github.com/ader1990/go@v0.0.0-20140630135419-8c24447fa791/src/pkg/os/file_posix.go (about) 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 }