summaryrefslogtreecommitdiffstats
path: root/src/os/file_posix.go
blob: 5692657753372f678363525b53df54bbb559d828 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
// Copyright 2009 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

//go:build unix || (js && wasm) || wasip1 || windows

package os

import (
	"runtime"
	"syscall"
	"time"
)

// Close closes the File, rendering it unusable for I/O.
// On files that support SetDeadline, any pending I/O operations will
// be canceled and return immediately with an ErrClosed error.
// Close will return an error if it has already been called.
func (f *File) Close() error {
	if f == nil {
		return ErrInvalid
	}
	return f.file.close()
}

// read reads up to len(b) bytes from the File.
// It returns the number of bytes read and an error, if any.
func (f *File) read(b []byte) (n int, err error) {
	n, err = f.pfd.Read(b)
	runtime.KeepAlive(f)
	return n, err
}

// pread reads len(b) bytes from the File starting at byte offset off.
// It returns the number of bytes read and the error, if any.
// EOF is signaled by a zero count with err set to nil.
func (f *File) pread(b []byte, off int64) (n int, err error) {
	n, err = f.pfd.Pread(b, off)
	runtime.KeepAlive(f)
	return n, err
}

// write writes len(b) bytes to the File.
// It returns the number of bytes written and an error, if any.
func (f *File) write(b []byte) (n int, err error) {
	n, err = f.pfd.Write(b)
	runtime.KeepAlive(f)
	return n, err
}

// pwrite writes len(b) bytes to the File starting at byte offset off.
// It returns the number of bytes written and an error, if any.
func (f *File) pwrite(b []byte, off int64) (n int, err error) {
	n, err = f.pfd.Pwrite(b, off)
	runtime.KeepAlive(f)
	return n, err
}

// syscallMode returns the syscall-specific mode bits from Go's portable mode bits.
func syscallMode(i FileMode) (o uint32) {
	o |= uint32(i.Perm())
	if i&ModeSetuid != 0 {
		o |= syscall.S_ISUID
	}
	if i&ModeSetgid != 0 {
		o |= syscall.S_ISGID
	}
	if i&ModeSticky != 0 {
		o |= syscall.S_ISVTX
	}
	// No mapping for Go's ModeTemporary (plan9 only).
	return
}

// See docs in file.go:Chmod.
func chmod(name string, mode FileMode) error {
	longName := fixLongPath(name)
	e := ignoringEINTR(func() error {
		return syscall.Chmod(longName, syscallMode(mode))
	})
	if e != nil {
		return &PathError{Op: "chmod", Path: name, Err: e}
	}
	return nil
}

// See docs in file.go:(*File).Chmod.
func (f *File) chmod(mode FileMode) error {
	if err := f.checkValid("chmod"); err != nil {
		return err
	}
	if e := f.pfd.Fchmod(syscallMode(mode)); e != nil {
		return f.wrapErr("chmod", e)
	}
	return nil
}

// Chown changes the numeric uid and gid of the named file.
// If the file is a symbolic link, it changes the uid and gid of the link's target.
// A uid or gid of -1 means to not change that value.
// If there is an error, it will be of type *PathError.
//
// On Windows or Plan 9, Chown always returns the syscall.EWINDOWS or
// EPLAN9 error, wrapped in *PathError.
func Chown(name string, uid, gid int) error {
	e := ignoringEINTR(func() error {
		return syscall.Chown(name, uid, gid)
	})
	if e != nil {
		return &PathError{Op: "chown", Path: name, Err: e}
	}
	return nil
}

// Lchown changes the numeric uid and gid of the named file.
// If the file is a symbolic link, it changes the uid and gid of the link itself.
// If there is an error, it will be of type *PathError.
//
// On Windows, it always returns the syscall.EWINDOWS error, wrapped
// in *PathError.
func Lchown(name string, uid, gid int) error {
	e := ignoringEINTR(func() error {
		return syscall.Lchown(name, uid, gid)
	})
	if e != nil {
		return &PathError{Op: "lchown", Path: name, Err: e}
	}
	return nil
}

// Chown changes the numeric uid and gid of the named file.
// If there is an error, it will be of type *PathError.
//
// On Windows, it always returns the syscall.EWINDOWS error, wrapped
// in *PathError.
func (f *File) Chown(uid, gid int) error {
	if err := f.checkValid("chown"); err != nil {
		return err
	}
	if e := f.pfd.Fchown(uid, gid); e != nil {
		return f.wrapErr("chown", e)
	}
	return nil
}

// Truncate changes the size of the file.
// It does not change the I/O offset.
// If there is an error, it will be of type *PathError.
func (f *File) Truncate(size int64) error {
	if err := f.checkValid("truncate"); err != nil {
		return err
	}
	if e := f.pfd.Ftruncate(size); e != nil {
		return f.wrapErr("truncate", e)
	}
	return nil
}

// Sync commits the current contents of the file to stable storage.
// Typically, this means flushing the file system's in-memory copy
// of recently written data to disk.
func (f *File) Sync() error {
	if err := f.checkValid("sync"); err != nil {
		return err
	}
	if e := f.pfd.Fsync(); e != nil {
		return f.wrapErr("sync", e)
	}
	return nil
}

// Chtimes changes the access and modification times of the named
// file, similar to the Unix utime() or utimes() functions.
// A zero time.Time value will leave the corresponding file time unchanged.
//
// The underlying filesystem may truncate or round the values to a
// less precise time unit.
// If there is an error, it will be of type *PathError.
func Chtimes(name string, atime time.Time, mtime time.Time) error {
	var utimes [2]syscall.Timespec
	set := func(i int, t time.Time) {
		if t.IsZero() {
			utimes[i] = syscall.Timespec{Sec: _UTIME_OMIT, Nsec: _UTIME_OMIT}
		} else {
			utimes[i] = syscall.NsecToTimespec(t.UnixNano())
		}
	}
	set(0, atime)
	set(1, mtime)
	if e := syscall.UtimesNano(fixLongPath(name), utimes[0:]); e != nil {
		return &PathError{Op: "chtimes", Path: name, Err: e}
	}
	return nil
}

// Chdir changes the current working directory to the file,
// which must be a directory.
// If there is an error, it will be of type *PathError.
func (f *File) Chdir() error {
	if err := f.checkValid("chdir"); err != nil {
		return err
	}
	if e := f.pfd.Fchdir(); e != nil {
		return f.wrapErr("chdir", e)
	}
	return nil
}

// setDeadline sets the read and write deadline.
func (f *File) setDeadline(t time.Time) error {
	if err := f.checkValid("SetDeadline"); err != nil {
		return err
	}
	return f.pfd.SetDeadline(t)
}

// setReadDeadline sets the read deadline.
func (f *File) setReadDeadline(t time.Time) error {
	if err := f.checkValid("SetReadDeadline"); err != nil {
		return err
	}
	return f.pfd.SetReadDeadline(t)
}

// setWriteDeadline sets the write deadline.
func (f *File) setWriteDeadline(t time.Time) error {
	if err := f.checkValid("SetWriteDeadline"); err != nil {
		return err
	}
	return f.pfd.SetWriteDeadline(t)
}

// checkValid checks whether f is valid for use.
// If not, it returns an appropriate error, perhaps incorporating the operation name op.
func (f *File) checkValid(op string) error {
	if f == nil {
		return ErrInvalid
	}
	return nil
}

// ignoringEINTR makes a function call and repeats it if it returns an
// EINTR error. This appears to be required even though we install all
// signal handlers with SA_RESTART: see #22838, #38033, #38836, #40846.
// Also #20400 and #36644 are issues in which a signal handler is
// installed without setting SA_RESTART. None of these are the common case,
// but there are enough of them that it seems that we can't avoid
// an EINTR loop.
func ignoringEINTR(fn func() error) error {
	for {
		err := fn()
		if err != syscall.EINTR {
			return err
		}
	}
}