summaryrefslogtreecommitdiffstats
path: root/stat.c
blob: 47e60b6e9391e6dfefbe98de820adcb066703b5f (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
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
/****************************************************************************
 * bfs                                                                      *
 * Copyright (C) 2018-2019 Tavian Barnes <tavianator@tavianator.com>        *
 *                                                                          *
 * Permission to use, copy, modify, and/or distribute this software for any *
 * purpose with or without fee is hereby granted.                           *
 *                                                                          *
 * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES *
 * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF         *
 * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR  *
 * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES   *
 * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN    *
 * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF  *
 * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.           *
 ****************************************************************************/

#include "stat.h"
#include "util.h"
#include <assert.h>
#include <errno.h>
#include <fcntl.h>
#include <stdbool.h>
#include <string.h>
#include <sys/types.h>
#include <sys/stat.h>

#if BFS_HAS_SYS_PARAM
#	include <sys/param.h>
#endif

#ifdef STATX_BASIC_STATS
#	define HAVE_STATX true
#elif __linux__
#	include <linux/stat.h>
#	include <sys/syscall.h>
#	include <unistd.h>
#endif

#if HAVE_STATX || defined(__NR_statx)
#	define HAVE_BFS_STATX true
#endif

#if __APPLE__
#	define st_atim st_atimespec
#	define st_ctim st_ctimespec
#	define st_mtim st_mtimespec
#	define st_birthtim st_birthtimespec
#endif

const char *bfs_stat_field_name(enum bfs_stat_field field) {
	switch (field) {
	case BFS_STAT_DEV:
		return "device number";
	case BFS_STAT_INO:
		return "inode nunmber";
	case BFS_STAT_TYPE:
		return "type";
	case BFS_STAT_MODE:
		return "mode";
	case BFS_STAT_NLINK:
		return "link count";
	case BFS_STAT_GID:
		return "group ID";
	case BFS_STAT_UID:
		return "user ID";
	case BFS_STAT_SIZE:
		return "size";
	case BFS_STAT_BLOCKS:
		return "block count";
	case BFS_STAT_RDEV:
		return "underlying device";
	case BFS_STAT_ATTRS:
		return "attributes";
	case BFS_STAT_ATIME:
		return "access time";
	case BFS_STAT_BTIME:
		return "birth time";
	case BFS_STAT_CTIME:
		return "change time";
	case BFS_STAT_MTIME:
		return "modification time";
	}

	assert(!"Unrecognized stat field");
	return "???";
}

/**
 * Check if we should retry a failed stat() due to a potentially broken link.
 */
static bool bfs_stat_retry(int ret, enum bfs_stat_flags flags) {
	return ret != 0
		&& (flags & (BFS_STAT_NOFOLLOW | BFS_STAT_TRYFOLLOW)) == BFS_STAT_TRYFOLLOW
		&& is_nonexistence_error(errno);
}

/**
 * Convert a struct stat to a struct bfs_stat.
 */
static void bfs_stat_convert(const struct stat *statbuf, struct bfs_stat *buf) {
	buf->mask = 0;

	buf->dev = statbuf->st_dev;
	buf->mask |= BFS_STAT_DEV;

	buf->ino = statbuf->st_ino;
	buf->mask |= BFS_STAT_INO;

	buf->mode = statbuf->st_mode;
	buf->mask |= BFS_STAT_TYPE | BFS_STAT_MODE;

	buf->nlink = statbuf->st_nlink;
	buf->mask |= BFS_STAT_NLINK;

	buf->gid = statbuf->st_gid;
	buf->mask |= BFS_STAT_GID;

	buf->uid = statbuf->st_uid;
	buf->mask |= BFS_STAT_UID;

	buf->size = statbuf->st_size;
	buf->mask |= BFS_STAT_SIZE;

	buf->blocks = statbuf->st_blocks;
	buf->mask |= BFS_STAT_BLOCKS;

	buf->rdev = statbuf->st_rdev;
	buf->mask |= BFS_STAT_RDEV;

#if BSD
	buf->attrs = statbuf->st_flags;
	buf->mask |= BFS_STAT_ATTRS;
#endif

	buf->atime = statbuf->st_atim;
	buf->mask |= BFS_STAT_ATIME;

	buf->ctime = statbuf->st_ctim;
	buf->mask |= BFS_STAT_CTIME;

	buf->mtime = statbuf->st_mtim;
	buf->mask |= BFS_STAT_MTIME;

#if __APPLE__ || __FreeBSD__ || __NetBSD__
	buf->btime = statbuf->st_birthtim;
	buf->mask |= BFS_STAT_BTIME;
#endif
}

/**
 * bfs_stat() implementation backed by stat().
 */
static int bfs_stat_impl(int at_fd, const char *at_path, int at_flags, enum bfs_stat_flags flags, struct bfs_stat *buf) {
	struct stat statbuf;
	int ret = fstatat(at_fd, at_path, &statbuf, at_flags);

	if (bfs_stat_retry(ret, flags)) {
		at_flags |= AT_SYMLINK_NOFOLLOW;
		ret = fstatat(at_fd, at_path, &statbuf, at_flags);
	}

	if (ret == 0) {
		bfs_stat_convert(&statbuf, buf);
	}

	return ret;
}

#if HAVE_BFS_STATX

/**
 * Wrapper for the statx() system call, which had no glibc wrapper prior to 2.28.
 */
static int bfs_statx(int at_fd, const char *at_path, int at_flags, unsigned int mask, struct statx *buf) {
#if BFS_HAS_FEATURE(memory_sanitizer, false)
	// -fsanitize=memory doesn't know about statx(), so tell it the memory
	// got initialized
	memset(buf, 0, sizeof(*buf));
#endif

#if HAVE_STATX
	return statx(at_fd, at_path, at_flags, mask, buf);
#else
	return syscall(__NR_statx, at_fd, at_path, at_flags, mask, buf);
#endif
}

/**
 * bfs_stat() implementation backed by statx().
 */
static int bfs_statx_impl(int at_fd, const char *at_path, int at_flags, enum bfs_stat_flags flags, struct bfs_stat *buf) {
	unsigned int mask = STATX_BASIC_STATS | STATX_BTIME;
	struct statx xbuf;
	int ret = bfs_statx(at_fd, at_path, at_flags, mask, &xbuf);

	if (bfs_stat_retry(ret, flags)) {
		at_flags |= AT_SYMLINK_NOFOLLOW;
		ret = bfs_statx(at_fd, at_path, at_flags, mask, &xbuf);
	}

	if (ret != 0) {
		return ret;
	}

	// Callers shouldn't have to check anything except the times
	const unsigned int guaranteed = STATX_BASIC_STATS ^ (STATX_ATIME | STATX_CTIME | STATX_MTIME);
	if ((xbuf.stx_mask & guaranteed) != guaranteed) {
		errno = ENOTSUP;
		return -1;
	}

	buf->mask = 0;

	buf->dev = bfs_makedev(xbuf.stx_dev_major, xbuf.stx_dev_minor);
	buf->mask |= BFS_STAT_DEV;

	if (xbuf.stx_mask & STATX_INO) {
		buf->ino = xbuf.stx_ino;
		buf->mask |= BFS_STAT_INO;
	}

	buf->mode = xbuf.stx_mode;
	if (xbuf.stx_mask & STATX_TYPE) {
		buf->mask |= BFS_STAT_TYPE;
	}
	if (xbuf.stx_mask & STATX_MODE) {
		buf->mask |= BFS_STAT_MODE;
	}

	if (xbuf.stx_mask & STATX_NLINK) {
		buf->nlink = xbuf.stx_nlink;
		buf->mask |= BFS_STAT_NLINK;
	}

	if (xbuf.stx_mask & STATX_GID) {
		buf->gid = xbuf.stx_gid;
		buf->mask |= BFS_STAT_GID;
	}

	if (xbuf.stx_mask & STATX_UID) {
		buf->uid = xbuf.stx_uid;
		buf->mask |= BFS_STAT_UID;
	}

	if (xbuf.stx_mask & STATX_SIZE) {
		buf->size = xbuf.stx_size;
		buf->mask |= BFS_STAT_SIZE;
	}

	if (xbuf.stx_mask & STATX_BLOCKS) {
		buf->blocks = xbuf.stx_blocks;
		buf->mask |= BFS_STAT_BLOCKS;
	}

	buf->rdev = bfs_makedev(xbuf.stx_rdev_major, xbuf.stx_rdev_minor);
	buf->mask |= BFS_STAT_RDEV;

	buf->attrs = xbuf.stx_attributes;
	buf->mask |= BFS_STAT_ATTRS;

	if (xbuf.stx_mask & STATX_ATIME) {
		buf->atime.tv_sec = xbuf.stx_atime.tv_sec;
		buf->atime.tv_nsec = xbuf.stx_atime.tv_nsec;
		buf->mask |= BFS_STAT_ATIME;
	}

	if (xbuf.stx_mask & STATX_BTIME) {
		buf->btime.tv_sec = xbuf.stx_btime.tv_sec;
		buf->btime.tv_nsec = xbuf.stx_btime.tv_nsec;
		buf->mask |= BFS_STAT_BTIME;
	}

	if (xbuf.stx_mask & STATX_CTIME) {
		buf->ctime.tv_sec = xbuf.stx_ctime.tv_sec;
		buf->ctime.tv_nsec = xbuf.stx_ctime.tv_nsec;
		buf->mask |= BFS_STAT_CTIME;
	}

	if (xbuf.stx_mask & STATX_MTIME) {
		buf->mtime.tv_sec = xbuf.stx_mtime.tv_sec;
		buf->mtime.tv_nsec = xbuf.stx_mtime.tv_nsec;
		buf->mask |= BFS_STAT_MTIME;
	}

	return ret;
}

#endif // HAVE_BFS_STATX

/**
 * Allows calling stat with custom at_flags.
 */
static int bfs_stat_explicit(int at_fd, const char *at_path, int at_flags, enum bfs_stat_flags flags, struct bfs_stat *buf) {
#if HAVE_BFS_STATX
	static bool has_statx = true;

	if (has_statx) {
		int ret = bfs_statx_impl(at_fd, at_path, at_flags, flags, buf);
		// EPERM is commonly returned in a seccomp() sandbox that does
		// not allow statx()
		if (ret != 0 && (errno == ENOSYS || errno == EPERM)) {
			has_statx = false;
		} else {
			return ret;
		}
	}
#endif

	return bfs_stat_impl(at_fd, at_path, at_flags, flags, buf);
}

int bfs_stat(int at_fd, const char *at_path, enum bfs_stat_flags flags, struct bfs_stat *buf) {
	int at_flags = 0;
	if (flags & BFS_STAT_NOFOLLOW) {
		at_flags |= AT_SYMLINK_NOFOLLOW;
	}

#ifdef AT_STATX_DONT_SYNC
	if (flags & BFS_STAT_NOSYNC) {
		at_flags |= AT_STATX_DONT_SYNC;
	}
#endif

	if (at_path) {
		return bfs_stat_explicit(at_fd, at_path, at_flags, flags, buf);
	}

	// Check __GNU__ to work around https://lists.gnu.org/archive/html/bug-hurd/2021-12/msg00001.html
#if defined(AT_EMPTY_PATH) && !__GNU__
	static bool has_at_ep = true;
	if (has_at_ep) {
		at_flags |= AT_EMPTY_PATH;
		int ret = bfs_stat_explicit(at_fd, "", at_flags, flags, buf);
		if (ret != 0 && errno == EINVAL) {
			has_at_ep = false;
		} else {
			return ret;
		}
	}
#endif

	struct stat statbuf;
	if (fstat(at_fd, &statbuf) == 0) {
		bfs_stat_convert(&statbuf, buf);
		return 0;
	} else {
		return -1;
	}
}

const struct timespec *bfs_stat_time(const struct bfs_stat *buf, enum bfs_stat_field field) {
	if (!(buf->mask & field)) {
		errno = ENOTSUP;
		return NULL;
	}

	switch (field) {
	case BFS_STAT_ATIME:
		return &buf->atime;
	case BFS_STAT_BTIME:
		return &buf->btime;
	case BFS_STAT_CTIME:
		return &buf->ctime;
	case BFS_STAT_MTIME:
		return &buf->mtime;
	default:
		assert(!"Invalid stat field for time");
		errno = EINVAL;
		return NULL;
	}
}

void bfs_stat_id(const struct bfs_stat *buf, bfs_file_id *id) {
	memcpy(*id, &buf->dev, sizeof(buf->dev));
	memcpy(*id + sizeof(buf->dev), &buf->ino, sizeof(buf->ino));
}