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