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