  3134  ** CAPI3REF: Retrieving Statement SQL
  3135  **
  3136  ** ^This interface can be used to retrieve a saved copy of the original
  3137  ** SQL text used to create a [prepared statement] if that statement was
  3138  ** compiled using either [sqlite3_prepare_v2()] or [sqlite3_prepare16_v2()].
  3139  */
  3140  SQLITE_API const char *sqlite3_sql(sqlite3_stmt *pStmt);
  3141  
  3142  /*
  3143  ** CAPI3REF: Determine If An SQL Statement Writes The Database
  3144  **
  3145  ** ^The sqlite3_stmt_readonly(X) interface returns true (non-zero) if
  3146  ** and only if the [prepared statement] X makes no direct changes to
  3147  ** the content of the database file.
  3148  **
  3149  ** Note that [application-defined SQL functions] or
  3150  ** [virtual tables] might change the database indirectly as a side effect.  
  3151  ** ^(For example, if an application defines a function "eval()" that 
  3152  ** calls [sqlite3_exec()], then the following SQL statement would
  3153  ** change the database file through side-effects:
  3154  **
  3155  ** <blockquote><pre>
  3156  **    SELECT eval('DELETE FROM t1') FROM t2;
  3157  ** </pre></blockquote>
  3158  **
  3159  ** But because the [SELECT] statement does not change the database file
  3160  ** directly, sqlite3_stmt_readonly() would still return true.)^
  3161  **
  3162  ** ^Transaction control statements such as [BEGIN], [COMMIT], [ROLLBACK],
  3163  ** [SAVEPOINT], and [RELEASE] cause sqlite3_stmt_readonly() to return true,
  3164  ** since the statements themselves do not actually modify the database but
  3165  ** rather they control the timing of when other statements modify the 
  3166  ** database.  ^The [ATTACH] and [DETACH] statements also cause
  3167  ** sqlite3_stmt_readonly() to return true since, while those statements
  3168  ** change the configuration of a database connection, they do not make 
  3169  ** changes to the content of the database files on disk.
  3170  */
  3171  SQLITE_API int sqlite3_stmt_readonly(sqlite3_stmt *pStmt);
  3172  
  3173  /*
  3174  ** CAPI3REF: Determine If A Prepared Statement Has Been Reset
  3175  **
  3176  ** ^The sqlite3_stmt_busy(S) interface returns true (non-zero) if the
  3177  ** [prepared statement] S has been stepped at least once using 
  3178  ** [sqlite3_step(S)] but has not run to completion and/or has not 
  3179  ** been reset using [sqlite3_reset(S)].  ^The sqlite3_stmt_busy(S)
  3180  ** interface returns false if S is a NULL pointer.  If S is not a 
  3181  ** NULL pointer and is not a pointer to a valid [prepared statement]
  3182  ** object, then the behavior is undefined and probably undesirable.
  3183  **
  3184  ** This interface can be used in combination [sqlite3_next_stmt()]
  3185  ** to locate all prepared statements associated with a database 
  3186  ** connection that are in need of being reset.  This can be used,
  3187  ** for example, in diagnostic routines to search for prepared 
  3188  ** statements that are holding a transaction open.
  3189  */
  3190  SQLITE_API int sqlite3_stmt_busy(sqlite3_stmt*);
  3191  
  3192  /*
  3193  ** CAPI3REF: Dynamically Typed Value Object
  3194  ** KEYWORDS: {protected sqlite3_value} {unprotected sqlite3_value}
  3195  **
  3196  ** SQLite uses the sqlite3_value object to represent all values
  3197  ** that can be stored in a database table. SQLite uses dynamic typing
  3198  ** for the values it stores.  ^Values stored in sqlite3_value objects
  3199  ** can be integers, floating point values, strings, BLOBs, or NULL.
  3200  **
  3201  ** An sqlite3_value object may be either "protected" or "unprotected".
  3202  ** Some interfaces require a protected sqlite3_value.  Other interfaces
  3203  ** will accept either a protected or an unprotected sqlite3_value.
  3204  ** Every interface that accepts sqlite3_value arguments specifies
  3205  ** whether or not it requires a protected sqlite3_value.
  3206  **
  3207  ** The terms "protected" and "unprotected" refer to whether or not
  3208  ** a mutex is held.  An internal mutex is held for a protected
  3209  ** sqlite3_value object but no mutex is held for an unprotected
  3210  ** sqlite3_value object.  If SQLite is compiled to be single-threaded
  3211  ** (with [SQLITE_THREADSAFE=0] and with [sqlite3_threadsafe()] returning 0)
  3212  ** or if SQLite is run in one of reduced mutex modes 
  3213  ** [SQLITE_CONFIG_SINGLETHREAD] or [SQLITE_CONFIG_MULTITHREAD]
  3214  ** then there is no distinction between protected and unprotected
  3215  ** sqlite3_value objects and they can be used interchangeably.  However,
  3216  ** for maximum code portability it is recommended that applications
  3217  ** still make the distinction between protected and unprotected
  3218  ** sqlite3_value objects even when not strictly required.
  3219  **
  3220  ** ^The sqlite3_value objects that are passed as parameters into the
  3221  ** implementation of [application-defined SQL functions] are protected.
  3222  ** ^The sqlite3_value object returned by
  3223  ** [sqlite3_column_value()] is unprotected.
  3224  ** Unprotected sqlite3_value objects may only be used with
  3225  ** [sqlite3_result_value()] and [sqlite3_bind_value()].
  3226  ** The [sqlite3_value_blob | sqlite3_value_type()] family of
  3227  ** interfaces require protected sqlite3_value objects.
  3228  */
  3229  typedef struct Mem sqlite3_value;
  3230  
  3231  /*
  3232  ** CAPI3REF: SQL Function Context Object
  3233  **
  3234  ** The context in which an SQL function executes is stored in an
  3235  ** sqlite3_context object.  ^A pointer to an sqlite3_context object
  3236  ** is always first parameter to [application-defined SQL functions].
  3237  ** The application-defined SQL function implementation will pass this
  3238  ** pointer through into calls to [sqlite3_result_int | sqlite3_result()],
  3239  ** [sqlite3_aggregate_context()], [sqlite3_user_data()],
  3240  ** [sqlite3_context_db_handle()], [sqlite3_get_auxdata()],
  3241  ** and/or [sqlite3_set_auxdata()].
  3242  */
  3243  typedef struct sqlite3_context sqlite3_context;
  3244  
  3245  /*
  3246  ** CAPI3REF: Binding Values To Prepared Statements
  3247  ** KEYWORDS: {host parameter} {host parameters} {host parameter name}
  3248  ** KEYWORDS: {SQL parameter} {SQL parameters} {parameter binding}
  3249  **
  3250  ** ^(In the SQL statement text input to [sqlite3_prepare_v2()] and its variants,
  3251  ** literals may be replaced by a [parameter] that matches one of following
  3252  ** templates:
  3253  **
  3254  ** <ul>
  3255  ** <li>  ?
  3256  ** <li>  ?NNN
  3257  ** <li>  :VVV
  3258  ** <li>  @VVV
  3259  ** <li>  $VVV
  3260  ** </ul>
  3261  **
  3262  ** In the templates above, NNN represents an integer literal,
  3263  ** and VVV represents an alphanumeric identifier.)^  ^The values of these
  3264  ** parameters (also called "host parameter names" or "SQL parameters")
  3265  ** can be set using the sqlite3_bind_*() routines defined here.
  3266  **
  3267  ** ^The first argument to the sqlite3_bind_*() routines is always
  3268  ** a pointer to the [sqlite3_stmt] object returned from
  3269  ** [sqlite3_prepare_v2()] or its variants.
  3270  **
  3271  ** ^The second argument is the index of the SQL parameter to be set.
  3272  ** ^The leftmost SQL parameter has an index of 1.  ^When the same named
  3273  ** SQL parameter is used more than once, second and subsequent
  3274  ** occurrences have the same index as the first occurrence.
  3275  ** ^The index for named parameters can be looked up using the
  3276  ** [sqlite3_bind_parameter_index()] API if desired.  ^The index
  3277  ** for "?NNN" parameters is the value of NNN.
  3278  ** ^The NNN value must be between 1 and the [sqlite3_limit()]
  3279  ** parameter [SQLITE_LIMIT_VARIABLE_NUMBER] (default value: 999).
  3280  **
  3281  ** ^The third argument is the value to bind to the parameter.
  3282  ** ^If the third parameter to sqlite3_bind_text() or sqlite3_bind_text16()
  3283  ** or sqlite3_bind_blob() is a NULL pointer then the fourth parameter
  3284  ** is ignored and the end result is the same as sqlite3_bind_null().
  3285  **
  3286  ** ^(In those routines that have a fourth argument, its value is the
  3287  ** number of bytes in the parameter.  To be clear: the value is the
  3288  ** number of <u>bytes</u> in the value, not the number of characters.)^
  3289  ** ^If the fourth parameter to sqlite3_bind_text() or sqlite3_bind_text16()
  3290  ** is negative, then the length of the string is
  3291  ** the number of bytes up to the first zero terminator.
  3292  ** If the fourth parameter to sqlite3_bind_blob() is negative, then
  3293  ** the behavior is undefined.
  3294  ** If a non-negative fourth parameter is provided to sqlite3_bind_text()
  3295  ** or sqlite3_bind_text16() then that parameter must be the byte offset
  3296  ** where the NUL terminator would occur assuming the string were NUL
  3297  ** terminated.  If any NUL characters occur at byte offsets less than 
  3298  ** the value of the fourth parameter then the resulting string value will
  3299  ** contain embedded NULs.  The result of expressions involving strings
  3300  ** with embedded NULs is undefined.
  3301  **
  3302  ** ^The fifth argument to sqlite3_bind_blob(), sqlite3_bind_text(), and
  3303  ** sqlite3_bind_text16() is a destructor used to dispose of the BLOB or
  3304  ** string after SQLite has finished with it.  ^The destructor is called
  3305  ** to dispose of the BLOB or string even if the call to sqlite3_bind_blob(),
  3306  ** sqlite3_bind_text(), or sqlite3_bind_text16() fails.  
  3307  ** ^If the fifth argument is
  3308  ** the special value [SQLITE_STATIC], then SQLite assumes that the
  3309  ** information is in static, unmanaged space and does not need to be freed.
  3310  ** ^If the fifth argument has the value [SQLITE_TRANSIENT], then
  3311  ** SQLite makes its own private copy of the data immediately, before
  3312  ** the sqlite3_bind_*() routine returns.
  3313  **
  3314  ** ^The sqlite3_bind_zeroblob() routine binds a BLOB of length N that
  3315  ** is filled with zeroes.  ^A zeroblob uses a fixed amount of memory
  3316  ** (just an integer to hold its size) while it is being processed.
  3317  ** Zeroblobs are intended to serve as placeholders for BLOBs whose
  3318  ** content is later written using
  3319  ** [sqlite3_blob_open | incremental BLOB I/O] routines.
  3320  ** ^A negative value for the zeroblob results in a zero-length BLOB.
  3321  **
  3322  ** ^If any of the sqlite3_bind_*() routines are called with a NULL pointer
  3323  ** for the [prepared statement] or with a prepared statement for which
  3324  ** [sqlite3_step()] has been called more recently than [sqlite3_reset()],
  3325  ** then the call will return [SQLITE_MISUSE].  If any sqlite3_bind_()
  3326  ** routine is passed a [prepared statement] that has been finalized, the
  3327  ** result is undefined and probably harmful.
  3328  **
  3329  ** ^Bindings are not cleared by the [sqlite3_reset()] routine.
  3330  ** ^Unbound parameters are interpreted as NULL.
  3331  **
  3332  ** ^The sqlite3_bind_* routines return [SQLITE_OK] on success or an
  3333  ** [error code] if anything goes wrong.
  3334  ** ^[SQLITE_RANGE] is returned if the parameter
  3335  ** index is out of range.  ^[SQLITE_NOMEM] is returned if malloc() fails.
  3336  **
  3337  ** See also: [sqlite3_bind_parameter_count()],
  3338  ** [sqlite3_bind_parameter_name()], and [sqlite3_bind_parameter_index()].
  3339  */
  3340  SQLITE_API int sqlite3_bind_blob(sqlite3_stmt*, int, const void*, int n, void(*)(void*));
  3341  SQLITE_API int sqlite3_bind_double(sqlite3_stmt*, int, double);
  3342  SQLITE_API int sqlite3_bind_int(sqlite3_stmt*, int, int);
  3343  SQLITE_API int sqlite3_bind_int64(sqlite3_stmt*, int, sqlite3_int64);
  3344  SQLITE_API int sqlite3_bind_null(sqlite3_stmt*, int);
  3345  SQLITE_API int sqlite3_bind_text(sqlite3_stmt*, int, const char*, int n, void(*)(void*));
  3346  SQLITE_API int sqlite3_bind_text16(sqlite3_stmt*, int, const void*, int, void(*)(void*));
  3347  SQLITE_API int sqlite3_bind_value(sqlite3_stmt*, int, const sqlite3_value*);
  3348  SQLITE_API int sqlite3_bind_zeroblob(sqlite3_stmt*, int, int n);
  3349  
  3350  /*
  3351  ** CAPI3REF: Number Of SQL Parameters
  3352  **
  3353  ** ^This routine can be used to find the number of [SQL parameters]
  3354  ** in a [prepared statement].  SQL parameters are tokens of the
  3355  ** form "?", "?NNN", ":AAA", "$AAA", or "@AAA" that serve as
  3356  ** placeholders for values that are [sqlite3_bind_blob | bound]
  3357  ** to the parameters at a later time.
  3358  **
  3359  ** ^(This routine actually returns the index of the largest (rightmost)
  3360  ** parameter. For all forms except ?NNN, this will correspond to the
  3361  ** number of unique parameters.  If parameters of the ?NNN form are used,
  3362  ** there may be gaps in the list.)^
  3363  **
  3364  ** See also: [sqlite3_bind_blob|sqlite3_bind()],
  3365  ** [sqlite3_bind_parameter_name()], and
  3366  ** [sqlite3_bind_parameter_index()].
  3367  */
  3368  SQLITE_API int sqlite3_bind_parameter_count(sqlite3_stmt*);
  3369  
  3370  /*
  3371  ** CAPI3REF: Name Of A Host Parameter
  3372  **
  3373  ** ^The sqlite3_bind_parameter_name(P,N) interface returns
  3374  ** the name of the N-th [SQL parameter] in the [prepared statement] P.
  3375  ** ^(SQL parameters of the form "?NNN" or ":AAA" or "@AAA" or "$AAA"
  3376  ** have a name which is the string "?NNN" or ":AAA" or "@AAA" or "$AAA"
  3377  ** respectively.
  3378  ** In other words, the initial ":" or "$" or "@" or "?"
  3379  ** is included as part of the name.)^
  3380  ** ^Parameters of the form "?" without a following integer have no name
  3381  ** and are referred to as "nameless" or "anonymous parameters".
  3382  **
  3383  ** ^The first host parameter has an index of 1, not 0.
  3384  **
  3385  ** ^If the value N is out of range or if the N-th parameter is
  3386  ** nameless, then NULL is returned.  ^The returned string is
  3387  ** always in UTF-8 encoding even if the named parameter was
  3388  ** originally specified as UTF-16 in [sqlite3_prepare16()] or
  3389  ** [sqlite3_prepare16_v2()].
  3390  **
  3391  ** See also: [sqlite3_bind_blob|sqlite3_bind()],
  3392  ** [sqlite3_bind_parameter_count()], and
  3393  ** [sqlite3_bind_parameter_index()].
  3394  */
  3395  SQLITE_API const char *sqlite3_bind_parameter_name(sqlite3_stmt*, int);
  3396  
  3397  /*
  3398  ** CAPI3REF: Index Of A Parameter With A Given Name
  3399  **
  3400  ** ^Return the index of an SQL parameter given its name.  ^The
  3401  ** index value returned is suitable for use as the second
  3402  ** parameter to [sqlite3_bind_blob|sqlite3_bind()].  ^A zero
  3403  ** is returned if no matching parameter is found.  ^The parameter
  3404  ** name must be given in UTF-8 even if the original statement
  3405  ** was prepared from UTF-16 text using [sqlite3_prepare16_v2()].
  3406  **
  3407  ** See also: [sqlite3_bind_blob|sqlite3_bind()],
  3408  ** [sqlite3_bind_parameter_count()], and
  3409  ** [sqlite3_bind_parameter_index()].
  3410  */
  3411  SQLITE_API int sqlite3_bind_parameter_index(sqlite3_stmt*, const char *zName);
  3412  
  3413  /*
  3414  ** CAPI3REF: Reset All Bindings On A Prepared Statement
  3415  **
  3416  ** ^Contrary to the intuition of many, [sqlite3_reset()] does not reset
  3417  ** the [sqlite3_bind_blob | bindings] on a [prepared statement].
  3418  ** ^Use this routine to reset all host parameters to NULL.
  3419  */
  3420  SQLITE_API int sqlite3_clear_bindings(sqlite3_stmt*);
  3421  
  3422  /*
  3423  ** CAPI3REF: Number Of Columns In A Result Set
  3424  **
  3425  ** ^Return the number of columns in the result set returned by the
  3426  ** [prepared statement]. ^This routine returns 0 if pStmt is an SQL
  3427  ** statement that does not return data (for example an [UPDATE]).
  3428  **
  3429  ** See also: [sqlite3_data_count()]
  3430  */
  3431  SQLITE_API int sqlite3_column_count(sqlite3_stmt *pStmt);
  3432  
  3433  /*
  3434  ** CAPI3REF: Column Names In A Result Set
  3435  **
  3436  ** ^These routines return the name assigned to a particular column
  3437  ** in the result set of a [SELECT] statement.  ^The sqlite3_column_name()
  3438  ** interface returns a pointer to a zero-terminated UTF-8 string
  3439  ** and sqlite3_column_name16() returns a pointer to a zero-terminated
  3440  ** UTF-16 string.  ^The first parameter is the [prepared statement]
  3441  ** that implements the [SELECT] statement. ^The second parameter is the
  3442  ** column number.  ^The leftmost column is number 0.
  3443  **
  3444  ** ^The returned string pointer is valid until either the [prepared statement]
  3445  ** is destroyed by [sqlite3_finalize()] or until the statement is automatically
  3446  ** reprepared by the first call to [sqlite3_step()] for a particular run
  3447  ** or until the next call to
  3448  ** sqlite3_column_name() or sqlite3_column_name16() on the same column.
  3449  **
  3450  ** ^If sqlite3_malloc() fails during the processing of either routine
  3451  ** (for example during a conversion from UTF-8 to UTF-16) then a
  3452  ** NULL pointer is returned.
  3453  **
  3454  ** ^The name of a result column is the value of the "AS" clause for
  3455  ** that column, if there is an AS clause.  If there is no AS clause
  3456  ** then the name of the column is unspecified and may change from
  3457  ** one release of SQLite to the next.
  3458  */
  3459  SQLITE_API const char *sqlite3_column_name(sqlite3_stmt*, int N);
  3460  SQLITE_API const void *sqlite3_column_name16(sqlite3_stmt*, int N);
  3461  
  3462  /*
  3463  ** CAPI3REF: Source Of Data In A Query Result
  3464  **
  3465  ** ^These routines provide a means to determine the database, table, and
  3466  ** table column that is the origin of a particular result column in
  3467  ** [SELECT] statement.
  3468  ** ^The name of the database or table or column can be returned as
  3469  ** either a UTF-8 or UTF-16 string.  ^The _database_ routines return
  3470  ** the database name, the _table_ routines return the table name, and
  3471  ** the origin_ routines return the column name.
  3472  ** ^The returned string is valid until the [prepared statement] is destroyed
  3473  ** using [sqlite3_finalize()] or until the statement is automatically
  3474  ** reprepared by the first call to [sqlite3_step()] for a particular run
  3475  ** or until the same information is requested
  3476  ** again in a different encoding.
  3477  **
  3478  ** ^The names returned are the original un-aliased names of the
  3479  ** database, table, and column.
  3480  **
  3481  ** ^The first argument to these interfaces is a [prepared statement].
  3482  ** ^These functions return information about the Nth result column returned by
  3483  ** the statement, where N is the second function argument.
  3484  ** ^The left-most column is column 0 for these routines.
  3485  **
  3486  ** ^If the Nth column returned by the statement is an expression or
  3487  ** subquery and is not a column value, then all of these functions return
  3488  ** NULL.  ^These routine might also return NULL if a memory allocation error
  3489  ** occurs.  ^Otherwise, they return the name of the attached database, table,
  3490  ** or column that query result column was extracted from.
  3491  **
  3492  ** ^As with all other SQLite APIs, those whose names end with "16" return
  3493  ** UTF-16 encoded strings and the other functions return UTF-8.
  3494  **
  3495  ** ^These APIs are only available if the library was compiled with the
  3496  ** [SQLITE_ENABLE_COLUMN_METADATA] C-preprocessor symbol.
  3497  **
  3498  ** If two or more threads call one or more of these routines against the same
  3499  ** prepared statement and column at the same time then the results are
  3500  ** undefined.
  3501  **
  3502  ** If two or more threads call one or more
  3503  ** [sqlite3_column_database_name | column metadata interfaces]
  3504  ** for the same [prepared statement] and result column
  3505  ** at the same time then the results are undefined.
  3506  */
  3507  SQLITE_API const char *sqlite3_column_database_name(sqlite3_stmt*,int);
  3508  SQLITE_API const void *sqlite3_column_database_name16(sqlite3_stmt*,int);
  3509  SQLITE_API const char *sqlite3_column_table_name(sqlite3_stmt*,int);
  3510  SQLITE_API const void *sqlite3_column_table_name16(sqlite3_stmt*,int);
  3511  SQLITE_API const char *sqlite3_column_origin_name(sqlite3_stmt*,int);
  3512  SQLITE_API const void *sqlite3_column_origin_name16(sqlite3_stmt*,int);
  3513  
  3514  /*
  3515  ** CAPI3REF: Declared Datatype Of A Query Result
  3516  **
  3517  ** ^(The first parameter is a [prepared statement].
  3518  ** If this statement is a [SELECT] statement and the Nth column of the
  3519  ** returned result set of that [SELECT] is a table column (not an
  3520  ** expression or subquery) then the declared type of the table
  3521  ** column is returned.)^  ^If the Nth column of the result set is an
  3522  ** expression or subquery, then a NULL pointer is returned.
  3523  ** ^The returned string is always UTF-8 encoded.
  3524  **
  3525  ** ^(For example, given the database schema:
  3526  **
  3527  ** CREATE TABLE t1(c1 VARIANT);
  3528  **
  3529  ** and the following statement to be compiled:
  3530  **
  3531  ** SELECT c1 + 1, c1 FROM t1;
  3532  **
  3533  ** this routine would return the string "VARIANT" for the second result
  3534  ** column (i==1), and a NULL pointer for the first result column (i==0).)^
  3535  **
  3536  ** ^SQLite uses dynamic run-time typing.  ^So just because a column
  3537  ** is declared to contain a particular type does not mean that the
  3538  ** data stored in that column is of the declared type.  SQLite is
  3539  ** strongly typed, but the typing is dynamic not static.  ^Type
  3540  ** is associated with individual values, not with the containers
  3541  ** used to hold those values.
  3542  */
  3543  SQLITE_API const char *sqlite3_column_decltype(sqlite3_stmt*,int);
  3544  SQLITE_API const void *sqlite3_column_decltype16(sqlite3_stmt*,int);
  3545  
  3546  /*
  3547  ** CAPI3REF: Evaluate An SQL Statement
  3548  **
  3549  ** After a [prepared statement] has been prepared using either
  3550  ** [sqlite3_prepare_v2()] or [sqlite3_prepare16_v2()] or one of the legacy
  3551  ** interfaces [sqlite3_prepare()] or [sqlite3_prepare16()], this function
  3552  ** must be called one or more times to evaluate the statement.
  3553  **
  3554  ** The details of the behavior of the sqlite3_step() interface depend
  3555  ** on whether the statement was prepared using the newer "v2" interface
  3556  ** [sqlite3_prepare_v2()] and [sqlite3_prepare16_v2()] or the older legacy
  3557  ** interface [sqlite3_prepare()] and [sqlite3_prepare16()].  The use of the
  3558  ** new "v2" interface is recommended for new applications but the legacy
  3559  ** interface will continue to be supported.
  3560  **
  3561  ** ^In the legacy interface, the return value will be either [SQLITE_BUSY],
  3562  ** [SQLITE_DONE], [SQLITE_ROW], [SQLITE_ERROR], or [SQLITE_MISUSE].
  3563  ** ^With the "v2" interface, any of the other [result codes] or
  3564  ** [extended result codes] might be returned as well.
  3565  **
  3566  ** ^[SQLITE_BUSY] means that the database engine was unable to acquire the
  3567  ** database locks it needs to do its job.  ^If the statement is a [COMMIT]
  3568  ** or occurs outside of an explicit transaction, then you can retry the
  3569  ** statement.  If the statement is not a [COMMIT] and occurs within an
  3570  ** explicit transaction then you should rollback the transaction before
  3571  ** continuing.
  3572  **
  3573  ** ^[SQLITE_DONE] means that the statement has finished executing
  3574  ** successfully.  sqlite3_step() should not be called again on this virtual
  3575  ** machine without first calling [sqlite3_reset()] to reset the virtual
  3576  ** machine back to its initial state.
  3577  **
  3578  ** ^If the SQL statement being executed returns any data, then [SQLITE_ROW]
  3579  ** is returned each time a new row of data is ready for processing by the
  3580  ** caller. The values may be accessed using the [column access functions].
  3581  ** sqlite3_step() is called again to retrieve the next row of data.
  3582  **
  3583  ** ^[SQLITE_ERROR] means that a run-time error (such as a constraint
  3584  ** violation) has occurred.  sqlite3_step() should not be called again on
  3585  ** the VM. More information may be found by calling [sqlite3_errmsg()].
  3586  ** ^With the legacy interface, a more specific error code (for example,
  3587  ** [SQLITE_INTERRUPT], [SQLITE_SCHEMA], [SQLITE_CORRUPT], and so forth)
  3588  ** can be obtained by calling [sqlite3_reset()] on the
  3589  ** [prepared statement].  ^In the "v2" interface,
  3590  ** the more specific error code is returned directly by sqlite3_step().
  3591  **
  3592  ** [SQLITE_MISUSE] means that the this routine was called inappropriately.
  3593  ** Perhaps it was called on a [prepared statement] that has
  3594  ** already been [sqlite3_finalize | finalized] or on one that had
  3595  ** previously returned [SQLITE_ERROR] or [SQLITE_DONE].  Or it could
  3596  ** be the case that the same database connection is being used by two or
  3597  ** more threads at the same moment in time.
  3598  **
  3599  ** For all versions of SQLite up to and including 3.6.23.1, a call to
  3600  ** [sqlite3_reset()] was required after sqlite3_step() returned anything
  3601  ** other than [SQLITE_ROW] before any subsequent invocation of
  3602  ** sqlite3_step().  Failure to reset the prepared statement using 
  3603  ** [sqlite3_reset()] would result in an [SQLITE_MISUSE] return from
  3604  ** sqlite3_step().  But after version 3.6.23.1, sqlite3_step() began
  3605  ** calling [sqlite3_reset()] automatically in this circumstance rather
  3606  ** than returning [SQLITE_MISUSE].  This is not considered a compatibility
  3607  ** break because any application that ever receives an SQLITE_MISUSE error
  3608  ** is broken by definition.  The [SQLITE_OMIT_AUTORESET] compile-time option
  3609  ** can be used to restore the legacy behavior.
  3610  **
  3611  ** <b>Goofy Interface Alert:</b> In the legacy interface, the sqlite3_step()
  3612  ** API always returns a generic error code, [SQLITE_ERROR], following any
  3613  ** error other than [SQLITE_BUSY] and [SQLITE_MISUSE].  You must call
  3614  ** [sqlite3_reset()] or [sqlite3_finalize()] in order to find one of the
  3615  ** specific [error codes] that better describes the error.
  3616  ** We admit that this is a goofy design.  The problem has been fixed
  3617  ** with the "v2" interface.  If you prepare all of your SQL statements
  3618  ** using either [sqlite3_prepare_v2()] or [sqlite3_prepare16_v2()] instead
  3619  ** of the legacy [sqlite3_prepare()] and [sqlite3_prepare16()] interfaces,
  3620  ** then the more specific [error codes] are returned directly
  3621  ** by sqlite3_step().  The use of the "v2" interface is recommended.
  3622  */
  3623  SQLITE_API int sqlite3_step(sqlite3_stmt*);
  3624  
  3625  /*
  3626  ** CAPI3REF: Number of columns in a result set
  3627  **
  3628  ** ^The sqlite3_data_count(P) interface returns the number of columns in the
  3629  ** current row of the result set of [prepared statement] P.
  3630  ** ^If prepared statement P does not have results ready to return
  3631  ** (via calls to the [sqlite3_column_int | sqlite3_column_*()] of
  3632  ** interfaces) then sqlite3_data_count(P) returns 0.
  3633  ** ^The sqlite3_data_count(P) routine also returns 0 if P is a NULL pointer.
  3634  ** ^The sqlite3_data_count(P) routine returns 0 if the previous call to
  3635  ** [sqlite3_step](P) returned [SQLITE_DONE].  ^The sqlite3_data_count(P)
  3636  ** will return non-zero if previous call to [sqlite3_step](P) returned
  3637  ** [SQLITE_ROW], except in the case of the [PRAGMA incremental_vacuum]
  3638  ** where it always returns zero since each step of that multi-step
  3639  ** pragma returns 0 columns of data.
  3640  **
  3641  ** See also: [sqlite3_column_count()]
  3642  */
  3643  SQLITE_API int sqlite3_data_count(sqlite3_stmt *pStmt);
  3644  
  3645  /*
  3646  ** CAPI3REF: Fundamental Datatypes
  3647  ** KEYWORDS: SQLITE_TEXT
  3648  **
  3649  ** ^(Every value in SQLite has one of five fundamental datatypes:
  3650  **
  3651  ** <ul>
  3652  ** <li> 64-bit signed integer
  3653  ** <li> 64-bit IEEE floating point number
  3654  ** <li> string
  3655  ** <li> BLOB
  3656  ** <li> NULL
  3657  ** </ul>)^
  3658  **
  3659  ** These constants are codes for each of those types.
  3660  **
  3661  ** Note that the SQLITE_TEXT constant was also used in SQLite version 2
  3662  ** for a completely different meaning.  Software that links against both
  3663  ** SQLite version 2 and SQLite version 3 should use SQLITE3_TEXT, not
  3664  ** SQLITE_TEXT.
  3665  */
  3666  #define SQLITE_INTEGER  1
  3667  #define SQLITE_FLOAT    2
  3668  #define SQLITE_BLOB     4
  3669  #define SQLITE_NULL     5
  3670  #ifdef SQLITE_TEXT
  3671  # undef SQLITE_TEXT
  3672  #else
  3673  # define SQLITE_TEXT     3
  3674  #endif
  3675  #define SQLITE3_TEXT     3
  3676  
  3677  /*
  3678  ** CAPI3REF: Result Values From A Query
  3679  ** KEYWORDS: {column access functions}
  3680  **
  3681  ** These routines form the "result set" interface.
  3682  **
  3683  ** ^These routines return information about a single column of the current
  3684  ** result row of a query.  ^In every case the first argument is a pointer
  3685  ** to the [prepared statement] that is being evaluated (the [sqlite3_stmt*]
  3686  ** that was returned from [sqlite3_prepare_v2()] or one of its variants)
  3687  ** and the second argument is the index of the column for which information
  3688  ** should be returned. ^The leftmost column of the result set has the index 0.
  3689  ** ^The number of columns in the result can be determined using
  3690  ** [sqlite3_column_count()].
  3691  **
  3692  ** If the SQL statement does not currently point to a valid row, or if the
  3693  ** column index is out of range, the result is undefined.
  3694  ** These routines may only be called when the most recent call to
  3695  ** [sqlite3_step()] has returned [SQLITE_ROW] and neither
  3696  ** [sqlite3_reset()] nor [sqlite3_finalize()] have been called subsequently.
  3697  ** If any of these routines are called after [sqlite3_reset()] or
  3698  ** [sqlite3_finalize()] or after [sqlite3_step()] has returned
  3699  ** something other than [SQLITE_ROW], the results are undefined.
  3700  ** If [sqlite3_step()] or [sqlite3_reset()] or [sqlite3_finalize()]
  3701  ** are called from a different thread while any of these routines
  3702  ** are pending, then the results are undefined.
  3703  **
  3704  ** ^The sqlite3_column_type() routine returns the
  3705  ** [SQLITE_INTEGER | datatype code] for the initial data type
  3706  ** of the result column.  ^The returned value is one of [SQLITE_INTEGER],
  3707  ** [SQLITE_FLOAT], [SQLITE_TEXT], [SQLITE_BLOB], or [SQLITE_NULL].  The value
  3708  ** returned by sqlite3_column_type() is only meaningful if no type
  3709  ** conversions have occurred as described below.  After a type conversion,
  3710  ** the value returned by sqlite3_column_type() is undefined.  Future
  3711  ** versions of SQLite may change the behavior of sqlite3_column_type()
  3712  ** following a type conversion.
  3713  **
  3714  ** ^If the result is a BLOB or UTF-8 string then the sqlite3_column_bytes()
  3715  ** routine returns the number of bytes in that BLOB or string.
  3716  ** ^If the result is a UTF-16 string, then sqlite3_column_bytes() converts
  3717  ** the string to UTF-8 and then returns the number of bytes.
  3718  ** ^If the result is a numeric value then sqlite3_column_bytes() uses
  3719  ** [sqlite3_snprintf()] to convert that value to a UTF-8 string and returns
  3720  ** the number of bytes in that string.
  3721  ** ^If the result is NULL, then sqlite3_column_bytes() returns zero.
  3722  **
  3723  ** ^If the result is a BLOB or UTF-16 string then the sqlite3_column_bytes16()
  3724  ** routine returns the number of bytes in that BLOB or string.
  3725  ** ^If the result is a UTF-8 string, then sqlite3_column_bytes16() converts
  3726  ** the string to UTF-16 and then returns the number of bytes.
  3727  ** ^If the result is a numeric value then sqlite3_column_bytes16() uses
  3728  ** [sqlite3_snprintf()] to convert that value to a UTF-16 string and returns
  3729  ** the number of bytes in that string.
  3730  ** ^If the result is NULL, then sqlite3_column_bytes16() returns zero.
  3731  **
  3732  ** ^The values returned by [sqlite3_column_bytes()] and 
  3733  ** [sqlite3_column_bytes16()] do not include the zero terminators at the end
  3734  ** of the string.  ^For clarity: the values returned by
  3735  ** [sqlite3_column_bytes()] and [sqlite3_column_bytes16()] are the number of
  3736  ** bytes in the string, not the number of characters.
  3737  **
  3738  ** ^Strings returned by sqlite3_column_text() and sqlite3_column_text16(),
  3739  ** even empty strings, are always zero-terminated.  ^The return
  3740  ** value from sqlite3_column_blob() for a zero-length BLOB is a NULL pointer.
  3741  **
  3742  ** ^The object returned by [sqlite3_column_value()] is an
  3743  ** [unprotected sqlite3_value] object.  An unprotected sqlite3_value object
  3744  ** may only be used with [sqlite3_bind_value()] and [sqlite3_result_value()].
  3745  ** If the [unprotected sqlite3_value] object returned by
  3746  ** [sqlite3_column_value()] is used in any other way, including calls
  3747  ** to routines like [sqlite3_value_int()], [sqlite3_value_text()],
  3748  ** or [sqlite3_value_bytes()], then the behavior is undefined.
  3749  **
  3750  ** These routines attempt to convert the value where appropriate.  ^For
  3751  ** example, if the internal representation is FLOAT and a text result
  3752  ** is requested, [sqlite3_snprintf()] is used internally to perform the
  3753  ** conversion automatically.  ^(The following table details the conversions
  3754  ** that are applied:
  3755  **
  3756  ** <blockquote>
  3757  ** <table border="1">
  3758  ** <tr><th> Internal<br>Type <th> Requested<br>Type <th>  Conversion
  3759  **
  3760  ** <tr><td>  NULL    <td> INTEGER   <td> Result is 0
  3761  ** <tr><td>  NULL    <td>  FLOAT    <td> Result is 0.0
  3762  ** <tr><td>  NULL    <td>   TEXT    <td> Result is NULL pointer
  3763  ** <tr><td>  NULL    <td>   BLOB    <td> Result is NULL pointer
  3764  ** <tr><td> INTEGER  <td>  FLOAT    <td> Convert from integer to float
  3765  ** <tr><td> INTEGER  <td>   TEXT    <td> ASCII rendering of the integer
  3766  ** <tr><td> INTEGER  <td>   BLOB    <td> Same as INTEGER->TEXT
  3767  ** <tr><td>  FLOAT   <td> INTEGER   <td> Convert from float to integer
  3768  ** <tr><td>  FLOAT   <td>   TEXT    <td> ASCII rendering of the float
  3769  ** <tr><td>  FLOAT   <td>   BLOB    <td> Same as FLOAT->TEXT
  3770  ** <tr><td>  TEXT    <td> INTEGER   <td> Use atoi()
  3771  ** <tr><td>  TEXT    <td>  FLOAT    <td> Use atof()
  3772  ** <tr><td>  TEXT    <td>   BLOB    <td> No change
  3773  ** <tr><td>  BLOB    <td> INTEGER   <td> Convert to TEXT then use atoi()
  3774  ** <tr><td>  BLOB    <td>  FLOAT    <td> Convert to TEXT then use atof()
  3775  ** <tr><td>  BLOB    <td>   TEXT    <td> Add a zero terminator if needed
  3776  ** </table>
  3777  ** </blockquote>)^
  3778  **
  3779  ** The table above makes reference to standard C library functions atoi()
  3780  ** and atof().  SQLite does not really use these functions.  It has its
  3781  ** own equivalent internal routines.  The atoi() and atof() names are
  3782  ** used in the table for brevity and because they are familiar to most
  3783  ** C programmers.
  3784  **
  3785  ** Note that when type conversions occur, pointers returned by prior
  3786  ** calls to sqlite3_column_blob(), sqlite3_column_text(), and/or
  3787  ** sqlite3_column_text16() may be invalidated.
  3788  ** Type conversions and pointer invalidations might occur
  3789  ** in the following cases:
  3790  **
  3791  ** <ul>
  3792  ** <li> The initial content is a BLOB and sqlite3_column_text() or
  3793  **      sqlite3_column_text16() is called.  A zero-terminator might
  3794  **      need to be added to the string.</li>
  3795  ** <li> The initial content is UTF-8 text and sqlite3_column_bytes16() or
  3796  **      sqlite3_column_text16() is called.  The content must be converted
  3797  **      to UTF-16.</li>
  3798  ** <li> The initial content is UTF-16 text and sqlite3_column_bytes() or
  3799  **      sqlite3_column_text() is called.  The content must be converted
  3800  **      to UTF-8.</li>
  3801  ** </ul>
  3802  **
  3803  ** ^Conversions between UTF-16be and UTF-16le are always done in place and do
  3804  ** not invalidate a prior pointer, though of course the content of the buffer
  3805  ** that the prior pointer references will have been modified.  Other kinds
  3806  ** of conversion are done in place when it is possible, but sometimes they
  3807  ** are not possible and in those cases prior pointers are invalidated.
  3808  **
  3809  ** The safest and easiest to remember policy is to invoke these routines
  3810  ** in one of the following ways:
  3811  **
  3812  ** <ul>
  3813  **  <li>sqlite3_column_text() followed by sqlite3_column_bytes()</li>
  3814  **  <li>sqlite3_column_blob() followed by sqlite3_column_bytes()</li>
  3815  **  <li>sqlite3_column_text16() followed by sqlite3_column_bytes16()</li>
  3816  ** </ul>
  3817  **
  3818  ** In other words, you should call sqlite3_column_text(),
  3819  ** sqlite3_column_blob(), or sqlite3_column_text16() first to force the result
  3820  ** into the desired format, then invoke sqlite3_column_bytes() or
  3821  ** sqlite3_column_bytes16() to find the size of the result.  Do not mix calls
  3822  ** to sqlite3_column_text() or sqlite3_column_blob() with calls to
  3823  ** sqlite3_column_bytes16(), and do not mix calls to sqlite3_column_text16()
  3824  ** with calls to sqlite3_column_bytes().
  3825  **
  3826  ** ^The pointers returned are valid until a type conversion occurs as
  3827  ** described above, or until [sqlite3_step()] or [sqlite3_reset()] or
  3828  ** [sqlite3_finalize()] is called.  ^The memory space used to hold strings
  3829  ** and BLOBs is freed automatically.  Do <b>not</b> pass the pointers returned
  3830  ** [sqlite3_column_blob()], [sqlite3_column_text()], etc. into
  3831  ** [sqlite3_free()].
  3832  **
  3833  ** ^(If a memory allocation error occurs during the evaluation of any
  3834  ** of these routines, a default value is returned.  The default value
  3835  ** is either the integer 0, the floating point number 0.0, or a NULL
  3836  ** pointer.  Subsequent calls to [sqlite3_errcode()] will return
  3837  ** [SQLITE_NOMEM].)^
  3838  */
  3839  SQLITE_API const void *sqlite3_column_blob(sqlite3_stmt*, int iCol);
  3840  SQLITE_API int sqlite3_column_bytes(sqlite3_stmt*, int iCol);
  3841  SQLITE_API int sqlite3_column_bytes16(sqlite3_stmt*, int iCol);
  3842  SQLITE_API double sqlite3_column_double(sqlite3_stmt*, int iCol);
  3843  SQLITE_API int sqlite3_column_int(sqlite3_stmt*, int iCol);
  3844  SQLITE_API sqlite3_int64 sqlite3_column_int64(sqlite3_stmt*, int iCol);
  3845  SQLITE_API const unsigned char *sqlite3_column_text(sqlite3_stmt*, int iCol);
  3846  SQLITE_API const void *sqlite3_column_text16(sqlite3_stmt*, int iCol);
  3847  SQLITE_API int sqlite3_column_type(sqlite3_stmt*, int iCol);
  3848  SQLITE_API sqlite3_value *sqlite3_column_value(sqlite3_stmt*, int iCol);
  3849  
  3850  /*
  3851  ** CAPI3REF: Destroy A Prepared Statement Object
  3852  **
  3853  ** ^The sqlite3_finalize() function is called to delete a [prepared statement].
  3854  ** ^If the most recent evaluation of the statement encountered no errors
  3855  ** or if the statement is never been evaluated, then sqlite3_finalize() returns
  3856  ** SQLITE_OK.  ^If the most recent evaluation of statement S failed, then
  3857  ** sqlite3_finalize(S) returns the appropriate [error code] or
  3858  ** [extended error code].
  3859  **
  3860  ** ^The sqlite3_finalize(S) routine can be called at any point during
  3861  ** the life cycle of [prepared statement] S:
  3862  ** before statement S is ever evaluated, after
  3863  ** one or more calls to [sqlite3_reset()], or after any call
  3864  ** to [sqlite3_step()] regardless of whether or not the statement has
  3865  ** completed execution.
  3866  **
  3867  ** ^Invoking sqlite3_finalize() on a NULL pointer is a harmless no-op.
  3868  **
  3869  ** The application must finalize every [prepared statement] in order to avoid
  3870  ** resource leaks.  It is a grievous error for the application to try to use
  3871  ** a prepared statement after it has been finalized.  Any use of a prepared
  3872  ** statement after it has been finalized can result in undefined and
  3873  ** undesirable behavior such as segfaults and heap corruption.
  3874  */
  3875  SQLITE_API int sqlite3_finalize(sqlite3_stmt *pStmt);
  3876  
  3877  /*
  3878  ** CAPI3REF: Reset A Prepared Statement Object
  3879  **
  3880  ** The sqlite3_reset() function is called to reset a [prepared statement]
  3881  ** object back to its initial state, ready to be re-executed.
  3882  ** ^Any SQL statement variables that had values bound to them using
  3883  ** the [sqlite3_bind_blob | sqlite3_bind_*() API] retain their values.
  3884  ** Use [sqlite3_clear_bindings()] to reset the bindings.
  3885  **
  3886  ** ^The [sqlite3_reset(S)] interface resets the [prepared statement] S
  3887  ** back to the beginning of its program.
  3888  **
  3889  ** ^If the most recent call to [sqlite3_step(S)] for the
  3890  ** [prepared statement] S returned [SQLITE_ROW] or [SQLITE_DONE],
  3891  ** or if [sqlite3_step(S)] has never before been called on S,
  3892  ** then [sqlite3_reset(S)] returns [SQLITE_OK].
  3893  **
  3894  ** ^If the most recent call to [sqlite3_step(S)] for the
  3895  ** [prepared statement] S indicated an error, then
  3896  ** [sqlite3_reset(S)] returns an appropriate [error code].
  3897  **
  3898  ** ^The [sqlite3_reset(S)] interface does not change the values
  3899  ** of any [sqlite3_bind_blob|bindings] on the [prepared statement] S.
  3900  */
  3901  SQLITE_API int sqlite3_reset(sqlite3_stmt *pStmt);
  3902  
  3903  /*
  3904  ** CAPI3REF: Create Or Redefine SQL Functions
  3905  ** KEYWORDS: {function creation routines}
  3906  ** KEYWORDS: {application-defined SQL function}
  3907  ** KEYWORDS: {application-defined SQL functions}
  3908  **
  3909  ** ^These functions (collectively known as "function creation routines")
  3910  ** are used to add SQL functions or aggregates or to redefine the behavior
  3911  ** of existing SQL functions or aggregates.  The only differences between
  3912  ** these routines are the text encoding expected for
  3913  ** the second parameter (the name of the function being created)
  3914  ** and the presence or absence of a destructor callback for
  3915  ** the application data pointer.
  3916  **
  3917  ** ^The first parameter is the [database connection] to which the SQL
  3918  ** function is to be added.  ^If an application uses more than one database
  3919  ** connection then application-defined SQL functions must be added
  3920  ** to each database connection separately.
  3921  **
  3922  ** ^The second parameter is the name of the SQL function to be created or
  3923  ** redefined.  ^The length of the name is limited to 255 bytes in a UTF-8
  3924  ** representation, exclusive of the zero-terminator.  ^Note that the name
  3925  ** length limit is in UTF-8 bytes, not characters nor UTF-16 bytes.  
  3926  ** ^Any attempt to create a function with a longer name
  3927  ** will result in [SQLITE_MISUSE] being returned.
  3928  **
  3929  ** ^The third parameter (nArg)
  3930  ** is the number of arguments that the SQL function or
  3931  ** aggregate takes. ^If this parameter is -1, then the SQL function or
  3932  ** aggregate may take any number of arguments between 0 and the limit
  3933  ** set by [sqlite3_limit]([SQLITE_LIMIT_FUNCTION_ARG]).  If the third
  3934  ** parameter is less than -1 or greater than 127 then the behavior is
  3935  ** undefined.
  3936  **
  3937  ** ^The fourth parameter, eTextRep, specifies what
  3938  ** [SQLITE_UTF8 | text encoding] this SQL function prefers for
  3939  ** its parameters.  Every SQL function implementation must be able to work
  3940  ** with UTF-8, UTF-16le, or UTF-16be.  But some implementations may be
  3941  ** more efficient with one encoding than another.  ^An application may
  3942  ** invoke sqlite3_create_function() or sqlite3_create_function16() multiple
  3943  ** times with the same function but with different values of eTextRep.
  3944  ** ^When multiple implementations of the same function are available, SQLite
  3945  ** will pick the one that involves the least amount of data conversion.
  3946  ** If there is only a single implementation which does not care what text
  3947  ** encoding is used, then the fourth argument should be [SQLITE_ANY].
  3948  **
  3949  ** ^(The fifth parameter is an arbitrary pointer.  The implementation of the
  3950  ** function can gain access to this pointer using [sqlite3_user_data()].)^
  3951  **
  3952  ** ^The sixth, seventh and eighth parameters, xFunc, xStep and xFinal, are
  3953  ** pointers to C-language functions that implement the SQL function or
  3954  ** aggregate. ^A scalar SQL function requires an implementation of the xFunc
  3955  ** callback only; NULL pointers must be passed as the xStep and xFinal
  3956  ** parameters. ^An aggregate SQL function requires an implementation of xStep
  3957  ** and xFinal and NULL pointer must be passed for xFunc. ^To delete an existing
  3958  ** SQL function or aggregate, pass NULL pointers for all three function
  3959  ** callbacks.
  3960  **
  3961  ** ^(If the ninth parameter to sqlite3_create_function_v2() is not NULL,
  3962  ** then it is destructor for the application data pointer. 
  3963  ** The destructor is invoked when the function is deleted, either by being
  3964  ** overloaded or when the database connection closes.)^
  3965  ** ^The destructor is also invoked if the call to
  3966  ** sqlite3_create_function_v2() fails.
  3967  ** ^When the destructor callback of the tenth parameter is invoked, it
  3968  ** is passed a single argument which is a copy of the application data 
  3969  ** pointer which was the fifth parameter to sqlite3_create_function_v2().
  3970  **
  3971  ** ^It is permitted to register multiple implementations of the same
  3972  ** functions with the same name but with either differing numbers of
  3973  ** arguments or differing preferred text encodings.  ^SQLite will use
  3974  ** the implementation that most closely matches the way in which the
  3975  ** SQL function is used.  ^A function implementation with a non-negative
  3976  ** nArg parameter is a better match than a function implementation with
  3977  ** a negative nArg.  ^A function where the preferred text encoding
  3978  ** matches the database encoding is a better
  3979  ** match than a function where the encoding is different.  
  3980  ** ^A function where the encoding difference is between UTF16le and UTF16be
  3981  ** is a closer match than a function where the encoding difference is
  3982  ** between UTF8 and UTF16.
  3983  **
  3984  ** ^Built-in functions may be overloaded by new application-defined functions.
  3985  **
  3986  ** ^An application-defined function is permitted to call other
  3987  ** SQLite interfaces.  However, such calls must not
  3988  ** close the database connection nor finalize or reset the prepared
  3989  ** statement in which the function is running.
  3990  */
  3991  SQLITE_API int sqlite3_create_function(
  3992    sqlite3 *db,
  3993    const char *zFunctionName,
  3994    int nArg,
  3995    int eTextRep,
  3996    void *pApp,
  3997    void (*xFunc)(sqlite3_context*,int,sqlite3_value**),
  3998    void (*xStep)(sqlite3_context*,int,sqlite3_value**),
  3999    void (*xFinal)(sqlite3_context*)
  4000  );
  4001  SQLITE_API int sqlite3_create_function16(
  4002    sqlite3 *db,
  4003    const void *zFunctionName,
  4004    int nArg,
  4005    int eTextRep,
  4006    void *pApp,
  4007    void (*xFunc)(sqlite3_context*,int,sqlite3_value**),
  4008    void (*xStep)(sqlite3_context*,int,sqlite3_value**),
  4009    void (*xFinal)(sqlite3_context*)
  4010  );
  4011  SQLITE_API int sqlite3_create_function_v2(
  4012    sqlite3 *db,
  4013    const char *zFunctionName,
  4014    int nArg,
  4015    int eTextRep,
  4016    void *pApp,
  4017    void (*xFunc)(sqlite3_context*,int,sqlite3_value**),
  4018    void (*xStep)(sqlite3_context*,int,sqlite3_value**),
  4019    void (*xFinal)(sqlite3_context*),
  4020    void(*xDestroy)(void*)
  4021  );
  4022  
  4023  /*
  4024  ** CAPI3REF: Text Encodings
  4025  **
  4026  ** These constant define integer codes that represent the various
  4027  ** text encodings supported by SQLite.
  4028  */
  4029  #define SQLITE_UTF8           1
  4030  #define SQLITE_UTF16LE        2
  4031  #define SQLITE_UTF16BE        3
  4032  #define SQLITE_UTF16          4    /* Use native byte order */
  4033  #define SQLITE_ANY            5    /* sqlite3_create_function only */
  4034  #define SQLITE_UTF16_ALIGNED  8    /* sqlite3_create_collation only */
  4035  
  4036  /*
  4037  ** CAPI3REF: Deprecated Functions
  4038  ** DEPRECATED
  4039  **
  4040  ** These functions are [deprecated].  In order to maintain
  4041  ** backwards compatibility with older code, these functions continue 
  4042  ** to be supported.  However, new applications should avoid
  4043  ** the use of these functions.  To help encourage people to avoid
  4044  ** using these functions, we are not going to tell you what they do.
  4045  */
  4046  #ifndef SQLITE_OMIT_DEPRECATED
  4047  SQLITE_API SQLITE_DEPRECATED int sqlite3_aggregate_count(sqlite3_context*);
  4048  SQLITE_API SQLITE_DEPRECATED int sqlite3_expired(sqlite3_stmt*);
  4049  SQLITE_API SQLITE_DEPRECATED int sqlite3_transfer_bindings(sqlite3_stmt*, sqlite3_stmt*);
  4050  SQLITE_API SQLITE_DEPRECATED int sqlite3_global_recover(void);
  4051  SQLITE_API SQLITE_DEPRECATED void sqlite3_thread_cleanup(void);
  4052  SQLITE_API SQLITE_DEPRECATED int sqlite3_memory_alarm(void(*)(void*,sqlite3_int64,int),
  4053                        void*,sqlite3_int64);
  4054  #endif
  4055  
  4056  /*
  4057  ** CAPI3REF: Obtaining SQL Function Parameter Values
  4058  **
  4059  ** The C-language implementation of SQL functions and aggregates uses
  4060  ** this set of interface routines to access the parameter values on
  4061  ** the function or aggregate.
  4062  **
  4063  ** The xFunc (for scalar functions) or xStep (for aggregates) parameters
  4064  ** to [sqlite3_create_function()] and [sqlite3_create_function16()]
  4065  ** define callbacks that implement the SQL functions and aggregates.
  4066  ** The 3rd parameter to these callbacks is an array of pointers to
  4067  ** [protected sqlite3_value] objects.  There is one [sqlite3_value] object for
  4068  ** each parameter to the SQL function.  These routines are used to
  4069  ** extract values from the [sqlite3_value] objects.
  4070  **
  4071  ** These routines work only with [protected sqlite3_value] objects.
  4072  ** Any attempt to use these routines on an [unprotected sqlite3_value]
  4073  ** object results in undefined behavior.
  4074  **
  4075  ** ^These routines work just like the corresponding [column access functions]
  4076  ** except that  these routines take a single [protected sqlite3_value] object
  4077  ** pointer instead of a [sqlite3_stmt*] pointer and an integer column number.
  4078  **
  4079  ** ^The sqlite3_value_text16() interface extracts a UTF-16 string
  4080  ** in the native byte-order of the host machine.  ^The
  4081  ** sqlite3_value_text16be() and sqlite3_value_text16le() interfaces
  4082  ** extract UTF-16 strings as big-endian and little-endian respectively.
  4083  **
  4084  ** ^(The sqlite3_value_numeric_type() interface attempts to apply
  4085  ** numeric affinity to the value.  This means that an attempt is
  4086  ** made to convert the value to an integer or floating point.  If
  4087  ** such a conversion is possible without loss of information (in other
  4088  ** words, if the value is a string that looks like a number)
  4089  ** then the conversion is performed.  Otherwise no conversion occurs.
  4090  ** The [SQLITE_INTEGER | datatype] after conversion is returned.)^
  4091  **
  4092  ** Please pay particular attention to the fact that the pointer returned
  4093  ** from [sqlite3_value_blob()], [sqlite3_value_text()], or
  4094  ** [sqlite3_value_text16()] can be invalidated by a subsequent call to
  4095  ** [sqlite3_value_bytes()], [sqlite3_value_bytes16()], [sqlite3_value_text()],
  4096  ** or [sqlite3_value_text16()].
  4097  **
  4098  ** These routines must be called from the same thread as
  4099  ** the SQL function that supplied the [sqlite3_value*] parameters.
  4100  */
  4101  SQLITE_API const void *sqlite3_value_blob(sqlite3_value*);
  4102  SQLITE_API int sqlite3_value_bytes(sqlite3_value*);
  4103  SQLITE_API int sqlite3_value_bytes16(sqlite3_value*);
  4104  SQLITE_API double sqlite3_value_double(sqlite3_value*);
  4105  SQLITE_API int sqlite3_value_int(sqlite3_value*);
  4106  SQLITE_API sqlite3_int64 sqlite3_value_int64(sqlite3_value*);
  4107  SQLITE_API const unsigned char *sqlite3_value_text(sqlite3_value*);
  4108  SQLITE_API const void *sqlite3_value_text16(sqlite3_value*);
  4109  SQLITE_API const void *sqlite3_value_text16le(sqlite3_value*);
  4110  SQLITE_API const void *sqlite3_value_text16be(sqlite3_value*);
  4111  SQLITE_API int sqlite3_value_type(sqlite3_value*);
  4112  SQLITE_API int sqlite3_value_numeric_type(sqlite3_value*);
  4113  
  4114  /*
  4115  ** CAPI3REF: Obtain Aggregate Function Context
  4116  **
  4117  ** Implementations of aggregate SQL functions use this
  4118  ** routine to allocate memory for storing their state.
  4119  **
  4120  ** ^The first time the sqlite3_aggregate_context(C,N) routine is called 
  4121  ** for a particular aggregate function, SQLite
  4122  ** allocates N of memory, zeroes out that memory, and returns a pointer
  4123  ** to the new memory. ^On second and subsequent calls to
  4124  ** sqlite3_aggregate_context() for the same aggregate function instance,
  4125  ** the same buffer is returned.  Sqlite3_aggregate_context() is normally
  4126  ** called once for each invocation of the xStep callback and then one
  4127  ** last time when the xFinal callback is invoked.  ^(When no rows match
  4128  ** an aggregate query, the xStep() callback of the aggregate function
  4129  ** implementation is never called and xFinal() is called exactly once.
  4130  ** In those cases, sqlite3_aggregate_context() might be called for the
  4131  ** first time from within xFinal().)^
  4132  **
  4133  ** ^The sqlite3_aggregate_context(C,N) routine returns a NULL pointer 
  4134  ** when first called if N is less than or equal to zero or if a memory
  4135  ** allocate error occurs.
  4136  **
  4137  ** ^(The amount of space allocated by sqlite3_aggregate_context(C,N) is
  4138  ** determined by the N parameter on first successful call.  Changing the
  4139  ** value of N in subsequent call to sqlite3_aggregate_context() within
  4140  ** the same aggregate function instance will not resize the memory
  4141  ** allocation.)^  Within the xFinal callback, it is customary to set
  4142  ** N=0 in calls to sqlite3_aggregate_context(C,N) so that no 
  4143  ** pointless memory allocations occur.
  4144  **
  4145  ** ^SQLite automatically frees the memory allocated by 
  4146  ** sqlite3_aggregate_context() when the aggregate query concludes.
  4147  **
  4148  ** The first parameter must be a copy of the
  4149  ** [sqlite3_context | SQL function context] that is the first parameter
  4150  ** to the xStep or xFinal callback routine that implements the aggregate
  4151  ** function.
  4152  **
  4153  ** This routine must be called from the same thread in which
  4154  ** the aggregate SQL function is running.
  4155  */
  4156  SQLITE_API void *sqlite3_aggregate_context(sqlite3_context*, int nBytes);
  4157  
  4158  /*
  4159  ** CAPI3REF: User Data For Functions
  4160  **
  4161  ** ^The sqlite3_user_data() interface returns a copy of
  4162  ** the pointer that was the pUserData parameter (the 5th parameter)
  4163  ** of the [sqlite3_create_function()]
  4164  ** and [sqlite3_create_function16()] routines that originally
  4165  ** registered the application defined function.
  4166  **
  4167  ** This routine must be called from the same thread in which
  4168  ** the application-defined function is running.
  4169  */
  4170  SQLITE_API void *sqlite3_user_data(sqlite3_context*);
  4171  
  4172  /*
  4173  ** CAPI3REF: Database Connection For Functions
  4174  **
  4175  ** ^The sqlite3_context_db_handle() interface returns a copy of
  4176  ** the pointer to the [database connection] (the 1st parameter)
  4177  ** of the [sqlite3_create_function()]
  4178  ** and [sqlite3_create_function16()] routines that originally
  4179  ** registered the application defined function.
  4180  */
  4181  SQLITE_API sqlite3 *sqlite3_context_db_handle(sqlite3_context*);
  4182  
  4183  /*
  4184  ** CAPI3REF: Function Auxiliary Data
  4185  **
  4186  ** These functions may be used by (non-aggregate) SQL functions to
  4187  ** associate metadata with argument values. If the same value is passed to
  4188  ** multiple invocations of the same SQL function during query execution, under
  4189  ** some circumstances the associated metadata may be preserved.  An example
  4190  ** of where this might be useful is in a regular-expression matching
  4191  ** function. The compiled version of the regular expression can be stored as
  4192  ** metadata associated with the pattern string.  
  4193  ** Then as long as the pattern string remains the same,
  4194  ** the compiled regular expression can be reused on multiple
  4195  ** invocations of the same function.
  4196  **
  4197  ** ^The sqlite3_get_auxdata() interface returns a pointer to the metadata
  4198  ** associated by the sqlite3_set_auxdata() function with the Nth argument
  4199  ** value to the application-defined function. ^If there is no metadata
  4200  ** associated with the function argument, this sqlite3_get_auxdata() interface
  4201  ** returns a NULL pointer.
  4202  **
  4203  ** ^The sqlite3_set_auxdata(C,N,P,X) interface saves P as metadata for the N-th
  4204  ** argument of the application-defined function.  ^Subsequent
  4205  ** calls to sqlite3_get_auxdata(C,N) return P from the most recent
  4206  ** sqlite3_set_auxdata(C,N,P,X) call if the metadata is still valid or
  4207  ** NULL if the metadata has been discarded.
  4208  ** ^After each call to sqlite3_set_auxdata(C,N,P,X) where X is not NULL,
  4209  ** SQLite will invoke the destructor function X with parameter P exactly
  4210  ** once, when the metadata is discarded.
  4211  ** SQLite is free to discard the metadata at any time, including: <ul>
  4212  ** <li> when the corresponding function parameter changes, or
  4213  ** <li> when [sqlite3_reset()] or [sqlite3_finalize()] is called for the
  4214  **      SQL statement, or
  4215  ** <li> when sqlite3_set_auxdata() is invoked again on the same parameter, or
  4216  ** <li> during the original sqlite3_set_auxdata() call when a memory 
  4217  **      allocation error occurs. </ul>)^
  4218  **
  4219  ** Note the last bullet in particular.  The destructor X in 
  4220  ** sqlite3_set_auxdata(C,N,P,X) might be called immediately, before the
  4221  ** sqlite3_set_auxdata() interface even returns.  Hence sqlite3_set_auxdata()
  4222  ** should be called near the end of the function implementation and the
  4223  ** function implementation should not make any use of P after
  4224  ** sqlite3_set_auxdata() has been called.
  4225  **
  4226  ** ^(In practice, metadata is preserved between function calls for
  4227  ** function parameters that are compile-time constants, including literal
  4228  ** values and [parameters] and expressions composed from the same.)^
  4229  **
  4230  ** These routines must be called from the same thread in which
  4231  ** the SQL function is running.
  4232  */
  4233  SQLITE_API void *sqlite3_get_auxdata(sqlite3_context*, int N);
  4234  SQLITE_API void sqlite3_set_auxdata(sqlite3_context*, int N, void*, void (*)(void*));
  4235  
  4236  
  4237  /*
  4238  ** CAPI3REF: Constants Defining Special Destructor Behavior
  4239  **
  4240  ** These are special values for the destructor that is passed in as the
  4241  ** final argument to routines like [sqlite3_result_blob()].  ^If the destructor
  4242  ** argument is SQLITE_STATIC, it means that the content pointer is constant
  4243  ** and will never change.  It does not need to be destroyed.  ^The
  4244  ** SQLITE_TRANSIENT value means that the content will likely change in
  4245  ** the near future and that SQLite should make its own private copy of
  4246  ** the content before returning.
  4247  **
  4248  ** The typedef is necessary to work around problems in certain
  4249  ** C++ compilers.
  4250  */
  4251  typedef void (*sqlite3_destructor_type)(void*);
  4252  #define SQLITE_STATIC      ((sqlite3_destructor_type)0)
  4253  #define SQLITE_TRANSIENT   ((sqlite3_destructor_type)-1)
  4254  
  4255  /*
  4256  ** CAPI3REF: Setting The Result Of An SQL Function
  4257  **
  4258  ** These routines are used by the xFunc or xFinal callbacks that
  4259  ** implement SQL functions and aggregates.  See
  4260  ** [sqlite3_create_function()] and [sqlite3_create_function16()]
  4261  ** for additional information.
  4262  **
  4263  ** These functions work very much like the [parameter binding] family of
  4264  ** functions used to bind values to host parameters in prepared statements.
  4265  ** Refer to the [SQL parameter] documentation for additional information.
  4266  **
  4267  ** ^The sqlite3_result_blob() interface sets the result from
  4268  ** an application-defined function to be the BLOB whose content is pointed
  4269  ** to by the second parameter and which is N bytes long where N is the
  4270  ** third parameter.
  4271  **
  4272  ** ^The sqlite3_result_zeroblob() interfaces set the result of
  4273  ** the application-defined function to be a BLOB containing all zero
  4274  ** bytes and N bytes in size, where N is the value of the 2nd parameter.
  4275  **
  4276  ** ^The sqlite3_result_double() interface sets the result from
  4277  ** an application-defined function to be a floating point value specified
  4278  ** by its 2nd argument.
  4279  **
  4280  ** ^The sqlite3_result_error() and sqlite3_result_error16() functions
  4281  ** cause the implemented SQL function to throw an exception.
  4282  ** ^SQLite uses the string pointed to by the
  4283  ** 2nd parameter of sqlite3_result_error() or sqlite3_result_error16()
  4284  ** as the text of an error message.  ^SQLite interprets the error
  4285  ** message string from sqlite3_result_error() as UTF-8. ^SQLite
  4286  ** interprets the string from sqlite3_result_error16() as UTF-16 in native
  4287  ** byte order.  ^If the third parameter to sqlite3_result_error()
  4288  ** or sqlite3_result_error16() is negative then SQLite takes as the error
  4289  ** message all text up through the first zero character.
  4290  ** ^If the third parameter to sqlite3_result_error() or
  4291  ** sqlite3_result_error16() is non-negative then SQLite takes that many
  4292  ** bytes (not characters) from the 2nd parameter as the error message.
  4293  ** ^The sqlite3_result_error() and sqlite3_result_error16()
  4294  ** routines make a private copy of the error message text before
  4295  ** they return.  Hence, the calling function can deallocate or
  4296  ** modify the text after they return without harm.
  4297  ** ^The sqlite3_result_error_code() function changes the error code
  4298  ** returned by SQLite as a result of an error in a function.  ^By default,
  4299  ** the error code is SQLITE_ERROR.  ^A subsequent call to sqlite3_result_error()
  4300  ** or sqlite3_result_error16() resets the error code to SQLITE_ERROR.
  4301  **
  4302  ** ^The sqlite3_result_error_toobig() interface causes SQLite to throw an
  4303  ** error indicating that a string or BLOB is too long to represent.
  4304  **
  4305  ** ^The sqlite3_result_error_nomem() interface causes SQLite to throw an
  4306  ** error indicating that a memory allocation failed.
  4307  **
  4308  ** ^The sqlite3_result_int() interface sets the return value
  4309  ** of the application-defined function to be the 32-bit signed integer
  4310  ** value given in the 2nd argument.
  4311  ** ^The sqlite3_result_int64() interface sets the return value
  4312  ** of the application-defined function to be the 64-bit signed integer
  4313  ** value given in the 2nd argument.
  4314  **
  4315  ** ^The sqlite3_result_null() interface sets the return value
  4316  ** of the application-defined function to be NULL.
  4317  **
  4318  ** ^The sqlite3_result_text(), sqlite3_result_text16(),
  4319  ** sqlite3_result_text16le(), and sqlite3_result_text16be() interfaces
  4320  ** set the return value of the application-defined function to be
  4321  ** a text string which is represented as UTF-8, UTF-16 native byte order,
  4322  ** UTF-16 little endian, or UTF-16 big endian, respectively.
  4323  ** ^SQLite takes the text result from the application from
  4324  ** the 2nd parameter of the sqlite3_result_text* interfaces.
  4325  ** ^If the 3rd parameter to the sqlite3_result_text* interfaces
  4326  ** is negative, then SQLite takes result text from the 2nd parameter
  4327  ** through the first zero character.
  4328  ** ^If the 3rd parameter to the sqlite3_result_text* interfaces
  4329  ** is non-negative, then as many bytes (not characters) of the text
  4330  ** pointed to by the 2nd parameter are taken as the application-defined
  4331  ** function result.  If the 3rd parameter is non-negative, then it
  4332  ** must be the byte offset into the string where the NUL terminator would
  4333  ** appear if the string where NUL terminated.  If any NUL characters occur
  4334  ** in the string at a byte offset that is less than the value of the 3rd
  4335  ** parameter, then the resulting string will contain embedded NULs and the
  4336  ** result of expressions operating on strings with embedded NULs is undefined.
  4337  ** ^If the 4th parameter to the sqlite3_result_text* interfaces
  4338  ** or sqlite3_result_blob is a non-NULL pointer, then SQLite calls that
  4339  ** function as the destructor on the text or BLOB result when it has
  4340  ** finished using that result.
  4341  ** ^If the 4th parameter to the sqlite3_result_text* interfaces or to
  4342  ** sqlite3_result_blob is the special constant SQLITE_STATIC, then SQLite
  4343  ** assumes that the text or BLOB result is in constant space and does not
  4344  ** copy the content of the parameter nor call a destructor on the content
  4345  ** when it has finished using that result.
  4346  ** ^If the 4th parameter to the sqlite3_result_text* interfaces
  4347  ** or sqlite3_result_blob is the special constant SQLITE_TRANSIENT
  4348  ** then SQLite makes a copy of the result into space obtained from
  4349  ** from [sqlite3_malloc()] before it returns.
  4350  **
  4351  ** ^The sqlite3_result_value() interface sets the result of
  4352  ** the application-defined function to be a copy the
  4353  ** [unprotected sqlite3_value] object specified by the 2nd parameter.  ^The
  4354  ** sqlite3_result_value() interface makes a copy of the [sqlite3_value]
  4355  ** so that the [sqlite3_value] specified in the parameter may change or
  4356  ** be deallocated after sqlite3_result_value() returns without harm.
  4357  ** ^A [protected sqlite3_value] object may always be used where an
  4358  ** [unprotected sqlite3_value] object is required, so either
  4359  ** kind of [sqlite3_value] object can be used with this interface.
  4360  **
  4361  ** If these routines are called from within the different thread
  4362  ** than the one containing the application-defined function that received
  4363  ** the [sqlite3_context] pointer, the results are undefined.
  4364  */
  4365  SQLITE_API void sqlite3_result_blob(sqlite3_context*, const void*, int, void(*)(void*));
  4366  SQLITE_API void sqlite3_result_double(sqlite3_context*, double);
  4367  SQLITE_API void sqlite3_result_error(sqlite3_context*, const char*, int);
  4368  SQLITE_API void sqlite3_result_error16(sqlite3_context*, const void*, int);
  4369  SQLITE_API void sqlite3_result_error_toobig(sqlite3_context*);
  4370  SQLITE_API void sqlite3_result_error_nomem(sqlite3_context*);
  4371  SQLITE_API void sqlite3_result_error_code(sqlite3_context*, int);
  4372  SQLITE_API void sqlite3_result_int(sqlite3_context*, int);
  4373  SQLITE_API void sqlite3_result_int64(sqlite3_context*, sqlite3_int64);
  4374  SQLITE_API void sqlite3_result_null(sqlite3_context*);
  4375  SQLITE_API void sqlite3_result_text(sqlite3_context*, const char*, int, void(*)(void*));
  4376  SQLITE_API void sqlite3_result_text16(sqlite3_context*, const void*, int, void(*)(void*));
  4377  SQLITE_API void sqlite3_result_text16le(sqlite3_context*, const void*, int,void(*)(void*));
  4378  SQLITE_API void sqlite3_result_text16be(sqlite3_context*, const void*, int,void(*)(void*));
  4379  SQLITE_API void sqlite3_result_value(sqlite3_context*, sqlite3_value*);
  4380  SQLITE_API void sqlite3_result_zeroblob(sqlite3_context*, int n);
  4381  
  4382  /*
  4383  ** CAPI3REF: Define New Collating Sequences
  4384  **
  4385  ** ^These functions add, remove, or modify a [collation] associated
  4386  ** with the [database connection] specified as the first argument.
  4387  **
  4388  ** ^The name of the collation is a UTF-8 string
  4389  ** for sqlite3_create_collation() and sqlite3_create_collation_v2()
  4390  ** and a UTF-16 string in native byte order for sqlite3_create_collation16().
  4391  ** ^Collation names that compare equal according to [sqlite3_strnicmp()] are
  4392  ** considered to be the same name.
  4393  **
  4394  ** ^(The third argument (eTextRep) must be one of the constants:
  4395  ** <ul>
  4396  ** <li> [SQLITE_UTF8],
  4397  ** <li> [SQLITE_UTF16LE],
  4398  ** <li> [SQLITE_UTF16BE],
  4399  ** <li> [SQLITE_UTF16], or
  4400  ** <li> [SQLITE_UTF16_ALIGNED].
  4401  ** </ul>)^
  4402  ** ^The eTextRep argument determines the encoding of strings passed
  4403  ** to the collating function callback, xCallback.
  4404  ** ^The [SQLITE_UTF16] and [SQLITE_UTF16_ALIGNED] values for eTextRep
  4405  ** force strings to be UTF16 with native byte order.
  4406  ** ^The [SQLITE_UTF16_ALIGNED] value for eTextRep forces strings to begin
  4407  ** on an even byte address.
  4408  **
  4409  ** ^The fourth argument, pArg, is an application data pointer that is passed
  4410  ** through as the first argument to the collating function callback.
  4411  **
  4412  ** ^The fifth argument, xCallback, is a pointer to the collating function.
  4413  ** ^Multiple collating functions can be registered using the same name but
  4414  ** with different eTextRep parameters and SQLite will use whichever
  4415  ** function requires the least amount of data transformation.
  4416  ** ^If the xCallback argument is NULL then the collating function is
  4417  ** deleted.  ^When all collating functions having the same name are deleted,
  4418  ** that collation is no longer usable.
  4419  **
  4420  ** ^The collating function callback is invoked with a copy of the pArg 
  4421  ** application data pointer and with two strings in the encoding specified
  4422  ** by the eTextRep argument.  The collating function must return an
  4423  ** integer that is negative, zero, or positive
  4424  ** if the first string is less than, equal to, or greater than the second,
  4425  ** respectively.  A collating function must always return the same answer
  4426  ** given the same inputs.  If two or more collating functions are registered
  4427  ** to the same collation name (using different eTextRep values) then all
  4428  ** must give an equivalent answer when invoked with equivalent strings.
  4429  ** The collating function must obey the following properties for all
  4430  ** strings A, B, and C:
  4431  **
  4432  ** <ol>
  4433  ** <li> If A==B then B==A.
  4434  ** <li> If A==B and B==C then A==C.
  4435  ** <li> If A&lt;B THEN B&gt;A.
  4436  ** <li> If A&lt;B and B&lt;C then A&lt;C.
  4437  ** </ol>
  4438  **
  4439  ** If a collating function fails any of the above constraints and that
  4440  ** collating function is  registered and used, then the behavior of SQLite
  4441  ** is undefined.
  4442  **
  4443  ** ^The sqlite3_create_collation_v2() works like sqlite3_create_collation()
  4444  ** with the addition that the xDestroy callback is invoked on pArg when
  4445  ** the collating function is deleted.
  4446  ** ^Collating functions are deleted when they are overridden by later
  4447  ** calls to the collation creation functions or when the
  4448  ** [database connection] is closed using [sqlite3_close()].
  4449  **
  4450  ** ^The xDestroy callback is <u>not</u> called if the 
  4451  ** sqlite3_create_collation_v2() function fails.  Applications that invoke
  4452  ** sqlite3_create_collation_v2() with a non-NULL xDestroy argument should 
  4453  ** check the return code and dispose of the application data pointer
  4454  ** themselves rather than expecting SQLite to deal with it for them.
  4455  ** This is different from every other SQLite interface.  The inconsistency 
  4456  ** is unfortunate but cannot be changed without breaking backwards 
  4457  ** compatibility.
  4458  **
  4459  ** See also:  [sqlite3_collation_needed()] and [sqlite3_collation_needed16()].
  4460  */
  4461  SQLITE_API int sqlite3_create_collation(
  4462    sqlite3*, 
  4463    const char *zName, 
  4464    int eTextRep, 
  4465    void *pArg,
  4466    int(*xCompare)(void*,int,const void*,int,const void*)
  4467  );
  4468  SQLITE_API int sqlite3_create_collation_v2(
  4469    sqlite3*, 
  4470    const char *zName, 
  4471    int eTextRep, 
  4472    void *pArg,
  4473    int(*xCompare)(void*,int,const void*,int,const void*),
  4474    void(*xDestroy)(void*)
  4475  );
  4476  SQLITE_API int sqlite3_create_collation16(
  4477    sqlite3*, 
  4478    const void *zName,
  4479    int eTextRep, 
  4480    void *pArg,
  4481    int(*xCompare)(void*,int,const void*,int,const void*)
  4482  );
  4483  
  4484  /*
  4485  ** CAPI3REF: Collation Needed Callbacks
  4486  **
  4487  ** ^To avoid having to register all collation sequences before a database
  4488  ** can be used, a single callback function may be registered with the
  4489  ** [database connection] to be invoked whenever an undefined collation
  4490  ** sequence is required.
  4491  **
  4492  ** ^If the function is registered using the sqlite3_collation_needed() API,
  4493  ** then it is passed the names of undefined collation sequences as strings
  4494  ** encoded in UTF-8. ^If sqlite3_collation_needed16() is used,
  4495  ** the names are passed as UTF-16 in machine native byte order.
  4496  ** ^A call to either function replaces the existing collation-needed callback.
  4497  **
  4498  ** ^(When the callback is invoked, the first argument passed is a copy
  4499  ** of the second argument to sqlite3_collation_needed() or
  4500  ** sqlite3_collation_needed16().  The second argument is the database
  4501  ** connection.  The third argument is one of [SQLITE_UTF8], [SQLITE_UTF16BE],
  4502  ** or [SQLITE_UTF16LE], indicating the most desirable form of the collation
  4503  ** sequence function required.  The fourth parameter is the name of the
  4504  ** required collation sequence.)^
  4505  **
  4506  ** The callback function should register the desired collation using
  4507  ** [sqlite3_create_collation()], [sqlite3_create_collation16()], or
  4508  ** [sqlite3_create_collation_v2()].
  4509  */
  4510  SQLITE_API int sqlite3_collation_needed(
  4511    sqlite3*, 
  4512    void*, 
  4513    void(*)(void*,sqlite3*,int eTextRep,const char*)
  4514  );
  4515  SQLITE_API int sqlite3_collation_needed16(
  4516    sqlite3*, 
  4517    void*,
  4518    void(*)(void*,sqlite3*,int eTextRep,const void*)
  4519  );
  4520  
  4521  #ifdef SQLITE_HAS_CODEC
  4522  /*
  4523  ** Specify the key for an encrypted database.  This routine should be
  4524  ** called right after sqlite3_open().
  4525  **
  4526  ** The code to implement this API is not available in the public release
  4527  ** of SQLite.
  4528  */
  4529  SQLITE_API int sqlite3_key(
  4530    sqlite3 *db,                   /* Database to be rekeyed */
  4531    const void *pKey, int nKey     /* The key */
  4532  );
  4533  SQLITE_API int sqlite3_key_v2(
  4534    sqlite3 *db,                   /* Database to be rekeyed */
  4535    const char *zDbName,           /* Name of the database */
  4536    const void *pKey, int nKey     /* The key */
  4537  );
  4538  
  4539  /*
  4540  ** Change the key on an open database.  If the current database is not
  4541  ** encrypted, this routine will encrypt it.  If pNew==0 or nNew==0, the
  4542  ** database is decrypted.
  4543  **
  4544  ** The code to implement this API is not available in the public release
  4545  ** of SQLite.
  4546  */
  4547  SQLITE_API int sqlite3_rekey(
  4548    sqlite3 *db,                   /* Database to be rekeyed */
  4549    const void *pKey, int nKey     /* The new key */
  4550  );
  4551  SQLITE_API int sqlite3_rekey_v2(
  4552    sqlite3 *db,                   /* Database to be rekeyed */
  4553    const char *zDbName,           /* Name of the database */
  4554    const void *pKey, int nKey     /* The new key */
  4555  );
  4556  
  4557  /*
  4558  ** Specify the activation key for a SEE database.  Unless 
  4559  ** activated, none of the SEE routines will work.
  4560  */
  4561  SQLITE_API void sqlite3_activate_see(
  4562    const char *zPassPhrase        /* Activation phrase */
  4563  );
  4564  #endif
  4565  
  4566  #ifdef SQLITE_ENABLE_CEROD
  4567  /*
  4568  ** Specify the activation key for a CEROD database.  Unless 
  4569  ** activated, none of the CEROD routines will work.
  4570  */
  4571  SQLITE_API void sqlite3_activate_cerod(
  4572    const char *zPassPhrase        /* Activation phrase */
  4573  );
  4574  #endif
  4575  
  4576  /*
  4577  ** CAPI3REF: Suspend Execution For A Short Time
  4578  **
  4579  ** The sqlite3_sleep() function causes the current thread to suspend execution
  4580  ** for at least a number of milliseconds specified in its parameter.
  4581  **
  4582  ** If the operating system does not support sleep requests with
  4583  ** millisecond time resolution, then the time will be rounded up to
  4584  ** the nearest second. The number of milliseconds of sleep actually
  4585  ** requested from the operating system is returned.
  4586  **
  4587  ** ^SQLite implements this interface by calling the xSleep()
  4588  ** method of the default [sqlite3_vfs] object.  If the xSleep() method
  4589  ** of the default VFS is not implemented correctly, or not implemented at
  4590  ** all, then the behavior of sqlite3_sleep() may deviate from the description
  4591  ** in the previous paragraphs.
  4592  */
  4593  SQLITE_API int sqlite3_sleep(int);
  4594  
  4595  /*
  4596  ** CAPI3REF: Name Of The Folder Holding Temporary Files
  4597  **
  4598  ** ^(If this global variable is made to point to a string which is
  4599  ** the name of a folder (a.k.a. directory), then all temporary files
  4600  ** created by SQLite when using a built-in [sqlite3_vfs | VFS]
  4601  ** will be placed in that directory.)^  ^If this variable
  4602  ** is a NULL pointer, then SQLite performs a search for an appropriate
  4603  ** temporary file directory.
  4604  **
  4605  ** It is not safe to read or modify this variable in more than one
  4606  ** thread at a time.  It is not safe to read or modify this variable
  4607  ** if a [database connection] is being used at the same time in a separate
  4608  ** thread.
  4609  ** It is intended that this variable be set once
  4610  ** as part of process initialization and before any SQLite interface
  4611  ** routines have been called and that this variable remain unchanged
  4612  ** thereafter.
  4613  **
  4614  ** ^The [temp_store_directory pragma] may modify this variable and cause
  4615  ** it to point to memory obtained from [sqlite3_malloc].  ^Furthermore,
  4616  ** the [temp_store_directory pragma] always assumes that any string
  4617  ** that this variable points to is held in memory obtained from 
  4618  ** [sqlite3_malloc] and the pragma may attempt to free that memory
  4619  ** using [sqlite3_free].
  4620  ** Hence, if this variable is modified directly, either it should be
  4621  ** made NULL or made to point to memory obtained from [sqlite3_malloc]
  4622  ** or else the use of the [temp_store_directory pragma] should be avoided.
  4623  **
  4624  ** <b>Note to Windows Runtime users:</b>  The temporary directory must be set
  4625  ** prior to calling [sqlite3_open] or [sqlite3_open_v2].  Otherwise, various
  4626  ** features that require the use of temporary files may fail.  Here is an
  4627  ** example of how to do this using C++ with the Windows Runtime:
  4628  **
  4629  ** <blockquote><pre>
  4630  ** LPCWSTR zPath = Windows::Storage::ApplicationData::Current->
  4631  ** &nbsp;     TemporaryFolder->Path->Data();
  4632  ** char zPathBuf&#91;MAX_PATH + 1&#93;;
  4633  ** memset(zPathBuf, 0, sizeof(zPathBuf));
  4634  ** WideCharToMultiByte(CP_UTF8, 0, zPath, -1, zPathBuf, sizeof(zPathBuf),
  4635  ** &nbsp;     NULL, NULL);
  4636  ** sqlite3_temp_directory = sqlite3_mprintf("%s", zPathBuf);
  4637  ** </pre></blockquote>
  4638  */
  4639  SQLITE_API SQLITE_EXTERN char *sqlite3_temp_directory;
  4640  
  4641  /*
  4642  ** CAPI3REF: Name Of The Folder Holding Database Files
  4643  **
  4644  ** ^(If this global variable is made to point to a string which is
  4645  ** the name of a folder (a.k.a. directory), then all database files
  4646  ** specified with a relative pathname and created or accessed by
  4647  ** SQLite when using a built-in windows [sqlite3_vfs | VFS] will be assumed
  4648  ** to be relative to that directory.)^ ^If this variable is a NULL
  4649  ** pointer, then SQLite assumes that all database files specified
  4650  ** with a relative pathname are relative to the current directory
  4651  ** for the process.  Only the windows VFS makes use of this global
  4652  ** variable; it is ignored by the unix VFS.
  4653  **
  4654  ** Changing the value of this variable while a database connection is
  4655  ** open can result in a corrupt database.
  4656  **
  4657  ** It is not safe to read or modify this variable in more than one
  4658  ** thread at a time.  It is not safe to read or modify this variable
  4659  ** if a [database connection] is being used at the same time in a separate
  4660  ** thread.
  4661  ** It is intended that this variable be set once
  4662  ** as part of process initialization and before any SQLite interface
  4663  ** routines have been called and that this variable remain unchanged
  4664  ** thereafter.
  4665  **
  4666  ** ^The [data_store_directory pragma] may modify this variable and cause
  4667  ** it to point to memory obtained from [sqlite3_malloc].  ^Furthermore,
  4668  ** the [data_store_directory pragma] always assumes that any string
  4669  ** that this variable points to is held in memory obtained from 
  4670  ** [sqlite3_malloc] and the pragma may attempt to free that memory
  4671  ** using [sqlite3_free].
  4672  ** Hence, if this variable is modified directly, either it should be
  4673  ** made NULL or made to point to memory obtained from [sqlite3_malloc]
  4674  ** or else the use of the [data_store_directory pragma] should be avoided.
  4675  */
  4676  SQLITE_API SQLITE_EXTERN char *sqlite3_data_directory;
  4677  
  4678  /*
  4679  ** CAPI3REF: Test For Auto-Commit Mode
  4680  ** KEYWORDS: {autocommit mode}
  4681  **
  4682  ** ^The sqlite3_get_autocommit() interface returns non-zero or
  4683  ** zero if the given database connection is or is not in autocommit mode,
  4684  ** respectively.  ^Autocommit mode is on by default.
  4685  ** ^Autocommit mode is disabled by a [BEGIN] statement.
  4686  ** ^Autocommit mode is re-enabled by a [COMMIT] or [ROLLBACK].
  4687  **
  4688  ** If certain kinds of errors occur on a statement within a multi-statement
  4689  ** transaction (errors including [SQLITE_FULL], [SQLITE_IOERR],
  4690  ** [SQLITE_NOMEM], [SQLITE_BUSY], and [SQLITE_INTERRUPT]) then the
  4691  ** transaction might be rolled back automatically.  The only way to
  4692  ** find out whether SQLite automatically rolled back the transaction after
  4693  ** an error is to use this function.
  4694  **
  4695  ** If another thread changes the autocommit status of the database
  4696  ** connection while this routine is running, then the return value
  4697  ** is undefined.
  4698  */
  4699  SQLITE_API int sqlite3_get_autocommit(sqlite3*);
  4700  
  4701  /*
  4702  ** CAPI3REF: Find The Database Handle Of A Prepared Statement
  4703  **
  4704  ** ^The sqlite3_db_handle interface returns the [database connection] handle
  4705  ** to which a [prepared statement] belongs.  ^The [database connection]
  4706  ** returned by sqlite3_db_handle is the same [database connection]
  4707  ** that was the first argument
  4708  ** to the [sqlite3_prepare_v2()] call (or its variants) that was used to
  4709  ** create the statement in the first place.
  4710  */
  4711  SQLITE_API sqlite3 *sqlite3_db_handle(sqlite3_stmt*);
  4712  
  4713  /*
  4714  ** CAPI3REF: Return The Filename For A Database Connection
  4715  **
  4716  ** ^The sqlite3_db_filename(D,N) interface returns a pointer to a filename
  4717  ** associated with database N of connection D.  ^The main database file
  4718  ** has the name "main".  If there is no attached database N on the database
  4719  ** connection D, or if database N is a temporary or in-memory database, then
  4720  ** a NULL pointer is returned.
  4721  **
  4722  ** ^The filename returned by this function is the output of the
  4723  ** xFullPathname method of the [VFS].  ^In other words, the filename
  4724  ** will be an absolute pathname, even if the filename used
  4725  ** to open the database originally was a URI or relative pathname.
  4726  */
  4727  SQLITE_API const char *sqlite3_db_filename(sqlite3 *db, const char *zDbName);
  4728  
  4729  /*
  4730  ** CAPI3REF: Determine if a database is read-only
  4731  **
  4732  ** ^The sqlite3_db_readonly(D,N) interface returns 1 if the database N
  4733  ** of connection D is read-only, 0 if it is read/write, or -1 if N is not
  4734  ** the name of a database on connection D.
  4735  */
  4736  SQLITE_API int sqlite3_db_readonly(sqlite3 *db, const char *zDbName);
  4737  
  4738  /*
  4739  ** CAPI3REF: Find the next prepared statement
  4740  **
  4741  ** ^This interface returns a pointer to the next [prepared statement] after
  4742  ** pStmt associated with the [database connection] pDb.  ^If pStmt is NULL
  4743  ** then this interface returns a pointer to the first prepared statement
  4744  ** associated with the database connection pDb.  ^If no prepared statement
  4745  ** satisfies the conditions of this routine, it returns NULL.
  4746  **
  4747  ** The [database connection] pointer D in a call to
  4748  ** [sqlite3_next_stmt(D,S)] must refer to an open database
  4749  ** connection and in particular must not be a NULL pointer.
  4750  */
  4751  SQLITE_API sqlite3_stmt *sqlite3_next_stmt(sqlite3 *pDb, sqlite3_stmt *pStmt);
  4752  
  4753  /*
  4754  ** CAPI3REF: Commit And Rollback Notification Callbacks
  4755  **
  4756  ** ^The sqlite3_commit_hook() interface registers a callback
  4757  ** function to be invoked whenever a transaction is [COMMIT | committed].
  4758  ** ^Any callback set by a previous call to sqlite3_commit_hook()
  4759  ** for the same database connection is overridden.
  4760  ** ^The sqlite3_rollback_hook() interface registers a callback
  4761  ** function to be invoked whenever a transaction is [ROLLBACK | rolled back].
  4762  ** ^Any callback set by a previous call to sqlite3_rollback_hook()
  4763  ** for the same database connection is overridden.
  4764  ** ^The pArg argument is passed through to the callback.
  4765  ** ^If the callback on a commit hook function returns non-zero,
  4766  ** then the commit is converted into a rollback.
  4767  **
  4768  ** ^The sqlite3_commit_hook(D,C,P) and sqlite3_rollback_hook(D,C,P) functions
  4769  ** return the P argument from the previous call of the same function
  4770  ** on the same [database connection] D, or NULL for
  4771  ** the first call for each function on D.
  4772  **
  4773  ** The commit and rollback hook callbacks are not reentrant.
  4774  ** The callback implementation must not do anything that will modify
  4775  ** the database connection that invoked the callback.  Any actions
  4776  ** to modify the database connection must be deferred until after the
  4777  ** completion of the [sqlite3_step()] call that triggered the commit
  4778  ** or rollback hook in the first place.
  4779  ** Note that running any other SQL statements, including SELECT statements,
  4780  ** or merely calling [sqlite3_prepare_v2()] and [sqlite3_step()] will modify
  4781  ** the database connections for the meaning of "modify" in this paragraph.
  4782  **
  4783  ** ^Registering a NULL function disables the callback.
  4784  **
  4785  ** ^When the commit hook callback routine returns zero, the [COMMIT]
  4786  ** operation is allowed to continue normally.  ^If the commit hook
  4787  ** returns non-zero, then the [COMMIT] is converted into a [ROLLBACK].
  4788  ** ^The rollback hook is invoked on a rollback that results from a commit
  4789  ** hook returning non-zero, just as it would be with any other rollback.
  4790  **
  4791  ** ^For the purposes of this API, a transaction is said to have been
  4792  ** rolled back if an explicit "ROLLBACK" statement is executed, or
  4793  ** an error or constraint causes an implicit rollback to occur.
  4794  ** ^The rollback callback is not invoked if a transaction is
  4795  ** automatically rolled back because the database connection is closed.
  4796  **
  4797  ** See also the [sqlite3_update_hook()] interface.
  4798  */
  4799  SQLITE_API void *sqlite3_commit_hook(sqlite3*, int(*)(void*), void*);
  4800  SQLITE_API void *sqlite3_rollback_hook(sqlite3*, void(*)(void *), void*);
  4801  
  4802  /*
  4803  ** CAPI3REF: Data Change Notification Callbacks
  4804  **
  4805  ** ^The sqlite3_update_hook() interface registers a callback function
  4806  ** with the [database connection] identified by the first argument
  4807  ** to be invoked whenever a row is updated, inserted or deleted.
  4808  ** ^Any callback set by a previous call to this function
  4809  ** for the same database connection is overridden.
  4810  **
  4811  ** ^The second argument is a pointer to the function to invoke when a
  4812  ** row is updated, inserted or deleted.
  4813  ** ^The first argument to the callback is a copy of the third argument
  4814  ** to sqlite3_update_hook().
  4815  ** ^The second callback argument is one of [SQLITE_INSERT], [SQLITE_DELETE],
  4816  ** or [SQLITE_UPDATE], depending on the operation that caused the callback
  4817  ** to be invoked.
  4818  ** ^The third and fourth arguments to the callback contain pointers to the
  4819  ** database and table name containing the affected row.
  4820  ** ^The final callback parameter is the [rowid] of the row.
  4821  ** ^In the case of an update, this is the [rowid] after the update takes place.
  4822  **
  4823  ** ^(The update hook is not invoked when internal system tables are
  4824  ** modified (i.e. sqlite_master and sqlite_sequence).)^
  4825  **
  4826  ** ^In the current implementation, the update hook
  4827  ** is not invoked when duplication rows are deleted because of an
  4828  ** [ON CONFLICT | ON CONFLICT REPLACE] clause.  ^Nor is the update hook
  4829  ** invoked when rows are deleted using the [truncate optimization].
  4830  ** The exceptions defined in this paragraph might change in a future
  4831  ** release of SQLite.
  4832  **
  4833  ** The update hook implementation must not do anything that will modify
  4834  ** the database connection that invoked the update hook.  Any actions
  4835  ** to modify the database connection must be deferred until after the
  4836  ** completion of the [sqlite3_step()] call that triggered the update hook.
  4837  ** Note that [sqlite3_prepare_v2()] and [sqlite3_step()] both modify their
  4838  ** database connections for the meaning of "modify" in this paragraph.
  4839  **
  4840  ** ^The sqlite3_update_hook(D,C,P) function
  4841  ** returns the P argument from the previous call
  4842  ** on the same [database connection] D, or NULL for
  4843  ** the first call on D.
  4844  **
  4845  ** See also the [sqlite3_commit_hook()] and [sqlite3_rollback_hook()]
  4846  ** interfaces.
  4847  */
  4848  SQLITE_API void *sqlite3_update_hook(
  4849    sqlite3*, 
  4850    void(*)(void *,int ,char const *,char const *,sqlite3_int64),
  4851    void*
  4852  );
  4853  
  4854  /*
  4855  ** CAPI3REF: Enable Or Disable Shared Pager Cache
  4856  **
  4857  ** ^(This routine enables or disables the sharing of the database cache
  4858  ** and schema data structures between [database connection | connections]
  4859  ** to the same database. Sharing is enabled if the argument is true
  4860  ** and disabled if the argument is false.)^
  4861  **
  4862  ** ^Cache sharing is enabled and disabled for an entire process.
  4863  ** This is a change as of SQLite version 3.5.0. In prior versions of SQLite,
  4864  ** sharing was enabled or disabled for each thread separately.
  4865  **
  4866  ** ^(The cache sharing mode set by this interface effects all subsequent
  4867  ** calls to [sqlite3_open()], [sqlite3_open_v2()], and [sqlite3_open16()].
  4868  ** Existing database connections continue use the sharing mode
  4869  ** that was in effect at the time they were opened.)^
  4870  **
  4871  ** ^(This routine returns [SQLITE_OK] if shared cache was enabled or disabled
  4872  ** successfully.  An [error code] is returned otherwise.)^
  4873  **
  4874  ** ^Shared cache is disabled by default. But this might change in
  4875  ** future releases of SQLite.  Applications that care about shared
  4876  ** cache setting should set it explicitly.
  4877  **
  4878  ** This interface is threadsafe on processors where writing a
  4879  ** 32-bit integer is atomic.
  4880  **
  4881  ** See Also:  [SQLite Shared-Cache Mode]
  4882  */
  4883  SQLITE_API int sqlite3_enable_shared_cache(int);
  4884  
  4885  /*
  4886  ** CAPI3REF: Attempt To Free Heap Memory
  4887  **
  4888  ** ^The sqlite3_release_memory() interface attempts to free N bytes
  4889  ** of heap memory by deallocating non-essential memory allocations
  4890  ** held by the database library.   Memory used to cache database
  4891  ** pages to improve performance is an example of non-essential memory.
  4892  ** ^sqlite3_release_memory() returns the number of bytes actually freed,
  4893  ** which might be more or less than the amount requested.
  4894  ** ^The sqlite3_release_memory() routine is a no-op returning zero
  4895  ** if SQLite is not compiled with [SQLITE_ENABLE_MEMORY_MANAGEMENT].
  4896  **
  4897  ** See also: [sqlite3_db_release_memory()]
  4898  */
  4899  SQLITE_API int sqlite3_release_memory(int);
  4900  
  4901  /*
  4902  ** CAPI3REF: Free Memory Used By A Database Connection
  4903  **
  4904  ** ^The sqlite3_db_release_memory(D) interface attempts to free as much heap
  4905  ** memory as possible from database connection D. Unlike the
  4906  ** [sqlite3_release_memory()] interface, this interface is effect even
  4907  ** when then [SQLITE_ENABLE_MEMORY_MANAGEMENT] compile-time option is
  4908  ** omitted.
  4909  **
  4910  ** See also: [sqlite3_release_memory()]
  4911  */
  4912  SQLITE_API int sqlite3_db_release_memory(sqlite3*);
  4913  
  4914  /*
  4915  ** CAPI3REF: Impose A Limit On Heap Size
  4916  **
  4917  ** ^The sqlite3_soft_heap_limit64() interface sets and/or queries the
  4918  ** soft limit on the amount of heap memory that may be allocated by SQLite.
  4919  ** ^SQLite strives to keep heap memory utilization below the soft heap
  4920  ** limit by reducing the number of pages held in the page cache
  4921  ** as heap memory usages approaches the limit.
  4922  ** ^The soft heap limit is "soft" because even though SQLite strives to stay
  4923  ** below the limit, it will exceed the limit rather than generate
  4924  ** an [SQLITE_NOMEM] error.  In other words, the soft heap limit 
  4925  ** is advisory only.
  4926  **
  4927  ** ^The return value from sqlite3_soft_heap_limit64() is the size of
  4928  ** the soft heap limit prior to the call, or negative in the case of an
  4929  ** error.  ^If the argument N is negative
  4930  ** then no change is made to the soft heap limit.  Hence, the current
  4931  ** size of the soft heap limit can be determined by invoking
  4932  ** sqlite3_soft_heap_limit64() with a negative argument.
  4933  **
  4934  ** ^If the argument N is zero then the soft heap limit is disabled.
  4935  **
  4936  ** ^(The soft heap limit is not enforced in the current implementation
  4937  ** if one or more of following conditions are true:
  4938  **
  4939  ** <ul>
  4940  ** <li> The soft heap limit is set to zero.
  4941  ** <li> Memory accounting is disabled using a combination of the
  4942  **      [sqlite3_config]([SQLITE_CONFIG_MEMSTATUS],...) start-time option and
  4943  **      the [SQLITE_DEFAULT_MEMSTATUS] compile-time option.
  4944  ** <li> An alternative page cache implementation is specified using
  4945  **      [sqlite3_config]([SQLITE_CONFIG_PCACHE2],...).
  4946  ** <li> The page cache allocates from its own memory pool supplied
  4947  **      by [sqlite3_config]([SQLITE_CONFIG_PAGECACHE],...) rather than
  4948  **      from the heap.
  4949  ** </ul>)^
  4950  **
  4951  ** Beginning with SQLite version 3.7.3, the soft heap limit is enforced
  4952  ** regardless of whether or not the [SQLITE_ENABLE_MEMORY_MANAGEMENT]
  4953  ** compile-time option is invoked.  With [SQLITE_ENABLE_MEMORY_MANAGEMENT],
  4954  ** the soft heap limit is enforced on every memory allocation.  Without
  4955  ** [SQLITE_ENABLE_MEMORY_MANAGEMENT], the soft heap limit is only enforced
  4956  ** when memory is allocated by the page cache.  Testing suggests that because
  4957  ** the page cache is the predominate memory user in SQLite, most
  4958  ** applications will achieve adequate soft heap limit enforcement without
  4959  ** the use of [SQLITE_ENABLE_MEMORY_MANAGEMENT].
  4960  **
  4961  ** The circumstances under which SQLite will enforce the soft heap limit may
  4962  ** changes in future releases of SQLite.
  4963  */
  4964  SQLITE_API sqlite3_int64 sqlite3_soft_heap_limit64(sqlite3_int64 N);
  4965  
  4966  /*
  4967  ** CAPI3REF: Deprecated Soft Heap Limit Interface
  4968  ** DEPRECATED
  4969  **
  4970  ** This is a deprecated version of the [sqlite3_soft_heap_limit64()]
  4971  ** interface.  This routine is provided for historical compatibility
  4972  ** only.  All new applications should use the
  4973  ** [sqlite3_soft_heap_limit64()] interface rather than this one.
  4974  */
  4975  SQLITE_API SQLITE_DEPRECATED void sqlite3_soft_heap_limit(int N);
  4976  
  4977  
  4978  /*
  4979  ** CAPI3REF: Extract Metadata About A Column Of A Table
  4980  **
  4981  ** ^This routine returns metadata about a specific column of a specific
  4982  ** database table accessible using the [database connection] handle
  4983  ** passed as the first function argument.
  4984  **
  4985  ** ^The column is identified by the second, third and fourth parameters to
  4986  ** this function. ^The second parameter is either the name of the database
  4987  ** (i.e. "main", "temp", or an attached database) containing the specified
  4988  ** table or NULL. ^If it is NULL, then all attached databases are searched
  4989  ** for the table using the same algorithm used by the database engine to
  4990  ** resolve unqualified table references.
  4991  **
  4992  ** ^The third and fourth parameters to this function are the table and column
  4993  ** name of the desired column, respectively. Neither of these parameters
  4994  ** may be NULL.
  4995  **
  4996  ** ^Metadata is returned by writing to the memory locations passed as the 5th
  4997  ** and subsequent parameters to this function. ^Any of these arguments may be
  4998  ** NULL, in which case the corresponding element of metadata is omitted.
  4999  **
  5000  ** ^(<blockquote>
  5001  ** <table border="1">
  5002  ** <tr><th> Parameter <th> Output<br>Type <th>  Description
  5003  **
  5004  ** <tr><td> 5th <td> const char* <td> Data type
  5005  ** <tr><td> 6th <td> const char* <td> Name of default collation sequence
  5006  ** <tr><td> 7th <td> int         <td> True if column has a NOT NULL constraint
  5007  ** <tr><td> 8th <td> int         <td> True if column is part of the PRIMARY KEY
  5008  ** <tr><td> 9th <td> int         <td> True if column is [AUTOINCREMENT]
  5009  ** </table>
  5010  ** </blockquote>)^
  5011  **
  5012  ** ^The memory pointed to by the character pointers returned for the
  5013  ** declaration type and collation sequence is valid only until the next
  5014  ** call to any SQLite API function.
  5015  **
  5016  ** ^If the specified table is actually a view, an [error code] is returned.
  5017  **
  5018  ** ^If the specified column is "rowid", "oid" or "_rowid_" and an
  5019  ** [INTEGER PRIMARY KEY] column has been explicitly declared, then the output
  5020  ** parameters are set for the explicitly declared column. ^(If there is no
  5021  ** explicitly declared [INTEGER PRIMARY KEY] column, then the output
  5022  ** parameters are set as follows:
  5023  **
  5024  ** <pre>
  5025  **     data type: "INTEGER"
  5026  **     collation sequence: "BINARY"
  5027  **     not null: 0
  5028  **     primary key: 1
  5029  **     auto increment: 0
  5030  ** </pre>)^
  5031  **
  5032  ** ^(This function may load one or more schemas from database files. If an
  5033  ** error occurs during this process, or if the requested table or column
  5034  ** cannot be found, an [error code] is returned and an error message left
  5035  ** in the [database connection] (to be retrieved using sqlite3_errmsg()).)^
  5036  **
  5037  ** ^This API is only available if the library was compiled with the
  5038  ** [SQLITE_ENABLE_COLUMN_METADATA] C-preprocessor symbol defined.
  5039  */
  5040  SQLITE_API int sqlite3_table_column_metadata(
  5041    sqlite3 *db,                /* Connection handle */
  5042    const char *zDbName,        /* Database name or NULL */
  5043    const char *zTableName,     /* Table name */
  5044    const char *zColumnName,    /* Column name */
  5045    char const **pzDataType,    /* OUTPUT: Declared data type */
  5046    char const **pzCollSeq,     /* OUTPUT: Collation sequence name */
  5047    int *pNotNull,              /* OUTPUT: True if NOT NULL constraint exists */
  5048    int *pPrimaryKey,           /* OUTPUT: True if column part of PK */
  5049    int *pAutoinc               /* OUTPUT: True if column is auto-increment */
  5050  );
  5051  
  5052  /*
  5053  ** CAPI3REF: Load An Extension
  5054  **
  5055  ** ^This interface loads an SQLite extension library from the named file.
  5056  **
  5057  ** ^The sqlite3_load_extension() interface attempts to load an
  5058  ** [SQLite extension] library contained in the file zFile.  If
  5059  ** the file cannot be loaded directly, attempts are made to load
  5060  ** with various operating-system specific extensions added.
  5061  ** So for example, if "samplelib" cannot be loaded, then names like
  5062  ** "samplelib.so" or "samplelib.dylib" or "samplelib.dll" might
  5063  ** be tried also.
  5064  **
  5065  ** ^The entry point is zProc.
  5066  ** ^(zProc may be 0, in which case SQLite will try to come up with an
  5067  ** entry point name on its own.  It first tries "sqlite3_extension_init".
  5068  ** If that does not work, it constructs a name "sqlite3_X_init" where the
  5069  ** X is consists of the lower-case equivalent of all ASCII alphabetic
  5070  ** characters in the filename from the last "/" to the first following
  5071  ** "." and omitting any initial "lib".)^
  5072  ** ^The sqlite3_load_extension() interface returns
  5073  ** [SQLITE_OK] on success and [SQLITE_ERROR] if something goes wrong.
  5074  ** ^If an error occurs and pzErrMsg is not 0, then the
  5075  ** [sqlite3_load_extension()] interface shall attempt to
  5076  ** fill *pzErrMsg with error message text stored in memory
  5077  ** obtained from [sqlite3_malloc()]. The calling function
  5078  ** should free this memory by calling [sqlite3_free()].
  5079  **
  5080  ** ^Extension loading must be enabled using
  5081  ** [sqlite3_enable_load_extension()] prior to calling this API,
  5082  ** otherwise an error will be returned.
  5083  **
  5084  ** See also the [load_extension() SQL function].
  5085  */
  5086  SQLITE_API int sqlite3_load_extension(
  5087    sqlite3 *db,          /* Load the extension into this database connection */
  5088    const char *zFile,    /* Name of the shared library containing extension */
  5089    const char *zProc,    /* Entry point.  Derived from zFile if 0 */
  5090    char **pzErrMsg       /* Put error message here if not 0 */
  5091  );
  5092  
  5093  /*
  5094  ** CAPI3REF: Enable Or Disable Extension Loading
  5095  **
  5096  ** ^So as not to open security holes in older applications that are
  5097  ** unprepared to deal with [extension loading], and as a means of disabling
  5098  ** [extension loading] while evaluating user-entered SQL, the following API
  5099  ** is provided to turn the [sqlite3_load_extension()] mechanism on and off.
  5100  **
  5101  ** ^Extension loading is off by default.
  5102  ** ^Call the sqlite3_enable_load_extension() routine with onoff==1
  5103  ** to turn extension loading on and call it with onoff==0 to turn
  5104  ** it back off again.
  5105  */
  5106  SQLITE_API int sqlite3_enable_load_extension(sqlite3 *db, int onoff);
  5107  
  5108  /*
  5109  ** CAPI3REF: Automatically Load Statically Linked Extensions
  5110  **
  5111  ** ^This interface causes the xEntryPoint() function to be invoked for
  5112  ** each new [database connection] that is created.  The idea here is that
  5113  ** xEntryPoint() is the entry point for a statically linked [SQLite extension]
  5114  ** that is to be automatically loaded into all new database connections.
  5115  **
  5116  ** ^(Even though the function prototype shows that xEntryPoint() takes
  5117  ** no arguments and returns void, SQLite invokes xEntryPoint() with three
  5118  ** arguments and expects and integer result as if the signature of the
  5119  ** entry point where as follows:
  5120  **
  5121  ** <blockquote><pre>
  5122  ** &nbsp;  int xEntryPoint(
  5123  ** &nbsp;    sqlite3 *db,
  5124  ** &nbsp;    const char **pzErrMsg,
  5125  ** &nbsp;    const struct sqlite3_api_routines *pThunk
  5126  ** &nbsp;  );
  5127  ** </pre></blockquote>)^
  5128  **
  5129  ** If the xEntryPoint routine encounters an error, it should make *pzErrMsg
  5130  ** point to an appropriate error message (obtained from [sqlite3_mprintf()])
  5131  ** and return an appropriate [error code].  ^SQLite ensures that *pzErrMsg
  5132  ** is NULL before calling the xEntryPoint().  ^SQLite will invoke
  5133  ** [sqlite3_free()] on *pzErrMsg after xEntryPoint() returns.  ^If any
  5134  ** xEntryPoint() returns an error, the [sqlite3_open()], [sqlite3_open16()],
  5135  ** or [sqlite3_open_v2()] call that provoked the xEntryPoint() will fail.
  5136  **
  5137  ** ^Calling sqlite3_auto_extension(X) with an entry point X that is already
  5138  ** on the list of automatic extensions is a harmless no-op. ^No entry point
  5139  ** will be called more than once for each database connection that is opened.
  5140  **
  5141  ** See also: [sqlite3_reset_auto_extension()]
  5142  ** and [sqlite3_cancel_auto_extension()]
  5143  */
  5144  SQLITE_API int sqlite3_auto_extension(void (*xEntryPoint)(void));
  5145  
  5146  /*
  5147  ** CAPI3REF: Cancel Automatic Extension Loading
  5148  **
  5149  ** ^The [sqlite3_cancel_auto_extension(X)] interface unregisters the
  5150  ** initialization routine X that was registered using a prior call to
  5151  ** [sqlite3_auto_extension(X)].  ^The [sqlite3_cancel_auto_extension(X)]
  5152  ** routine returns 1 if initialization routine X was successfully 
  5153  ** unregistered and it returns 0 if X was not on the list of initialization
  5154  ** routines.
  5155  */
  5156  SQLITE_API int sqlite3_cancel_auto_extension(void (*xEntryPoint)(void));
  5157  
  5158  /*
  5159  ** CAPI3REF: Reset Automatic Extension Loading
  5160  **
  5161  ** ^This interface disables all automatic extensions previously
  5162  ** registered using [sqlite3_auto_extension()].
  5163  */
  5164  SQLITE_API void sqlite3_reset_auto_extension(void);
  5165  
  5166  /*
  5167  ** The interface to the virtual-table mechanism is currently considered
  5168  ** to be experimental.  The interface might change in incompatible ways.
  5169  ** If this is a problem for you, do not use the interface at this time.
  5170  **
  5171  ** When the virtual-table mechanism stabilizes, we will declare the
  5172  ** interface fixed, support it indefinitely, and remove this comment.
  5173  */
  5174  
  5175  /*
  5176  ** Structures used by the virtual table interface
  5177  */
  5178  typedef struct sqlite3_vtab sqlite3_vtab;
  5179  typedef struct sqlite3_index_info sqlite3_index_info;
  5180  typedef struct sqlite3_vtab_cursor sqlite3_vtab_cursor;
  5181  typedef struct sqlite3_module sqlite3_module;
  5182  
  5183  /*
  5184  ** CAPI3REF: Virtual Table Object
  5185  ** KEYWORDS: sqlite3_module {virtual table module}
  5186  **
  5187  ** This structure, sometimes called a "virtual table module", 
  5188  ** defines the implementation of a [virtual tables].  
  5189  ** This structure consists mostly of methods for the module.
  5190  **
  5191  ** ^A virtual table module is created by filling in a persistent
  5192  ** instance of this structure and passing a pointer to that instance
  5193  ** to [sqlite3_create_module()] or [sqlite3_create_module_v2()].
  5194  ** ^The registration remains valid until it is replaced by a different
  5195  ** module or until the [database connection] closes.  The content
  5196  ** of this structure must not change while it is registered with
  5197  ** any database connection.
  5198  */
  5199  struct sqlite3_module {
  5200    int iVersion;
  5201    int (*xCreate)(sqlite3*, void *pAux,
  5202                 int argc, const char *const*argv,
  5203                 sqlite3_vtab **ppVTab, char**);
  5204    int (*xConnect)(sqlite3*, void *pAux,
  5205                 int argc, const char *const*argv,
  5206                 sqlite3_vtab **ppVTab, char**);
  5207    int (*xBestIndex)(sqlite3_vtab *pVTab, sqlite3_index_info*);
  5208    int (*xDisconnect)(sqlite3_vtab *pVTab);
  5209    int (*xDestroy)(sqlite3_vtab *pVTab);
  5210    int (*xOpen)(sqlite3_vtab *pVTab, sqlite3_vtab_cursor **ppCursor);
  5211    int (*xClose)(sqlite3_vtab_cursor*);
  5212    int (*xFilter)(sqlite3_vtab_cursor*, int idxNum, const char *idxStr,
  5213                  int argc, sqlite3_value **argv);
  5214    int (*xNext)(sqlite3_vtab_cursor*);
  5215    int (*xEof)(sqlite3_vtab_cursor*);
  5216    int (*xColumn)(sqlite3_vtab_cursor*, sqlite3_context*, int);
  5217    int (*xRowid)(sqlite3_vtab_cursor*, sqlite3_int64 *pRowid);
  5218    int (*xUpdate)(sqlite3_vtab *, int, sqlite3_value **, sqlite3_int64 *);
  5219    int (*xBegin)(sqlite3_vtab *pVTab);
  5220    int (*xSync)(sqlite3_vtab *pVTab);
  5221    int (*xCommit)(sqlite3_vtab *pVTab);
  5222    int (*xRollback)(sqlite3_vtab *pVTab);
  5223    int (*xFindFunction)(sqlite3_vtab *pVtab, int nArg, const char *zName,
  5224                         void (**pxFunc)(sqlite3_context*,int,sqlite3_value**),
  5225                         void **ppArg);
  5226    int (*xRename)(sqlite3_vtab *pVtab, const char *zNew);
  5227    /* The methods above are in version 1 of the sqlite_module object. Those 
  5228    ** below are for version 2 and greater. */
  5229    int (*xSavepoint)(sqlite3_vtab *pVTab, int);
  5230    int (*xRelease)(sqlite3_vtab *pVTab, int);
  5231    int (*xRollbackTo)(sqlite3_vtab *pVTab, int);
  5232  };
  5233  
  5234  /*
  5235  ** CAPI3REF: Virtual Table Indexing Information
  5236  ** KEYWORDS: sqlite3_index_info
  5237  **
  5238  ** The sqlite3_index_info structure and its substructures is used as part
  5239  ** of the [virtual table] interface to
  5240  ** pass information into and receive the reply from the [xBestIndex]
  5241  ** method of a [virtual table module].  The fields under **Inputs** are the
  5242  ** inputs to xBestIndex and are read-only.  xBestIndex inserts its
  5243  ** results into the **Outputs** fields.
  5244  **
  5245  ** ^(The aConstraint[] array records WHERE clause constraints of the form:
  5246  **
  5247  ** <blockquote>column OP expr</blockquote>
  5248  **
  5249  ** where OP is =, &lt;, &lt;=, &gt;, or &gt;=.)^  ^(The particular operator is
  5250  ** stored in aConstraint[].op using one of the
  5251  ** [SQLITE_INDEX_CONSTRAINT_EQ | SQLITE_INDEX_CONSTRAINT_ values].)^
  5252  ** ^(The index of the column is stored in
  5253  ** aConstraint[].iColumn.)^  ^(aConstraint[].usable is TRUE if the
  5254  ** expr on the right-hand side can be evaluated (and thus the constraint
  5255  ** is usable) and false if it cannot.)^
  5256  **
  5257  ** ^The optimizer automatically inverts terms of the form "expr OP column"
  5258  ** and makes other simplifications to the WHERE clause in an attempt to
  5259  ** get as many WHERE clause terms into the form shown above as possible.
  5260  ** ^The aConstraint[] array only reports WHERE clause terms that are
  5261  ** relevant to the particular virtual table being queried.
  5262  **
  5263  ** ^Information about the ORDER BY clause is stored in aOrderBy[].
  5264  ** ^Each term of aOrderBy records a column of the ORDER BY clause.
  5265  **
  5266  ** The [xBestIndex] method must fill aConstraintUsage[] with information
  5267  ** about what parameters to pass to xFilter.  ^If argvIndex>0 then
  5268  ** the right-hand side of the corresponding aConstraint[] is evaluated
  5269  ** and becomes the argvIndex-th entry in argv.  ^(If aConstraintUsage[].omit
  5270  ** is true, then the constraint is assumed to be fully handled by the
  5271  ** virtual table and is not checked again by SQLite.)^
  5272  **
  5273  ** ^The idxNum and idxPtr values are recorded and passed into the
  5274  ** [xFilter] method.
  5275  ** ^[sqlite3_free()] is used to free idxPtr if and only if
  5276  ** needToFreeIdxPtr is true.
  5277  **
  5278  ** ^The orderByConsumed means that output from [xFilter]/[xNext] will occur in
  5279  ** the correct order to satisfy the ORDER BY clause so that no separate
  5280  ** sorting step is required.
  5281  **
  5282  ** ^The estimatedCost value is an estimate of the cost of doing the
  5283  ** particular lookup.  A full scan of a table with N entries should have
  5284  ** a cost of N.  A binary search of a table of N entries should have a
  5285  ** cost of approximately log(N).
  5286  */
  5287  struct sqlite3_index_info {
  5288    /* Inputs */
  5289    int nConstraint;           /* Number of entries in aConstraint */
  5290    struct sqlite3_index_constraint {
  5291       int iColumn;              /* Column on left-hand side of constraint */
  5292       unsigned char op;         /* Constraint operator */
  5293       unsigned char usable;     /* True if this constraint is usable */
  5294       int iTermOffset;          /* Used internally - xBestIndex should ignore */
  5295    } *aConstraint;            /* Table of WHERE clause constraints */
  5296    int nOrderBy;              /* Number of terms in the ORDER BY clause */
  5297    struct sqlite3_index_orderby {
  5298       int iColumn;              /* Column number */
  5299       unsigned char desc;       /* True for DESC.  False for ASC. */
  5300    } *aOrderBy;               /* The ORDER BY clause */
  5301    /* Outputs */
  5302    struct sqlite3_index_constraint_usage {
  5303      int argvIndex;           /* if >0, constraint is part of argv to xFilter */
  5304      unsigned char omit;      /* Do not code a test for this constraint */
  5305    } *aConstraintUsage;
  5306    int idxNum;                /* Number used to identify the index */
  5307    char *idxStr;              /* String, possibly obtained from sqlite3_malloc */
  5308    int needToFreeIdxStr;      /* Free idxStr using sqlite3_free() if true */
  5309    int orderByConsumed;       /* True if output is already ordered */
  5310    double estimatedCost;      /* Estimated cost of using this index */
  5311  };
  5312  
  5313  /*
  5314  ** CAPI3REF: Virtual Table Constraint Operator Codes
  5315  **
  5316  ** These macros defined the allowed values for the
  5317  ** [sqlite3_index_info].aConstraint[].op field.  Each value represents
  5318  ** an operator that is part of a constraint term in the wHERE clause of
  5319  ** a query that uses a [virtual table].
  5320  */
  5321  #define SQLITE_INDEX_CONSTRAINT_EQ    2
  5322  #define SQLITE_INDEX_CONSTRAINT_GT    4
  5323  #define SQLITE_INDEX_CONSTRAINT_LE    8
  5324  #define SQLITE_INDEX_CONSTRAINT_LT    16
  5325  #define SQLITE_INDEX_CONSTRAINT_GE    32
  5326  #define SQLITE_INDEX_CONSTRAINT_MATCH 64
  5327  
  5328  /*
  5329  ** CAPI3REF: Register A Virtual Table Implementation
  5330  **
  5331  ** ^These routines are used to register a new [virtual table module] name.
  5332  ** ^Module names must be registered before
  5333  ** creating a new [virtual table] using the module and before using a
  5334  ** preexisting [virtual table] for the module.
  5335  **
  5336  ** ^The module name is registered on the [database connection] specified
  5337  ** by the first parameter.  ^The name of the module is given by the 
  5338  ** second parameter.  ^The third parameter is a pointer to
  5339  ** the implementation of the [virtual table module].   ^The fourth
  5340  ** parameter is an arbitrary client data pointer that is passed through
  5341  ** into the [xCreate] and [xConnect] methods of the virtual table module
  5342  ** when a new virtual table is be being created or reinitialized.
  5343  **
  5344  ** ^The sqlite3_create_module_v2() interface has a fifth parameter which
  5345  ** is a pointer to a destructor for the pClientData.  ^SQLite will
  5346  ** invoke the destructor function (if it is not NULL) when SQLite
  5347  ** no longer needs the pClientData pointer.  ^The destructor will also
  5348  ** be invoked if the call to sqlite3_create_module_v2() fails.
  5349  ** ^The sqlite3_create_module()
  5350  ** interface is equivalent to sqlite3_create_module_v2() with a NULL
  5351  ** destructor.
  5352  */
  5353  SQLITE_API int sqlite3_create_module(
  5354    sqlite3 *db,               /* SQLite connection to register module with */
  5355    const char *zName,         /* Name of the module */
  5356    const sqlite3_module *p,   /* Methods for the module */
  5357    void *pClientData          /* Client data for xCreate/xConnect */
  5358  );
  5359  SQLITE_API int sqlite3_create_module_v2(
  5360    sqlite3 *db,               /* SQLite connection to register module with */
  5361    const char *zName,         /* Name of the module */
  5362    const sqlite3_module *p,   /* Methods for the module */
  5363    void *pClientData,         /* Client data for xCreate/xConnect */
  5364    void(*xDestroy)(void*)     /* Module destructor function */
  5365  );
  5366  
  5367  /*
  5368  ** CAPI3REF: Virtual Table Instance Object
  5369  ** KEYWORDS: sqlite3_vtab
  5370  **
  5371  ** Every [virtual table module] implementation uses a subclass
  5372  ** of this object to describe a particular instance
  5373  ** of the [virtual table].  Each subclass will
  5374  ** be tailored to the specific needs of the module implementation.
  5375  ** The purpose of this superclass is to define certain fields that are
  5376  ** common to all module implementations.
  5377  **
  5378  ** ^Virtual tables methods can set an error message by assigning a
  5379  ** string obtained from [sqlite3_mprintf()] to zErrMsg.  The method should
  5380  ** take care that any prior string is freed by a call to [sqlite3_free()]
  5381  ** prior to assigning a new string to zErrMsg.  ^After the error message
  5382  ** is delivered up to the client application, the string will be automatically
  5383  ** freed by sqlite3_free() and the zErrMsg field will be zeroed.
  5384  */
  5385  struct sqlite3_vtab {
  5386    const sqlite3_module *pModule;  /* The module for this virtual table */
  5387    int nRef;                       /* NO LONGER USED */
  5388    char *zErrMsg;                  /* Error message from sqlite3_mprintf() */
  5389    /* Virtual table implementations will typically add additional fields */
  5390  };
  5391  
  5392  /*
  5393  ** CAPI3REF: Virtual Table Cursor Object
  5394  ** KEYWORDS: sqlite3_vtab_cursor {virtual table cursor}
  5395  **
  5396  ** Every [virtual table module] implementation uses a subclass of the
  5397  ** following structure to describe cursors that point into the
  5398  ** [virtual table] and are used
  5399  ** to loop through the virtual table.  Cursors are created using the
  5400  ** [sqlite3_module.xOpen | xOpen] method of the module and are destroyed
  5401  ** by the [sqlite3_module.xClose | xClose] method.  Cursors are used
  5402  ** by the [xFilter], [xNext], [xEof], [xColumn], and [xRowid] methods
  5403  ** of the module.  Each module implementation will define
  5404  ** the content of a cursor structure to suit its own needs.
  5405  **
  5406  ** This superclass exists in order to define fields of the cursor that
  5407  ** are common to all implementations.
  5408  */
  5409  struct sqlite3_vtab_cursor {
  5410    sqlite3_vtab *pVtab;      /* Virtual table of this cursor */
  5411    /* Virtual table implementations will typically add additional fields */
  5412  };
  5413  
  5414  /*
  5415  ** CAPI3REF: Declare The Schema Of A Virtual Table
  5416  **
  5417  ** ^The [xCreate] and [xConnect] methods of a
  5418  ** [virtual table module] call this interface
  5419  ** to declare the format (the names and datatypes of the columns) of
  5420  ** the virtual tables they implement.
  5421  */
  5422  SQLITE_API int sqlite3_declare_vtab(sqlite3*, const char *zSQL);
  5423  
  5424  /*
  5425  ** CAPI3REF: Overload A Function For A Virtual Table
  5426  **
  5427  ** ^(Virtual tables can provide alternative implementations of functions
  5428  ** using the [xFindFunction] method of the [virtual table module].  
  5429  ** But global versions of those functions
  5430  ** must exist in order to be overloaded.)^
  5431  **
  5432  ** ^(This API makes sure a global version of a function with a particular
  5433  ** name and number of parameters exists.  If no such function exists
  5434  ** before this API is called, a new function is created.)^  ^The implementation
  5435  ** of the new function always causes an exception to be thrown.  So
  5436  ** the new function is not good for anything by itself.  Its only
  5437  ** purpose is to be a placeholder function that can be overloaded
  5438  ** by a [virtual table].
  5439  */
  5440  SQLITE_API int sqlite3_overload_function(sqlite3*, const char *zFuncName, int nArg);
  5441  
  5442  /*
  5443  ** The interface to the virtual-table mechanism defined above (back up
  5444  ** to a comment remarkably similar to this one) is currently considered
  5445  ** to be experimental.  The interface might change in incompatible ways.
  5446  ** If this is a problem for you, do not use the interface at this time.
  5447  **
  5448  ** When the virtual-table mechanism stabilizes, we will declare the
  5449  ** interface fixed, support it indefinitely, and remove this comment.
  5450  */
  5451  
  5452  /*
  5453  ** CAPI3REF: A Handle To An Open BLOB
  5454  ** KEYWORDS: {BLOB handle} {BLOB handles}
  5455  **
  5456  ** An instance of this object represents an open BLOB on which
  5457  ** [sqlite3_blob_open | incremental BLOB I/O] can be performed.
  5458  ** ^Objects of this type are created by [sqlite3_blob_open()]
  5459  ** and destroyed by [sqlite3_blob_close()].
  5460  ** ^The [sqlite3_blob_read()] and [sqlite3_blob_write()] interfaces
  5461  ** can be used to read or write small subsections of the BLOB.
  5462  ** ^The [sqlite3_blob_bytes()] interface returns the size of the BLOB in bytes.
  5463  */
  5464  typedef struct sqlite3_blob sqlite3_blob;
  5465  
  5466  /*
  5467  ** CAPI3REF: Open A BLOB For Incremental I/O
  5468  **
  5469  ** ^(This interfaces opens a [BLOB handle | handle] to the BLOB located
  5470  ** in row iRow, column zColumn, table zTable in database zDb;
  5471  ** in other words, the same BLOB that would be selected by:
  5472  **
  5473  ** <pre>
  5474  **     SELECT zColumn FROM zDb.zTable WHERE [rowid] = iRow;
  5475  ** </pre>)^
  5476  **
  5477  ** ^If the flags parameter is non-zero, then the BLOB is opened for read
  5478  ** and write access. ^If it is zero, the BLOB is opened for read access.
  5479  ** ^It is not possible to open a column that is part of an index or primary 
  5480  ** key for writing. ^If [foreign key constraints] are enabled, it is 
  5481  ** not possible to open a column that is part of a [child key] for writing.
  5482  **
  5483  ** ^Note that the database name is not the filename that contains
  5484  ** the database but rather the symbolic name of the database that
  5485  ** appears after the AS keyword when the database is connected using [ATTACH].
  5486  ** ^For the main database file, the database name is "main".
  5487  ** ^For TEMP tables, the database name is "temp".
  5488  **
  5489  ** ^(On success, [SQLITE_OK] is returned and the new [BLOB handle] is written
  5490  ** to *ppBlob. Otherwise an [error code] is returned and *ppBlob is set
  5491  ** to be a null pointer.)^
  5492  ** ^This function sets the [database connection] error code and message
  5493  ** accessible via [sqlite3_errcode()] and [sqlite3_errmsg()] and related
  5494  ** functions. ^Note that the *ppBlob variable is always initialized in a
  5495  ** way that makes it safe to invoke [sqlite3_blob_close()] on *ppBlob
  5496  ** regardless of the success or failure of this routine.
  5497  **
  5498  ** ^(If the row that a BLOB handle points to is modified by an
  5499  ** [UPDATE], [DELETE], or by [ON CONFLICT] side-effects
  5500  ** then the BLOB handle is marked as "expired".
  5501  ** This is true if any column of the row is changed, even a column
  5502  ** other than the one the BLOB handle is open on.)^
  5503  ** ^Calls to [sqlite3_blob_read()] and [sqlite3_blob_write()] for
  5504  ** an expired BLOB handle fail with a return code of [SQLITE_ABORT].
  5505  ** ^(Changes written into a BLOB prior to the BLOB expiring are not
  5506  ** rolled back by the expiration of the BLOB.  Such changes will eventually
  5507  ** commit if the transaction continues to completion.)^
  5508  **
  5509  ** ^Use the [sqlite3_blob_bytes()] interface to determine the size of
  5510  ** the opened blob.  ^The size of a blob may not be changed by this
  5511  ** interface.  Use the [UPDATE] SQL command to change the size of a
  5512  ** blob.
  5513  **
  5514  ** ^The [sqlite3_bind_zeroblob()] and [sqlite3_result_zeroblob()] interfaces
  5515  ** and the built-in [zeroblob] SQL function can be used, if desired,
  5516  ** to create an empty, zero-filled blob in which to read or write using
  5517  ** this interface.
  5518  **
  5519  ** To avoid a resource leak, every open [BLOB handle] should eventually
  5520  ** be released by a call to [sqlite3_blob_close()].
  5521  */
  5522  SQLITE_API int sqlite3_blob_open(
  5523    sqlite3*,
  5524    const char *zDb,
  5525    const char *zTable,
  5526    const char *zColumn,
  5527    sqlite3_int64 iRow,
  5528    int flags,
  5529    sqlite3_blob **ppBlob
  5530  );
  5531  
  5532  /*
  5533  ** CAPI3REF: Move a BLOB Handle to a New Row
  5534  **
  5535  ** ^This function is used to move an existing blob handle so that it points
  5536  ** to a different row of the same database table. ^The new row is identified
  5537  ** by the rowid value passed as the second argument. Only the row can be
  5538  ** changed. ^The database, table and column on which the blob handle is open
  5539  ** remain the same. Moving an existing blob handle to a new row can be
  5540  ** faster than closing the existing handle and opening a new one.
  5541  **
  5542  ** ^(The new row must meet the same criteria as for [sqlite3_blob_open()] -
  5543  ** it must exist and there must be either a blob or text value stored in
  5544  ** the nominated column.)^ ^If the new row is not present in the table, or if
  5545  ** it does not contain a blob or text value, or if another error occurs, an
  5546  ** SQLite error code is returned and the blob handle is considered aborted.
  5547  ** ^All subsequent calls to [sqlite3_blob_read()], [sqlite3_blob_write()] or
  5548  ** [sqlite3_blob_reopen()] on an aborted blob handle immediately return
  5549  ** SQLITE_ABORT. ^Calling [sqlite3_blob_bytes()] on an aborted blob handle
  5550  ** always returns zero.
  5551  **
  5552  ** ^This function sets the database handle error code and message.
  5553  */
  5554  SQLITE_API SQLITE_EXPERIMENTAL int sqlite3_blob_reopen(sqlite3_blob *, sqlite3_int64);
  5555  
  5556  /*
  5557  ** CAPI3REF: Close A BLOB Handle
  5558  **
  5559  ** ^Closes an open [BLOB handle].
  5560  **
  5561  ** ^Closing a BLOB shall cause the current transaction to commit
  5562  ** if there are no other BLOBs, no pending prepared statements, and the
  5563  ** database connection is in [autocommit mode].
  5564  ** ^If any writes were made to the BLOB, they might be held in cache
  5565  ** until the close operation if they will fit.
  5566  **
  5567  ** ^(Closing the BLOB often forces the changes
  5568  ** out to disk and so if any I/O errors occur, they will likely occur
  5569  ** at the time when the BLOB is closed.  Any errors that occur during
  5570  ** closing are reported as a non-zero return value.)^
  5571  **
  5572  ** ^(The BLOB is closed unconditionally.  Even if this routine returns
  5573  ** an error code, the BLOB is still closed.)^
  5574  **
  5575  ** ^Calling this routine with a null pointer (such as would be returned
  5576  ** by a failed call to [sqlite3_blob_open()]) is a harmless no-op.
  5577  */
  5578  SQLITE_API int sqlite3_blob_close(sqlite3_blob *);
  5579  
  5580  /*
  5581  ** CAPI3REF: Return The Size Of An Open BLOB
  5582  **
  5583  ** ^Returns the size in bytes of the BLOB accessible via the 
  5584  ** successfully opened [BLOB handle] in its only argument.  ^The
  5585  ** incremental blob I/O routines can only read or overwriting existing
  5586  ** blob content; they cannot change the size of a blob.
  5587  **
  5588  ** This routine only works on a [BLOB handle] which has been created
  5589  ** by a prior successful call to [sqlite3_blob_open()] and which has not
  5590  ** been closed by [sqlite3_blob_close()].  Passing any other pointer in
  5591  ** to this routine results in undefined and probably undesirable behavior.
  5592  */
  5593  SQLITE_API int sqlite3_blob_bytes(sqlite3_blob *);
  5594  
  5595  /*
  5596  ** CAPI3REF: Read Data From A BLOB Incrementally
  5597  **
  5598  ** ^(This function is used to read data from an open [BLOB handle] into a
  5599  ** caller-supplied buffer. N bytes of data are copied into buffer Z
  5600  ** from the open BLOB, starting at offset iOffset.)^
  5601  **
  5602  ** ^If offset iOffset is less than N bytes from the end of the BLOB,
  5603  ** [SQLITE_ERROR] is returned and no data is read.  ^If N or iOffset is
  5604  ** less than zero, [SQLITE_ERROR] is returned and no data is read.
  5605  ** ^The size of the blob (and hence the maximum value of N+iOffset)
  5606  ** can be determined using the [sqlite3_blob_bytes()] interface.
  5607  **
  5608  ** ^An attempt to read from an expired [BLOB handle] fails with an
  5609  ** error code of [SQLITE_ABORT].
  5610  **
  5611  ** ^(On success, sqlite3_blob_read() returns SQLITE_OK.
  5612  ** Otherwise, an [error code] or an [extended error code] is returned.)^
  5613  **
  5614  ** This routine only works on a [BLOB handle] which has been created
  5615  ** by a prior successful call to [sqlite3_blob_open()] and which has not
  5616  ** been closed by [sqlite3_blob_close()].  Passing any other pointer in
  5617  ** to this routine results in undefined and probably undesirable behavior.
  5618  **
  5619  ** See also: [sqlite3_blob_write()].
  5620  */
  5621  SQLITE_API int sqlite3_blob_read(sqlite3_blob *, void *Z, int N, int iOffset);
  5622  
  5623  /*
  5624  ** CAPI3REF: Write Data Into A BLOB Incrementally
  5625  **
  5626  ** ^This function is used to write data into an open [BLOB handle] from a
  5627  ** caller-supplied buffer. ^N bytes of data are copied from the buffer Z
  5628  ** into the open BLOB, starting at offset iOffset.
  5629  **
  5630  ** ^If the [BLOB handle] passed as the first argument was not opened for
  5631  ** writing (the flags parameter to [sqlite3_blob_open()] was zero),
  5632  ** this function returns [SQLITE_READONLY].
  5633  **
  5634  ** ^This function may only modify the contents of the BLOB; it is
  5635  ** not possible to increase the size of a BLOB using this API.
  5636  ** ^If offset iOffset is less than N bytes from the end of the BLOB,
  5637  ** [SQLITE_ERROR] is returned and no data is written.  ^If N is
  5638  ** less than zero [SQLITE_ERROR] is returned and no data is written.
  5639  ** The size of the BLOB (and hence the maximum value of N+iOffset)
  5640  ** can be determined using the [sqlite3_blob_bytes()] interface.
  5641  **
  5642  ** ^An attempt to write to an expired [BLOB handle] fails with an
  5643  ** error code of [SQLITE_ABORT].  ^Writes to the BLOB that occurred
  5644  ** before the [BLOB handle] expired are not rolled back by the
  5645  ** expiration of the handle, though of course those changes might
  5646  ** have been overwritten by the statement that expired the BLOB handle
  5647  ** or by other independent statements.
  5648  **
  5649  ** ^(On success, sqlite3_blob_write() returns SQLITE_OK.
  5650  ** Otherwise, an  [error code] or an [extended error code] is returned.)^
  5651  **
  5652  ** This routine only works on a [BLOB handle] which has been created
  5653  ** by a prior successful call to [sqlite3_blob_open()] and which has not
  5654  ** been closed by [sqlite3_blob_close()].  Passing any other pointer in
  5655  ** to this routine results in undefined and probably undesirable behavior.
  5656  **
  5657  ** See also: [sqlite3_blob_read()].
  5658  */
  5659  SQLITE_API int sqlite3_blob_write(sqlite3_blob *, const void *z, int n, int iOffset);
  5660  
  5661  /*
  5662  ** CAPI3REF: Virtual File System Objects
  5663  **
  5664  ** A virtual filesystem (VFS) is an [sqlite3_vfs] object
  5665  ** that SQLite uses to interact
  5666  ** with the underlying operating system.  Most SQLite builds come with a
  5667  ** single default VFS that is appropriate for the host computer.
  5668  ** New VFSes can be registered and existing VFSes can be unregistered.
  5669  ** The following interfaces are provided.
  5670  **
  5671  ** ^The sqlite3_vfs_find() interface returns a pointer to a VFS given its name.
  5672  ** ^Names are case sensitive.
  5673  ** ^Names are zero-terminated UTF-8 strings.
  5674  ** ^If there is no match, a NULL pointer is returned.
  5675  ** ^If zVfsName is NULL then the default VFS is returned.
  5676  **
  5677  ** ^New VFSes are registered with sqlite3_vfs_register().
  5678  ** ^Each new VFS becomes the default VFS if the makeDflt flag is set.
  5679  ** ^The same VFS can be registered multiple times without injury.
  5680  ** ^To make an existing VFS into the default VFS, register it again
  5681  ** with the makeDflt flag set.  If two different VFSes with the
  5682  ** same name are registered, the behavior is undefined.  If a
  5683  ** VFS is registered with a name that is NULL or an empty string,
  5684  ** then the behavior is undefined.
  5685  **
  5686  ** ^Unregister a VFS with the sqlite3_vfs_unregister() interface.
  5687  ** ^(If the default VFS is unregistered, another VFS is chosen as
  5688  ** the default.  The choice for the new VFS is arbitrary.)^
  5689  */
  5690  SQLITE_API sqlite3_vfs *sqlite3_vfs_find(const char *zVfsName);
  5691  SQLITE_API int sqlite3_vfs_register(sqlite3_vfs*, int makeDflt);
  5692  SQLITE_API int sqlite3_vfs_unregister(sqlite3_vfs*);
  5693  
  5694  /*
  5695  ** CAPI3REF: Mutexes
  5696  **
  5697  ** The SQLite core uses these routines for thread
  5698  ** synchronization. Though they are intended for internal
  5699  ** use by SQLite, code that links against SQLite is
  5700  ** permitted to use any of these routines.
  5701  **
  5702  ** The SQLite source code contains multiple implementations
  5703  ** of these mutex routines.  An appropriate implementation
  5704  ** is selected automatically at compile-time.  ^(The following
  5705  ** implementations are available in the SQLite core:
  5706  **
  5707  ** <ul>
  5708  ** <li>   SQLITE_MUTEX_PTHREADS
  5709  ** <li>   SQLITE_MUTEX_W32
  5710  ** <li>   SQLITE_MUTEX_NOOP
  5711  ** </ul>)^
  5712  **
  5713  ** ^The SQLITE_MUTEX_NOOP implementation is a set of routines
  5714  ** that does no real locking and is appropriate for use in
  5715  ** a single-threaded application.  ^The SQLITE_MUTEX_PTHREADS and
  5716  ** SQLITE_MUTEX_W32 implementations are appropriate for use on Unix
  5717  ** and Windows.
  5718  **
  5719  ** ^(If SQLite is compiled with the SQLITE_MUTEX_APPDEF preprocessor
  5720  ** macro defined (with "-DSQLITE_MUTEX_APPDEF=1"), then no mutex
  5721  ** implementation is included with the library. In this case the
  5722  ** application must supply a custom mutex implementation using the
  5723  ** [SQLITE_CONFIG_MUTEX] option of the sqlite3_config() function
  5724  ** before calling sqlite3_initialize() or any other public sqlite3_
  5725  ** function that calls sqlite3_initialize().)^
  5726  **
  5727  ** ^The sqlite3_mutex_alloc() routine allocates a new
  5728  ** mutex and returns a pointer to it. ^If it returns NULL
  5729  ** that means that a mutex could not be allocated.  ^SQLite
  5730  ** will unwind its stack and return an error.  ^(The argument
  5731  ** to sqlite3_mutex_alloc() is one of these integer constants:
  5732  **
  5733  ** <ul>
  5734  ** <li>  SQLITE_MUTEX_FAST
  5735  ** <li>  SQLITE_MUTEX_RECURSIVE
  5736  ** <li>  SQLITE_MUTEX_STATIC_MASTER
  5737  ** <li>  SQLITE_MUTEX_STATIC_MEM
  5738  ** <li>  SQLITE_MUTEX_STATIC_MEM2
  5739  ** <li>  SQLITE_MUTEX_STATIC_PRNG
  5740  ** <li>  SQLITE_MUTEX_STATIC_LRU
  5741  ** <li>  SQLITE_MUTEX_STATIC_LRU2
  5742  ** </ul>)^
  5743  **
  5744  ** ^The first two constants (SQLITE_MUTEX_FAST and SQLITE_MUTEX_RECURSIVE)
  5745  ** cause sqlite3_mutex_alloc() to create
  5746  ** a new mutex.  ^The new mutex is recursive when SQLITE_MUTEX_RECURSIVE
  5747  ** is used but not necessarily so when SQLITE_MUTEX_FAST is used.
  5748  ** The mutex implementation does not need to make a distinction
  5749  ** between SQLITE_MUTEX_RECURSIVE and SQLITE_MUTEX_FAST if it does
  5750  ** not want to.  ^SQLite will only request a recursive mutex in
  5751  ** cases where it really needs one.  ^If a faster non-recursive mutex
  5752  ** implementation is available on the host platform, the mutex subsystem
  5753  ** might return such a mutex in response to SQLITE_MUTEX_FAST.
  5754  **
  5755  ** ^The other allowed parameters to sqlite3_mutex_alloc() (anything other
  5756  ** than SQLITE_MUTEX_FAST and SQLITE_MUTEX_RECURSIVE) each return
  5757  ** a pointer to a static preexisting mutex.  ^Six static mutexes are
  5758  ** used by the current version of SQLite.  Future versions of SQLite
  5759  ** may add additional static mutexes.  Static mutexes are for internal
  5760  ** use by SQLite only.  Applications that use SQLite mutexes should
  5761  ** use only the dynamic mutexes returned by SQLITE_MUTEX_FAST or
  5762  ** SQLITE_MUTEX_RECURSIVE.
  5763  **
  5764  ** ^Note that if one of the dynamic mutex parameters (SQLITE_MUTEX_FAST
  5765  ** or SQLITE_MUTEX_RECURSIVE) is used then sqlite3_mutex_alloc()
  5766  ** returns a different mutex on every call.  ^But for the static
  5767  ** mutex types, the same mutex is returned on every call that has
  5768  ** the same type number.
  5769  **
  5770  ** ^The sqlite3_mutex_free() routine deallocates a previously
  5771  ** allocated dynamic mutex.  ^SQLite is careful to deallocate every
  5772  ** dynamic mutex that it allocates.  The dynamic mutexes must not be in
  5773  ** use when they are deallocated.  Attempting to deallocate a static
  5774  ** mutex results in undefined behavior.  ^SQLite never deallocates
  5775  ** a static mutex.
  5776  **
  5777  ** ^The sqlite3_mutex_enter() and sqlite3_mutex_try() routines attempt
  5778  ** to enter a mutex.  ^If another thread is already within the mutex,
  5779  ** sqlite3_mutex_enter() will block and sqlite3_mutex_try() will return
  5780  ** SQLITE_BUSY.  ^The sqlite3_mutex_try() interface returns [SQLITE_OK]
  5781  ** upon successful entry.  ^(Mutexes created using
  5782  ** SQLITE_MUTEX_RECURSIVE can be entered multiple times by the same thread.
  5783  ** In such cases the,
  5784  ** mutex must be exited an equal number of times before another thread
  5785  ** can enter.)^  ^(If the same thread tries to enter any other
  5786  ** kind of mutex more than once, the behavior is undefined.
  5787  ** SQLite will never exhibit
  5788  ** such behavior in its own use of mutexes.)^
  5789  **
  5790  ** ^(Some systems (for example, Windows 95) do not support the operation
  5791  ** implemented by sqlite3_mutex_try().  On those systems, sqlite3_mutex_try()
  5792  ** will always return SQLITE_BUSY.  The SQLite core only ever uses
  5793  ** sqlite3_mutex_try() as an optimization so this is acceptable behavior.)^
  5794  **
  5795  ** ^The sqlite3_mutex_leave() routine exits a mutex that was
  5796  ** previously entered by the same thread.   ^(The behavior
  5797  ** is undefined if the mutex is not currently entered by the
  5798  ** calling thread or is not currently allocated.  SQLite will
  5799  ** never do either.)^
  5800  **
  5801  ** ^If the argument to sqlite3_mutex_enter(), sqlite3_mutex_try(), or
  5802  ** sqlite3_mutex_leave() is a NULL pointer, then all three routines
  5803  ** behave as no-ops.
  5804  **
  5805  ** See also: [sqlite3_mutex_held()] and [sqlite3_mutex_notheld()].
  5806  */
  5807  SQLITE_API sqlite3_mutex *sqlite3_mutex_alloc(int);
  5808  SQLITE_API void sqlite3_mutex_free(sqlite3_mutex*);
  5809  SQLITE_API void sqlite3_mutex_enter(sqlite3_mutex*);
  5810  SQLITE_API int sqlite3_mutex_try(sqlite3_mutex*);
  5811  SQLITE_API void sqlite3_mutex_leave(sqlite3_mutex*);
  5812  
  5813  /*
  5814  ** CAPI3REF: Mutex Methods Object
  5815  **
  5816  ** An instance of this structure defines the low-level routines
  5817  ** used to allocate and use mutexes.
  5818  **
  5819  ** Usually, the default mutex implementations provided by SQLite are
  5820  ** sufficient, however the user has the option of substituting a custom
  5821  ** implementation for specialized deployments or systems for which SQLite
  5822  ** does not provide a suitable implementation. In this case, the user
  5823  ** creates and populates an instance of this structure to pass
  5824  ** to sqlite3_config() along with the [SQLITE_CONFIG_MUTEX] option.
  5825  ** Additionally, an instance of this structure can be used as an
  5826  ** output variable when querying the system for the current mutex
  5827  ** implementation, using the [SQLITE_CONFIG_GETMUTEX] option.
  5828  **
  5829  ** ^The xMutexInit method defined by this structure is invoked as
  5830  ** part of system initialization by the sqlite3_initialize() function.
  5831  ** ^The xMutexInit routine is called by SQLite exactly once for each
  5832  ** effective call to [sqlite3_initialize()].
  5833  **
  5834  ** ^The xMutexEnd method defined by this structure is invoked as
  5835  ** part of system shutdown by the sqlite3_shutdown() function. The
  5836  ** implementation of this method is expected to release all outstanding
  5837  ** resources obtained by the mutex methods implementation, especially
  5838  ** those obtained by the xMutexInit method.  ^The xMutexEnd()
  5839  ** interface is invoked exactly once for each call to [sqlite3_shutdown()].
  5840  **
  5841  ** ^(The remaining seven methods defined by this structure (xMutexAlloc,
  5842  ** xMutexFree, xMutexEnter, xMutexTry, xMutexLeave, xMutexHeld and
  5843  ** xMutexNotheld) implement the following interfaces (respectively):
  5844  **
  5845  ** <ul>
  5846  **   <li>  [sqlite3_mutex_alloc()] </li>
  5847  **   <li>  [sqlite3_mutex_free()] </li>
  5848  **   <li>  [sqlite3_mutex_enter()] </li>
  5849  **   <li>  [sqlite3_mutex_try()] </li>
  5850  **   <li>  [sqlite3_mutex_leave()] </li>
  5851  **   <li>  [sqlite3_mutex_held()] </li>
  5852  **   <li>  [sqlite3_mutex_notheld()] </li>
  5853  ** </ul>)^
  5854  **
  5855  ** The only difference is that the public sqlite3_XXX functions enumerated
  5856  ** above silently ignore any invocations that pass a NULL pointer instead
  5857  ** of a valid mutex handle. The implementations of the methods defined
  5858  ** by this structure are not required to handle this case, the results
  5859  ** of passing a NULL pointer instead of a valid mutex handle are undefined
  5860  ** (i.e. it is acceptable to provide an implementation that segfaults if
  5861  ** it is passed a NULL pointer).
  5862  **
  5863  ** The xMutexInit() method must be threadsafe.  ^It must be harmless to
  5864  ** invoke xMutexInit() multiple times within the same process and without
  5865  ** intervening calls to xMutexEnd().  Second and subsequent calls to
  5866  ** xMutexInit() must be no-ops.
  5867  **
  5868  ** ^xMutexInit() must not use SQLite memory allocation ([sqlite3_malloc()]
  5869  ** and its associates).  ^Similarly, xMutexAlloc() must not use SQLite memory
  5870  ** allocation for a static mutex.  ^However xMutexAlloc() may use SQLite
  5871  ** memory allocation for a fast or recursive mutex.
  5872  **
  5873  ** ^SQLite will invoke the xMutexEnd() method when [sqlite3_shutdown()] is
  5874  ** called, but only if the prior call to xMutexInit returned SQLITE_OK.
  5875  ** If xMutexInit fails in any way, it is expected to clean up after itself
  5876  ** prior to returning.
  5877  */
  5878  typedef struct sqlite3_mutex_methods sqlite3_mutex_methods;
  5879  struct sqlite3_mutex_methods {
  5880    int (*xMutexInit)(void);
  5881    int (*xMutexEnd)(void);
  5882    sqlite3_mutex *(*xMutexAlloc)(int);
  5883    void (*xMutexFree)(sqlite3_mutex *);
  5884    void (*xMutexEnter)(sqlite3_mutex *);
  5885    int (*xMutexTry)(sqlite3_mutex *);
  5886    void (*xMutexLeave)(sqlite3_mutex *);
  5887    int (*xMutexHeld)(sqlite3_mutex *);
  5888    int (*xMutexNotheld)(sqlite3_mutex *);
  5889  };
  5890  
  5891  /*
  5892  ** CAPI3REF: Mutex Verification Routines
  5893  **
  5894  ** The sqlite3_mutex_held() and sqlite3_mutex_notheld() routines
  5895  ** are intended for use inside assert() statements.  ^The SQLite core
  5896  ** never uses these routines except inside an assert() and applications
  5897  ** are advised to follow the lead of the core.  ^The SQLite core only
  5898  ** provides implementations for these routines when it is compiled
  5899  ** with the SQLITE_DEBUG flag.  ^External mutex implementations
  5900  ** are only required to provide these routines if SQLITE_DEBUG is
  5901  ** defined and if NDEBUG is not defined.
  5902  **
  5903  ** ^These routines should return true if the mutex in their argument
  5904  ** is held or not held, respectively, by the calling thread.
  5905  **
  5906  ** ^The implementation is not required to provide versions of these
  5907  ** routines that actually work. If the implementation does not provide working
  5908  ** versions of these routines, it should at least provide stubs that always
  5909  ** return true so that one does not get spurious assertion failures.
  5910  **
  5911  ** ^If the argument to sqlite3_mutex_held() is a NULL pointer then
  5912  ** the routine should return 1.   This seems counter-intuitive since
  5913  ** clearly the mutex cannot be held if it does not exist.  But
  5914  ** the reason the mutex does not exist is because the build is not
  5915  ** using mutexes.  And we do not want the assert() containing the
  5916  ** call to sqlite3_mutex_held() to fail, so a non-zero return is
  5917  ** the appropriate thing to do.  ^The sqlite3_mutex_notheld()
  5918  ** interface should also return 1 when given a NULL pointer.
  5919  */
  5920  #ifndef NDEBUG
  5921  SQLITE_API int sqlite3_mutex_held(sqlite3_mutex*);
  5922  SQLITE_API int sqlite3_mutex_notheld(sqlite3_mutex*);
  5923  #endif
  5924  
  5925  /*
  5926  ** CAPI3REF: Mutex Types
  5927  **
  5928  ** The [sqlite3_mutex_alloc()] interface takes a single argument
  5929  ** which is one of these integer constants.
  5930  **
  5931  ** The set of static mutexes may change from one SQLite release to the
  5932  ** next.  Applications that override the built-in mutex logic must be
  5933  ** prepared to accommodate additional static mutexes.
  5934  */
  5935  #define SQLITE_MUTEX_FAST             0
  5936  #define SQLITE_MUTEX_RECURSIVE        1
  5937  #define SQLITE_MUTEX_STATIC_MASTER    2
  5938  #define SQLITE_MUTEX_STATIC_MEM       3  /* sqlite3_malloc() */
  5939  #define SQLITE_MUTEX_STATIC_MEM2      4  /* NOT USED */
  5940  #define SQLITE_MUTEX_STATIC_OPEN      4  /* sqlite3BtreeOpen() */
  5941  #define SQLITE_MUTEX_STATIC_PRNG      5  /* sqlite3_random() */
  5942  #define SQLITE_MUTEX_STATIC_LRU       6  /* lru page list */
  5943  #define SQLITE_MUTEX_STATIC_LRU2      7  /* NOT USED */
  5944  #define SQLITE_MUTEX_STATIC_PMEM      7  /* sqlite3PageMalloc() */
  5945  
  5946  /*
  5947  ** CAPI3REF: Retrieve the mutex for a database connection
  5948  **
  5949  ** ^This interface returns a pointer the [sqlite3_mutex] object that 
  5950  ** serializes access to the [database connection] given in the argument
  5951  ** when the [threading mode] is Serialized.
  5952  ** ^If the [threading mode] is Single-thread or Multi-thread then this
  5953  ** routine returns a NULL pointer.
  5954  */
  5955  SQLITE_API sqlite3_mutex *sqlite3_db_mutex(sqlite3*);
  5956  
  5957  /*
  5958  ** CAPI3REF: Low-Level Control Of Database Files
  5959  **
  5960  ** ^The [sqlite3_file_control()] interface makes a direct call to the
  5961  ** xFileControl method for the [sqlite3_io_methods] object associated
  5962  ** with a particular database identified by the second argument. ^The
  5963  ** name of the database is "main" for the main database or "temp" for the
  5964  ** TEMP database, or the name that appears after the AS keyword for
  5965  ** databases that are added using the [ATTACH] SQL command.
  5966  ** ^A NULL pointer can be used in place of "main" to refer to the
  5967  ** main database file.
  5968  ** ^The third and fourth parameters to this routine
  5969  ** are passed directly through to the second and third parameters of
  5970  ** the xFileControl method.  ^The return value of the xFileControl
  5971  ** method becomes the return value of this routine.
  5972  **
  5973  ** ^The SQLITE_FCNTL_FILE_POINTER value for the op parameter causes
  5974  ** a pointer to the underlying [sqlite3_file] object to be written into
  5975  ** the space pointed to by the 4th parameter.  ^The SQLITE_FCNTL_FILE_POINTER
  5976  ** case is a short-circuit path which does not actually invoke the
  5977  ** underlying sqlite3_io_methods.xFileControl method.
  5978  **
  5979  ** ^If the second parameter (zDbName) does not match the name of any
  5980  ** open database file, then SQLITE_ERROR is returned.  ^This error
  5981  ** code is not remembered and will not be recalled by [sqlite3_errcode()]
  5982  ** or [sqlite3_errmsg()].  The underlying xFileControl method might
  5983  ** also return SQLITE_ERROR.  There is no way to distinguish between
  5984  ** an incorrect zDbName and an SQLITE_ERROR return from the underlying
  5985  ** xFileControl method.
  5986  **
  5987  ** See also: [SQLITE_FCNTL_LOCKSTATE]
  5988  */
  5989  SQLITE_API int sqlite3_file_control(sqlite3*, const char *zDbName, int op, void*);
  5990  
  5991  /*
  5992  ** CAPI3REF: Testing Interface
  5993  **
  5994  ** ^The sqlite3_test_control() interface is used to read out internal
  5995  ** state of SQLite and to inject faults into SQLite for testing
  5996  ** purposes.  ^The first parameter is an operation code that determines
  5997  ** the number, meaning, and operation of all subsequent parameters.
  5998  **
  5999  ** This interface is not for use by applications.  It exists solely
  6000  ** for verifying the correct operation of the SQLite library.  Depending
  6001  ** on how the SQLite library is compiled, this interface might not exist.
  6002  **
  6003  ** The details of the operation codes, their meanings, the parameters
  6004  ** they take, and what they do are all subject to change without notice.
  6005  ** Unlike most of the SQLite API, this function is not guaranteed to
  6006  ** operate consistently from one release to the next.
  6007  */
  6008  SQLITE_API int sqlite3_test_control(int op, ...);
  6009  
  6010  /*
  6011  ** CAPI3REF: Testing Interface Operation Codes
  6012  **
  6013  ** These constants are the valid operation code parameters used
  6014  ** as the first argument to [sqlite3_test_control()].
  6015  **
  6016  ** These parameters and their meanings are subject to change
  6017  ** without notice.  These values are for testing purposes only.
  6018  ** Applications should not use any of these parameters or the
  6019  ** [sqlite3_test_control()] interface.
  6020  */
  6021  #define SQLITE_TESTCTRL_FIRST                    5
  6022  #define SQLITE_TESTCTRL_PRNG_SAVE                5
  6023  #define SQLITE_TESTCTRL_PRNG_RESTORE             6
  6024  #define SQLITE_TESTCTRL_PRNG_RESET               7
  6025  #define SQLITE_TESTCTRL_BITVEC_TEST              8
  6026  #define SQLITE_TESTCTRL_FAULT_INSTALL            9
  6027  #define SQLITE_TESTCTRL_BENIGN_MALLOC_HOOKS     10
  6028  #define SQLITE_TESTCTRL_PENDING_BYTE            11
  6029  #define SQLITE_TESTCTRL_ASSERT                  12
  6030  #define SQLITE_TESTCTRL_ALWAYS                  13
  6031  #define SQLITE_TESTCTRL_RESERVE                 14
  6032  #define SQLITE_TESTCTRL_OPTIMIZATIONS           15
  6033  #define SQLITE_TESTCTRL_ISKEYWORD               16
  6034  #define SQLITE_TESTCTRL_SCRATCHMALLOC           17
  6035  #define SQLITE_TESTCTRL_LOCALTIME_FAULT         18
  6036  #define SQLITE_TESTCTRL_EXPLAIN_STMT            19
  6037  #define SQLITE_TESTCTRL_LAST                    19
  6038  
  6039  /*
  6040  ** CAPI3REF: SQLite Runtime Status
  6041  **
  6042  ** ^This interface is used to retrieve runtime status information
  6043  ** about the performance of SQLite, and optionally to reset various
  6044  ** highwater marks.  ^The first argument is an integer code for
  6045  ** the specific parameter to measure.  ^(Recognized integer codes
  6046  ** are of the form [status parameters | SQLITE_STATUS_...].)^
  6047  ** ^The current value of the parameter is returned into *pCurrent.
  6048  ** ^The highest recorded value is returned in *pHighwater.  ^If the
  6049  ** resetFlag is true, then the highest record value is reset after
  6050  ** *pHighwater is written.  ^(Some parameters do not record the highest
  6051  ** value.  For those parameters
  6052  ** nothing is written into *pHighwater and the resetFlag is ignored.)^
  6053  ** ^(Other parameters record only the highwater mark and not the current
  6054  ** value.  For these latter parameters nothing is written into *pCurrent.)^
  6055  **
  6056  ** ^The sqlite3_status() routine returns SQLITE_OK on success and a
  6057  ** non-zero [error code] on failure.
  6058  **
  6059  ** This routine is threadsafe but is not atomic.  This routine can be
  6060  ** called while other threads are running the same or different SQLite
  6061  ** interfaces.  However the values returned in *pCurrent and
  6062  ** *pHighwater reflect the status of SQLite at different points in time
  6063  ** and it is possible that another thread might change the parameter
  6064  ** in between the times when *pCurrent and *pHighwater are written.
  6065  **
  6066  ** See also: [sqlite3_db_status()]
  6067  */
  6068  SQLITE_API int sqlite3_status(int op, int *pCurrent, int *pHighwater, int resetFlag);
  6069  
  6070  
  6071  /*
  6072  ** CAPI3REF: Status Parameters
  6073  ** KEYWORDS: {status parameters}
  6074  **
  6075  ** These integer constants designate various run-time status parameters
  6076  ** that can be returned by [sqlite3_status()].
  6077  **
  6078  ** <dl>
  6079  ** [[SQLITE_STATUS_MEMORY_USED]] ^(<dt>SQLITE_STATUS_MEMORY_USED</dt>
  6080  ** <dd>This parameter is the current amount of memory checked out
  6081  ** using [sqlite3_malloc()], either directly or indirectly.  The
  6082  ** figure includes calls made to [sqlite3_malloc()] by the application
  6083  ** and internal memory usage by the SQLite library.  Scratch memory
  6084  ** controlled by [SQLITE_CONFIG_SCRATCH] and auxiliary page-cache
  6085  ** memory controlled by [SQLITE_CONFIG_PAGECACHE] is not included in
  6086  ** this parameter.  The amount returned is the sum of the allocation
  6087  ** sizes as reported by the xSize method in [sqlite3_mem_methods].</dd>)^
  6088  **
  6089  ** [[SQLITE_STATUS_MALLOC_SIZE]] ^(<dt>SQLITE_STATUS_MALLOC_SIZE</dt>
  6090  ** <dd>This parameter records the largest memory allocation request
  6091  ** handed to [sqlite3_malloc()] or [sqlite3_realloc()] (or their
  6092  ** internal equivalents).  Only the value returned in the
  6093  ** *pHighwater parameter to [sqlite3_status()] is of interest.  
  6094  ** The value written into the *pCurrent parameter is undefined.</dd>)^
  6095  **
  6096  ** [[SQLITE_STATUS_MALLOC_COUNT]] ^(<dt>SQLITE_STATUS_MALLOC_COUNT</dt>
  6097  ** <dd>This parameter records the number of separate memory allocations
  6098  ** currently checked out.</dd>)^
  6099  **
  6100  ** [[SQLITE_STATUS_PAGECACHE_USED]] ^(<dt>SQLITE_STATUS_PAGECACHE_USED</dt>
  6101  ** <dd>This parameter returns the number of pages used out of the
  6102  ** [pagecache memory allocator] that was configured using 
  6103  ** [SQLITE_CONFIG_PAGECACHE].  The
  6104  ** value returned is in pages, not in bytes.</dd>)^
  6105  **
  6106  ** [[SQLITE_STATUS_PAGECACHE_OVERFLOW]] 
  6107  ** ^(<dt>SQLITE_STATUS_PAGECACHE_OVERFLOW</dt>
  6108  ** <dd>This parameter returns the number of bytes of page cache
  6109  ** allocation which could not be satisfied by the [SQLITE_CONFIG_PAGECACHE]
  6110  ** buffer and where forced to overflow to [sqlite3_malloc()].  The
  6111  ** returned value includes allocations that overflowed because they
  6112  ** where too large (they were larger than the "sz" parameter to
  6113  ** [SQLITE_CONFIG_PAGECACHE]) and allocations that overflowed because
  6114  ** no space was left in the page cache.</dd>)^
  6115  **
  6116  ** [[SQLITE_STATUS_PAGECACHE_SIZE]] ^(<dt>SQLITE_STATUS_PAGECACHE_SIZE</dt>
  6117  ** <dd>This parameter records the largest memory allocation request
  6118  ** handed to [pagecache memory allocator].  Only the value returned in the
  6119  ** *pHighwater parameter to [sqlite3_status()] is of interest.  
  6120  ** The value written into the *pCurrent parameter is undefined.</dd>)^
  6121  **
  6122  ** [[SQLITE_STATUS_SCRATCH_USED]] ^(<dt>SQLITE_STATUS_SCRATCH_USED</dt>
  6123  ** <dd>This parameter returns the number of allocations used out of the
  6124  ** [scratch memory allocator] configured using
  6125  ** [SQLITE_CONFIG_SCRATCH].  The value returned is in allocations, not
  6126  ** in bytes.  Since a single thread may only have one scratch allocation
  6127  ** outstanding at time, this parameter also reports the number of threads
  6128  ** using scratch memory at the same time.</dd>)^
  6129  **
  6130  ** [[SQLITE_STATUS_SCRATCH_OVERFLOW]] ^(<dt>SQLITE_STATUS_SCRATCH_OVERFLOW</dt>
  6131  ** <dd>This parameter returns the number of bytes of scratch memory
  6132  ** allocation which could not be satisfied by the [SQLITE_CONFIG_SCRATCH]
  6133  ** buffer and where forced to overflow to [sqlite3_malloc()].  The values
  6134  ** returned include overflows because the requested allocation was too
  6135  ** larger (that is, because the requested allocation was larger than the
  6136  ** "sz" parameter to [SQLITE_CONFIG_SCRATCH]) and because no scratch buffer
  6137  ** slots were available.
  6138  ** </dd>)^
  6139  **
  6140  ** [[SQLITE_STATUS_SCRATCH_SIZE]] ^(<dt>SQLITE_STATUS_SCRATCH_SIZE</dt>
  6141  ** <dd>This parameter records the largest memory allocation request
  6142  ** handed to [scratch memory allocator].  Only the value returned in the
  6143  ** *pHighwater parameter to [sqlite3_status()] is of interest.  
  6144  ** The value written into the *pCurrent parameter is undefined.</dd>)^
  6145  **
  6146  ** [[SQLITE_STATUS_PARSER_STACK]] ^(<dt>SQLITE_STATUS_PARSER_STACK</dt>
  6147  ** <dd>This parameter records the deepest parser stack.  It is only
  6148  ** meaningful if SQLite is compiled with [YYTRACKMAXSTACKDEPTH].</dd>)^
  6149  ** </dl>
  6150  **
  6151  ** New status parameters may be added from time to time.
  6152  */
  6153  #define SQLITE_STATUS_MEMORY_USED          0
  6154  #define SQLITE_STATUS_PAGECACHE_USED       1
  6155  #define SQLITE_STATUS_PAGECACHE_OVERFLOW   2
  6156  #define SQLITE_STATUS_SCRATCH_USED         3
  6157  #define SQLITE_STATUS_SCRATCH_OVERFLOW     4
  6158  #define SQLITE_STATUS_MALLOC_SIZE          5
  6159  #define SQLITE_STATUS_PARSER_STACK         6
  6160  #define SQLITE_STATUS_PAGECACHE_SIZE       7
  6161  #define SQLITE_STATUS_SCRATCH_SIZE         8
  6162  #define SQLITE_STATUS_MALLOC_COUNT         9
  6163  
  6164  /*
  6165  ** CAPI3REF: Database Connection Status
  6166  **
  6167  ** ^This interface is used to retrieve runtime status information 
  6168  ** about a single [database connection].  ^The first argument is the
  6169  ** database connection object to be interrogated.  ^The second argument
  6170  ** is an integer constant, taken from the set of
  6171  ** [SQLITE_DBSTATUS options], that
  6172  ** determines the parameter to interrogate.  The set of 
  6173  ** [SQLITE_DBSTATUS options] is likely
  6174  ** to grow in future releases of SQLite.
  6175  **
  6176  ** ^The current value of the requested parameter is written into *pCur
  6177  ** and the highest instantaneous value is written into *pHiwtr.  ^If
  6178  ** the resetFlg is true, then the highest instantaneous value is
  6179  ** reset back down to the current value.
  6180  **
  6181  ** ^The sqlite3_db_status() routine returns SQLITE_OK on success and a
  6182  ** non-zero [error code] on failure.
  6183  **
  6184  ** See also: [sqlite3_status()] and [sqlite3_stmt_status()].
  6185  */
  6186  SQLITE_API int sqlite3_db_status(sqlite3*, int op, int *pCur, int *pHiwtr, int resetFlg);
  6187  
  6188  /*
  6189  ** CAPI3REF: Status Parameters for database connections
  6190  ** KEYWORDS: {SQLITE_DBSTATUS options}
  6191  **
  6192  ** These constants are the available integer "verbs" that can be passed as
  6193  ** the second argument to the [sqlite3_db_status()] interface.
  6194  **
  6195  ** New verbs may be added in future releases of SQLite. Existing verbs
  6196  ** might be discontinued. Applications should check the return code from
  6197  ** [sqlite3_db_status()] to make sure that the call worked.
  6198  ** The [sqlite3_db_status()] interface will return a non-zero error code
  6199  ** if a discontinued or unsupported verb is invoked.
  6200  **
  6201  ** <dl>
  6202  ** [[SQLITE_DBSTATUS_LOOKASIDE_USED]] ^(<dt>SQLITE_DBSTATUS_LOOKASIDE_USED</dt>
  6203  ** <dd>This parameter returns the number of lookaside memory slots currently
  6204  ** checked out.</dd>)^
  6205  **
  6206  ** [[SQLITE_DBSTATUS_LOOKASIDE_HIT]] ^(<dt>SQLITE_DBSTATUS_LOOKASIDE_HIT</dt>
  6207  ** <dd>This parameter returns the number malloc attempts that were 
  6208  ** satisfied using lookaside memory. Only the high-water value is meaningful;
  6209  ** the current value is always zero.)^
  6210  **
  6211  ** [[SQLITE_DBSTATUS_LOOKASIDE_MISS_SIZE]]
  6212  ** ^(<dt>SQLITE_DBSTATUS_LOOKASIDE_MISS_SIZE</dt>
  6213  ** <dd>This parameter returns the number malloc attempts that might have
  6214  ** been satisfied using lookaside memory but failed due to the amount of
  6215  ** memory requested being larger than the lookaside slot size.
  6216  ** Only the high-water value is meaningful;
  6217  ** the current value is always zero.)^
  6218  **
  6219  ** [[SQLITE_DBSTATUS_LOOKASIDE_MISS_FULL]]
  6220  ** ^(<dt>SQLITE_DBSTATUS_LOOKASIDE_MISS_FULL</dt>
  6221  ** <dd>This parameter returns the number malloc attempts that might have
  6222  ** been satisfied using lookaside memory but failed due to all lookaside
  6223  ** memory already being in use.
  6224  ** Only the high-water value is meaningful;
  6225  ** the current value is always zero.)^
  6226  **
  6227  ** [[SQLITE_DBSTATUS_CACHE_USED]] ^(<dt>SQLITE_DBSTATUS_CACHE_USED</dt>
  6228  ** <dd>This parameter returns the approximate number of of bytes of heap
  6229  ** memory used by all pager caches associated with the database connection.)^
  6230  ** ^The highwater mark associated with SQLITE_DBSTATUS_CACHE_USED is always 0.
  6231  **
  6232  ** [[SQLITE_DBSTATUS_SCHEMA_USED]] ^(<dt>SQLITE_DBSTATUS_SCHEMA_USED</dt>
  6233  ** <dd>This parameter returns the approximate number of of bytes of heap
  6234  ** memory used to store the schema for all databases associated
  6235  ** with the connection - main, temp, and any [ATTACH]-ed databases.)^ 
  6236  ** ^The full amount of memory used by the schemas is reported, even if the
  6237  ** schema memory is shared with other database connections due to
  6238  ** [shared cache mode] being enabled.
  6239  ** ^The highwater mark associated with SQLITE_DBSTATUS_SCHEMA_USED is always 0.
  6240  **
  6241  ** [[SQLITE_DBSTATUS_STMT_USED]] ^(<dt>SQLITE_DBSTATUS_STMT_USED</dt>
  6242  ** <dd>This parameter returns the approximate number of of bytes of heap
  6243  ** and lookaside memory used by all prepared statements associated with
  6244  ** the database connection.)^
  6245  ** ^The highwater mark associated with SQLITE_DBSTATUS_STMT_USED is always 0.
  6246  ** </dd>
  6247  **
  6248  ** [[SQLITE_DBSTATUS_CACHE_HIT]] ^(<dt>SQLITE_DBSTATUS_CACHE_HIT</dt>
  6249  ** <dd>This parameter returns the number of pager cache hits that have
  6250  ** occurred.)^ ^The highwater mark associated with SQLITE_DBSTATUS_CACHE_HIT 
  6251  ** is always 0.
  6252  ** </dd>
  6253  **
  6254  ** [[SQLITE_DBSTATUS_CACHE_MISS]] ^(<dt>SQLITE_DBSTATUS_CACHE_MISS</dt>
  6255  ** <dd>This parameter returns the number of pager cache misses that have
  6256  ** occurred.)^ ^The highwater mark associated with SQLITE_DBSTATUS_CACHE_MISS 
  6257  ** is always 0.
  6258  ** </dd>
  6259  **
  6260  ** [[SQLITE_DBSTATUS_CACHE_WRITE]] ^(<dt>SQLITE_DBSTATUS_CACHE_WRITE</dt>
  6261  ** <dd>This parameter returns the number of dirty cache entries that have
  6262  ** been written to disk. Specifically, the number of pages written to the
  6263  ** wal file in wal mode databases, or the number of pages written to the
  6264  ** database file in rollback mode databases. Any pages written as part of
  6265  ** transaction rollback or database recovery operations are not included.
  6266  ** If an IO or other error occurs while writing a page to disk, the effect
  6267  ** on subsequent SQLITE_DBSTATUS_CACHE_WRITE requests is undefined.)^ ^The
  6268  ** highwater mark associated with SQLITE_DBSTATUS_CACHE_WRITE is always 0.
  6269  ** </dd>
  6270  **
  6271  ** [[SQLITE_DBSTATUS_DEFERRED_FKS]] ^(<dt>SQLITE_DBSTATUS_DEFERRED_FKS</dt>
  6272  ** <dd>This parameter returns zero for the current value if and only if
  6273  ** all foreign key constraints (deferred or immediate) have been
  6274  ** resolved.)^  ^The highwater mark is always 0.
  6275  ** </dd>
  6276  ** </dl>
  6277  */
  6278  #define SQLITE_DBSTATUS_LOOKASIDE_USED       0
  6279  #define SQLITE_DBSTATUS_CACHE_USED           1
  6280  #define SQLITE_DBSTATUS_SCHEMA_USED          2
  6281  #define SQLITE_DBSTATUS_STMT_USED            3
  6282  #define SQLITE_DBSTATUS_LOOKASIDE_HIT        4
  6283  #define SQLITE_DBSTATUS_LOOKASIDE_MISS_SIZE  5
  6284  #define SQLITE_DBSTATUS_LOOKASIDE_MISS_FULL  6
  6285  #define SQLITE_DBSTATUS_CACHE_HIT            7
  6286  #define SQLITE_DBSTATUS_CACHE_MISS           8
  6287  #define SQLITE_DBSTATUS_CACHE_WRITE          9
  6288  #define SQLITE_DBSTATUS_DEFERRED_FKS        10
  6289  #define SQLITE_DBSTATUS_MAX                 10   /* Largest defined DBSTATUS */
  6290  
  6291  
  6292  /*
  6293  ** CAPI3REF: Prepared Statement Status
  6294  **
  6295  ** ^(Each prepared statement maintains various
  6296  ** [SQLITE_STMTSTATUS counters] that measure the number
  6297  ** of times it has performed specific operations.)^  These counters can
  6298  ** be used to monitor the performance characteristics of the prepared
  6299  ** statements.  For example, if the number of table steps greatly exceeds
  6300  ** the number of table searches or result rows, that would tend to indicate
  6301  ** that the prepared statement is using a full table scan rather than
  6302  ** an index.  
  6303  **
  6304  ** ^(This interface is used to retrieve and reset counter values from
  6305  ** a [prepared statement].  The first argument is the prepared statement
  6306  ** object to be interrogated.  The second argument
  6307  ** is an integer code for a specific [SQLITE_STMTSTATUS counter]
  6308  ** to be interrogated.)^
  6309  ** ^The current value of the requested counter is returned.
  6310  ** ^If the resetFlg is true, then the counter is reset to zero after this
  6311  ** interface call returns.
  6312  **
  6313  ** See also: [sqlite3_status()] and [sqlite3_db_status()].
  6314  */
  6315  SQLITE_API int sqlite3_stmt_status(sqlite3_stmt*, int op,int resetFlg);
  6316  
  6317  /*
  6318  ** CAPI3REF: Status Parameters for prepared statements
  6319  ** KEYWORDS: {SQLITE_STMTSTATUS counter} {SQLITE_STMTSTATUS counters}
  6320  **
  6321  ** These preprocessor macros define integer codes that name counter
  6322  ** values associated with the [sqlite3_stmt_status()] interface.
  6323  ** The meanings of the various counters are as follows:
  6324  **
  6325  ** <dl>
  6326  ** [[SQLITE_STMTSTATUS_FULLSCAN_STEP]] <dt>SQLITE_STMTSTATUS_FULLSCAN_STEP</dt>
  6327  ** <dd>^This is the number of times that SQLite has stepped forward in
  6328  ** a table as part of a full table scan.  Large numbers for this counter
  6329  ** may indicate opportunities for performance improvement through 
  6330  ** careful use of indices.</dd>
  6331  **
  6332  ** [[SQLITE_STMTSTATUS_SORT]] <dt>SQLITE_STMTSTATUS_SORT</dt>
  6333  ** <dd>^This is the number of sort operations that have occurred.
  6334  ** A non-zero value in this counter may indicate an opportunity to
  6335  ** improvement performance through careful use of indices.</dd>
  6336  **
  6337  ** [[SQLITE_STMTSTATUS_AUTOINDEX]] <dt>SQLITE_STMTSTATUS_AUTOINDEX</dt>
  6338  ** <dd>^This is the number of rows inserted into transient indices that
  6339  ** were created automatically in order to help joins run faster.
  6340  ** A non-zero value in this counter may indicate an opportunity to
  6341  ** improvement performance by adding permanent indices that do not
  6342  ** need to be reinitialized each time the statement is run.</dd>
  6343  **
  6344  ** [[SQLITE_STMTSTATUS_VM_STEP]] <dt>SQLITE_STMTSTATUS_VM_STEP</dt>
  6345  ** <dd>^This is the number of virtual machine operations executed
  6346  ** by the prepared statement if that number is less than or equal
  6347  ** to 2147483647.  The number of virtual machine operations can be 
  6348  ** used as a proxy for the total work done by the prepared statement.
  6349  ** If the number of virtual machine operations exceeds 2147483647
  6350  ** then the value returned by this statement status code is undefined.
  6351  ** </dd>
  6352  ** </dl>
  6353  */
  6354  #define SQLITE_STMTSTATUS_FULLSCAN_STEP     1
  6355  #define SQLITE_STMTSTATUS_SORT              2
  6356  #define SQLITE_STMTSTATUS_AUTOINDEX         3
  6357  #define SQLITE_STMTSTATUS_VM_STEP           4
  6358  
  6359  /*
  6360  ** CAPI3REF: Custom Page Cache Object
  6361  **
  6362  ** The sqlite3_pcache type is opaque.  It is implemented by
  6363  ** the pluggable module.  The SQLite core has no knowledge of
  6364  ** its size or internal structure and never deals with the
  6365  ** sqlite3_pcache object except by holding and passing pointers
  6366  ** to the object.
  6367  **
  6368  ** See [sqlite3_pcache_methods2] for additional information.
  6369  */
  6370  typedef struct sqlite3_pcache sqlite3_pcache;
  6371  
  6372  /*
  6373  ** CAPI3REF: Custom Page Cache Object
  6374  **
  6375  ** The sqlite3_pcache_page object represents a single page in the
  6376  ** page cache.  The page cache will allocate instances of this
  6377  ** object.  Various methods of the page cache use pointers to instances
  6378  ** of this object as parameters or as their return value.
  6379  **
  6380  ** See [sqlite3_pcache_methods2] for additional information.
  6381  */
  6382  typedef struct sqlite3_pcache_page sqlite3_pcache_page;
  6383  struct sqlite3_pcache_page {
  6384    void *pBuf;        /* The content of the page */
  6385    void *pExtra;      /* Extra information associated with the page */
  6386  };
  6387  
  6388  /*
  6389  ** CAPI3REF: Application Defined Page Cache.
  6390  ** KEYWORDS: {page cache}
  6391  **
  6392  ** ^(The [sqlite3_config]([SQLITE_CONFIG_PCACHE2], ...) interface can
  6393  ** register an alternative page cache implementation by passing in an 
  6394  ** instance of the sqlite3_pcache_methods2 structure.)^
  6395  ** In many applications, most of the heap memory allocated by 
  6396  ** SQLite is used for the page cache.
  6397  ** By implementing a 
  6398  ** custom page cache using this API, an application can better control
  6399  ** the amount of memory consumed by SQLite, the way in which 
  6400  ** that memory is allocated and released, and the policies used to 
  6401  ** determine exactly which parts of a database file are cached and for 
  6402  ** how long.
  6403  **
  6404  ** The alternative page cache mechanism is an
  6405  ** extreme measure that is only needed by the most demanding applications.
  6406  ** The built-in page cache is recommended for most uses.
  6407  **
  6408  ** ^(The contents of the sqlite3_pcache_methods2 structure are copied to an
  6409  ** internal buffer by SQLite within the call to [sqlite3_config].  Hence
  6410  ** the application may discard the parameter after the call to
  6411  ** [sqlite3_config()] returns.)^
  6412  **
  6413  ** [[the xInit() page cache method]]
  6414  ** ^(The xInit() method is called once for each effective 
  6415  ** call to [sqlite3_initialize()])^
  6416  ** (usually only once during the lifetime of the process). ^(The xInit()
  6417  ** method is passed a copy of the sqlite3_pcache_methods2.pArg value.)^
  6418  ** The intent of the xInit() method is to set up global data structures 
  6419  ** required by the custom page cache implementation. 
  6420  ** ^(If the xInit() method is NULL, then the 
  6421  ** built-in default page cache is used instead of the application defined
  6422  ** page cache.)^
  6423  **
  6424  ** [[the xShutdown() page cache method]]
  6425  ** ^The xShutdown() method is called by [sqlite3_shutdown()].
  6426  ** It can be used to clean up 
  6427  ** any outstanding resources before process shutdown, if required.
  6428  ** ^The xShutdown() method may be NULL.
  6429  **
  6430  ** ^SQLite automatically serializes calls to the xInit method,
  6431  ** so the xInit method need not be threadsafe.  ^The
  6432  ** xShutdown method is only called from [sqlite3_shutdown()] so it does
  6433  ** not need to be threadsafe either.  All other methods must be threadsafe
  6434  ** in multithreaded applications.
  6435  **
  6436  ** ^SQLite will never invoke xInit() more than once without an intervening
  6437  ** call to xShutdown().
  6438  **
  6439  ** [[the xCreate() page cache methods]]
  6440  ** ^SQLite invokes the xCreate() method to construct a new cache instance.
  6441  ** SQLite will typically create one cache instance for each open database file,
  6442  ** though this is not guaranteed. ^The
  6443  ** first parameter, szPage, is the size in bytes of the pages that must
  6444  ** be allocated by the cache.  ^szPage will always a power of two.  ^The
  6445  ** second parameter szExtra is a number of bytes of extra storage 
  6446  ** associated with each page cache entry.  ^The szExtra parameter will
  6447  ** a number less than 250.  SQLite will use the
  6448  ** extra szExtra bytes on each page to store metadata about the underlying
  6449  ** database page on disk.  The value passed into szExtra depends
  6450  ** on the SQLite version, the target platform, and how SQLite was compiled.
  6451  ** ^The third argument to xCreate(), bPurgeable, is true if the cache being
  6452  ** created will be used to cache database pages of a file stored on disk, or
  6453  ** false if it is used for an in-memory database. The cache implementation
  6454  ** does not have to do anything special based with the value of bPurgeable;
  6455  ** it is purely advisory.  ^On a cache where bPurgeable is false, SQLite will
  6456  ** never invoke xUnpin() except to deliberately delete a page.
  6457  ** ^In other words, calls to xUnpin() on a cache with bPurgeable set to
  6458  ** false will always have the "discard" flag set to true.  
  6459  ** ^Hence, a cache created with bPurgeable false will
  6460  ** never contain any unpinned pages.
  6461  **
  6462  ** [[the xCachesize() page cache method]]
  6463  ** ^(The xCachesize() method may be called at any time by SQLite to set the
  6464  ** suggested maximum cache-size (number of pages stored by) the cache
  6465  ** instance passed as the first argument. This is the value configured using
  6466  ** the SQLite "[PRAGMA cache_size]" command.)^  As with the bPurgeable
  6467  ** parameter, the implementation is not required to do anything with this
  6468  ** value; it is advisory only.
  6469  **
  6470  ** [[the xPagecount() page cache methods]]
  6471  ** The xPagecount() method must return the number of pages currently
  6472  ** stored in the cache, both pinned and unpinned.
  6473  ** 
  6474  ** [[the xFetch() page cache methods]]
  6475  ** The xFetch() method locates a page in the cache and returns a pointer to 
  6476  ** an sqlite3_pcache_page object associated with that page, or a NULL pointer.
  6477  ** The pBuf element of the returned sqlite3_pcache_page object will be a
  6478  ** pointer to a buffer of szPage bytes used to store the content of a 
  6479  ** single database page.  The pExtra element of sqlite3_pcache_page will be
  6480  ** a pointer to the szExtra bytes of extra storage that SQLite has requested
  6481  ** for each entry in the page cache.
  6482  **
  6483  ** The page to be fetched is determined by the key. ^The minimum key value
  6484  ** is 1.  After it has been retrieved using xFetch, the page is considered
  6485  ** to be "pinned".
  6486  **
  6487  ** If the requested page is already in the page cache, then the page cache
  6488  ** implementation must return a pointer to the page buffer with its content
  6489  ** intact.  If the requested page is not already in the cache, then the
  6490  ** cache implementation should use the value of the createFlag
  6491  ** parameter to help it determined what action to take:
  6492  **
  6493  ** <table border=1 width=85% align=center>
  6494  ** <tr><th> createFlag <th> Behavior when page is not already in cache
  6495  ** <tr><td> 0 <td> Do not allocate a new page.  Return NULL.
  6496  ** <tr><td> 1 <td> Allocate a new page if it easy and convenient to do so.
  6497  **                 Otherwise return NULL.
  6498  ** <tr><td> 2 <td> Make every effort to allocate a new page.  Only return
  6499  **                 NULL if allocating a new page is effectively impossible.
  6500  ** </table>
  6501  **
  6502  ** ^(SQLite will normally invoke xFetch() with a createFlag of 0 or 1.  SQLite
  6503  ** will only use a createFlag of 2 after a prior call with a createFlag of 1
  6504  ** failed.)^  In between the to xFetch() calls, SQLite may
  6505  ** attempt to unpin one or more cache pages by spilling the content of
  6506  ** pinned pages to disk and synching the operating system disk cache.
  6507  **
  6508  ** [[the xUnpin() page cache method]]
  6509  ** ^xUnpin() is called by SQLite with a pointer to a currently pinned page
  6510  ** as its second argument.  If the third parameter, discard, is non-zero,
  6511  ** then the page must be evicted from the cache.
  6512  ** ^If the discard parameter is
  6513  ** zero, then the page may be discarded or retained at the discretion of
  6514  ** page cache implementation. ^The page cache implementation
  6515  ** may choose to evict unpinned pages at any time.
  6516  **
  6517  ** The cache must not perform any reference counting. A single 
  6518  ** call to xUnpin() unpins the page regardless of the number of prior calls 
  6519  ** to xFetch().
  6520  **
  6521  ** [[the xRekey() page cache methods]]
  6522  ** The xRekey() method is used to change the key value associated with the
  6523  ** page passed as the second argument. If the cache
  6524  ** previously contains an entry associated with newKey, it must be
  6525  ** discarded. ^Any prior cache entry associated with newKey is guaranteed not
  6526  ** to be pinned.
  6527  **
  6528  ** When SQLite calls the xTruncate() method, the cache must discard all
  6529  ** existing cache entries with page numbers (keys) greater than or equal
  6530  ** to the value of the iLimit parameter passed to xTruncate(). If any
  6531  ** of these pages are pinned, they are implicitly unpinned, meaning that
  6532  ** they can be safely discarded.
  6533  **
  6534  ** [[the xDestroy() page cache method]]
  6535  ** ^The xDestroy() method is used to delete a cache allocated by xCreate().
  6536  ** All resources associated with the specified cache should be freed. ^After
  6537  ** calling the xDestroy() method, SQLite considers the [sqlite3_pcache*]
  6538  ** handle invalid, and will not use it with any other sqlite3_pcache_methods2
  6539  ** functions.
  6540  **
  6541  ** [[the xShrink() page cache method]]
  6542  ** ^SQLite invokes the xShrink() method when it wants the page cache to
  6543  ** free up as much of heap memory as possible.  The page cache implementation
  6544  ** is not obligated to free any memory, but well-behaved implementations should
  6545  ** do their best.
  6546  */
  6547  typedef struct sqlite3_pcache_methods2 sqlite3_pcache_methods2;
  6548  struct sqlite3_pcache_methods2 {
  6549    int iVersion;
  6550    void *pArg;
  6551    int (*xInit)(void*);
  6552    void (*xShutdown)(void*);
  6553    sqlite3_pcache *(*xCreate)(int szPage, int szExtra, int bPurgeable);
  6554    void (*xCachesize)(sqlite3_pcache*, int nCachesize);
  6555    int (*xPagecount)(sqlite3_pcache*);
  6556    sqlite3_pcache_page *(*xFetch)(sqlite3_pcache*, unsigned key, int createFlag);
  6557    void (*xUnpin)(sqlite3_pcache*, sqlite3_pcache_page*, int discard);
  6558    void (*xRekey)(sqlite3_pcache*, sqlite3_pcache_page*, 
  6559        unsigned oldKey, unsigned newKey);
  6560    void (*xTruncate)(sqlite3_pcache*, unsigned iLimit);
  6561    void (*xDestroy)(sqlite3_pcache*);
  6562    void (*xShrink)(sqlite3_pcache*);
  6563  };
  6564  
  6565  /*
  6566  ** This is the obsolete pcache_methods object that has now been replaced
  6567  ** by sqlite3_pcache_methods2.  This object is not used by SQLite.  It is
  6568  ** retained in the header file for backwards compatibility only.
  6569  */
  6570  typedef struct sqlite3_pcache_methods sqlite3_pcache_methods;
  6571  struct sqlite3_pcache_methods {
  6572    void *pArg;
  6573    int (*xInit)(void*);
  6574    void (*xShutdown)(void*);
  6575    sqlite3_pcache *(*xCreate)(int szPage, int bPurgeable);
  6576    void (*xCachesize)(sqlite3_pcache*, int nCachesize);
  6577    int (*xPagecount)(sqlite3_pcache*);
  6578    void *(*xFetch)(sqlite3_pcache*, unsigned key, int createFlag);
  6579    void (*xUnpin)(sqlite3_pcache*, void*, int discard);
  6580    void (*xRekey)(sqlite3_pcache*, void*, unsigned oldKey, unsigned newKey);
  6581    void (*xTruncate)(sqlite3_pcache*, unsigned iLimit);
  6582    void (*xDestroy)(sqlite3_pcache*);
  6583  };
  6584  
  6585  
  6586  /*
  6587  ** CAPI3REF: Online Backup Object
  6588  **
  6589  ** The sqlite3_backup object records state information about an ongoing
  6590  ** online backup operation.  ^The sqlite3_backup object is created by
  6591  ** a call to [sqlite3_backup_init()] and is destroyed by a call to
  6592  ** [sqlite3_backup_finish()].
  6593  **
  6594  ** See Also: [Using the SQLite Online Backup API]
  6595  */
  6596  typedef struct sqlite3_backup sqlite3_backup;
  6597  
  6598  /*
  6599  ** CAPI3REF: Online Backup API.
  6600  **
  6601  ** The backup API copies the content of one database into another.
  6602  ** It is useful either for creating backups of databases or
  6603  ** for copying in-memory databases to or from persistent files. 
  6604  **
  6605  ** See Also: [Using the SQLite Online Backup API]
  6606  **
  6607  ** ^SQLite holds a write transaction open on the destination database file
  6608  ** for the duration of the backup operation.
  6609  ** ^The source database is read-locked only while it is being read;
  6610  ** it is not locked continuously for the entire backup operation.
  6611  ** ^Thus, the backup may be performed on a live source database without
  6612  ** preventing other database connections from
  6613  ** reading or writing to the source database while the backup is underway.
  6614  ** 
  6615  ** ^(To perform a backup operation: 
  6616  **   <ol>
  6617  **     <li><b>sqlite3_backup_init()</b> is called once to initialize the
  6618  **         backup, 
  6619  **     <li><b>sqlite3_backup_step()</b> is called one or more times to transfer 
  6620  **         the data between the two databases, and finally
  6621  **     <li><b>sqlite3_backup_finish()</b> is called to release all resources 
  6622  **         associated with the backup operation. 
  6623  **   </ol>)^
  6624  ** There should be exactly one call to sqlite3_backup_finish() for each
  6625  ** successful call to sqlite3_backup_init().
  6626  **
  6627  ** [[sqlite3_backup_init()]] <b>sqlite3_backup_init()</b>
  6628  **
  6629  ** ^The D and N arguments to sqlite3_backup_init(D,N,S,M) are the 
  6630  ** [database connection] associated with the destination database 
  6631  ** and the database name, respectively.
  6632  ** ^The database name is "main" for the main database, "temp" for the
  6633  ** temporary database, or the name specified after the AS keyword in
  6634  ** an [ATTACH] statement for an attached database.
  6635  ** ^The S and M arguments passed to 
  6636  ** sqlite3_backup_init(D,N,S,M) identify the [database connection]
  6637  ** and database name of the source database, respectively.
  6638  ** ^The source and destination [database connections] (parameters S and D)
  6639  ** must be different or else sqlite3_backup_init(D,N,S,M) will fail with
  6640  ** an error.
  6641  **
  6642  ** ^If an error occurs within sqlite3_backup_init(D,N,S,M), then NULL is
  6643  ** returned and an error code and error message are stored in the
  6644  ** destination [database connection] D.
  6645  ** ^The error code and message for the failed call to sqlite3_backup_init()
  6646  ** can be retrieved using the [sqlite3_errcode()], [sqlite3_errmsg()], and/or
  6647  ** [sqlite3_errmsg16()] functions.
  6648  ** ^A successful call to sqlite3_backup_init() returns a pointer to an
  6649  ** [sqlite3_backup] object.
  6650  ** ^The [sqlite3_backup] object may be used with the sqlite3_backup_step() and
  6651  ** sqlite3_backup_finish() functions to perform the specified backup 
  6652  ** operation.
  6653  **
  6654  ** [[sqlite3_backup_step()]] <b>sqlite3_backup_step()</b>
  6655  **
  6656  ** ^Function sqlite3_backup_step(B,N) will copy up to N pages between 
  6657  ** the source and destination databases specified by [sqlite3_backup] object B.
  6658  ** ^If N is negative, all remaining source pages are copied. 
  6659  ** ^If sqlite3_backup_step(B,N) successfully copies N pages and there
  6660  ** are still more pages to be copied, then the function returns [SQLITE_OK].
  6661  ** ^If sqlite3_backup_step(B,N) successfully finishes copying all pages
  6662  ** from source to destination, then it returns [SQLITE_DONE].
  6663  ** ^If an error occurs while running sqlite3_backup_step(B,N),
  6664  ** then an [error code] is returned. ^As well as [SQLITE_OK] and
  6665  ** [SQLITE_DONE], a call to sqlite3_backup_step() may return [SQLITE_READONLY],
  6666  ** [SQLITE_NOMEM], [SQLITE_BUSY], [SQLITE_LOCKED], or an
  6667  ** [SQLITE_IOERR_ACCESS | SQLITE_IOERR_XXX] extended error code.
  6668  **
  6669  ** ^(The sqlite3_backup_step() might return [SQLITE_READONLY] if
  6670  ** <ol>
  6671  ** <li> the destination database was opened read-only, or
  6672  ** <li> the destination database is using write-ahead-log journaling
  6673  ** and the destination and source page sizes differ, or
  6674  ** <li> the destination database is an in-memory database and the
  6675  ** destination and source page sizes differ.
  6676  ** </ol>)^
  6677  **
  6678  ** ^If sqlite3_backup_step() cannot obtain a required file-system lock, then
  6679  ** the [sqlite3_busy_handler | busy-handler function]
  6680  ** is invoked (if one is specified). ^If the 
  6681  ** busy-handler returns non-zero before the lock is available, then 
  6682  ** [SQLITE_BUSY] is returned to the caller. ^In this case the call to
  6683  ** sqlite3_backup_step() can be retried later. ^If the source
  6684  ** [database connection]
  6685  ** is being used to write to the source database when sqlite3_backup_step()
  6686  ** is called, then [SQLITE_LOCKED] is returned immediately. ^Again, in this
  6687  ** case the call to sqlite3_backup_step() can be retried later on. ^(If
  6688  ** [SQLITE_IOERR_ACCESS | SQLITE_IOERR_XXX], [SQLITE_NOMEM], or
  6689  ** [SQLITE_READONLY] is returned, then 
  6690  ** there is no point in retrying the call to sqlite3_backup_step(). These 
  6691  ** errors are considered fatal.)^  The application must accept 
  6692  ** that the backup operation has failed and pass the backup operation handle 
  6693  ** to the sqlite3_backup_finish() to release associated resources.
  6694  **
  6695  ** ^The first call to sqlite3_backup_step() obtains an exclusive lock
  6696  ** on the destination file. ^The exclusive lock is not released until either 
  6697  ** sqlite3_backup_finish() is called or the backup operation is complete 
  6698  ** and sqlite3_backup_step() returns [SQLITE_DONE].  ^Every call to
  6699  ** sqlite3_backup_step() obtains a [shared lock] on the source database that
  6700  ** lasts for the duration of the sqlite3_backup_step() call.
  6701  ** ^Because the source database is not locked between calls to
  6702  ** sqlite3_backup_step(), the source database may be modified mid-way
  6703  ** through the backup process.  ^If the source database is modified by an
  6704  ** external process or via a database connection other than the one being
  6705  ** used by the backup operation, then the backup will be automatically
  6706  ** restarted by the next call to sqlite3_backup_step(). ^If the source 
  6707  ** database is modified by the using the same database connection as is used
  6708  ** by the backup operation, then the backup database is automatically
  6709  ** updated at the same time.
  6710  **
  6711  ** [[sqlite3_backup_finish()]] <b>sqlite3_backup_finish()</b>
  6712  **
  6713  ** When sqlite3_backup_step() has returned [SQLITE_DONE], or when the 
  6714  ** application wishes to abandon the backup operation, the application
  6715  ** should destroy the [sqlite3_backup] by passing it to sqlite3_backup_finish().
  6716  ** ^The sqlite3_backup_finish() interfaces releases all
  6717  ** resources associated with the [sqlite3_backup] object. 
  6718  ** ^If sqlite3_backup_step() has not yet returned [SQLITE_DONE], then any
  6719  ** active write-transaction on the destination database is rolled back.
  6720  ** The [sqlite3_backup] object is invalid
  6721  ** and may not be used following a call to sqlite3_backup_finish().
  6722  **
  6723  ** ^The value returned by sqlite3_backup_finish is [SQLITE_OK] if no
  6724  ** sqlite3_backup_step() errors occurred, regardless or whether or not
  6725  ** sqlite3_backup_step() completed.
  6726  ** ^If an out-of-memory condition or IO error occurred during any prior
  6727  ** sqlite3_backup_step() call on the same [sqlite3_backup] object, then
  6728  ** sqlite3_backup_finish() returns the corresponding [error code].
  6729  **
  6730  ** ^A return of [SQLITE_BUSY] or [SQLITE_LOCKED] from sqlite3_backup_step()
  6731  ** is not a permanent error and does not affect the return value of
  6732  ** sqlite3_backup_finish().
  6733  **
  6734  ** [[sqlite3_backup__remaining()]] [[sqlite3_backup_pagecount()]]
  6735  ** <b>sqlite3_backup_remaining() and sqlite3_backup_pagecount()</b>
  6736  **
  6737  ** ^Each call to sqlite3_backup_step() sets two values inside
  6738  ** the [sqlite3_backup] object: the number of pages still to be backed
  6739  ** up and the total number of pages in the source database file.
  6740  ** The sqlite3_backup_remaining() and sqlite3_backup_pagecount() interfaces
  6741  ** retrieve these two values, respectively.
  6742  **
  6743  ** ^The values returned by these functions are only updated by
  6744  ** sqlite3_backup_step(). ^If the source database is modified during a backup
  6745  ** operation, then the values are not updated to account for any extra
  6746  ** pages that need to be updated or the size of the source database file
  6747  ** changing.
  6748  **
  6749  ** <b>Concurrent Usage of Database Handles</b>
  6750  **
  6751  ** ^The source [database connection] may be used by the application for other
  6752  ** purposes while a backup operation is underway or being initialized.
  6753  ** ^If SQLite is compiled and configured to support threadsafe database
  6754  ** connections, then the source database connection may be used concurrently
  6755  ** from within other threads.
  6756  **
  6757  ** However, the application must guarantee that the destination 
  6758  ** [database connection] is not passed to any other API (by any thread) after 
  6759  ** sqlite3_backup_init() is called and before the corresponding call to
  6760  ** sqlite3_backup_finish().  SQLite does not currently check to see
  6761  ** if the application incorrectly accesses the destination [database connection]
  6762  ** and so no error code is reported, but the operations may malfunction
  6763  ** nevertheless.  Use of the destination database connection while a
  6764  ** backup is in progress might also also cause a mutex deadlock.
  6765  **
  6766  ** If running in [shared cache mode], the application must
  6767  ** guarantee that the shared cache used by the destination database
  6768  ** is not accessed while the backup is running. In practice this means
  6769  ** that the application must guarantee that the disk file being 
  6770  ** backed up to is not accessed by any connection within the process,
  6771  ** not just the specific connection that was passed to sqlite3_backup_init().
  6772  **
  6773  ** The [sqlite3_backup] object itself is partially threadsafe. Multiple 
  6774  ** threads may safely make multiple concurrent calls to sqlite3_backup_step().
  6775  ** However, the sqlite3_backup_remaining() and sqlite3_backup_pagecount()
  6776  ** APIs are not strictly speaking threadsafe. If they are invoked at the
  6777  ** same time as another thread is invoking sqlite3_backup_step() it is
  6778  ** possible that they return invalid values.
  6779  */
  6780  SQLITE_API sqlite3_backup *sqlite3_backup_init(
  6781    sqlite3 *pDest,                        /* Destination database handle */
  6782    const char *zDestName,                 /* Destination database name */
  6783    sqlite3 *pSource,                      /* Source database handle */
  6784    const char *zSourceName                /* Source database name */
  6785  );
  6786  SQLITE_API int sqlite3_backup_step(sqlite3_backup *p, int nPage);
  6787  SQLITE_API int sqlite3_backup_finish(sqlite3_backup *p);
  6788  SQLITE_API int sqlite3_backup_remaining(sqlite3_backup *p);
  6789  SQLITE_API int sqlite3_backup_pagecount(sqlite3_backup *p);
  6790  
  6791  /*
  6792  ** CAPI3REF: Unlock Notification
  6793  **
  6794  ** ^When running in shared-cache mode, a database operation may fail with
  6795  ** an [SQLITE_LOCKED] error if the required locks on the shared-cache or
  6796  ** individual tables within the shared-cache cannot be obtained. See
  6797  ** [SQLite Shared-Cache Mode] for a description of shared-cache locking. 
  6798  ** ^This API may be used to register a callback that SQLite will invoke 
  6799  ** when the connection currently holding the required lock relinquishes it.
  6800  ** ^This API is only available if the library was compiled with the
  6801  ** [SQLITE_ENABLE_UNLOCK_NOTIFY] C-preprocessor symbol defined.
  6802  **
  6803  ** See Also: [Using the SQLite Unlock Notification Feature].
  6804  **
  6805  ** ^Shared-cache locks are released when a database connection concludes
  6806  ** its current transaction, either by committing it or rolling it back. 
  6807  **
  6808  ** ^When a connection (known as the blocked connection) fails to obtain a
  6809  ** shared-cache lock and SQLITE_LOCKED is returned to the caller, the
  6810  ** identity of the database connection (the blocking connection) that
  6811  ** has locked the required resource is stored internally. ^After an 
  6812  ** application receives an SQLITE_LOCKED error, it may call the
  6813  ** sqlite3_unlock_notify() method with the blocked connection handle as 
  6814  ** the first argument to register for a callback that will be invoked
  6815  ** when the blocking connections current transaction is concluded. ^The
  6816  ** callback is invoked from within the [sqlite3_step] or [sqlite3_close]
  6817  ** call that concludes the blocking connections transaction.
  6818  **
  6819  ** ^(If sqlite3_unlock_notify() is called in a multi-threaded application,
  6820  ** there is a chance that the blocking connection will have already
  6821  ** concluded its transaction by the time sqlite3_unlock_notify() is invoked.
  6822  ** If this happens, then the specified callback is invoked immediately,
  6823  ** from within the call to sqlite3_unlock_notify().)^
  6824  **
  6825  ** ^If the blocked connection is attempting to obtain a write-lock on a
  6826  ** shared-cache table, and more than one other connection currently holds
  6827  ** a read-lock on the same table, then SQLite arbitrarily selects one of 
  6828  ** the other connections to use as the blocking connection.
  6829  **
  6830  ** ^(There may be at most one unlock-notify callback registered by a 
  6831  ** blocked connection. If sqlite3_unlock_notify() is called when the
  6832  ** blocked connection already has a registered unlock-notify callback,
  6833  ** then the new callback replaces the old.)^ ^If sqlite3_unlock_notify() is
  6834  ** called with a NULL pointer as its second argument, then any existing
  6835  ** unlock-notify callback is canceled. ^The blocked connections 
  6836  ** unlock-notify callback may also be canceled by closing the blocked
  6837  ** connection using [sqlite3_close()].
  6838  **
  6839  ** The unlock-notify callback is not reentrant. If an application invokes
  6840  ** any sqlite3_xxx API functions from within an unlock-notify callback, a
  6841  ** crash or deadlock may be the result.
  6842  **
  6843  ** ^Unless deadlock is detected (see below), sqlite3_unlock_notify() always
  6844  ** returns SQLITE_OK.
  6845  **
  6846  ** <b>Callback Invocation Details</b>
  6847  **
  6848  ** When an unlock-notify callback is registered, the application provides a 
  6849  ** single void* pointer that is passed to the callback when it is invoked.
  6850  ** However, the signature of the callback function allows SQLite to pass
  6851  ** it an array of void* context pointers. The first argument passed to
  6852  ** an unlock-notify callback is a pointer to an array of void* pointers,
  6853  ** and the second is the number of entries in the array.
  6854  **
  6855  ** When a blocking connections transaction is concluded, there may be
  6856  ** more than one blocked connection that has registered for an unlock-notify
  6857  ** callback. ^If two or more such blocked connections have specified the
  6858  ** same callback function, then instead of invoking the callback function
  6859  ** multiple times, it is invoked once with the set of void* context pointers
  6860  ** specified by the blocked connections bundled together into an array.
  6861  ** This gives the application an opportunity to prioritize any actions 
  6862  ** related to the set of unblocked database connections.
  6863  **
  6864  ** <b>Deadlock Detection</b>
  6865  **
  6866  ** Assuming that after registering for an unlock-notify callback a 
  6867  ** database waits for the callback to be issued before taking any further
  6868  ** action (a reasonable assumption), then using this API may cause the
  6869  ** application to deadlock. For example, if connection X is waiting for
  6870  ** connection Y's transaction to be concluded, and similarly connection
  6871  ** Y is waiting on connection X's transaction, then neither connection
  6872  ** will proceed and the system may remain deadlocked indefinitely.
  6873  **
  6874  ** To avoid this scenario, the sqlite3_unlock_notify() performs deadlock
  6875  ** detection. ^If a given call to sqlite3_unlock_notify() would put the
  6876  ** system in a deadlocked state, then SQLITE_LOCKED is returned and no
  6877  ** unlock-notify callback is registered. The system is said to be in
  6878  ** a deadlocked state if connection A has registered for an unlock-notify
  6879  ** callback on the conclusion of connection B's transaction, and connection
  6880  ** B has itself registered for an unlock-notify callback when connection
  6881  ** A's transaction is concluded. ^Indirect deadlock is also detected, so
  6882  ** the system is also considered to be deadlocked if connection B has
  6883  ** registered for an unlock-notify callback on the conclusion of connection
  6884  ** C's transaction, where connection C is waiting on connection A. ^Any
  6885  ** number of levels of indirection are allowed.
  6886  **
  6887  ** <b>The "DROP TABLE" Exception</b>
  6888  **
  6889  ** When a call to [sqlite3_step()] returns SQLITE_LOCKED, it is almost 
  6890  ** always appropriate to call sqlite3_unlock_notify(). There is however,
  6891  ** one exception. When executing a "DROP TABLE" or "DROP INDEX" statement,
  6892  ** SQLite checks if there are any currently executing SELECT statements
  6893  ** that belong to the same connection. If there are, SQLITE_LOCKED is
  6894  ** returned. In this case there is no "blocking connection", so invoking
  6895  ** sqlite3_unlock_notify() results in the unlock-notify callback being
  6896  ** invoked immediately. If the application then re-attempts the "DROP TABLE"
  6897  ** or "DROP INDEX" query, an infinite loop might be the result.
  6898  **
  6899  ** One way around this problem is to check the extended error code returned
  6900  ** by an sqlite3_step() call. ^(If there is a blocking connection, then the
  6901  ** extended error code is set to SQLITE_LOCKED_SHAREDCACHE. Otherwise, in
  6902  ** the special "DROP TABLE/INDEX" case, the extended error code is just 
  6903  ** SQLITE_LOCKED.)^
  6904  */
  6905  SQLITE_API int sqlite3_unlock_notify(
  6906    sqlite3 *pBlocked,                          /* Waiting connection */
  6907    void (*xNotify)(void **apArg, int nArg),    /* Callback function to invoke */
  6908    void *pNotifyArg                            /* Argument to pass to xNotify */
  6909  );
  6910  
  6911  
  6912  /*
  6913  ** CAPI3REF: String Comparison
  6914  **
  6915  ** ^The [sqlite3_stricmp()] and [sqlite3_strnicmp()] APIs allow applications
  6916  ** and extensions to compare the contents of two buffers containing UTF-8
  6917  ** strings in a case-independent fashion, using the same definition of "case
  6918  ** independence" that SQLite uses internally when comparing identifiers.
  6919  */
  6920  SQLITE_API int sqlite3_stricmp(const char *, const char *);
  6921  SQLITE_API int sqlite3_strnicmp(const char *, const char *, int);
  6922  
  6923  /*
  6924  ** CAPI3REF: String Globbing
  6925  *
  6926  ** ^The [sqlite3_strglob(P,X)] interface returns zero if string X matches
  6927  ** the glob pattern P, and it returns non-zero if string X does not match
  6928  ** the glob pattern P.  ^The definition of glob pattern matching used in
  6929  ** [sqlite3_strglob(P,X)] is the same as for the "X GLOB P" operator in the
  6930  ** SQL dialect used by SQLite.  ^The sqlite3_strglob(P,X) function is case
  6931  ** sensitive.
  6932  **
  6933  ** Note that this routine returns zero on a match and non-zero if the strings
  6934  ** do not match, the same as [sqlite3_stricmp()] and [sqlite3_strnicmp()].
  6935  */
  6936  SQLITE_API int sqlite3_strglob(const char *zGlob, const char *zStr);
  6937  
  6938  /*
  6939  ** CAPI3REF: Error Logging Interface
  6940  **
  6941  ** ^The [sqlite3_log()] interface writes a message into the [error log]
  6942  ** established by the [SQLITE_CONFIG_LOG] option to [sqlite3_config()].
  6943  ** ^If logging is enabled, the zFormat string and subsequent arguments are
  6944  ** used with [sqlite3_snprintf()] to generate the final output string.
  6945  **
  6946  ** The sqlite3_log() interface is intended for use by extensions such as
  6947  ** virtual tables, collating functions, and SQL functions.  While there is
  6948  ** nothing to prevent an application from calling sqlite3_log(), doing so
  6949  ** is considered bad form.
  6950  **
  6951  ** The zFormat string must not be NULL.
  6952  **
  6953  ** To avoid deadlocks and other threading problems, the sqlite3_log() routine
  6954  ** will not use dynamically allocated memory.  The log message is stored in
  6955  ** a fixed-length buffer on the stack.  If the log message is longer than
  6956  ** a few hundred characters, it will be truncated to the length of the
  6957  ** buffer.
  6958  */
  6959  SQLITE_API void sqlite3_log(int iErrCode, const char *zFormat, ...);
  6960  
  6961  /*
  6962  ** CAPI3REF: Write-Ahead Log Commit Hook
  6963  **
  6964  ** ^The [sqlite3_wal_hook()] function is used to register a callback that
  6965  ** will be invoked each time a database connection commits data to a
  6966  ** [write-ahead log] (i.e. whenever a transaction is committed in
  6967  ** [journal_mode | journal_mode=WAL mode]). 
  6968  **
  6969  ** ^The callback is invoked by SQLite after the commit has taken place and 
  6970  ** the associated write-lock on the database released, so the implementation 
  6971  ** may read, write or [checkpoint] the database as required.
  6972  **
  6973  ** ^The first parameter passed to the callback function when it is invoked
  6974  ** is a copy of the third parameter passed to sqlite3_wal_hook() when
  6975  ** registering the callback. ^The second is a copy of the database handle.
  6976  ** ^The third parameter is the name of the database that was written to -
  6977  ** either "main" or the name of an [ATTACH]-ed database. ^The fourth parameter
  6978  ** is the number of pages currently in the write-ahead log file,
  6979  ** including those that were just committed.
  6980  **
  6981  ** The callback function should normally return [SQLITE_OK].  ^If an error
  6982  ** code is returned, that error will propagate back up through the
  6983  ** SQLite code base to cause the statement that provoked the callback
  6984  ** to report an error, though the commit will have still occurred. If the
  6985  ** callback returns [SQLITE_ROW] or [SQLITE_DONE], or if it returns a value
  6986  ** that does not correspond to any valid SQLite error code, the results
  6987  ** are undefined.
  6988  **
  6989  ** A single database handle may have at most a single write-ahead log callback 
  6990  ** registered at one time. ^Calling [sqlite3_wal_hook()] replaces any
  6991  ** previously registered write-ahead log callback. ^Note that the
  6992  ** [sqlite3_wal_autocheckpoint()] interface and the
  6993  ** [wal_autocheckpoint pragma] both invoke [sqlite3_wal_hook()] and will
  6994  ** those overwrite any prior [sqlite3_wal_hook()] settings.
  6995  */
  6996  SQLITE_API void *sqlite3_wal_hook(
  6997    sqlite3*, 
  6998    int(*)(void *,sqlite3*,const char*,int),
  6999    void*
  7000  );
  7001  
  7002  /*
  7003  ** CAPI3REF: Configure an auto-checkpoint
  7004  **
  7005  ** ^The [sqlite3_wal_autocheckpoint(D,N)] is a wrapper around
  7006  ** [sqlite3_wal_hook()] that causes any database on [database connection] D
  7007  ** to automatically [checkpoint]
  7008  ** after committing a transaction if there are N or
  7009  ** more frames in the [write-ahead log] file.  ^Passing zero or 
  7010  ** a negative value as the nFrame parameter disables automatic
  7011  ** checkpoints entirely.
  7012  **
  7013  ** ^The callback registered by this function replaces any existing callback
  7014  ** registered using [sqlite3_wal_hook()].  ^Likewise, registering a callback
  7015  ** using [sqlite3_wal_hook()] disables the automatic checkpoint mechanism
  7016  ** configured by this function.
  7017  **
  7018  ** ^The [wal_autocheckpoint pragma] can be used to invoke this interface
  7019  ** from SQL.
  7020  **
  7021  ** ^Every new [database connection] defaults to having the auto-checkpoint
  7022  ** enabled with a threshold of 1000 or [SQLITE_DEFAULT_WAL_AUTOCHECKPOINT]
  7023  ** pages.  The use of this interface
  7024  ** is only necessary if the default setting is found to be suboptimal
  7025  ** for a particular application.
  7026  */
  7027  SQLITE_API int sqlite3_wal_autocheckpoint(sqlite3 *db, int N);
  7028  
  7029  /*
  7030  ** CAPI3REF: Checkpoint a database
  7031  **
  7032  ** ^The [sqlite3_wal_checkpoint(D,X)] interface causes database named X
  7033  ** on [database connection] D to be [checkpointed].  ^If X is NULL or an
  7034  ** empty string, then a checkpoint is run on all databases of
  7035  ** connection D.  ^If the database connection D is not in
  7036  ** [WAL | write-ahead log mode] then this interface is a harmless no-op.
  7037  **
  7038  ** ^The [wal_checkpoint pragma] can be used to invoke this interface
  7039  ** from SQL.  ^The [sqlite3_wal_autocheckpoint()] interface and the
  7040  ** [wal_autocheckpoint pragma] can be used to cause this interface to be
  7041  ** run whenever the WAL reaches a certain size threshold.
  7042  **
  7043  ** See also: [sqlite3_wal_checkpoint_v2()]
  7044  */
  7045  SQLITE_API int sqlite3_wal_checkpoint(sqlite3 *db, const char *zDb);
  7046  
  7047  /*
  7048  ** CAPI3REF: Checkpoint a database
  7049  **
  7050  ** Run a checkpoint operation on WAL database zDb attached to database 
  7051  ** handle db. The specific operation is determined by the value of the 
  7052  ** eMode parameter:
  7053  **
  7054  ** <dl>
  7055  ** <dt>SQLITE_CHECKPOINT_PASSIVE<dd>
  7056  **   Checkpoint as many frames as possible without waiting for any database 
  7057  **   readers or writers to finish. Sync the db file if all frames in the log
  7058  **   are checkpointed. This mode is the same as calling 
  7059  **   sqlite3_wal_checkpoint(). The busy-handler callback is never invoked.
  7060  **
  7061  ** <dt>SQLITE_CHECKPOINT_FULL<dd>
  7062  **   This mode blocks (calls the busy-handler callback) until there is no
  7063  **   database writer and all readers are reading from the most recent database
  7064  **   snapshot. It then checkpoints all frames in the log file and syncs the
  7065  **   database file. This call blocks database writers while it is running,
  7066  **   but not database readers.
  7067  **
  7068  ** <dt>SQLITE_CHECKPOINT_RESTART<dd>
  7069  **   This mode works the same way as SQLITE_CHECKPOINT_FULL, except after 
  7070  **   checkpointing the log file it blocks (calls the busy-handler callback)
  7071  **   until all readers are reading from the database file only. This ensures 
  7072  **   that the next client to write to the database file restarts the log file 
  7073  **   from the beginning. This call blocks database writers while it is running,
  7074  **   but not database readers.
  7075  ** </dl>
  7076  **
  7077  ** If pnLog is not NULL, then *pnLog is set to the total number of frames in
  7078  ** the log file before returning. If pnCkpt is not NULL, then *pnCkpt is set to
  7079  ** the total number of checkpointed frames (including any that were already
  7080  ** checkpointed when this function is called). *pnLog and *pnCkpt may be
  7081  ** populated even if sqlite3_wal_checkpoint_v2() returns other than SQLITE_OK.
  7082  ** If no values are available because of an error, they are both set to -1
  7083  ** before returning to communicate this to the caller.
  7084  **
  7085  ** All calls obtain an exclusive "checkpoint" lock on the database file. If
  7086  ** any other process is running a checkpoint operation at the same time, the 
  7087  ** lock cannot be obtained and SQLITE_BUSY is returned. Even if there is a 
  7088  ** busy-handler configured, it will not be invoked in this case.
  7089  **
  7090  ** The SQLITE_CHECKPOINT_FULL and RESTART modes also obtain the exclusive 
  7091  ** "writer" lock on the database file. If the writer lock cannot be obtained
  7092  ** immediately, and a busy-handler is configured, it is invoked and the writer
  7093  ** lock retried until either the busy-handler returns 0 or the lock is
  7094  ** successfully obtained. The busy-handler is also invoked while waiting for
  7095  ** database readers as described above. If the busy-handler returns 0 before
  7096  ** the writer lock is obtained or while waiting for database readers, the
  7097  ** checkpoint operation proceeds from that point in the same way as 
  7098  ** SQLITE_CHECKPOINT_PASSIVE - checkpointing as many frames as possible 
  7099  ** without blocking any further. SQLITE_BUSY is returned in this case.
  7100  **
  7101  ** If parameter zDb is NULL or points to a zero length string, then the
  7102  ** specified operation is attempted on all WAL databases. In this case the
  7103  ** values written to output parameters *pnLog and *pnCkpt are undefined. If 
  7104  ** an SQLITE_BUSY error is encountered when processing one or more of the 
  7105  ** attached WAL databases, the operation is still attempted on any remaining 
  7106  ** attached databases and SQLITE_BUSY is returned to the caller. If any other 
  7107  ** error occurs while processing an attached database, processing is abandoned 
  7108  ** and the error code returned to the caller immediately. If no error 
  7109  ** (SQLITE_BUSY or otherwise) is encountered while processing the attached 
  7110  ** databases, SQLITE_OK is returned.
  7111  **
  7112  ** If database zDb is the name of an attached database that is not in WAL
  7113  ** mode, SQLITE_OK is returned and both *pnLog and *pnCkpt set to -1. If
  7114  ** zDb is not NULL (or a zero length string) and is not the name of any
  7115  ** attached database, SQLITE_ERROR is returned to the caller.
  7116  */
  7117  SQLITE_API int sqlite3_wal_checkpoint_v2(
  7118    sqlite3 *db,                    /* Database handle */
  7119    const char *zDb,                /* Name of attached database (or NULL) */
  7120    int eMode,                      /* SQLITE_CHECKPOINT_* value */
  7121    int *pnLog,                     /* OUT: Size of WAL log in frames */
  7122    int *pnCkpt                     /* OUT: Total number of frames checkpointed */
  7123  );
  7124  
  7125  /*
  7126  ** CAPI3REF: Checkpoint operation parameters
  7127  **
  7128  ** These constants can be used as the 3rd parameter to
  7129  ** [sqlite3_wal_checkpoint_v2()].  See the [sqlite3_wal_checkpoint_v2()]
  7130  ** documentation for additional information about the meaning and use of
  7131  ** each of these values.
  7132  */
  7133  #define SQLITE_CHECKPOINT_PASSIVE 0
  7134  #define SQLITE_CHECKPOINT_FULL    1
  7135  #define SQLITE_CHECKPOINT_RESTART 2
  7136  
  7137  /*
  7138  ** CAPI3REF: Virtual Table Interface Configuration
  7139  **
  7140  ** This function may be called by either the [xConnect] or [xCreate] method
  7141  ** of a [virtual table] implementation to configure
  7142  ** various facets of the virtual table interface.
  7143  **
  7144  ** If this interface is invoked outside the context of an xConnect or
  7145  ** xCreate virtual table method then the behavior is undefined.
  7146  **
  7147  ** At present, there is only one option that may be configured using
  7148  ** this function. (See [SQLITE_VTAB_CONSTRAINT_SUPPORT].)  Further options
  7149  ** may be added in the future.
  7150  */
  7151  SQLITE_API int sqlite3_vtab_config(sqlite3*, int op, ...);
  7152  
  7153  /*
  7154  ** CAPI3REF: Virtual Table Configuration Options
  7155  **
  7156  ** These macros define the various options to the
  7157  ** [sqlite3_vtab_config()] interface that [virtual table] implementations
  7158  ** can use to customize and optimize their behavior.
  7159  **
  7160  ** <dl>
  7161  ** <dt>SQLITE_VTAB_CONSTRAINT_SUPPORT
  7162  ** <dd>Calls of the form
  7163  ** [sqlite3_vtab_config](db,SQLITE_VTAB_CONSTRAINT_SUPPORT,X) are supported,
  7164  ** where X is an integer.  If X is zero, then the [virtual table] whose
  7165  ** [xCreate] or [xConnect] method invoked [sqlite3_vtab_config()] does not
  7166  ** support constraints.  In this configuration (which is the default) if
  7167  ** a call to the [xUpdate] method returns [SQLITE_CONSTRAINT], then the entire
  7168  ** statement is rolled back as if [ON CONFLICT | OR ABORT] had been
  7169  ** specified as part of the users SQL statement, regardless of the actual
  7170  ** ON CONFLICT mode specified.
  7171  **
  7172  ** If X is non-zero, then the virtual table implementation guarantees
  7173  ** that if [xUpdate] returns [SQLITE_CONSTRAINT], it will do so before
  7174  ** any modifications to internal or persistent data structures have been made.
  7175  ** If the [ON CONFLICT] mode is ABORT, FAIL, IGNORE or ROLLBACK, SQLite 
  7176  ** is able to roll back a statement or database transaction, and abandon
  7177  ** or continue processing the current SQL statement as appropriate. 
  7178  ** If the ON CONFLICT mode is REPLACE and the [xUpdate] method returns
  7179  ** [SQLITE_CONSTRAINT], SQLite handles this as if the ON CONFLICT mode
  7180  ** had been ABORT.
  7181  **
  7182  ** Virtual table implementations that are required to handle OR REPLACE
  7183  ** must do so within the [xUpdate] method. If a call to the 
  7184  ** [sqlite3_vtab_on_conflict()] function indicates that the current ON 
  7185  ** CONFLICT policy is REPLACE, the virtual table implementation should 
  7186  ** silently replace the appropriate rows within the xUpdate callback and
  7187  ** return SQLITE_OK. Or, if this is not possible, it may return
  7188  ** SQLITE_CONSTRAINT, in which case SQLite falls back to OR ABORT 
  7189  ** constraint handling.
  7190  ** </dl>
  7191  */
  7192  #define SQLITE_VTAB_CONSTRAINT_SUPPORT 1
  7193  
  7194  /*
  7195  ** CAPI3REF: Determine The Virtual Table Conflict Policy
  7196  **
  7197  ** This function may only be called from within a call to the [xUpdate] method
  7198  ** of a [virtual table] implementation for an INSERT or UPDATE operation. ^The
  7199  ** value returned is one of [SQLITE_ROLLBACK], [SQLITE_IGNORE], [SQLITE_FAIL],
  7200  ** [SQLITE_ABORT], or [SQLITE_REPLACE], according to the [ON CONFLICT] mode
  7201  ** of the SQL statement that triggered the call to the [xUpdate] method of the
  7202  ** [virtual table].
  7203  */
  7204  SQLITE_API int sqlite3_vtab_on_conflict(sqlite3 *);
  7205  
  7206  /*
  7207  ** CAPI3REF: Conflict resolution modes
  7208  **
  7209  ** These constants are returned by [sqlite3_vtab_on_conflict()] to
  7210  ** inform a [virtual table] implementation what the [ON CONFLICT] mode
  7211  ** is for the SQL statement being evaluated.
  7212  **
  7213  ** Note that the [SQLITE_IGNORE] constant is also used as a potential
  7214  ** return value from the [sqlite3_set_authorizer()] callback and that
  7215  ** [SQLITE_ABORT] is also a [result code].
  7216  */
  7217  #define SQLITE_ROLLBACK 1
  7218  /* #define SQLITE_IGNORE 2 // Also used by sqlite3_authorizer() callback */
  7219  #define SQLITE_FAIL     3
  7220  /* #define SQLITE_ABORT 4  // Also an error code */
  7221  #define SQLITE_REPLACE  5
  7222  
  7223  
  7224  
  7225  /*
  7226  ** Undo the hack that converts floating point types to integer for
  7227  ** builds on processors without floating point support.
  7228  */
  7229  #ifdef SQLITE_OMIT_FLOATING_POINT
  7230  # undef double
  7231  #endif
  7232  
  7233  #ifdef __cplusplus
  7234  }  /* End of the 'extern "C"' block */
  7235  #endif
  7236  #endif /* _SQLITE3_H_ */
  7237  
  7238  /*
  7239  ** 2010 August 30
  7240  **
  7241  ** The author disclaims copyright to this source code.  In place of
  7242  ** a legal notice, here is a blessing:
  7243  **
  7244  **    May you do good and not evil.
  7245  **    May you find forgiveness for yourself and forgive others.
  7246  **    May you share freely, never taking more than you give.
  7247  **
  7248  *************************************************************************
  7249  */
  7250  
  7251  #ifndef _SQLITE3RTREE_H_
  7252  #define _SQLITE3RTREE_H_
  7253  
  7254  
  7255  #ifdef __cplusplus
  7256  extern "C" {
  7257  #endif
  7258  
  7259  typedef struct sqlite3_rtree_geometry sqlite3_rtree_geometry;
  7260  
  7261  /*
  7262  ** Register a geometry callback named zGeom that can be used as part of an
  7263  ** R-Tree geometry query as follows:
  7264  **
  7265  **   SELECT ... FROM <rtree> WHERE <rtree col> MATCH $zGeom(... params ...)
  7266  */
  7267  SQLITE_API int sqlite3_rtree_geometry_callback(
  7268    sqlite3 *db,
  7269    const char *zGeom,
  7270  #ifdef SQLITE_RTREE_INT_ONLY
  7271    int (*xGeom)(sqlite3_rtree_geometry*, int n, sqlite3_int64 *a, int *pRes),
  7272  #else
  7273    int (*xGeom)(sqlite3_rtree_geometry*, int n, double *a, int *pRes),
  7274  #endif
  7275    void *pContext
  7276  );
  7277  
  7278  
  7279  /*
  7280  ** A pointer to a structure of the following type is passed as the first
  7281  ** argument to callbacks registered using rtree_geometry_callback().
  7282  */
  7283  struct sqlite3_rtree_geometry {
  7284    void *pContext;                 /* Copy of pContext passed to s_r_g_c() */
  7285    int nParam;                     /* Size of array aParam[] */
  7286    double *aParam;                 /* Parameters passed to SQL geom function */
  7287    void *pUser;                    /* Callback implementation user data */
  7288    void (*xDelUser)(void *);       /* Called by SQLite to clean up pUser */
  7289  };
  7290  
  7291  
  7292  #ifdef __cplusplus
  7293  }  /* end of the 'extern "C"' block */
  7294  #endif
  7295  
  7296  #endif  /* ifndef _SQLITE3RTREE_H_ */
  7297