github.com/rakyll/go@v0.0.0-20170216000551-64c02460d703/src/os/file_plan9.go (about) 1 // Copyright 2011 The Go Authors. All rights reserved. 2 // Use of this source code is governed by a BSD-style 3 // license that can be found in the LICENSE file. 4 5 package os 6 7 import ( 8 "io" 9 "runtime" 10 "syscall" 11 "time" 12 ) 13 14 // fixLongPath is a noop on non-Windows platforms. 15 func fixLongPath(path string) string { 16 return path 17 } 18 19 // file is the real representation of *File. 20 // The extra level of indirection ensures that no clients of os 21 // can overwrite this data, which could cause the finalizer 22 // to close the wrong file descriptor. 23 type file struct { 24 fd int 25 name string 26 dirinfo *dirInfo // nil unless directory being read 27 } 28 29 // Fd returns the integer Plan 9 file descriptor referencing the open file. 30 // The file descriptor is valid only until f.Close is called or f is garbage collected. 31 func (f *File) Fd() uintptr { 32 if f == nil { 33 return ^(uintptr(0)) 34 } 35 return uintptr(f.fd) 36 } 37 38 // NewFile returns a new File with the given file descriptor and name. 39 func NewFile(fd uintptr, name string) *File { 40 fdi := int(fd) 41 if fdi < 0 { 42 return nil 43 } 44 f := &File{&file{fd: fdi, name: name}} 45 runtime.SetFinalizer(f.file, (*file).close) 46 return f 47 } 48 49 // Auxiliary information if the File describes a directory 50 type dirInfo struct { 51 buf [syscall.STATMAX]byte // buffer for directory I/O 52 nbuf int // length of buf; return value from Read 53 bufp int // location of next record in buf. 54 } 55 56 func epipecheck(file *File, e error) { 57 } 58 59 // DevNull is the name of the operating system's ``null device.'' 60 // On Unix-like systems, it is "/dev/null"; on Windows, "NUL". 61 const DevNull = "/dev/null" 62 63 // syscallMode returns the syscall-specific mode bits from Go's portable mode bits. 64 func syscallMode(i FileMode) (o uint32) { 65 o |= uint32(i.Perm()) 66 if i&ModeAppend != 0 { 67 o |= syscall.DMAPPEND 68 } 69 if i&ModeExclusive != 0 { 70 o |= syscall.DMEXCL 71 } 72 if i&ModeTemporary != 0 { 73 o |= syscall.DMTMP 74 } 75 return 76 } 77 78 // OpenFile is the generalized open call; most users will use Open 79 // or Create instead. It opens the named file with specified flag 80 // (O_RDONLY etc.) and perm, (0666 etc.) if applicable. If successful, 81 // methods on the returned File can be used for I/O. 82 // If there is an error, it will be of type *PathError. 83 func OpenFile(name string, flag int, perm FileMode) (*File, error) { 84 var ( 85 fd int 86 e error 87 create bool 88 excl bool 89 trunc bool 90 append bool 91 ) 92 93 if flag&O_CREATE == O_CREATE { 94 flag = flag & ^O_CREATE 95 create = true 96 } 97 if flag&O_EXCL == O_EXCL { 98 excl = true 99 } 100 if flag&O_TRUNC == O_TRUNC { 101 trunc = true 102 } 103 // O_APPEND is emulated on Plan 9 104 if flag&O_APPEND == O_APPEND { 105 flag = flag &^ O_APPEND 106 append = true 107 } 108 109 if (create && trunc) || excl { 110 fd, e = syscall.Create(name, flag, syscallMode(perm)) 111 } else { 112 fd, e = syscall.Open(name, flag) 113 if e != nil && create { 114 var e1 error 115 fd, e1 = syscall.Create(name, flag, syscallMode(perm)) 116 if e1 == nil { 117 e = nil 118 } 119 } 120 } 121 122 if e != nil { 123 return nil, &PathError{"open", name, e} 124 } 125 126 if append { 127 if _, e = syscall.Seek(fd, 0, io.SeekEnd); e != nil { 128 return nil, &PathError{"seek", name, e} 129 } 130 } 131 132 return NewFile(uintptr(fd), name), nil 133 } 134 135 // Close closes the File, rendering it unusable for I/O. 136 // It returns an error, if any. 137 func (f *File) Close() error { 138 if err := f.checkValid("close"); err != nil { 139 return err 140 } 141 return f.file.close() 142 } 143 144 func (file *file) close() error { 145 if file == nil || file.fd == badFd { 146 return ErrInvalid 147 } 148 var err error 149 if e := syscall.Close(file.fd); e != nil { 150 err = &PathError{"close", file.name, e} 151 } 152 file.fd = badFd // so it can't be closed again 153 154 // no need for a finalizer anymore 155 runtime.SetFinalizer(file, nil) 156 return err 157 } 158 159 // Stat returns the FileInfo structure describing file. 160 // If there is an error, it will be of type *PathError. 161 func (f *File) Stat() (FileInfo, error) { 162 if f == nil { 163 return nil, ErrInvalid 164 } 165 d, err := dirstat(f) 166 if err != nil { 167 return nil, err 168 } 169 return fileInfoFromStat(d), nil 170 } 171 172 // Truncate changes the size of the file. 173 // It does not change the I/O offset. 174 // If there is an error, it will be of type *PathError. 175 func (f *File) Truncate(size int64) error { 176 if f == nil { 177 return ErrInvalid 178 } 179 180 var d syscall.Dir 181 d.Null() 182 d.Length = size 183 184 var buf [syscall.STATFIXLEN]byte 185 n, err := d.Marshal(buf[:]) 186 if err != nil { 187 return &PathError{"truncate", f.name, err} 188 } 189 if err = syscall.Fwstat(f.fd, buf[:n]); err != nil { 190 return &PathError{"truncate", f.name, err} 191 } 192 return nil 193 } 194 195 const chmodMask = uint32(syscall.DMAPPEND | syscall.DMEXCL | syscall.DMTMP | ModePerm) 196 197 // Chmod changes the mode of the file to mode. 198 // If there is an error, it will be of type *PathError. 199 func (f *File) Chmod(mode FileMode) error { 200 if f == nil { 201 return ErrInvalid 202 } 203 var d syscall.Dir 204 205 odir, e := dirstat(f) 206 if e != nil { 207 return &PathError{"chmod", f.name, e} 208 } 209 d.Null() 210 d.Mode = odir.Mode&^chmodMask | syscallMode(mode)&chmodMask 211 212 var buf [syscall.STATFIXLEN]byte 213 n, err := d.Marshal(buf[:]) 214 if err != nil { 215 return &PathError{"chmod", f.name, err} 216 } 217 if err = syscall.Fwstat(f.fd, buf[:n]); err != nil { 218 return &PathError{"chmod", f.name, err} 219 } 220 return nil 221 } 222 223 // Sync commits the current contents of the file to stable storage. 224 // Typically, this means flushing the file system's in-memory copy 225 // of recently written data to disk. 226 func (f *File) Sync() error { 227 if f == nil { 228 return ErrInvalid 229 } 230 var d syscall.Dir 231 d.Null() 232 233 var buf [syscall.STATFIXLEN]byte 234 n, err := d.Marshal(buf[:]) 235 if err != nil { 236 return NewSyscallError("fsync", err) 237 } 238 if err = syscall.Fwstat(f.fd, buf[:n]); err != nil { 239 return NewSyscallError("fsync", err) 240 } 241 return nil 242 } 243 244 // read reads up to len(b) bytes from the File. 245 // It returns the number of bytes read and an error, if any. 246 func (f *File) read(b []byte) (n int, err error) { 247 n, e := fixCount(syscall.Read(f.fd, b)) 248 if n == 0 && len(b) > 0 && e == nil { 249 return 0, io.EOF 250 } 251 return n, e 252 } 253 254 // pread reads len(b) bytes from the File starting at byte offset off. 255 // It returns the number of bytes read and the error, if any. 256 // EOF is signaled by a zero count with err set to nil. 257 func (f *File) pread(b []byte, off int64) (n int, err error) { 258 n, e := fixCount(syscall.Pread(f.fd, b, off)) 259 if n == 0 && len(b) > 0 && e == nil { 260 return 0, io.EOF 261 } 262 return n, e 263 } 264 265 // write writes len(b) bytes to the File. 266 // It returns the number of bytes written and an error, if any. 267 // Since Plan 9 preserves message boundaries, never allow 268 // a zero-byte write. 269 func (f *File) write(b []byte) (n int, err error) { 270 if len(b) == 0 { 271 return 0, nil 272 } 273 return fixCount(syscall.Write(f.fd, b)) 274 } 275 276 // pwrite writes len(b) bytes to the File starting at byte offset off. 277 // It returns the number of bytes written and an error, if any. 278 // Since Plan 9 preserves message boundaries, never allow 279 // a zero-byte write. 280 func (f *File) pwrite(b []byte, off int64) (n int, err error) { 281 if len(b) == 0 { 282 return 0, nil 283 } 284 return fixCount(syscall.Pwrite(f.fd, b, off)) 285 } 286 287 // seek sets the offset for the next Read or Write on file to offset, interpreted 288 // according to whence: 0 means relative to the origin of the file, 1 means 289 // relative to the current offset, and 2 means relative to the end. 290 // It returns the new offset and an error, if any. 291 func (f *File) seek(offset int64, whence int) (ret int64, err error) { 292 return syscall.Seek(f.fd, offset, whence) 293 } 294 295 // Truncate changes the size of the named file. 296 // If the file is a symbolic link, it changes the size of the link's target. 297 // If there is an error, it will be of type *PathError. 298 func Truncate(name string, size int64) error { 299 var d syscall.Dir 300 301 d.Null() 302 d.Length = size 303 304 var buf [syscall.STATFIXLEN]byte 305 n, err := d.Marshal(buf[:]) 306 if err != nil { 307 return &PathError{"truncate", name, err} 308 } 309 if err = syscall.Wstat(name, buf[:n]); err != nil { 310 return &PathError{"truncate", name, err} 311 } 312 return nil 313 } 314 315 // Remove removes the named file or directory. 316 // If there is an error, it will be of type *PathError. 317 func Remove(name string) error { 318 if e := syscall.Remove(name); e != nil { 319 return &PathError{"remove", name, e} 320 } 321 return nil 322 } 323 324 // HasPrefix from the strings package. 325 func hasPrefix(s, prefix string) bool { 326 return len(s) >= len(prefix) && s[0:len(prefix)] == prefix 327 } 328 329 // LastIndexByte from the strings package. 330 func lastIndex(s string, sep byte) int { 331 for i := len(s) - 1; i >= 0; i-- { 332 if s[i] == sep { 333 return i 334 } 335 } 336 return -1 337 } 338 339 func rename(oldname, newname string) error { 340 dirname := oldname[:lastIndex(oldname, '/')+1] 341 if hasPrefix(newname, dirname) { 342 newname = newname[len(dirname):] 343 } else { 344 return &LinkError{"rename", oldname, newname, ErrInvalid} 345 } 346 347 // If newname still contains slashes after removing the oldname 348 // prefix, the rename is cross-directory and must be rejected. 349 if lastIndex(newname, '/') >= 0 { 350 return &LinkError{"rename", oldname, newname, ErrInvalid} 351 } 352 353 var d syscall.Dir 354 355 d.Null() 356 d.Name = newname 357 358 buf := make([]byte, syscall.STATFIXLEN+len(d.Name)) 359 n, err := d.Marshal(buf[:]) 360 if err != nil { 361 return &LinkError{"rename", oldname, newname, err} 362 } 363 364 // If newname already exists and is not a directory, rename replaces it. 365 f, err := Stat(dirname + newname) 366 if err == nil && !f.IsDir() { 367 Remove(dirname + newname) 368 } 369 370 if err = syscall.Wstat(oldname, buf[:n]); err != nil { 371 return &LinkError{"rename", oldname, newname, err} 372 } 373 return nil 374 } 375 376 // Chmod changes the mode of the named file to mode. 377 // If the file is a symbolic link, it changes the mode of the link's target. 378 // If there is an error, it will be of type *PathError. 379 func Chmod(name string, mode FileMode) error { 380 var d syscall.Dir 381 382 odir, e := dirstat(name) 383 if e != nil { 384 return &PathError{"chmod", name, e} 385 } 386 d.Null() 387 d.Mode = odir.Mode&^chmodMask | syscallMode(mode)&chmodMask 388 389 var buf [syscall.STATFIXLEN]byte 390 n, err := d.Marshal(buf[:]) 391 if err != nil { 392 return &PathError{"chmod", name, err} 393 } 394 if err = syscall.Wstat(name, buf[:n]); err != nil { 395 return &PathError{"chmod", name, err} 396 } 397 return nil 398 } 399 400 // Chtimes changes the access and modification times of the named 401 // file, similar to the Unix utime() or utimes() functions. 402 // 403 // The underlying filesystem may truncate or round the values to a 404 // less precise time unit. 405 // If there is an error, it will be of type *PathError. 406 func Chtimes(name string, atime time.Time, mtime time.Time) error { 407 var d syscall.Dir 408 409 d.Null() 410 d.Atime = uint32(atime.Unix()) 411 d.Mtime = uint32(mtime.Unix()) 412 413 var buf [syscall.STATFIXLEN]byte 414 n, err := d.Marshal(buf[:]) 415 if err != nil { 416 return &PathError{"chtimes", name, err} 417 } 418 if err = syscall.Wstat(name, buf[:n]); err != nil { 419 return &PathError{"chtimes", name, err} 420 } 421 return nil 422 } 423 424 // Pipe returns a connected pair of Files; reads from r return bytes 425 // written to w. It returns the files and an error, if any. 426 func Pipe() (r *File, w *File, err error) { 427 var p [2]int 428 429 if e := syscall.Pipe(p[0:]); e != nil { 430 return nil, nil, NewSyscallError("pipe", e) 431 } 432 433 return NewFile(uintptr(p[0]), "|0"), NewFile(uintptr(p[1]), "|1"), nil 434 } 435 436 // not supported on Plan 9 437 438 // Link creates newname as a hard link to the oldname file. 439 // If there is an error, it will be of type *LinkError. 440 func Link(oldname, newname string) error { 441 return &LinkError{"link", oldname, newname, syscall.EPLAN9} 442 } 443 444 // Symlink creates newname as a symbolic link to oldname. 445 // If there is an error, it will be of type *LinkError. 446 func Symlink(oldname, newname string) error { 447 return &LinkError{"symlink", oldname, newname, syscall.EPLAN9} 448 } 449 450 // Readlink returns the destination of the named symbolic link. 451 // If there is an error, it will be of type *PathError. 452 func Readlink(name string) (string, error) { 453 return "", &PathError{"readlink", name, syscall.EPLAN9} 454 } 455 456 // Chown changes the numeric uid and gid of the named file. 457 // If the file is a symbolic link, it changes the uid and gid of the link's target. 458 // If there is an error, it will be of type *PathError. 459 func Chown(name string, uid, gid int) error { 460 return &PathError{"chown", name, syscall.EPLAN9} 461 } 462 463 // Lchown changes the numeric uid and gid of the named file. 464 // If the file is a symbolic link, it changes the uid and gid of the link itself. 465 // If there is an error, it will be of type *PathError. 466 func Lchown(name string, uid, gid int) error { 467 return &PathError{"lchown", name, syscall.EPLAN9} 468 } 469 470 // Chown changes the numeric uid and gid of the named file. 471 // If there is an error, it will be of type *PathError. 472 func (f *File) Chown(uid, gid int) error { 473 if f == nil { 474 return ErrInvalid 475 } 476 return &PathError{"chown", f.name, syscall.EPLAN9} 477 } 478 479 // TempDir returns the default directory to use for temporary files. 480 func TempDir() string { 481 return "/tmp" 482 } 483 484 // Chdir changes the current working directory to the file, 485 // which must be a directory. 486 // If there is an error, it will be of type *PathError. 487 func (f *File) Chdir() error { 488 if err := f.checkValid("chdir"); err != nil { 489 return err 490 } 491 if e := syscall.Fchdir(f.fd); e != nil { 492 return &PathError{"chdir", f.name, e} 493 } 494 return nil 495 } 496 497 // checkValid checks whether f is valid for use. 498 // If not, it returns an appropriate error, perhaps incorporating the operation name op. 499 func (f *File) checkValid(op string) error { 500 if f == nil { 501 return ErrInvalid 502 } 503 if f.fd == badFd { 504 return &PathError{op, f.name, ErrClosed} 505 } 506 return nil 507 }