github.com/google/syzkaller@v0.0.0-20240517125934-c0f1611a36d6/executor/_include/flatbuffers/util.h (about)

     1  /*
     2   * Copyright 2014 Google Inc. All rights reserved.
     3   *
     4   * Licensed under the Apache License, Version 2.0 (the "License");
     5   * you may not use this file except in compliance with the License.
     6   * You may obtain a copy of the License at
     7   *
     8   *     http://www.apache.org/licenses/LICENSE-2.0
     9   *
    10   * Unless required by applicable law or agreed to in writing, software
    11   * distributed under the License is distributed on an "AS IS" BASIS,
    12   * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
    13   * See the License for the specific language governing permissions and
    14   * limitations under the License.
    15   */
    16  
    17  #ifndef FLATBUFFERS_UTIL_H_
    18  #define FLATBUFFERS_UTIL_H_
    19  
    20  #include <ctype.h>
    21  #include <errno.h>
    22  
    23  #include "flatbuffers/base.h"
    24  #include "flatbuffers/stl_emulation.h"
    25  
    26  #ifndef FLATBUFFERS_PREFER_PRINTF
    27  #  include <iomanip>
    28  #  include <sstream>
    29  #else  // FLATBUFFERS_PREFER_PRINTF
    30  #  include <float.h>
    31  #  include <stdio.h>
    32  #endif  // FLATBUFFERS_PREFER_PRINTF
    33  
    34  #include <string>
    35  
    36  namespace flatbuffers {
    37  
    38  // @locale-independent functions for ASCII characters set.
    39  
    40  // Fast checking that character lies in closed range: [a <= x <= b]
    41  // using one compare (conditional branch) operator.
    42  inline bool check_ascii_range(char x, char a, char b) {
    43    FLATBUFFERS_ASSERT(a <= b);
    44    // (Hacker's Delight): `a <= x <= b` <=> `(x-a) <={u} (b-a)`.
    45    // The x, a, b will be promoted to int and subtracted without overflow.
    46    return static_cast<unsigned int>(x - a) <= static_cast<unsigned int>(b - a);
    47  }
    48  
    49  // Case-insensitive isalpha
    50  inline bool is_alpha(char c) {
    51    // ASCII only: alpha to upper case => reset bit 0x20 (~0x20 = 0xDF).
    52    return check_ascii_range(c & 0xDF, 'a' & 0xDF, 'z' & 0xDF);
    53  }
    54  
    55  // Check for uppercase alpha
    56  inline bool is_alpha_upper(char c) { return check_ascii_range(c, 'A', 'Z'); }
    57  
    58  // Check (case-insensitive) that `c` is equal to alpha.
    59  inline bool is_alpha_char(char c, char alpha) {
    60    FLATBUFFERS_ASSERT(is_alpha(alpha));
    61    // ASCII only: alpha to upper case => reset bit 0x20 (~0x20 = 0xDF).
    62    return ((c & 0xDF) == (alpha & 0xDF));
    63  }
    64  
    65  // https://en.cppreference.com/w/cpp/string/byte/isxdigit
    66  // isdigit and isxdigit are the only standard narrow character classification
    67  // functions that are not affected by the currently installed C locale. although
    68  // some implementations (e.g. Microsoft in 1252 codepage) may classify
    69  // additional single-byte characters as digits.
    70  inline bool is_digit(char c) { return check_ascii_range(c, '0', '9'); }
    71  
    72  inline bool is_xdigit(char c) {
    73    // Replace by look-up table.
    74    return is_digit(c) || check_ascii_range(c & 0xDF, 'a' & 0xDF, 'f' & 0xDF);
    75  }
    76  
    77  // Case-insensitive isalnum
    78  inline bool is_alnum(char c) { return is_alpha(c) || is_digit(c); }
    79  
    80  inline char CharToUpper(char c) {
    81    return static_cast<char>(::toupper(static_cast<unsigned char>(c)));
    82  }
    83  
    84  inline char CharToLower(char c) {
    85    return static_cast<char>(::tolower(static_cast<unsigned char>(c)));
    86  }
    87  
    88  // @end-locale-independent functions for ASCII character set
    89  
    90  #ifdef FLATBUFFERS_PREFER_PRINTF
    91  template<typename T> size_t IntToDigitCount(T t) {
    92    size_t digit_count = 0;
    93    // Count the sign for negative numbers
    94    if (t < 0) digit_count++;
    95    // Count a single 0 left of the dot for fractional numbers
    96    if (-1 < t && t < 1) digit_count++;
    97    // Count digits until fractional part
    98    T eps = std::numeric_limits<T>::epsilon();
    99    while (t <= (-1 + eps) || (1 - eps) <= t) {
   100      t /= 10;
   101      digit_count++;
   102    }
   103    return digit_count;
   104  }
   105  
   106  template<typename T> size_t NumToStringWidth(T t, int precision = 0) {
   107    size_t string_width = IntToDigitCount(t);
   108    // Count the dot for floating point numbers
   109    if (precision) string_width += (precision + 1);
   110    return string_width;
   111  }
   112  
   113  template<typename T>
   114  std::string NumToStringImplWrapper(T t, const char *fmt, int precision = 0) {
   115    size_t string_width = NumToStringWidth(t, precision);
   116    std::string s(string_width, 0x00);
   117    // Allow snprintf to use std::string trailing null to detect buffer overflow
   118    snprintf(const_cast<char *>(s.data()), (s.size() + 1), fmt, string_width, t);
   119    return s;
   120  }
   121  #endif  // FLATBUFFERS_PREFER_PRINTF
   122  
   123  // Convert an integer or floating point value to a string.
   124  // In contrast to std::stringstream, "char" values are
   125  // converted to a string of digits, and we don't use scientific notation.
   126  template<typename T> std::string NumToString(T t) {
   127    // clang-format off
   128  
   129    #ifndef FLATBUFFERS_PREFER_PRINTF
   130      std::stringstream ss;
   131      ss << t;
   132      return ss.str();
   133    #else // FLATBUFFERS_PREFER_PRINTF
   134      auto v = static_cast<long long>(t);
   135      return NumToStringImplWrapper(v, "%.*lld");
   136    #endif // FLATBUFFERS_PREFER_PRINTF
   137    // clang-format on
   138  }
   139  // Avoid char types used as character data.
   140  template<> inline std::string NumToString<signed char>(signed char t) {
   141    return NumToString(static_cast<int>(t));
   142  }
   143  template<> inline std::string NumToString<unsigned char>(unsigned char t) {
   144    return NumToString(static_cast<int>(t));
   145  }
   146  template<> inline std::string NumToString<char>(char t) {
   147    return NumToString(static_cast<int>(t));
   148  }
   149  
   150  // Special versions for floats/doubles.
   151  template<typename T> std::string FloatToString(T t, int precision) {
   152    // clang-format off
   153  
   154    #ifndef FLATBUFFERS_PREFER_PRINTF
   155      // to_string() prints different numbers of digits for floats depending on
   156      // platform and isn't available on Android, so we use stringstream
   157      std::stringstream ss;
   158      // Use std::fixed to suppress scientific notation.
   159      ss << std::fixed;
   160      // Default precision is 6, we want that to be higher for doubles.
   161      ss << std::setprecision(precision);
   162      ss << t;
   163      auto s = ss.str();
   164    #else // FLATBUFFERS_PREFER_PRINTF
   165      auto v = static_cast<double>(t);
   166      auto s = NumToStringImplWrapper(v, "%0.*f", precision);
   167    #endif // FLATBUFFERS_PREFER_PRINTF
   168    // clang-format on
   169    // Sadly, std::fixed turns "1" into "1.00000", so here we undo that.
   170    auto p = s.find_last_not_of('0');
   171    if (p != std::string::npos) {
   172      // Strip trailing zeroes. If it is a whole number, keep one zero.
   173      s.resize(p + (s[p] == '.' ? 2 : 1));
   174    }
   175    return s;
   176  }
   177  
   178  template<> inline std::string NumToString<double>(double t) {
   179    return FloatToString(t, 12);
   180  }
   181  template<> inline std::string NumToString<float>(float t) {
   182    return FloatToString(t, 6);
   183  }
   184  
   185  // Convert an integer value to a hexadecimal string.
   186  // The returned string length is always xdigits long, prefixed by 0 digits.
   187  // For example, IntToStringHex(0x23, 8) returns the string "00000023".
   188  inline std::string IntToStringHex(int i, int xdigits) {
   189    FLATBUFFERS_ASSERT(i >= 0);
   190    // clang-format off
   191  
   192    #ifndef FLATBUFFERS_PREFER_PRINTF
   193      std::stringstream ss;
   194      ss << std::setw(xdigits) << std::setfill('0') << std::hex << std::uppercase
   195         << i;
   196      return ss.str();
   197    #else // FLATBUFFERS_PREFER_PRINTF
   198      return NumToStringImplWrapper(i, "%.*X", xdigits);
   199    #endif // FLATBUFFERS_PREFER_PRINTF
   200    // clang-format on
   201  }
   202  
   203  // clang-format off
   204  // Use locale independent functions {strtod_l, strtof_l, strtoll_l, strtoull_l}.
   205  #if defined(FLATBUFFERS_LOCALE_INDEPENDENT) && (FLATBUFFERS_LOCALE_INDEPENDENT > 0)
   206    class ClassicLocale {
   207      #ifdef _MSC_VER
   208        typedef _locale_t locale_type;
   209      #else
   210        typedef locale_t locale_type;  // POSIX.1-2008 locale_t type
   211      #endif
   212      ClassicLocale();
   213      ~ClassicLocale();
   214      locale_type locale_;
   215      static ClassicLocale instance_;
   216    public:
   217      static locale_type Get() { return instance_.locale_; }
   218    };
   219  
   220    #ifdef _MSC_VER
   221      #define __strtoull_impl(s, pe, b) _strtoui64_l(s, pe, b, ClassicLocale::Get())
   222      #define __strtoll_impl(s, pe, b) _strtoi64_l(s, pe, b, ClassicLocale::Get())
   223      #define __strtod_impl(s, pe) _strtod_l(s, pe, ClassicLocale::Get())
   224      #define __strtof_impl(s, pe) _strtof_l(s, pe, ClassicLocale::Get())
   225    #else
   226      #define __strtoull_impl(s, pe, b) strtoull_l(s, pe, b, ClassicLocale::Get())
   227      #define __strtoll_impl(s, pe, b) strtoll_l(s, pe, b, ClassicLocale::Get())
   228      #define __strtod_impl(s, pe) strtod_l(s, pe, ClassicLocale::Get())
   229      #define __strtof_impl(s, pe) strtof_l(s, pe, ClassicLocale::Get())
   230    #endif
   231  #else
   232    #define __strtod_impl(s, pe) strtod(s, pe)
   233    #define __strtof_impl(s, pe) static_cast<float>(strtod(s, pe))
   234    #ifdef _MSC_VER
   235      #define __strtoull_impl(s, pe, b) _strtoui64(s, pe, b)
   236      #define __strtoll_impl(s, pe, b) _strtoi64(s, pe, b)
   237    #else
   238      #define __strtoull_impl(s, pe, b) strtoull(s, pe, b)
   239      #define __strtoll_impl(s, pe, b) strtoll(s, pe, b)
   240    #endif
   241  #endif
   242  
   243  inline void strtoval_impl(int64_t *val, const char *str, char **endptr,
   244                                   int base) {
   245      *val = __strtoll_impl(str, endptr, base);
   246  }
   247  
   248  inline void strtoval_impl(uint64_t *val, const char *str, char **endptr,
   249                                   int base) {
   250    *val = __strtoull_impl(str, endptr, base);
   251  }
   252  
   253  inline void strtoval_impl(double *val, const char *str, char **endptr) {
   254    *val = __strtod_impl(str, endptr);
   255  }
   256  
   257  // UBSAN: double to float is safe if numeric_limits<float>::is_iec559 is true.
   258  __suppress_ubsan__("float-cast-overflow")
   259  inline void strtoval_impl(float *val, const char *str, char **endptr) {
   260    *val = __strtof_impl(str, endptr);
   261  }
   262  #undef __strtoull_impl
   263  #undef __strtoll_impl
   264  #undef __strtod_impl
   265  #undef __strtof_impl
   266  // clang-format on
   267  
   268  // Adaptor for strtoull()/strtoll().
   269  // Flatbuffers accepts numbers with any count of leading zeros (-009 is -9),
   270  // while strtoll with base=0 interprets first leading zero as octal prefix.
   271  // In future, it is possible to add prefixed 0b0101.
   272  // 1) Checks errno code for overflow condition (out of range).
   273  // 2) If base <= 0, function try to detect base of number by prefix.
   274  //
   275  // Return value (like strtoull and strtoll, but reject partial result):
   276  // - If successful, an integer value corresponding to the str is returned.
   277  // - If full string conversion can't be performed, 0 is returned.
   278  // - If the converted value falls out of range of corresponding return type, a
   279  // range error occurs. In this case value MAX(T)/MIN(T) is returned.
   280  template<typename T>
   281  inline bool StringToIntegerImpl(T *val, const char *const str,
   282                                  const int base = 0,
   283                                  const bool check_errno = true) {
   284    // T is int64_t or uint64_T
   285    FLATBUFFERS_ASSERT(str);
   286    if (base <= 0) {
   287      auto s = str;
   288      while (*s && !is_digit(*s)) s++;
   289      if (s[0] == '0' && is_alpha_char(s[1], 'X'))
   290        return StringToIntegerImpl(val, str, 16, check_errno);
   291      // if a prefix not match, try base=10
   292      return StringToIntegerImpl(val, str, 10, check_errno);
   293    } else {
   294      if (check_errno) errno = 0;  // clear thread-local errno
   295      auto endptr = str;
   296      strtoval_impl(val, str, const_cast<char **>(&endptr), base);
   297      if ((*endptr != '\0') || (endptr == str)) {
   298        *val = 0;      // erase partial result
   299        return false;  // invalid string
   300      }
   301      // errno is out-of-range, return MAX/MIN
   302      if (check_errno && errno) return false;
   303      return true;
   304    }
   305  }
   306  
   307  template<typename T>
   308  inline bool StringToFloatImpl(T *val, const char *const str) {
   309    // Type T must be either float or double.
   310    FLATBUFFERS_ASSERT(str && val);
   311    auto end = str;
   312    strtoval_impl(val, str, const_cast<char **>(&end));
   313    auto done = (end != str) && (*end == '\0');
   314    if (!done) *val = 0;  // erase partial result
   315    return done;
   316  }
   317  
   318  // Convert a string to an instance of T.
   319  // Return value (matched with StringToInteger64Impl and strtod):
   320  // - If successful, a numeric value corresponding to the str is returned.
   321  // - If full string conversion can't be performed, 0 is returned.
   322  // - If the converted value falls out of range of corresponding return type, a
   323  // range error occurs. In this case value MAX(T)/MIN(T) is returned.
   324  template<typename T> inline bool StringToNumber(const char *s, T *val) {
   325    // Assert on `unsigned long` and `signed long` on LP64.
   326    // If it is necessary, it could be solved with flatbuffers::enable_if<B,T>.
   327    static_assert(sizeof(T) < sizeof(int64_t), "unexpected type T");
   328    FLATBUFFERS_ASSERT(s && val);
   329    int64_t i64;
   330    // The errno check isn't needed, will return MAX/MIN on overflow.
   331    if (StringToIntegerImpl(&i64, s, 0, false)) {
   332      const int64_t max = (flatbuffers::numeric_limits<T>::max)();
   333      const int64_t min = flatbuffers::numeric_limits<T>::lowest();
   334      if (i64 > max) {
   335        *val = static_cast<T>(max);
   336        return false;
   337      }
   338      if (i64 < min) {
   339        // For unsigned types return max to distinguish from
   340        // "no conversion can be performed" when 0 is returned.
   341        *val = static_cast<T>(flatbuffers::is_unsigned<T>::value ? max : min);
   342        return false;
   343      }
   344      *val = static_cast<T>(i64);
   345      return true;
   346    }
   347    *val = 0;
   348    return false;
   349  }
   350  
   351  template<> inline bool StringToNumber<int64_t>(const char *str, int64_t *val) {
   352    return StringToIntegerImpl(val, str);
   353  }
   354  
   355  template<>
   356  inline bool StringToNumber<uint64_t>(const char *str, uint64_t *val) {
   357    if (!StringToIntegerImpl(val, str)) return false;
   358    // The strtoull accepts negative numbers:
   359    // If the minus sign was part of the input sequence, the numeric value
   360    // calculated from the sequence of digits is negated as if by unary minus
   361    // in the result type, which applies unsigned integer wraparound rules.
   362    // Fix this behaviour (except -0).
   363    if (*val) {
   364      auto s = str;
   365      while (*s && !is_digit(*s)) s++;
   366      s = (s > str) ? (s - 1) : s;  // step back to one symbol
   367      if (*s == '-') {
   368        // For unsigned types return the max to distinguish from
   369        // "no conversion can be performed".
   370        *val = (flatbuffers::numeric_limits<uint64_t>::max)();
   371        return false;
   372      }
   373    }
   374    return true;
   375  }
   376  
   377  template<> inline bool StringToNumber(const char *s, float *val) {
   378    return StringToFloatImpl(val, s);
   379  }
   380  
   381  template<> inline bool StringToNumber(const char *s, double *val) {
   382    return StringToFloatImpl(val, s);
   383  }
   384  
   385  inline int64_t StringToInt(const char *s, int base = 10) {
   386    int64_t val;
   387    return StringToIntegerImpl(&val, s, base) ? val : 0;
   388  }
   389  
   390  inline uint64_t StringToUInt(const char *s, int base = 10) {
   391    uint64_t val;
   392    return StringToIntegerImpl(&val, s, base) ? val : 0;
   393  }
   394  
   395  typedef bool (*LoadFileFunction)(const char *filename, bool binary,
   396                                   std::string *dest);
   397  typedef bool (*FileExistsFunction)(const char *filename);
   398  
   399  LoadFileFunction SetLoadFileFunction(LoadFileFunction load_file_function);
   400  
   401  FileExistsFunction SetFileExistsFunction(
   402      FileExistsFunction file_exists_function);
   403  
   404  // Check if file "name" exists.
   405  bool FileExists(const char *name);
   406  
   407  // Check if "name" exists and it is also a directory.
   408  bool DirExists(const char *name);
   409  
   410  // Load file "name" into "buf" returning true if successful
   411  // false otherwise.  If "binary" is false data is read
   412  // using ifstream's text mode, otherwise data is read with
   413  // no transcoding.
   414  bool LoadFile(const char *name, bool binary, std::string *buf);
   415  
   416  // Save data "buf" of length "len" bytes into a file
   417  // "name" returning true if successful, false otherwise.
   418  // If "binary" is false data is written using ifstream's
   419  // text mode, otherwise data is written with no
   420  // transcoding.
   421  bool SaveFile(const char *name, const char *buf, size_t len, bool binary);
   422  
   423  // Save data "buf" into file "name" returning true if
   424  // successful, false otherwise.  If "binary" is false
   425  // data is written using ifstream's text mode, otherwise
   426  // data is written with no transcoding.
   427  inline bool SaveFile(const char *name, const std::string &buf, bool binary) {
   428    return SaveFile(name, buf.c_str(), buf.size(), binary);
   429  }
   430  
   431  // Functionality for minimalistic portable path handling.
   432  
   433  // The functions below behave correctly regardless of whether posix ('/') or
   434  // Windows ('/' or '\\') separators are used.
   435  
   436  // Any new separators inserted are always posix.
   437  FLATBUFFERS_CONSTEXPR char kPathSeparator = '/';
   438  
   439  // Returns the path with the extension, if any, removed.
   440  std::string StripExtension(const std::string &filepath);
   441  
   442  // Returns the extension, if any.
   443  std::string GetExtension(const std::string &filepath);
   444  
   445  // Return the last component of the path, after the last separator.
   446  std::string StripPath(const std::string &filepath);
   447  
   448  // Strip the last component of the path + separator.
   449  std::string StripFileName(const std::string &filepath);
   450  
   451  std::string StripPrefix(const std::string &filepath,
   452                          const std::string &prefix_to_remove);
   453  
   454  // Concatenates a path with a filename, regardless of whether the path
   455  // ends in a separator or not.
   456  std::string ConCatPathFileName(const std::string &path,
   457                                 const std::string &filename);
   458  
   459  // Replaces any '\\' separators with '/'
   460  std::string PosixPath(const char *path);
   461  std::string PosixPath(const std::string &path);
   462  
   463  // This function ensure a directory exists, by recursively
   464  // creating dirs for any parts of the path that don't exist yet.
   465  void EnsureDirExists(const std::string &filepath);
   466  
   467  // Obtains the absolute path from any other path.
   468  // Returns the input path if the absolute path couldn't be resolved.
   469  std::string AbsolutePath(const std::string &filepath);
   470  
   471  // Returns files relative to the --project_root path, prefixed with `//`.
   472  std::string RelativeToRootPath(const std::string &project,
   473                                 const std::string &filepath);
   474  
   475  // To and from UTF-8 unicode conversion functions
   476  
   477  // Convert a unicode code point into a UTF-8 representation by appending it
   478  // to a string. Returns the number of bytes generated.
   479  inline int ToUTF8(uint32_t ucc, std::string *out) {
   480    FLATBUFFERS_ASSERT(!(ucc & 0x80000000));  // Top bit can't be set.
   481    // 6 possible encodings: http://en.wikipedia.org/wiki/UTF-8
   482    for (int i = 0; i < 6; i++) {
   483      // Max bits this encoding can represent.
   484      uint32_t max_bits = 6 + i * 5 + static_cast<int>(!i);
   485      if (ucc < (1u << max_bits)) {  // does it fit?
   486        // Remaining bits not encoded in the first byte, store 6 bits each
   487        uint32_t remain_bits = i * 6;
   488        // Store first byte:
   489        (*out) += static_cast<char>((0xFE << (max_bits - remain_bits)) |
   490                                    (ucc >> remain_bits));
   491        // Store remaining bytes:
   492        for (int j = i - 1; j >= 0; j--) {
   493          (*out) += static_cast<char>(((ucc >> (j * 6)) & 0x3F) | 0x80);
   494        }
   495        return i + 1;  // Return the number of bytes added.
   496      }
   497    }
   498    FLATBUFFERS_ASSERT(0);  // Impossible to arrive here.
   499    return -1;
   500  }
   501  
   502  // Converts whatever prefix of the incoming string corresponds to a valid
   503  // UTF-8 sequence into a unicode code. The incoming pointer will have been
   504  // advanced past all bytes parsed.
   505  // returns -1 upon corrupt UTF-8 encoding (ignore the incoming pointer in
   506  // this case).
   507  inline int FromUTF8(const char **in) {
   508    int len = 0;
   509    // Count leading 1 bits.
   510    for (int mask = 0x80; mask >= 0x04; mask >>= 1) {
   511      if (**in & mask) {
   512        len++;
   513      } else {
   514        break;
   515      }
   516    }
   517    if ((static_cast<unsigned char>(**in) << len) & 0x80)
   518      return -1;  // Bit after leading 1's must be 0.
   519    if (!len) return *(*in)++;
   520    // UTF-8 encoded values with a length are between 2 and 4 bytes.
   521    if (len < 2 || len > 4) { return -1; }
   522    // Grab initial bits of the code.
   523    int ucc = *(*in)++ & ((1 << (7 - len)) - 1);
   524    for (int i = 0; i < len - 1; i++) {
   525      if ((**in & 0xC0) != 0x80) return -1;  // Upper bits must 1 0.
   526      ucc <<= 6;
   527      ucc |= *(*in)++ & 0x3F;  // Grab 6 more bits of the code.
   528    }
   529    // UTF-8 cannot encode values between 0xD800 and 0xDFFF (reserved for
   530    // UTF-16 surrogate pairs).
   531    if (ucc >= 0xD800 && ucc <= 0xDFFF) { return -1; }
   532    // UTF-8 must represent code points in their shortest possible encoding.
   533    switch (len) {
   534      case 2:
   535        // Two bytes of UTF-8 can represent code points from U+0080 to U+07FF.
   536        if (ucc < 0x0080 || ucc > 0x07FF) { return -1; }
   537        break;
   538      case 3:
   539        // Three bytes of UTF-8 can represent code points from U+0800 to U+FFFF.
   540        if (ucc < 0x0800 || ucc > 0xFFFF) { return -1; }
   541        break;
   542      case 4:
   543        // Four bytes of UTF-8 can represent code points from U+10000 to U+10FFFF.
   544        if (ucc < 0x10000 || ucc > 0x10FFFF) { return -1; }
   545        break;
   546    }
   547    return ucc;
   548  }
   549  
   550  #ifndef FLATBUFFERS_PREFER_PRINTF
   551  // Wraps a string to a maximum length, inserting new lines where necessary. Any
   552  // existing whitespace will be collapsed down to a single space. A prefix or
   553  // suffix can be provided, which will be inserted before or after a wrapped
   554  // line, respectively.
   555  inline std::string WordWrap(const std::string in, size_t max_length,
   556                              const std::string wrapped_line_prefix,
   557                              const std::string wrapped_line_suffix) {
   558    std::istringstream in_stream(in);
   559    std::string wrapped, line, word;
   560  
   561    in_stream >> word;
   562    line = word;
   563  
   564    while (in_stream >> word) {
   565      if ((line.length() + 1 + word.length() + wrapped_line_suffix.length()) <
   566          max_length) {
   567        line += " " + word;
   568      } else {
   569        wrapped += line + wrapped_line_suffix + "\n";
   570        line = wrapped_line_prefix + word;
   571      }
   572    }
   573    wrapped += line;
   574  
   575    return wrapped;
   576  }
   577  #endif  // !FLATBUFFERS_PREFER_PRINTF
   578  
   579  inline bool EscapeString(const char *s, size_t length, std::string *_text,
   580                           bool allow_non_utf8, bool natural_utf8) {
   581    std::string &text = *_text;
   582    text += "\"";
   583    for (uoffset_t i = 0; i < length; i++) {
   584      char c = s[i];
   585      switch (c) {
   586        case '\n': text += "\\n"; break;
   587        case '\t': text += "\\t"; break;
   588        case '\r': text += "\\r"; break;
   589        case '\b': text += "\\b"; break;
   590        case '\f': text += "\\f"; break;
   591        case '\"': text += "\\\""; break;
   592        case '\\': text += "\\\\"; break;
   593        default:
   594          if (c >= ' ' && c <= '~') {
   595            text += c;
   596          } else {
   597            // Not printable ASCII data. Let's see if it's valid UTF-8 first:
   598            const char *utf8 = s + i;
   599            int ucc = FromUTF8(&utf8);
   600            if (ucc < 0) {
   601              if (allow_non_utf8) {
   602                text += "\\x";
   603                text += IntToStringHex(static_cast<uint8_t>(c), 2);
   604              } else {
   605                // There are two cases here:
   606                //
   607                // 1) We reached here by parsing an IDL file. In that case,
   608                // we previously checked for non-UTF-8, so we shouldn't reach
   609                // here.
   610                //
   611                // 2) We reached here by someone calling GenerateText()
   612                // on a previously-serialized flatbuffer. The data might have
   613                // non-UTF-8 Strings, or might be corrupt.
   614                //
   615                // In both cases, we have to give up and inform the caller
   616                // they have no JSON.
   617                return false;
   618              }
   619            } else {
   620              if (natural_utf8) {
   621                // utf8 points to past all utf-8 bytes parsed
   622                text.append(s + i, static_cast<size_t>(utf8 - s - i));
   623              } else if (ucc <= 0xFFFF) {
   624                // Parses as Unicode within JSON's \uXXXX range, so use that.
   625                text += "\\u";
   626                text += IntToStringHex(ucc, 4);
   627              } else if (ucc <= 0x10FFFF) {
   628                // Encode Unicode SMP values to a surrogate pair using two \u
   629                // escapes.
   630                uint32_t base = ucc - 0x10000;
   631                auto high_surrogate = (base >> 10) + 0xD800;
   632                auto low_surrogate = (base & 0x03FF) + 0xDC00;
   633                text += "\\u";
   634                text += IntToStringHex(high_surrogate, 4);
   635                text += "\\u";
   636                text += IntToStringHex(low_surrogate, 4);
   637              }
   638              // Skip past characters recognized.
   639              i = static_cast<uoffset_t>(utf8 - s - 1);
   640            }
   641          }
   642          break;
   643      }
   644    }
   645    text += "\"";
   646    return true;
   647  }
   648  
   649  inline std::string BufferToHexText(const void *buffer, size_t buffer_size,
   650                                     size_t max_length,
   651                                     const std::string &wrapped_line_prefix,
   652                                     const std::string &wrapped_line_suffix) {
   653    std::string text = wrapped_line_prefix;
   654    size_t start_offset = 0;
   655    const char *s = reinterpret_cast<const char *>(buffer);
   656    for (size_t i = 0; s && i < buffer_size; i++) {
   657      // Last iteration or do we have more?
   658      bool have_more = i + 1 < buffer_size;
   659      text += "0x";
   660      text += IntToStringHex(static_cast<uint8_t>(s[i]), 2);
   661      if (have_more) { text += ','; }
   662      // If we have more to process and we reached max_length
   663      if (have_more &&
   664          text.size() + wrapped_line_suffix.size() >= start_offset + max_length) {
   665        text += wrapped_line_suffix;
   666        text += '\n';
   667        start_offset = text.size();
   668        text += wrapped_line_prefix;
   669      }
   670    }
   671    text += wrapped_line_suffix;
   672    return text;
   673  }
   674  
   675  // Remove paired quotes in a string: "text"|'text' -> text.
   676  std::string RemoveStringQuotes(const std::string &s);
   677  
   678  // Change th global C-locale to locale with name <locale_name>.
   679  // Returns an actual locale name in <_value>, useful if locale_name is "" or
   680  // null.
   681  bool SetGlobalTestLocale(const char *locale_name,
   682                           std::string *_value = nullptr);
   683  
   684  // Read (or test) a value of environment variable.
   685  bool ReadEnvironmentVariable(const char *var_name,
   686                               std::string *_value = nullptr);
   687  
   688  // MSVC specific: Send all assert reports to STDOUT to prevent CI hangs.
   689  void SetupDefaultCRTReportMode();
   690  
   691  enum class Case {
   692    kUnknown = 0,
   693    // TheQuickBrownFox
   694    kUpperCamel = 1,
   695    // theQuickBrownFox
   696    kLowerCamel = 2,
   697    // the_quick_brown_fox
   698    kSnake = 3,
   699    // THE_QUICK_BROWN_FOX
   700    kScreamingSnake = 4,
   701    // THEQUICKBROWNFOX
   702    kAllUpper = 5,
   703    // thequickbrownfox
   704    kAllLower = 6,
   705    // the-quick-brown-fox
   706    kDasher = 7,
   707    // THEQuiCKBr_ownFox (or whatever you want, we won't change it)
   708    kKeep = 8,
   709    // the_quick_brown_fox123 (as opposed to the_quick_brown_fox_123)
   710    kSnake2 = 9,
   711  };
   712  
   713  // Convert the `input` string of case `input_case` to the specified `output_case`.
   714  std::string ConvertCase(const std::string &input, Case output_case,
   715                      Case input_case = Case::kSnake);
   716  
   717  }  // namespace flatbuffers
   718  
   719  #endif  // FLATBUFFERS_UTIL_H_