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Commit | Line | Data |
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27c6d415 KZ |
1 | /* |
2 | * Copyright (C) 2009 Karel Zak <kzak@redhat.com> | |
3 | * | |
4 | * This file may be redistributed under the terms of the | |
5 | * GNU Lesser General Public License. | |
6 | */ | |
192c6aad KZ |
7 | |
8 | /** | |
9 | * SECTION: lock | |
10 | * @title: Mtab locking | |
11 | * @short_description: locking methods for work with /etc/mtab | |
12 | * | |
13 | * The lock is backwardly compatible with the standard linux /etc/mtab locking. | |
14 | * Note, it's necessary to use the same locking schema in all application that | |
15 | * access the file. | |
16 | */ | |
27c6d415 KZ |
17 | #include <string.h> |
18 | #include <stdlib.h> | |
19 | #include <sys/types.h> | |
20 | #include <sys/stat.h> | |
21 | #include <unistd.h> | |
22 | #include <errno.h> | |
23 | #include <stdio.h> | |
24 | #include <sys/time.h> | |
25 | #include <time.h> | |
26 | #include <signal.h> | |
27 | #include <fcntl.h> | |
28 | #include <limits.h> | |
29 | ||
30 | #include "pathnames.h" | |
31 | #include "nls.h" | |
eb76ca98 | 32 | #include "c.h" |
27c6d415 KZ |
33 | |
34 | #include "mountP.h" | |
35 | ||
36 | /* | |
37 | * lock handler | |
38 | */ | |
68164f6c | 39 | struct libmnt_lock { |
27c6d415 KZ |
40 | char *lockfile; /* path to lock file (e.g. /etc/mtab~) */ |
41 | char *linkfile; /* path to link file (e.g. /etc/mtab~.<id>) */ | |
42 | int lockfile_fd; /* lock file descriptor */ | |
43 | int locked; /* do we own the lock? */ | |
44 | }; | |
45 | ||
46 | ||
47 | /** | |
48 | * mnt_new_lock: | |
0f32f1e2 | 49 | * @datafile: the file that should be covered by the lock |
27c6d415 KZ |
50 | * @id: unique linkfile identifier or 0 (default is getpid()) |
51 | * | |
192c6aad | 52 | * Returns: newly allocated lock handler or NULL on case of error. |
27c6d415 | 53 | */ |
68164f6c | 54 | struct libmnt_lock *mnt_new_lock(const char *datafile, pid_t id) |
27c6d415 | 55 | { |
68164f6c | 56 | struct libmnt_lock *ml = NULL; |
66c33aab | 57 | char *lo = NULL, *ln = NULL; |
27c6d415 | 58 | |
66c33aab KZ |
59 | /* lockfile */ |
60 | if (!datafile) | |
27c6d415 KZ |
61 | return NULL; |
62 | ||
66c33aab KZ |
63 | if (asprintf(&lo, "%s~", datafile) == -1) { |
64 | lo = NULL; | |
65 | goto err; | |
66 | } | |
67 | if (asprintf(&ln, "%s~.%d", datafile, id ? : getpid()) == -1) { | |
68 | ln = NULL; | |
69 | goto err; | |
27c6d415 | 70 | } |
68164f6c | 71 | ml = calloc(1, sizeof(*ml) ); |
66c33aab KZ |
72 | if (!ml) |
73 | goto err; | |
74 | ||
75 | ml->lockfile_fd = -1; | |
76 | ml->linkfile = ln; | |
77 | ml->lockfile = lo; | |
3f31a959 | 78 | |
9e10ad3d | 79 | DBG(LOCKS, mnt_debug_h(ml, "alloc: linkfile=%s, lockfile=%s", ln, lo)); |
27c6d415 | 80 | return ml; |
66c33aab KZ |
81 | err: |
82 | free(lo); | |
83 | free(ln); | |
84 | free(ml); | |
85 | return NULL; | |
27c6d415 KZ |
86 | } |
87 | ||
66c33aab | 88 | |
27c6d415 KZ |
89 | /** |
90 | * mnt_free_lock: | |
68164f6c | 91 | * @ml: struct libmnt_lock handler |
27c6d415 KZ |
92 | * |
93 | * Deallocates mnt_lock. | |
94 | */ | |
68164f6c | 95 | void mnt_free_lock(struct libmnt_lock *ml) |
27c6d415 KZ |
96 | { |
97 | if (!ml) | |
98 | return; | |
3f31a959 | 99 | DBG(LOCKS, mnt_debug_h(ml, "free")); |
27c6d415 KZ |
100 | free(ml->lockfile); |
101 | free(ml->linkfile); | |
102 | free(ml); | |
103 | } | |
104 | ||
0f32f1e2 KZ |
105 | /* |
106 | * Returns path to lockfile. | |
27c6d415 | 107 | */ |
68164f6c | 108 | static const char *mnt_lock_get_lockfile(struct libmnt_lock *ml) |
27c6d415 | 109 | { |
66c33aab | 110 | return ml ? ml->lockfile : NULL; |
27c6d415 KZ |
111 | } |
112 | ||
0f32f1e2 | 113 | /* |
66c33aab KZ |
114 | * Note that the filename is generated by mnt_new_lock() and depends on |
115 | * getpid() or 'id' argument of the mnt_new_lock() function. | |
116 | * | |
117 | * Returns: unique (per process/thread) path to linkfile. | |
27c6d415 | 118 | */ |
68164f6c | 119 | static const char *mnt_lock_get_linkfile(struct libmnt_lock *ml) |
27c6d415 | 120 | { |
66c33aab | 121 | return ml ? ml->linkfile : NULL; |
27c6d415 KZ |
122 | } |
123 | ||
124 | static void mnt_lockalrm_handler(int sig) | |
125 | { | |
126 | /* do nothing, say nothing, be nothing */ | |
127 | } | |
128 | ||
129 | /* | |
130 | * Waits for F_SETLKW, unfortunately we have to use SIGALRM here to interrupt | |
131 | * fcntl() to avoid never ending waiting. | |
132 | * | |
192c6aad | 133 | * Returns: 0 on success, 1 on timeout, -errno on error. |
27c6d415 | 134 | */ |
68164f6c | 135 | static int mnt_wait_lock(struct libmnt_lock *ml, struct flock *fl, time_t maxtime) |
27c6d415 KZ |
136 | { |
137 | struct timeval now; | |
138 | struct sigaction sa, osa; | |
139 | int ret = 0; | |
140 | ||
141 | gettimeofday(&now, NULL); | |
142 | ||
143 | if (now.tv_sec >= maxtime) | |
144 | return 1; /* timeout */ | |
145 | ||
146 | /* setup ALARM handler -- we don't want to wait forever */ | |
147 | sa.sa_flags = 0; | |
148 | sa.sa_handler = mnt_lockalrm_handler; | |
149 | sigfillset (&sa.sa_mask); | |
150 | ||
151 | sigaction(SIGALRM, &sa, &osa); | |
152 | ||
3f31a959 | 153 | DBG(LOCKS, mnt_debug_h(ml, "(%d) waiting for F_SETLKW", getpid())); |
27c6d415 KZ |
154 | |
155 | alarm(maxtime - now.tv_sec); | |
156 | if (fcntl(ml->lockfile_fd, F_SETLKW, fl) == -1) | |
157 | ret = errno == EINTR ? 1 : -errno; | |
158 | alarm(0); | |
159 | ||
160 | /* restore old sigaction */ | |
161 | sigaction(SIGALRM, &osa, NULL); | |
162 | ||
3f31a959 KZ |
163 | DBG(LOCKS, mnt_debug_h(ml, "(%d) leaving mnt_wait_setlkw(), rc=%d", |
164 | getpid(), ret)); | |
27c6d415 KZ |
165 | return ret; |
166 | } | |
167 | ||
168 | /* | |
169 | * Create the lock file. | |
170 | * | |
171 | * The old code here used flock on a lock file /etc/mtab~ and deleted | |
172 | * this lock file afterwards. However, as rgooch remarks, that has a | |
173 | * race: a second mount may be waiting on the lock and proceed as | |
174 | * soon as the lock file is deleted by the first mount, and immediately | |
175 | * afterwards a third mount comes, creates a new /etc/mtab~, applies | |
176 | * flock to that, and also proceeds, so that the second and third mount | |
177 | * now both are scribbling in /etc/mtab. | |
178 | * | |
179 | * The new code uses a link() instead of a creat(), where we proceed | |
180 | * only if it was us that created the lock, and hence we always have | |
181 | * to delete the lock afterwards. Now the use of flock() is in principle | |
182 | * superfluous, but avoids an arbitrary sleep(). | |
183 | * | |
184 | * Where does the link point to? Obvious choices are mtab and mtab~~. | |
185 | * HJLu points out that the latter leads to races. Right now we use | |
186 | * mtab~.<pid> instead. | |
187 | * | |
188 | * | |
189 | * The original mount locking code has used sleep(1) between attempts and | |
190 | * maximal number of attempts has been 5. | |
191 | * | |
192 | * There was very small number of attempts and extremely long waiting (1s) | |
193 | * that is useless on machines with large number of mount processes. | |
194 | * | |
192c6aad | 195 | * Now we wait few thousand microseconds between attempts and we have a global |
27c6d415 KZ |
196 | * time limit (30s) rather than limit for number of attempts. The advantage |
197 | * is that this method also counts time which we spend in fcntl(F_SETLKW) and | |
198 | * number of attempts is not restricted. | |
199 | * -- kzak@redhat.com [Mar-2007] | |
200 | * | |
201 | * | |
202 | * This mtab locking code has been refactored and moved to libmount. The mtab | |
203 | * locking is really not perfect (e.g. SIGALRM), but it's stable, reliable and | |
66c33aab KZ |
204 | * backwardly compatible code. |
205 | * | |
206 | * Don't forget that this code has to be compatible with 3rd party mounts | |
207 | * (/sbin/mount.<foo>) and has to work with NFS. | |
27c6d415 KZ |
208 | * -- kzak@redhat.com [May-2009] |
209 | */ | |
210 | ||
211 | /* maximum seconds between first and last attempt */ | |
212 | #define MOUNTLOCK_MAXTIME 30 | |
213 | ||
214 | /* sleep time (in microseconds, max=999999) between attempts */ | |
215 | #define MOUNTLOCK_WAITTIME 5000 | |
216 | ||
66c33aab KZ |
217 | /** |
218 | * mnt_unlock_file: | |
219 | * @ml: lock struct | |
220 | * | |
221 | * Unlocks the file. The function could be called independently on the | |
222 | * lock status (for example from exit(3)). | |
223 | */ | |
68164f6c | 224 | void mnt_unlock_file(struct libmnt_lock *ml) |
27c6d415 KZ |
225 | { |
226 | if (!ml) | |
227 | return; | |
228 | ||
27c6d415 KZ |
229 | |
230 | if (ml->locked == 0 && ml->lockfile && ml->linkfile) | |
231 | { | |
232 | /* We have (probably) all files, but we don't own the lock, | |
233 | * Really? Check it! Maybe ml->locked wasn't set properly | |
234 | * because code was interrupted by signal. Paranoia? Yes. | |
235 | * | |
236 | * We own the lock when linkfile == lockfile. | |
237 | */ | |
238 | struct stat lo, li; | |
239 | ||
240 | if (!stat(ml->lockfile, &lo) && !stat(ml->linkfile, &li) && | |
241 | lo.st_dev == li.st_dev && lo.st_ino == li.st_ino) | |
242 | ml->locked = 1; | |
243 | } | |
3a5b1b1d KZ |
244 | |
245 | DBG(LOCKS, mnt_debug_h(ml, "(%d) %s", getpid(), | |
246 | ml->locked ? "unlocking" : "cleaning")); | |
247 | ||
27c6d415 KZ |
248 | if (ml->linkfile) |
249 | unlink(ml->linkfile); | |
250 | if (ml->lockfile_fd >= 0) | |
251 | close(ml->lockfile_fd); | |
252 | if (ml->locked == 1 && ml->lockfile) | |
253 | unlink(ml->lockfile); | |
254 | ||
255 | ml->locked = 0; | |
256 | ml->lockfile_fd = -1; | |
257 | } | |
258 | ||
259 | /** | |
cbec3cbf | 260 | * mnt_lock_file |
68164f6c | 261 | * @ml: pointer to struct libmnt_lock instance |
27c6d415 KZ |
262 | * |
263 | * Creates lock file (e.g. /etc/mtab~). Note that this function uses | |
264 | * alarm(). | |
265 | * | |
266 | * Your application has to always call mnt_unlock_file() before exit. | |
267 | * | |
268 | * Locking scheme: | |
269 | * | |
3d735589 KZ |
270 | * 1. create linkfile (e.g. /etc/mtab~.$PID) |
271 | * 2. link linkfile --> lockfile (e.g. /etc/mtab~.$PID --> /etc/mtab~) | |
27c6d415 | 272 | * |
192c6aad KZ |
273 | * 3. a) link() success: setups F_SETLK lock (see fcnlt(2)) |
274 | * b) link() failed: wait (max 30s) on F_SETLKW lock, goto 2. | |
27c6d415 KZ |
275 | * |
276 | * Example: | |
277 | * | |
192c6aad KZ |
278 | * <informalexample> |
279 | * <programlisting> | |
68164f6c | 280 | * struct libmnt_lock *ml; |
27c6d415 | 281 | * |
3d735589 KZ |
282 | * void unlock_fallback(void) |
283 | * { | |
284 | * if (!ml) | |
285 | * return; | |
286 | * mnt_unlock_file(ml); | |
287 | * mnt_free_lock(ml); | |
288 | * } | |
27c6d415 | 289 | * |
3d735589 KZ |
290 | * int update_mtab() |
291 | * { | |
292 | * int sig = 0; | |
66c33aab | 293 | * const char *mtab; |
27c6d415 | 294 | * |
a7fd8a36 | 295 | * if (!(mtab = mnt_get_mtab_path())) |
66c33aab KZ |
296 | * return 0; // system without mtab |
297 | * if (!(ml = mnt_new_lock(mtab, 0))) | |
298 | * return -1; // error | |
27c6d415 | 299 | * |
66c33aab | 300 | * atexit(unlock_fallback); |
27c6d415 | 301 | * |
3d735589 KZ |
302 | * if (mnt_lock_file(ml) != 0) { |
303 | * printf(stderr, "cannot create %s lockfile\n", | |
304 | * mnt_lock_get_lockfile(ml)); | |
305 | * return -1; | |
306 | * } | |
27c6d415 | 307 | * |
3d735589 | 308 | * ... modify mtab ... |
27c6d415 | 309 | * |
3d735589 KZ |
310 | * mnt_unlock_file(ml); |
311 | * mnt_free_lock(ml); | |
312 | * ml = NULL; | |
313 | * return 0; | |
314 | * } | |
192c6aad KZ |
315 | * </programlisting> |
316 | * </informalexample> | |
27c6d415 | 317 | * |
03a8029b KZ |
318 | * Returns: 0 on success or negative number in case of error (-ETIMEOUT is case |
319 | * of stale lock file). | |
27c6d415 | 320 | */ |
68164f6c | 321 | int mnt_lock_file(struct libmnt_lock *ml) |
27c6d415 | 322 | { |
03a8029b | 323 | int i, rc = -1; |
27c6d415 KZ |
324 | struct timespec waittime; |
325 | struct timeval maxtime; | |
326 | const char *lockfile, *linkfile; | |
327 | ||
328 | if (!ml) | |
03a8029b | 329 | return -EINVAL; |
27c6d415 KZ |
330 | if (ml->locked) |
331 | return 0; | |
332 | ||
333 | lockfile = mnt_lock_get_lockfile(ml); | |
334 | if (!lockfile) | |
03a8029b | 335 | return -EINVAL; |
27c6d415 KZ |
336 | linkfile = mnt_lock_get_linkfile(ml); |
337 | if (!linkfile) | |
03a8029b | 338 | return -EINVAL; |
27c6d415 KZ |
339 | |
340 | i = open(linkfile, O_WRONLY|O_CREAT, S_IRUSR|S_IWUSR); | |
03a8029b KZ |
341 | if (i < 0) { |
342 | /* linkfile does not exist (as a file) and we cannot create it. | |
343 | * Read-only or full filesystem? Too many files open in the system? | |
344 | */ | |
345 | if (errno > 0) | |
346 | rc = -errno; | |
27c6d415 | 347 | goto failed; |
03a8029b | 348 | } |
27c6d415 KZ |
349 | close(i); |
350 | ||
351 | gettimeofday(&maxtime, NULL); | |
352 | maxtime.tv_sec += MOUNTLOCK_MAXTIME; | |
353 | ||
354 | waittime.tv_sec = 0; | |
355 | waittime.tv_nsec = (1000 * MOUNTLOCK_WAITTIME); | |
356 | ||
357 | /* Repeat until it was us who made the link */ | |
358 | while (ml->locked == 0) { | |
359 | struct timeval now; | |
360 | struct flock flock; | |
361 | int j; | |
362 | ||
363 | j = link(linkfile, lockfile); | |
364 | if (j == 0) | |
365 | ml->locked = 1; | |
366 | ||
03a8029b KZ |
367 | if (j < 0 && errno != EEXIST) { |
368 | if (errno > 0) | |
369 | rc = -errno; | |
27c6d415 | 370 | goto failed; |
03a8029b | 371 | } |
27c6d415 KZ |
372 | ml->lockfile_fd = open(lockfile, O_WRONLY); |
373 | ||
374 | if (ml->lockfile_fd < 0) { | |
375 | /* Strange... Maybe the file was just deleted? */ | |
376 | int errsv = errno; | |
377 | gettimeofday(&now, NULL); | |
378 | if (errsv == ENOENT && now.tv_sec < maxtime.tv_sec) { | |
379 | ml->locked = 0; | |
380 | continue; | |
381 | } | |
03a8029b KZ |
382 | if (errsv > 0) |
383 | rc = -errsv; | |
27c6d415 KZ |
384 | goto failed; |
385 | } | |
386 | ||
387 | flock.l_type = F_WRLCK; | |
388 | flock.l_whence = SEEK_SET; | |
389 | flock.l_start = 0; | |
390 | flock.l_len = 0; | |
391 | ||
392 | if (ml->locked) { | |
393 | /* We made the link. Now claim the lock. */ | |
394 | if (fcntl (ml->lockfile_fd, F_SETLK, &flock) == -1) { | |
3f31a959 | 395 | DBG(LOCKS, mnt_debug_h(ml, |
27c6d415 KZ |
396 | "%s: can't F_SETLK lockfile, errno=%d\n", |
397 | lockfile, errno)); | |
398 | /* proceed, since it was us who created the lockfile anyway */ | |
399 | } | |
400 | break; | |
401 | } else { | |
402 | /* Someone else made the link. Wait. */ | |
403 | int err = mnt_wait_lock(ml, &flock, maxtime.tv_sec); | |
404 | ||
405 | if (err == 1) { | |
3f31a959 | 406 | DBG(LOCKS, mnt_debug_h(ml, |
27c6d415 KZ |
407 | "%s: can't create link: time out (perhaps " |
408 | "there is a stale lock file?)", lockfile)); | |
03a8029b | 409 | rc = -ETIMEDOUT; |
27c6d415 KZ |
410 | goto failed; |
411 | ||
03a8029b KZ |
412 | } else if (err < 0) { |
413 | rc = err; | |
27c6d415 | 414 | goto failed; |
03a8029b | 415 | } |
27c6d415 KZ |
416 | nanosleep(&waittime, NULL); |
417 | close(ml->lockfile_fd); | |
418 | ml->lockfile_fd = -1; | |
419 | } | |
420 | } | |
3f31a959 | 421 | DBG(LOCKS, mnt_debug_h(ml, |
1d0cd73f | 422 | "%s: (%d) successfully locked\n", |
66c33aab | 423 | lockfile, getpid())); |
27c6d415 KZ |
424 | unlink(linkfile); |
425 | return 0; | |
426 | ||
427 | failed: | |
428 | mnt_unlock_file(ml); | |
03a8029b | 429 | return rc; |
27c6d415 KZ |
430 | } |
431 | ||
432 | #ifdef TEST_PROGRAM | |
27c6d415 | 433 | |
68164f6c | 434 | struct libmnt_lock *lock; |
27c6d415 KZ |
435 | |
436 | /* | |
437 | * read number from @filename, increment the number and | |
438 | * write the number back to the file | |
439 | */ | |
440 | void increment_data(const char *filename, int verbose, int loopno) | |
441 | { | |
442 | long num; | |
443 | FILE *f; | |
444 | char buf[256]; | |
445 | ||
446 | if (!(f = fopen(filename, "r"))) | |
447 | err(EXIT_FAILURE, "%d: failed to open: %s", getpid(), filename); | |
448 | ||
449 | if (!fgets(buf, sizeof(buf), f)) | |
450 | err(EXIT_FAILURE, "%d failed read: %s", getpid(), filename); | |
451 | ||
452 | fclose(f); | |
453 | num = atol(buf) + 1; | |
454 | ||
455 | if (!(f = fopen(filename, "w"))) | |
456 | err(EXIT_FAILURE, "%d: failed to open: %s", getpid(), filename); | |
457 | ||
458 | fprintf(f, "%ld", num); | |
459 | fclose(f); | |
460 | ||
461 | if (verbose) | |
462 | fprintf(stderr, "%d: %s: %ld --> %ld (loop=%d)\n", getpid(), | |
463 | filename, num - 1, num, loopno); | |
464 | } | |
465 | ||
466 | void clean_lock(void) | |
467 | { | |
27c6d415 KZ |
468 | if (!lock) |
469 | return; | |
470 | mnt_unlock_file(lock); | |
471 | mnt_free_lock(lock); | |
472 | } | |
473 | ||
474 | void sig_handler(int sig) | |
475 | { | |
476 | errx(EXIT_FAILURE, "\n%d: catch signal: %s\n", getpid(), strsignal(sig)); | |
477 | } | |
478 | ||
68164f6c | 479 | int test_lock(struct libmnt_test *ts, int argc, char *argv[]) |
27c6d415 | 480 | { |
9e10ad3d KZ |
481 | time_t synctime = 0; |
482 | unsigned int usecs; | |
483 | struct timeval tv; | |
484 | const char *datafile = NULL; | |
485 | int verbose = 0, loops = 0, l, idx = 1; | |
27c6d415 | 486 | |
66c33aab | 487 | if (argc < 3) |
9e10ad3d | 488 | return -EINVAL; |
27c6d415 | 489 | |
9e10ad3d KZ |
490 | if (strcmp(argv[idx], "--synctime") == 0) { |
491 | synctime = (time_t) atol(argv[idx + 1]); | |
492 | idx += 2; | |
493 | } | |
494 | if (idx < argc && strcmp(argv[idx], "--verbose") == 0) { | |
27c6d415 | 495 | verbose = 1; |
9e10ad3d KZ |
496 | idx++; |
497 | } | |
498 | ||
499 | if (idx < argc) | |
500 | datafile = argv[idx++]; | |
501 | if (idx < argc) | |
502 | loops = atoi(argv[idx++]); | |
503 | ||
504 | if (!datafile || !loops) | |
505 | return -EINVAL; | |
506 | ||
3a5b1b1d KZ |
507 | if (verbose) |
508 | fprintf(stderr, "%d: start: synctime=%u, datafile=%s, loops=%d\n", | |
509 | getpid(), (int) synctime, datafile, loops); | |
27c6d415 KZ |
510 | |
511 | atexit(clean_lock); | |
512 | ||
513 | /* be paranoid and call exit() (=clean_lock()) for all signals */ | |
514 | { | |
515 | int sig = 0; | |
516 | struct sigaction sa; | |
517 | ||
518 | sa.sa_handler = sig_handler; | |
519 | sa.sa_flags = 0; | |
520 | sigfillset(&sa.sa_mask); | |
521 | ||
522 | while (sigismember(&sa.sa_mask, ++sig) != -1 && sig != SIGCHLD) | |
523 | sigaction (sig, &sa, (struct sigaction *) 0); | |
524 | } | |
525 | ||
9e10ad3d KZ |
526 | /* start the test in exactly defined time */ |
527 | if (synctime) { | |
528 | gettimeofday(&tv, NULL); | |
529 | if (synctime && synctime - tv.tv_sec > 1) { | |
530 | usecs = ((synctime - tv.tv_sec) * 1000000UL) - | |
531 | (1000000UL - tv.tv_usec); | |
532 | usleep(usecs); | |
533 | } | |
534 | } | |
535 | ||
27c6d415 | 536 | for (l = 0; l < loops; l++) { |
66c33aab KZ |
537 | lock = mnt_new_lock(datafile, 0); |
538 | if (!lock) | |
539 | return -1; | |
27c6d415 | 540 | |
abc3d154 | 541 | if (mnt_lock_file(lock) != 0) { |
66c33aab KZ |
542 | fprintf(stderr, "%d: failed to lock %s file\n", |
543 | getpid(), datafile); | |
27c6d415 KZ |
544 | return -1; |
545 | } | |
546 | ||
547 | increment_data(datafile, verbose, l); | |
548 | ||
549 | mnt_unlock_file(lock); | |
550 | mnt_free_lock(lock); | |
551 | lock = NULL; | |
9e10ad3d KZ |
552 | |
553 | /* The mount command usually finish after mtab update. We | |
554 | * simulate this via short sleep -- it's also enough to make | |
555 | * concurrent processes happy. | |
556 | */ | |
557 | if (synctime) | |
558 | usleep(25000); | |
27c6d415 KZ |
559 | } |
560 | ||
561 | return 0; | |
562 | } | |
563 | ||
192c6aad KZ |
564 | /* |
565 | * Note that this test should be executed from a script that creates many | |
566 | * parallel processes, otherwise this test does not make sense. | |
567 | */ | |
27c6d415 KZ |
568 | int main(int argc, char *argv[]) |
569 | { | |
68164f6c | 570 | struct libmnt_test tss[] = { |
9e10ad3d KZ |
571 | { "--lock", test_lock, " [--synctime <time_t>] [--verbose] <datafile> <loops> " |
572 | "increment a number in datafile" }, | |
27c6d415 KZ |
573 | { NULL } |
574 | }; | |
575 | ||
576 | return mnt_run_test(tss, argc, argv); | |
577 | } | |
578 | ||
579 | #endif /* TEST_PROGRAM */ |