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 nacl netbsd openbsd solaris 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 func rename(oldname, newname string) error {
  52         e := syscall.Rename(oldname, newname)
  53         if e != nil {
  54                 return &LinkError{"rename", oldname, newname, e}
  55         }
  56         return nil
  57 }
  58
  59 // syscallMode returns the syscall-specific mode bits from Go's portable mode bits.
  60 func syscallMode(i FileMode) (o uint32) {
  61         o |= uint32(i.Perm())
  62         if i&ModeSetuid != 0 {
  63                 o |= syscall.S_ISUID
  64         }
  65         if i&ModeSetgid != 0 {
  66                 o |= syscall.S_ISGID
  67         }
  68         if i&ModeSticky != 0 {
  69                 o |= syscall.S_ISVTX
  70         }
  71         // No mapping for Go's ModeTemporary (plan9 only).
  72         return
  73 }
  74
  75 // Chmod changes the mode of the named file to mode.
  76 // If the file is a symbolic link, it changes the mode of the link's target.
  77 // If there is an error, it will be of type *PathError.
  78 func Chmod(name string, mode FileMode) error {
  79         if e := syscall.Chmod(name, syscallMode(mode)); e != nil {
  80                 return &PathError{"chmod", name, e}
  81         }
  82         return nil
  83 }
  84
  85 // Chmod changes the mode of the file to mode.
  86 // If there is an error, it will be of type *PathError.
  87 func (f *File) Chmod(mode FileMode) error {
  88         if f == nil {
  89                 return ErrInvalid
  90         }
  91         if e := syscall.Fchmod(f.fd, syscallMode(mode)); e != nil {
  92                 return &PathError{"chmod", f.name, e}
  93         }
  94         return nil
  95 }
  96
  97 // Chown changes the numeric uid and gid of the named file.
  98 // If the file is a symbolic link, it changes the uid and gid of the link's target.
  99 // If there is an error, it will be of type *PathError.
 100 func Chown(name string, uid, gid int) error {
 101         if e := syscall.Chown(name, uid, gid); e != nil {
 102                 return &PathError{"chown", name, e}
 103         }
 104         return nil
 105 }
 106
 107 // Lchown changes the numeric uid and gid of the named file.
 108 // If the file is a symbolic link, it changes the uid and gid of the link itself.
 109 // If there is an error, it will be of type *PathError.
 110 func Lchown(name string, uid, gid int) error {
 111         if e := syscall.Lchown(name, uid, gid); e != nil {
 112                 return &PathError{"lchown", name, e}
 113         }
 114         return nil
 115 }
 116
 117 // Chown changes the numeric uid and gid of the named file.
 118 // If there is an error, it will be of type *PathError.
 119 func (f *File) Chown(uid, gid int) error {
 120         if f == nil {
 121                 return ErrInvalid
 122         }
 123         if e := syscall.Fchown(f.fd, uid, gid); e != nil {
 124                 return &PathError{"chown", f.name, e}
 125         }
 126         return nil
 127 }
 128
 129 // Truncate changes the size of the file.
 130 // It does not change the I/O offset.
 131 // If there is an error, it will be of type *PathError.
 132 func (f *File) Truncate(size int64) error {
 133         if f == nil {
 134                 return ErrInvalid
 135         }
 136         if e := syscall.Ftruncate(f.fd, size); e != nil {
 137                 return &PathError{"truncate", f.name, e}
 138         }
 139         return nil
 140 }
 141
 142 // Sync commits the current contents of the file to stable storage.
 143 // Typically, this means flushing the file system's in-memory copy
 144 // of recently written data to disk.
 145 func (f *File) Sync() (err error) {
 146         if f == nil {
 147                 return ErrInvalid
 148         }
 149         if e := syscall.Fsync(f.fd); e != nil {
 150                 return NewSyscallError("fsync", e)
 151         }
 152         return nil
 153 }
 154
 155 // Chtimes changes the access and modification times of the named
 156 // file, similar to the Unix utime() or utimes() functions.
 157 //
 158 // The underlying filesystem may truncate or round the values to a
 159 // less precise time unit.
 160 // If there is an error, it will be of type *PathError.
 161 func Chtimes(name string, atime time.Time, mtime time.Time) error {
 162         var utimes [2]syscall.Timespec
 163         utimes[0] = syscall.NsecToTimespec(atime.UnixNano())
 164         utimes[1] = syscall.NsecToTimespec(mtime.UnixNano())
 165         if e := syscall.UtimesNano(name, utimes[0:]); e != nil {
 166                 return &PathError{"chtimes", name, e}
 167         }
 168         return nil
 169 }