aboutsummaryrefslogtreecommitdiffstats
path: root/contrib/go/_std_1.21/src/os/file_windows.go
blob: 8d77a63d37faa5e04cc88ff9be77fbbb44ada120 (plain) (blame)
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
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
// 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.

package os

import (
	"errors"
	"internal/poll"
	"internal/syscall/windows"
	"runtime"
	"sync"
	"syscall"
	"unsafe"
)

// This matches the value in syscall/syscall_windows.go.
const _UTIME_OMIT = -1

// file is the real representation of *File.
// The extra level of indirection ensures that no clients of os
// can overwrite this data, which could cause the finalizer
// to close the wrong file descriptor.
type file struct {
	pfd        poll.FD
	name       string
	dirinfo    *dirInfo // nil unless directory being read
	appendMode bool     // whether file is opened for appending
}

// Fd returns the Windows handle referencing the open file.
// If f is closed, the file descriptor becomes invalid.
// If f is garbage collected, a finalizer may close the file descriptor,
// making it invalid; see runtime.SetFinalizer for more information on when
// a finalizer might be run. On Unix systems this will cause the SetDeadline
// methods to stop working.
func (file *File) Fd() uintptr {
	if file == nil {
		return uintptr(syscall.InvalidHandle)
	}
	return uintptr(file.pfd.Sysfd)
}

// newFile returns a new File with the given file handle and name.
// Unlike NewFile, it does not check that h is syscall.InvalidHandle.
func newFile(h syscall.Handle, name string, kind string) *File {
	if kind == "file" {
		var m uint32
		if syscall.GetConsoleMode(h, &m) == nil {
			kind = "console"
		}
		if t, err := syscall.GetFileType(h); err == nil && t == syscall.FILE_TYPE_PIPE {
			kind = "pipe"
		}
	}

	f := &File{&file{
		pfd: poll.FD{
			Sysfd:         h,
			IsStream:      true,
			ZeroReadIsEOF: true,
		},
		name: name,
	}}
	runtime.SetFinalizer(f.file, (*file).close)

	// Ignore initialization errors.
	// Assume any problems will show up in later I/O.
	f.pfd.Init(kind, false)

	return f
}

// newConsoleFile creates new File that will be used as console.
func newConsoleFile(h syscall.Handle, name string) *File {
	return newFile(h, name, "console")
}

// NewFile returns a new File with the given file descriptor and
// name. The returned value will be nil if fd is not a valid file
// descriptor.
func NewFile(fd uintptr, name string) *File {
	h := syscall.Handle(fd)
	if h == syscall.InvalidHandle {
		return nil
	}
	return newFile(h, name, "file")
}

// Auxiliary information if the File describes a directory
type dirInfo struct {
	h       syscall.Handle // search handle created with FindFirstFile
	data    syscall.Win32finddata
	path    string
	isempty bool // set if FindFirstFile returns ERROR_FILE_NOT_FOUND
}

func (d *dirInfo) close() error {
	return syscall.FindClose(d.h)
}

func epipecheck(file *File, e error) {
}

// DevNull is the name of the operating system's “null device.”
// On Unix-like systems, it is "/dev/null"; on Windows, "NUL".
const DevNull = "NUL"

func openDir(name string) (d *dirInfo, e error) {
	var mask string

	path := fixLongPath(name)

	if len(path) == 2 && path[1] == ':' { // it is a drive letter, like C:
		mask = path + `*`
	} else if len(path) > 0 {
		lc := path[len(path)-1]
		if lc == '/' || lc == '\\' {
			mask = path + `*`
		} else {
			mask = path + `\*`
		}
	} else {
		mask = `\*`
	}
	maskp, e := syscall.UTF16PtrFromString(mask)
	if e != nil {
		return nil, e
	}
	d = new(dirInfo)
	d.h, e = syscall.FindFirstFile(maskp, &d.data)
	if e != nil {
		// FindFirstFile returns ERROR_FILE_NOT_FOUND when
		// no matching files can be found. Then, if directory
		// exists, we should proceed.
		// If FindFirstFile failed because name does not point
		// to a directory, we should return ENOTDIR.
		var fa syscall.Win32FileAttributeData
		pathp, e1 := syscall.UTF16PtrFromString(path)
		if e1 != nil {
			return nil, e
		}
		e1 = syscall.GetFileAttributesEx(pathp, syscall.GetFileExInfoStandard, (*byte)(unsafe.Pointer(&fa)))
		if e1 != nil {
			return nil, e
		}
		if fa.FileAttributes&syscall.FILE_ATTRIBUTE_DIRECTORY == 0 {
			return nil, syscall.ENOTDIR
		}
		if e != syscall.ERROR_FILE_NOT_FOUND {
			return nil, e
		}
		d.isempty = true
	}
	d.path = path
	if !isAbs(d.path) {
		d.path, e = syscall.FullPath(d.path)
		if e != nil {
			d.close()
			return nil, e
		}
	}
	return d, nil
}

// openFileNolog is the Windows implementation of OpenFile.
func openFileNolog(name string, flag int, perm FileMode) (*File, error) {
	if name == "" {
		return nil, &PathError{Op: "open", Path: name, Err: syscall.ENOENT}
	}
	path := fixLongPath(name)
	r, e := syscall.Open(path, flag|syscall.O_CLOEXEC, syscallMode(perm))
	if e != nil {
		// We should return EISDIR when we are trying to open a directory with write access.
		if e == syscall.ERROR_ACCESS_DENIED && (flag&O_WRONLY != 0 || flag&O_RDWR != 0) {
			pathp, e1 := syscall.UTF16PtrFromString(path)
			if e1 == nil {
				var fa syscall.Win32FileAttributeData
				e1 = syscall.GetFileAttributesEx(pathp, syscall.GetFileExInfoStandard, (*byte)(unsafe.Pointer(&fa)))
				if e1 == nil && fa.FileAttributes&syscall.FILE_ATTRIBUTE_DIRECTORY != 0 {
					e = syscall.EISDIR
				}
			}
		}
		return nil, &PathError{Op: "open", Path: name, Err: e}
	}
	f, e := newFile(r, name, "file"), nil
	if e != nil {
		return nil, &PathError{Op: "open", Path: name, Err: e}
	}
	return f, nil
}

func (file *file) close() error {
	if file == nil {
		return syscall.EINVAL
	}
	if file.dirinfo != nil {
		file.dirinfo.close()
		file.dirinfo = nil
	}
	var err error
	if e := file.pfd.Close(); e != nil {
		if e == poll.ErrFileClosing {
			e = ErrClosed
		}
		err = &PathError{Op: "close", Path: file.name, Err: e}
	}

	// no need for a finalizer anymore
	runtime.SetFinalizer(file, nil)
	return err
}

// seek sets the offset for the next Read or Write on file to offset, interpreted
// according to whence: 0 means relative to the origin of the file, 1 means
// relative to the current offset, and 2 means relative to the end.
// It returns the new offset and an error, if any.
func (f *File) seek(offset int64, whence int) (ret int64, err error) {
	if f.dirinfo != nil {
		// Free cached dirinfo, so we allocate a new one if we
		// access this file as a directory again. See #35767 and #37161.
		f.dirinfo.close()
		f.dirinfo = nil
	}
	ret, err = f.pfd.Seek(offset, whence)
	runtime.KeepAlive(f)
	return ret, err
}

// Truncate changes the size of the named file.
// If the file is a symbolic link, it changes the size of the link's target.
func Truncate(name string, size int64) error {
	f, e := OpenFile(name, O_WRONLY, 0666)
	if e != nil {
		return e
	}
	defer f.Close()
	e1 := f.Truncate(size)
	if e1 != nil {
		return e1
	}
	return nil
}

// Remove removes the named file or directory.
// If there is an error, it will be of type *PathError.
func Remove(name string) error {
	p, e := syscall.UTF16PtrFromString(fixLongPath(name))
	if e != nil {
		return &PathError{Op: "remove", Path: name, Err: e}
	}

	// Go file interface forces us to know whether
	// name is a file or directory. Try both.
	e = syscall.DeleteFile(p)
	if e == nil {
		return nil
	}
	e1 := syscall.RemoveDirectory(p)
	if e1 == nil {
		return nil
	}

	// Both failed: figure out which error to return.
	if e1 != e {
		a, e2 := syscall.GetFileAttributes(p)
		if e2 != nil {
			e = e2
		} else {
			if a&syscall.FILE_ATTRIBUTE_DIRECTORY != 0 {
				e = e1
			} else if a&syscall.FILE_ATTRIBUTE_READONLY != 0 {
				if e1 = syscall.SetFileAttributes(p, a&^syscall.FILE_ATTRIBUTE_READONLY); e1 == nil {
					if e = syscall.DeleteFile(p); e == nil {
						return nil
					}
				}
			}
		}
	}
	return &PathError{Op: "remove", Path: name, Err: e}
}

func rename(oldname, newname string) error {
	e := windows.Rename(fixLongPath(oldname), fixLongPath(newname))
	if e != nil {
		return &LinkError{"rename", oldname, newname, e}
	}
	return nil
}

// Pipe returns a connected pair of Files; reads from r return bytes written to w.
// It returns the files and an error, if any. The Windows handles underlying
// the returned files are marked as inheritable by child processes.
func Pipe() (r *File, w *File, err error) {
	var p [2]syscall.Handle
	e := syscall.Pipe(p[:])
	if e != nil {
		return nil, nil, NewSyscallError("pipe", e)
	}
	return newFile(p[0], "|0", "pipe"), newFile(p[1], "|1", "pipe"), nil
}

var (
	useGetTempPath2Once sync.Once
	useGetTempPath2     bool
)

func tempDir() string {
	useGetTempPath2Once.Do(func() {
		useGetTempPath2 = (windows.ErrorLoadingGetTempPath2() == nil)
	})
	getTempPath := syscall.GetTempPath
	if useGetTempPath2 {
		getTempPath = windows.GetTempPath2
	}
	n := uint32(syscall.MAX_PATH)
	for {
		b := make([]uint16, n)
		n, _ = getTempPath(uint32(len(b)), &b[0])
		if n > uint32(len(b)) {
			continue
		}
		if n == 3 && b[1] == ':' && b[2] == '\\' {
			// Do nothing for path, like C:\.
		} else if n > 0 && b[n-1] == '\\' {
			// Otherwise remove terminating \.
			n--
		}
		return syscall.UTF16ToString(b[:n])
	}
}

// Link creates newname as a hard link to the oldname file.
// If there is an error, it will be of type *LinkError.
func Link(oldname, newname string) error {
	n, err := syscall.UTF16PtrFromString(fixLongPath(newname))
	if err != nil {
		return &LinkError{"link", oldname, newname, err}
	}
	o, err := syscall.UTF16PtrFromString(fixLongPath(oldname))
	if err != nil {
		return &LinkError{"link", oldname, newname, err}
	}
	err = syscall.CreateHardLink(n, o, 0)
	if err != nil {
		return &LinkError{"link", oldname, newname, err}
	}
	return nil
}

// Symlink creates newname as a symbolic link to oldname.
// On Windows, a symlink to a non-existent oldname creates a file symlink;
// if oldname is later created as a directory the symlink will not work.
// If there is an error, it will be of type *LinkError.
func Symlink(oldname, newname string) error {
	// '/' does not work in link's content
	oldname = fromSlash(oldname)

	// need the exact location of the oldname when it's relative to determine if it's a directory
	destpath := oldname
	if v := volumeName(oldname); v == "" {
		if len(oldname) > 0 && IsPathSeparator(oldname[0]) {
			// oldname is relative to the volume containing newname.
			if v = volumeName(newname); v != "" {
				// Prepend the volume explicitly, because it may be different from the
				// volume of the current working directory.
				destpath = v + oldname
			}
		} else {
			// oldname is relative to newname.
			destpath = dirname(newname) + `\` + oldname
		}
	}

	fi, err := Stat(destpath)
	isdir := err == nil && fi.IsDir()

	n, err := syscall.UTF16PtrFromString(fixLongPath(newname))
	if err != nil {
		return &LinkError{"symlink", oldname, newname, err}
	}
	o, err := syscall.UTF16PtrFromString(fixLongPath(oldname))
	if err != nil {
		return &LinkError{"symlink", oldname, newname, err}
	}

	var flags uint32 = windows.SYMBOLIC_LINK_FLAG_ALLOW_UNPRIVILEGED_CREATE
	if isdir {
		flags |= syscall.SYMBOLIC_LINK_FLAG_DIRECTORY
	}
	err = syscall.CreateSymbolicLink(n, o, flags)
	if err != nil {
		// the unprivileged create flag is unsupported
		// below Windows 10 (1703, v10.0.14972). retry without it.
		flags &^= windows.SYMBOLIC_LINK_FLAG_ALLOW_UNPRIVILEGED_CREATE
		err = syscall.CreateSymbolicLink(n, o, flags)
		if err != nil {
			return &LinkError{"symlink", oldname, newname, err}
		}
	}
	return nil
}

// openSymlink calls CreateFile Windows API with FILE_FLAG_OPEN_REPARSE_POINT
// parameter, so that Windows does not follow symlink, if path is a symlink.
// openSymlink returns opened file handle.
func openSymlink(path string) (syscall.Handle, error) {
	p, err := syscall.UTF16PtrFromString(path)
	if err != nil {
		return 0, err
	}
	attrs := uint32(syscall.FILE_FLAG_BACKUP_SEMANTICS)
	// Use FILE_FLAG_OPEN_REPARSE_POINT, otherwise CreateFile will follow symlink.
	// See https://docs.microsoft.com/en-us/windows/desktop/FileIO/symbolic-link-effects-on-file-systems-functions#createfile-and-createfiletransacted
	attrs |= syscall.FILE_FLAG_OPEN_REPARSE_POINT
	h, err := syscall.CreateFile(p, 0, 0, nil, syscall.OPEN_EXISTING, attrs, 0)
	if err != nil {
		return 0, err
	}
	return h, nil
}

// normaliseLinkPath converts absolute paths returned by
// DeviceIoControl(h, FSCTL_GET_REPARSE_POINT, ...)
// into paths acceptable by all Windows APIs.
// For example, it converts
//
//	\??\C:\foo\bar into C:\foo\bar
//	\??\UNC\foo\bar into \\foo\bar
//	\??\Volume{abc}\ into C:\
func normaliseLinkPath(path string) (string, error) {
	if len(path) < 4 || path[:4] != `\??\` {
		// unexpected path, return it as is
		return path, nil
	}
	// we have path that start with \??\
	s := path[4:]
	switch {
	case len(s) >= 2 && s[1] == ':': // \??\C:\foo\bar
		return s, nil
	case len(s) >= 4 && s[:4] == `UNC\`: // \??\UNC\foo\bar
		return `\\` + s[4:], nil
	}

	// handle paths, like \??\Volume{abc}\...

	err := windows.LoadGetFinalPathNameByHandle()
	if err != nil {
		// we must be using old version of Windows
		return "", err
	}

	h, err := openSymlink(path)
	if err != nil {
		return "", err
	}
	defer syscall.CloseHandle(h)

	buf := make([]uint16, 100)
	for {
		n, err := windows.GetFinalPathNameByHandle(h, &buf[0], uint32(len(buf)), windows.VOLUME_NAME_DOS)
		if err != nil {
			return "", err
		}
		if n < uint32(len(buf)) {
			break
		}
		buf = make([]uint16, n)
	}
	s = syscall.UTF16ToString(buf)
	if len(s) > 4 && s[:4] == `\\?\` {
		s = s[4:]
		if len(s) > 3 && s[:3] == `UNC` {
			// return path like \\server\share\...
			return `\` + s[3:], nil
		}
		return s, nil
	}
	return "", errors.New("GetFinalPathNameByHandle returned unexpected path: " + s)
}

func readlink(path string) (string, error) {
	h, err := openSymlink(path)
	if err != nil {
		return "", err
	}
	defer syscall.CloseHandle(h)

	rdbbuf := make([]byte, syscall.MAXIMUM_REPARSE_DATA_BUFFER_SIZE)
	var bytesReturned uint32
	err = syscall.DeviceIoControl(h, syscall.FSCTL_GET_REPARSE_POINT, nil, 0, &rdbbuf[0], uint32(len(rdbbuf)), &bytesReturned, nil)
	if err != nil {
		return "", err
	}

	rdb := (*windows.REPARSE_DATA_BUFFER)(unsafe.Pointer(&rdbbuf[0]))
	switch rdb.ReparseTag {
	case syscall.IO_REPARSE_TAG_SYMLINK:
		rb := (*windows.SymbolicLinkReparseBuffer)(unsafe.Pointer(&rdb.DUMMYUNIONNAME))
		s := rb.Path()
		if rb.Flags&windows.SYMLINK_FLAG_RELATIVE != 0 {
			return s, nil
		}
		return normaliseLinkPath(s)
	case windows.IO_REPARSE_TAG_MOUNT_POINT:
		return normaliseLinkPath((*windows.MountPointReparseBuffer)(unsafe.Pointer(&rdb.DUMMYUNIONNAME)).Path())
	default:
		// the path is not a symlink or junction but another type of reparse
		// point
		return "", syscall.ENOENT
	}
}

// Readlink returns the destination of the named symbolic link.
// If there is an error, it will be of type *PathError.
func Readlink(name string) (string, error) {
	s, err := readlink(fixLongPath(name))
	if err != nil {
		return "", &PathError{Op: "readlink", Path: name, Err: err}
	}
	return s, nil
}