libgo/go/os/file_posix.go

   1 // Copyright 2009 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 // +build darwin dragonfly freebsd linux netbsd openbsd windows
   6
   7 package os
   8
   9 import (
  10         "syscall"
  11         "time"
  12 )
  13
  14 func sigpipe() // implemented in package runtime
  15
  16 // Link creates newname as a hard link to the oldname file.
  17 // If there is an error, it will be of type *LinkError.
  18 func Link(oldname, newname string) error {
  19         e := syscall.Link(oldname, newname)
  20         if e != nil {
  21                 return &LinkError{"link", oldname, newname, e}
  22         }
  23         return nil
  24 }
  25
  26 // Symlink creates newname as a symbolic link to oldname.
  27 // If there is an error, it will be of type *LinkError.
  28 func Symlink(oldname, newname string) error {
  29         e := syscall.Symlink(oldname, newname)
  30         if e != nil {
  31                 return &LinkError{"symlink", oldname, newname, e}
  32         }
  33         return nil
  34 }
  35
  36 // Readlink returns the destination of the named symbolic link.
  37 // If there is an error, it will be of type *PathError.
  38 func Readlink(name string) (string, error) {
  39         for len := 128; ; len *= 2 {
  40                 b := make([]byte, len)
  41                 n, e := syscall.Readlink(name, b)
  42                 if e != nil {
  43                         return "", &PathError{"readlink", name, e}
  44                 }
  45                 if n < len {
  46                         return string(b[0:n]), nil
  47                 }
  48         }
  49 }
  50
  51 // Rename renames a file.
  52 func Rename(oldname, newname string) error {
  53         e := syscall.Rename(oldname, newname)
  54         if e != nil {
  55                 return &LinkError{"rename", oldname, newname, e}
  56         }
  57         return nil
  58 }
  59
  60 // syscallMode returns the syscall-specific mode bits from Go's portable mode bits.
  61 func syscallMode(i FileMode) (o uint32) {
  62         o |= uint32(i.Perm())
  63         if i&ModeSetuid != 0 {
  64                 o |= syscall.S_ISUID
  65         }
  66         if i&ModeSetgid != 0 {
  67                 o |= syscall.S_ISGID
  68         }
  69         if i&ModeSticky != 0 {
  70                 o |= syscall.S_ISVTX
  71         }
  72         // No mapping for Go's ModeTemporary (plan9 only).
  73         return
  74 }
  75
  76 // Chmod changes the mode of the named file to mode.
  77 // If the file is a symbolic link, it changes the mode of the link's target.
  78 // If there is an error, it will be of type *PathError.
  79 func Chmod(name string, mode FileMode) error {
  80         if e := syscall.Chmod(name, syscallMode(mode)); e != nil {
  81                 return &PathError{"chmod", name, e}
  82         }
  83         return nil
  84 }
  85
  86 // Chmod changes the mode of the file to mode.
  87 // If there is an error, it will be of type *PathError.
  88 func (f *File) Chmod(mode FileMode) error {
  89         if f == nil {
  90                 return ErrInvalid
  91         }
  92         if e := syscall.Fchmod(f.fd, syscallMode(mode)); e != nil {
  93                 return &PathError{"chmod", f.name, e}
  94         }
  95         return nil
  96 }
  97
  98 // Chown changes the numeric uid and gid of the named file.
  99 // If the file is a symbolic link, it changes the uid and gid of the link's target.
 100 // If there is an error, it will be of type *PathError.
 101 func Chown(name string, uid, gid int) error {
 102         if e := syscall.Chown(name, uid, gid); e != nil {
 103                 return &PathError{"chown", name, e}
 104         }
 105         return nil
 106 }
 107
 108 // Lchown changes the numeric uid and gid of the named file.
 109 // If the file is a symbolic link, it changes the uid and gid of the link itself.
 110 // If there is an error, it will be of type *PathError.
 111 func Lchown(name string, uid, gid int) error {
 112         if e := syscall.Lchown(name, uid, gid); e != nil {
 113                 return &PathError{"lchown", name, e}
 114         }
 115         return nil
 116 }
 117
 118 // Chown changes the numeric uid and gid of the named file.
 119 // If there is an error, it will be of type *PathError.
 120 func (f *File) Chown(uid, gid int) error {
 121         if f == nil {
 122                 return ErrInvalid
 123         }
 124         if e := syscall.Fchown(f.fd, uid, gid); e != nil {
 125                 return &PathError{"chown", f.name, e}
 126         }
 127         return nil
 128 }
 129
 130 // Truncate changes the size of the file.
 131 // It does not change the I/O offset.
 132 // If there is an error, it will be of type *PathError.
 133 func (f *File) Truncate(size int64) error {
 134         if f == nil {
 135                 return ErrInvalid
 136         }
 137         if e := syscall.Ftruncate(f.fd, size); e != nil {
 138                 return &PathError{"truncate", f.name, e}
 139         }
 140         return nil
 141 }
 142
 143 // Sync commits the current contents of the file to stable storage.
 144 // Typically, this means flushing the file system's in-memory copy
 145 // of recently written data to disk.
 146 func (f *File) Sync() (err error) {
 147         if f == nil {
 148                 return syscall.EINVAL
 149         }
 150         if e := syscall.Fsync(f.fd); e != nil {
 151                 return NewSyscallError("fsync", e)
 152         }
 153         return nil
 154 }
 155
 156 // Chtimes changes the access and modification times of the named
 157 // file, similar to the Unix utime() or utimes() functions.
 158 //
 159 // The underlying filesystem may truncate or round the values to a
 160 // less precise time unit.
 161 // If there is an error, it will be of type *PathError.
 162 func Chtimes(name string, atime time.Time, mtime time.Time) error {
 163         var utimes [2]syscall.Timespec
 164         utimes[0] = syscall.NsecToTimespec(atime.UnixNano())
 165         utimes[1] = syscall.NsecToTimespec(mtime.UnixNano())
 166         if e := syscall.UtimesNano(name, utimes[0:]); e != nil {
 167                 return &PathError{"chtimes", name, e}
 168         }
 169         return nil
 170 }