github.com/ader1990/go@v0.0.0-20140630135419-8c24447fa791/src/pkg/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 "runtime" 9 "syscall" 10 "time" 11 ) 12 13 // File represents an open file descriptor. 14 type File struct { 15 *file 16 } 17 18 // file is the real representation of *File. 19 // The extra level of indirection ensures that no clients of os 20 // can overwrite this data, which could cause the finalizer 21 // to close the wrong file descriptor. 22 type file struct { 23 fd int 24 name string 25 dirinfo *dirInfo // nil unless directory being read 26 } 27 28 // Fd returns the integer Unix file descriptor referencing the open file. 29 func (f *File) Fd() uintptr { 30 if f == nil { 31 return ^(uintptr(0)) 32 } 33 return uintptr(f.fd) 34 } 35 36 // NewFile returns a new File with the given file descriptor and name. 37 func NewFile(fd uintptr, name string) *File { 38 fdi := int(fd) 39 if fdi < 0 { 40 return nil 41 } 42 f := &File{&file{fd: fdi, name: name}} 43 runtime.SetFinalizer(f.file, (*file).close) 44 return f 45 } 46 47 // Auxiliary information if the File describes a directory 48 type dirInfo struct { 49 buf [syscall.STATMAX]byte // buffer for directory I/O 50 nbuf int // length of buf; return value from Read 51 bufp int // location of next record in buf. 52 } 53 54 func epipecheck(file *File, e error) { 55 } 56 57 // DevNull is the name of the operating system's ``null device.'' 58 // On Unix-like systems, it is "/dev/null"; on Windows, "NUL". 59 const DevNull = "/dev/null" 60 61 // syscallMode returns the syscall-specific mode bits from Go's portable mode bits. 62 func syscallMode(i FileMode) (o uint32) { 63 o |= uint32(i.Perm()) 64 if i&ModeAppend != 0 { 65 o |= syscall.DMAPPEND 66 } 67 if i&ModeExclusive != 0 { 68 o |= syscall.DMEXCL 69 } 70 if i&ModeTemporary != 0 { 71 o |= syscall.DMTMP 72 } 73 return 74 } 75 76 // OpenFile is the generalized open call; most users will use Open 77 // or Create instead. It opens the named file with specified flag 78 // (O_RDONLY etc.) and perm, (0666 etc.) if applicable. If successful, 79 // methods on the returned File can be used for I/O. 80 // If there is an error, it will be of type *PathError. 81 func OpenFile(name string, flag int, perm FileMode) (file *File, err error) { 82 var ( 83 fd int 84 e error 85 create bool 86 excl bool 87 trunc bool 88 append bool 89 ) 90 91 if flag&O_CREATE == O_CREATE { 92 flag = flag & ^O_CREATE 93 create = true 94 } 95 if flag&O_EXCL == O_EXCL { 96 excl = true 97 } 98 if flag&O_TRUNC == O_TRUNC { 99 trunc = true 100 } 101 // O_APPEND is emulated on Plan 9 102 if flag&O_APPEND == O_APPEND { 103 flag = flag &^ O_APPEND 104 append = true 105 } 106 107 if (create && trunc) || excl { 108 fd, e = syscall.Create(name, flag, syscallMode(perm)) 109 } else { 110 fd, e = syscall.Open(name, flag) 111 if e != nil && create { 112 var e1 error 113 fd, e1 = syscall.Create(name, flag, syscallMode(perm)) 114 if e1 == nil { 115 e = nil 116 } 117 } 118 } 119 120 if e != nil { 121 return nil, &PathError{"open", name, e} 122 } 123 124 if append { 125 if _, e = syscall.Seek(fd, 0, SEEK_END); e != nil { 126 return nil, &PathError{"seek", name, e} 127 } 128 } 129 130 return NewFile(uintptr(fd), name), nil 131 } 132 133 // Close closes the File, rendering it unusable for I/O. 134 // It returns an error, if any. 135 func (f *File) Close() error { 136 if f == nil { 137 return ErrInvalid 138 } 139 return f.file.close() 140 } 141 142 func (file *file) close() error { 143 if file == nil || file.fd < 0 { 144 return ErrInvalid 145 } 146 var err error 147 syscall.ForkLock.RLock() 148 if e := syscall.Close(file.fd); e != nil { 149 err = &PathError{"close", file.name, e} 150 } 151 syscall.ForkLock.RUnlock() 152 file.fd = -1 // 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() (fi FileInfo, err 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() (err 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 return syscall.Read(f.fd, b) 248 } 249 250 // pread reads len(b) bytes from the File starting at byte offset off. 251 // It returns the number of bytes read and the error, if any. 252 // EOF is signaled by a zero count with err set to nil. 253 func (f *File) pread(b []byte, off int64) (n int, err error) { 254 return syscall.Pread(f.fd, b, off) 255 } 256 257 // write writes len(b) bytes to the File. 258 // It returns the number of bytes written and an error, if any. 259 // Since Plan 9 preserves message boundaries, never allow 260 // a zero-byte write. 261 func (f *File) write(b []byte) (n int, err error) { 262 if len(b) == 0 { 263 return 0, nil 264 } 265 return syscall.Write(f.fd, b) 266 } 267 268 // pwrite writes len(b) bytes to the File starting at byte offset off. 269 // It returns the number of bytes written and an error, if any. 270 // Since Plan 9 preserves message boundaries, never allow 271 // a zero-byte write. 272 func (f *File) pwrite(b []byte, off int64) (n int, err error) { 273 if len(b) == 0 { 274 return 0, nil 275 } 276 return syscall.Pwrite(f.fd, b, off) 277 } 278 279 // seek sets the offset for the next Read or Write on file to offset, interpreted 280 // according to whence: 0 means relative to the origin of the file, 1 means 281 // relative to the current offset, and 2 means relative to the end. 282 // It returns the new offset and an error, if any. 283 func (f *File) seek(offset int64, whence int) (ret int64, err error) { 284 return syscall.Seek(f.fd, offset, whence) 285 } 286 287 // Truncate changes the size of the named file. 288 // If the file is a symbolic link, it changes the size of the link's target. 289 // If there is an error, it will be of type *PathError. 290 func Truncate(name string, size int64) error { 291 var d syscall.Dir 292 293 d.Null() 294 d.Length = size 295 296 var buf [syscall.STATFIXLEN]byte 297 n, err := d.Marshal(buf[:]) 298 if err != nil { 299 return &PathError{"truncate", name, err} 300 } 301 if err = syscall.Wstat(name, buf[:n]); err != nil { 302 return &PathError{"truncate", name, err} 303 } 304 return nil 305 } 306 307 // Remove removes the named file or directory. 308 // If there is an error, it will be of type *PathError. 309 func Remove(name string) error { 310 if e := syscall.Remove(name); e != nil { 311 return &PathError{"remove", name, e} 312 } 313 return nil 314 } 315 316 // HasPrefix from the strings package. 317 func hasPrefix(s, prefix string) bool { 318 return len(s) >= len(prefix) && s[0:len(prefix)] == prefix 319 } 320 321 // Variant of LastIndex from the strings package. 322 func lastIndex(s string, sep byte) int { 323 for i := len(s) - 1; i >= 0; i-- { 324 if s[i] == sep { 325 return i 326 } 327 } 328 return -1 329 } 330 331 func rename(oldname, newname string) error { 332 dirname := oldname[:lastIndex(oldname, '/')+1] 333 if hasPrefix(newname, dirname) { 334 newname = newname[len(dirname):] 335 } else { 336 return &LinkError{"rename", oldname, newname, ErrInvalid} 337 } 338 339 // If newname still contains slashes after removing the oldname 340 // prefix, the rename is cross-directory and must be rejected. 341 // This case is caught by d.Marshal below. 342 343 var d syscall.Dir 344 345 d.Null() 346 d.Name = newname 347 348 buf := make([]byte, syscall.STATFIXLEN+len(d.Name)) 349 n, err := d.Marshal(buf[:]) 350 if err != nil { 351 return &LinkError{"rename", oldname, newname, err} 352 } 353 if err = syscall.Wstat(oldname, buf[:n]); err != nil { 354 return &LinkError{"rename", oldname, newname, err} 355 } 356 return nil 357 } 358 359 // Chmod changes the mode of the named file to mode. 360 // If the file is a symbolic link, it changes the mode of the link's target. 361 // If there is an error, it will be of type *PathError. 362 func Chmod(name string, mode FileMode) error { 363 var d syscall.Dir 364 365 odir, e := dirstat(name) 366 if e != nil { 367 return &PathError{"chmod", name, e} 368 } 369 d.Null() 370 d.Mode = odir.Mode&^chmodMask | syscallMode(mode)&chmodMask 371 372 var buf [syscall.STATFIXLEN]byte 373 n, err := d.Marshal(buf[:]) 374 if err != nil { 375 return &PathError{"chmod", name, err} 376 } 377 if err = syscall.Wstat(name, buf[:n]); err != nil { 378 return &PathError{"chmod", name, err} 379 } 380 return nil 381 } 382 383 // Chtimes changes the access and modification times of the named 384 // file, similar to the Unix utime() or utimes() functions. 385 // 386 // The underlying filesystem may truncate or round the values to a 387 // less precise time unit. 388 // If there is an error, it will be of type *PathError. 389 func Chtimes(name string, atime time.Time, mtime time.Time) error { 390 var d syscall.Dir 391 392 d.Null() 393 d.Atime = uint32(atime.Unix()) 394 d.Mtime = uint32(mtime.Unix()) 395 396 var buf [syscall.STATFIXLEN]byte 397 n, err := d.Marshal(buf[:]) 398 if err != nil { 399 return &PathError{"chtimes", name, err} 400 } 401 if err = syscall.Wstat(name, buf[:n]); err != nil { 402 return &PathError{"chtimes", name, err} 403 } 404 return nil 405 } 406 407 // Pipe returns a connected pair of Files; reads from r return bytes 408 // written to w. It returns the files and an error, if any. 409 func Pipe() (r *File, w *File, err error) { 410 var p [2]int 411 412 syscall.ForkLock.RLock() 413 if e := syscall.Pipe(p[0:]); e != nil { 414 syscall.ForkLock.RUnlock() 415 return nil, nil, NewSyscallError("pipe", e) 416 } 417 syscall.ForkLock.RUnlock() 418 419 return NewFile(uintptr(p[0]), "|0"), NewFile(uintptr(p[1]), "|1"), nil 420 } 421 422 // not supported on Plan 9 423 424 // Link creates newname as a hard link to the oldname file. 425 // If there is an error, it will be of type *LinkError. 426 func Link(oldname, newname string) error { 427 return &LinkError{"link", oldname, newname, syscall.EPLAN9} 428 } 429 430 // Symlink creates newname as a symbolic link to oldname. 431 // If there is an error, it will be of type *LinkError. 432 func Symlink(oldname, newname string) error { 433 return &LinkError{"symlink", oldname, newname, syscall.EPLAN9} 434 } 435 436 // Readlink returns the destination of the named symbolic link. 437 // If there is an error, it will be of type *PathError. 438 func Readlink(name string) (string, error) { 439 return "", &PathError{"readlink", name, syscall.EPLAN9} 440 } 441 442 // Chown changes the numeric uid and gid of the named file. 443 // If the file is a symbolic link, it changes the uid and gid of the link's target. 444 // If there is an error, it will be of type *PathError. 445 func Chown(name string, uid, gid int) error { 446 return &PathError{"chown", name, syscall.EPLAN9} 447 } 448 449 // Lchown changes the numeric uid and gid of the named file. 450 // If the file is a symbolic link, it changes the uid and gid of the link itself. 451 // If there is an error, it will be of type *PathError. 452 func Lchown(name string, uid, gid int) error { 453 return &PathError{"lchown", name, syscall.EPLAN9} 454 } 455 456 // Chown changes the numeric uid and gid of the named file. 457 // If there is an error, it will be of type *PathError. 458 func (f *File) Chown(uid, gid int) error { 459 if f == nil { 460 return ErrInvalid 461 } 462 return &PathError{"chown", f.name, syscall.EPLAN9} 463 } 464 465 // TempDir returns the default directory to use for temporary files. 466 func TempDir() string { 467 return "/tmp" 468 }