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nsswitch: fix some typos
[Samba/gebeck_regimport.git] / lib / ntdb / lock.c
blob71d6d8525b214fd34a42bd92c1ad6aa83308c466
1 /*
2 Unix SMB/CIFS implementation.
3
4 trivial database library
5
6 Copyright (C) Andrew Tridgell 1999-2005
7 Copyright (C) Paul `Rusty' Russell 2000
8 Copyright (C) Jeremy Allison 2000-2003
9
10 ** NOTE! The following LGPL license applies to the ntdb
11 ** library. This does NOT imply that all of Samba is released
12 ** under the LGPL
13
14 This library is free software; you can redistribute it and/or
15 modify it under the terms of the GNU Lesser General Public
16 License as published by the Free Software Foundation; either
17 version 3 of the License, or (at your option) any later version.
18
19 This library is distributed in the hope that it will be useful,
20 but WITHOUT ANY WARRANTY; without even the implied warranty of
21 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
22 Lesser General Public License for more details.
23
24 You should have received a copy of the GNU Lesser General Public
25 License along with this library; if not, see <http://www.gnu.org/licenses/>.
26 */
27
28 #include "private.h"
29 #include <ccan/build_assert/build_assert.h>
30
31 /* If we were threaded, we could wait for unlock, but we're not, so fail. */
32 enum NTDB_ERROR owner_conflict(struct ntdb_context *ntdb, const char *call)
33 {
34 return ntdb_logerr(ntdb, NTDB_ERR_LOCK, NTDB_LOG_USE_ERROR,
35 "%s: lock owned by another ntdb in this process.",
36 call);
37 }
38
39 /* If we fork, we no longer really own locks. */
40 bool check_lock_pid(struct ntdb_context *ntdb, const char *call, bool log)
41 {
42 /* No locks? No problem! */
43 if (ntdb->file->allrecord_lock.count == 0
44 && ntdb->file->num_lockrecs == 0) {
45 return true;
46 }
47
48 /* No fork? No problem! */
49 if (ntdb->file->locker == getpid()) {
50 return true;
51 }
52
53 if (log) {
54 ntdb_logerr(ntdb, NTDB_ERR_LOCK, NTDB_LOG_USE_ERROR,
55 "%s: fork() detected after lock acquisition!"
56 " (%u vs %u)", call,
57 (unsigned int)ntdb->file->locker,
58 (unsigned int)getpid());
59 }
60 return false;
61 }
62
63 int ntdb_fcntl_lock(int fd, int rw, off_t off, off_t len, bool waitflag,
64 void *unused)
65 {
66 struct flock fl;
67 int ret;
68
69 do {
70 fl.l_type = rw;
71 fl.l_whence = SEEK_SET;
72 fl.l_start = off;
73 fl.l_len = len;
74
75 if (waitflag)
76 ret = fcntl(fd, F_SETLKW, &fl);
77 else
78 ret = fcntl(fd, F_SETLK, &fl);
79 } while (ret != 0 && errno == EINTR);
80 return ret;
81 }
82
83 int ntdb_fcntl_unlock(int fd, int rw, off_t off, off_t len, void *unused)
84 {
85 struct flock fl;
86 int ret;
87
88 do {
89 fl.l_type = F_UNLCK;
90 fl.l_whence = SEEK_SET;
91 fl.l_start = off;
92 fl.l_len = len;
93
94 ret = fcntl(fd, F_SETLKW, &fl);
95 } while (ret != 0 && errno == EINTR);
96 return ret;
97 }
98
99 static int lock(struct ntdb_context *ntdb,
100 int rw, off_t off, off_t len, bool waitflag)
101 {
102 int ret;
103 if (ntdb->file->allrecord_lock.count == 0
104 && ntdb->file->num_lockrecs == 0) {
105 ntdb->file->locker = getpid();
106 }
107
108 ntdb->stats.lock_lowlevel++;
109 ret = ntdb->lock_fn(ntdb->file->fd, rw, off, len, waitflag,
110 ntdb->lock_data);
111 if (!waitflag) {
112 ntdb->stats.lock_nonblock++;
113 if (ret != 0)
114 ntdb->stats.lock_nonblock_fail++;
115 }
116 return ret;
117 }
118
119 static int unlock(struct ntdb_context *ntdb, int rw, off_t off, off_t len)
120 {
121 #if 0 /* Check they matched up locks and unlocks correctly. */
122 char line[80];
123 FILE *locks;
124 bool found = false;
125
126 locks = fopen("/proc/locks", "r");
127
128 while (fgets(line, 80, locks)) {
129 char *p;
130 int type, start, l;
131
132 /* eg. 1: FLOCK ADVISORY WRITE 2440 08:01:2180826 0 EOF */
133 p = strchr(line, ':') + 1;
134 if (strncmp(p, " POSIX ADVISORY ", strlen(" POSIX ADVISORY ")))
135 continue;
136 p += strlen(" FLOCK ADVISORY ");
137 if (strncmp(p, "READ ", strlen("READ ")) == 0)
138 type = F_RDLCK;
139 else if (strncmp(p, "WRITE ", strlen("WRITE ")) == 0)
140 type = F_WRLCK;
141 else
142 abort();
143 p += 6;
144 if (atoi(p) != getpid())
145 continue;
146 p = strchr(strchr(p, ' ') + 1, ' ') + 1;
147 start = atoi(p);
148 p = strchr(p, ' ') + 1;
149 if (strncmp(p, "EOF", 3) == 0)
150 l = 0;
151 else
152 l = atoi(p) - start + 1;
153
154 if (off == start) {
155 if (len != l) {
156 fprintf(stderr, "Len %u should be %u: %s",
157 (int)len, l, line);
158 abort();
159 }
160 if (type != rw) {
161 fprintf(stderr, "Type %s wrong: %s",
162 rw == F_RDLCK ? "READ" : "WRITE", line);
163 abort();
164 }
165 found = true;
166 break;
167 }
168 }
169
170 if (!found) {
171 fprintf(stderr, "Unlock on %u@%u not found!",
172 (int)off, (int)len);
173 abort();
174 }
175
176 fclose(locks);
177 #endif
178
179 return ntdb->unlock_fn(ntdb->file->fd, rw, off, len, ntdb->lock_data);
180 }
181
182 /* a byte range locking function - return 0 on success
183 this functions locks len bytes at the specified offset.
184
185 note that a len of zero means lock to end of file
186 */
187 static enum NTDB_ERROR ntdb_brlock(struct ntdb_context *ntdb,
188 int rw_type, ntdb_off_t offset, ntdb_off_t len,
189 enum ntdb_lock_flags flags)
190 {
191 int ret;
192
193 if (rw_type == F_WRLCK && (ntdb->flags & NTDB_RDONLY)) {
194 return ntdb_logerr(ntdb, NTDB_ERR_RDONLY, NTDB_LOG_USE_ERROR,
195 "Write lock attempted on read-only database");
196 }
197
198 if (ntdb->flags & NTDB_NOLOCK) {
199 return NTDB_SUCCESS;
200 }
201
202 /* A 32 bit system cannot open a 64-bit file, but it could have
203 * expanded since then: check here. */
204 if ((size_t)(offset + len) != offset + len) {
205 return ntdb_logerr(ntdb, NTDB_ERR_IO, NTDB_LOG_ERROR,
206 "ntdb_brlock: lock on giant offset %llu",
207 (long long)(offset + len));
208 }
209
210 ret = lock(ntdb, rw_type, offset, len, flags & NTDB_LOCK_WAIT);
211 if (ret != 0) {
212 /* Generic lock error. errno set by fcntl.
213 * EAGAIN is an expected return from non-blocking
214 * locks. */
215 if (!(flags & NTDB_LOCK_PROBE)
216 && (errno != EAGAIN && errno != EINTR)) {
217 ntdb_logerr(ntdb, NTDB_ERR_LOCK, NTDB_LOG_ERROR,
218 "ntdb_brlock failed (fd=%d) at"
219 " offset %zu rw_type=%d flags=%d len=%zu:"
220 " %s",
221 ntdb->file->fd, (size_t)offset, rw_type,
222 flags, (size_t)len, strerror(errno));
223 }
224 return NTDB_ERR_LOCK;
225 }
226 return NTDB_SUCCESS;
227 }
228
229 static enum NTDB_ERROR ntdb_brunlock(struct ntdb_context *ntdb,
230 int rw_type, ntdb_off_t offset, size_t len)
231 {
232 if (ntdb->flags & NTDB_NOLOCK) {
233 return NTDB_SUCCESS;
234 }
235
236 if (!check_lock_pid(ntdb, "ntdb_brunlock", false))
237 return NTDB_ERR_LOCK;
238
239 if (unlock(ntdb, rw_type, offset, len) == -1) {
240 return ntdb_logerr(ntdb, NTDB_ERR_LOCK, NTDB_LOG_ERROR,
241 "ntdb_brunlock failed (fd=%d) at offset %zu"
242 " rw_type=%d len=%zu: %s",
243 ntdb->file->fd, (size_t)offset, rw_type,
244 (size_t)len, strerror(errno));
245 }
246 return NTDB_SUCCESS;
247 }
248
249 /*
250 upgrade a read lock to a write lock. This needs to be handled in a
251 special way as some OSes (such as solaris) have too conservative
252 deadlock detection and claim a deadlock when progress can be
253 made. For those OSes we may loop for a while.
254 */
255 enum NTDB_ERROR ntdb_allrecord_upgrade(struct ntdb_context *ntdb, off_t start)
256 {
257 int count = 1000;
258
259 if (!check_lock_pid(ntdb, "ntdb_transaction_prepare_commit", true))
260 return NTDB_ERR_LOCK;
261
262 if (ntdb->file->allrecord_lock.count != 1) {
263 return ntdb_logerr(ntdb, NTDB_ERR_LOCK, NTDB_LOG_ERROR,
264 "ntdb_allrecord_upgrade failed:"
265 " count %u too high",
266 ntdb->file->allrecord_lock.count);
267 }
268
269 if (ntdb->file->allrecord_lock.off != 1) {
270 return ntdb_logerr(ntdb, NTDB_ERR_LOCK, NTDB_LOG_ERROR,
271 "ntdb_allrecord_upgrade failed:"
272 " already upgraded?");
273 }
274
275 if (ntdb->file->allrecord_lock.owner != ntdb) {
276 return owner_conflict(ntdb, "ntdb_allrecord_upgrade");
277 }
278
279 while (count--) {
280 struct timeval tv;
281 if (ntdb_brlock(ntdb, F_WRLCK, start, 0,
282 NTDB_LOCK_WAIT|NTDB_LOCK_PROBE) == NTDB_SUCCESS) {
283 ntdb->file->allrecord_lock.ltype = F_WRLCK;
284 ntdb->file->allrecord_lock.off = 0;
285 return NTDB_SUCCESS;
286 }
287 if (errno != EDEADLK) {
288 break;
289 }
290 /* sleep for as short a time as we can - more portable than usleep() */
291 tv.tv_sec = 0;
292 tv.tv_usec = 1;
293 select(0, NULL, NULL, NULL, &tv);
294 }
295
296 if (errno != EAGAIN && errno != EINTR)
297 ntdb_logerr(ntdb, NTDB_ERR_LOCK, NTDB_LOG_ERROR,
298 "ntdb_allrecord_upgrade failed");
299 return NTDB_ERR_LOCK;
300 }
301
302 static struct ntdb_lock *find_nestlock(struct ntdb_context *ntdb, ntdb_off_t offset,
303 const struct ntdb_context *owner)
304 {
305 unsigned int i;
306
307 for (i=0; i<ntdb->file->num_lockrecs; i++) {
308 if (ntdb->file->lockrecs[i].off == offset) {
309 if (owner && ntdb->file->lockrecs[i].owner != owner)
310 return NULL;
311 return &ntdb->file->lockrecs[i];
312 }
313 }
314 return NULL;
315 }
316
317 enum NTDB_ERROR ntdb_lock_and_recover(struct ntdb_context *ntdb)
318 {
319 enum NTDB_ERROR ecode;
320
321 if (!check_lock_pid(ntdb, "ntdb_transaction_prepare_commit", true))
322 return NTDB_ERR_LOCK;
323
324 ecode = ntdb_allrecord_lock(ntdb, F_WRLCK, NTDB_LOCK_WAIT|NTDB_LOCK_NOCHECK,
325 false);
326 if (ecode != NTDB_SUCCESS) {
327 return ecode;
328 }
329
330 ecode = ntdb_lock_open(ntdb, F_WRLCK, NTDB_LOCK_WAIT|NTDB_LOCK_NOCHECK);
331 if (ecode != NTDB_SUCCESS) {
332 ntdb_allrecord_unlock(ntdb, F_WRLCK);
333 return ecode;
334 }
335 ecode = ntdb_transaction_recover(ntdb);
336 ntdb_unlock_open(ntdb, F_WRLCK);
337 ntdb_allrecord_unlock(ntdb, F_WRLCK);
338
339 return ecode;
340 }
341
342 /* lock an offset in the database. */
343 static enum NTDB_ERROR ntdb_nest_lock(struct ntdb_context *ntdb,
344 ntdb_off_t offset, int ltype,
345 enum ntdb_lock_flags flags)
346 {
347 struct ntdb_lock *new_lck;
348 enum NTDB_ERROR ecode;
349
350 assert(offset <= (NTDB_HASH_LOCK_START + (1 << ntdb->hash_bits)
351 + ntdb->file->map_size / 8));
352
353 if (ntdb->flags & NTDB_NOLOCK)
354 return NTDB_SUCCESS;
355
356 if (!check_lock_pid(ntdb, "ntdb_nest_lock", true)) {
357 return NTDB_ERR_LOCK;
358 }
359
360 ntdb->stats.locks++;
361
362 new_lck = find_nestlock(ntdb, offset, NULL);
363 if (new_lck) {
364 if (new_lck->owner != ntdb) {
365 return owner_conflict(ntdb, "ntdb_nest_lock");
366 }
367
368 if (new_lck->ltype == F_RDLCK && ltype == F_WRLCK) {
369 return ntdb_logerr(ntdb, NTDB_ERR_LOCK, NTDB_LOG_ERROR,
370 "ntdb_nest_lock:"
371 " offset %zu has read lock",
372 (size_t)offset);
373 }
374 /* Just increment the struct, posix locks don't stack. */
375 new_lck->count++;
376 return NTDB_SUCCESS;
377 }
378
379 #if 0
380 if (ntdb->file->num_lockrecs
381 && offset >= NTDB_HASH_LOCK_START
382 && offset < NTDB_HASH_LOCK_START + NTDB_HASH_LOCK_RANGE) {
383 return ntdb_logerr(ntdb, NTDB_ERR_LOCK, NTDB_LOG_ERROR,
384 "ntdb_nest_lock: already have a hash lock?");
385 }
386 #endif
387 if (ntdb->file->lockrecs == NULL) {
388 new_lck = ntdb->alloc_fn(ntdb->file, sizeof(*ntdb->file->lockrecs),
389 ntdb->alloc_data);
390 } else {
391 new_lck = (struct ntdb_lock *)ntdb->expand_fn(
392 ntdb->file->lockrecs,
393 sizeof(*ntdb->file->lockrecs)
394 * (ntdb->file->num_lockrecs+1),
395 ntdb->alloc_data);
396 }
397 if (new_lck == NULL) {
398 return ntdb_logerr(ntdb, NTDB_ERR_OOM, NTDB_LOG_ERROR,
399 "ntdb_nest_lock:"
400 " unable to allocate %zu lock struct",
401 ntdb->file->num_lockrecs + 1);
402 }
403 ntdb->file->lockrecs = new_lck;
404
405 /* Since fcntl locks don't nest, we do a lock for the first one,
406 and simply bump the count for future ones */
407 ecode = ntdb_brlock(ntdb, ltype, offset, 1, flags);
408 if (ecode != NTDB_SUCCESS) {
409 return ecode;
410 }
411
412 /* First time we grab a lock, perhaps someone died in commit? */
413 if (!(flags & NTDB_LOCK_NOCHECK)
414 && ntdb->file->num_lockrecs == 0) {
415 ntdb_bool_err berr = ntdb_needs_recovery(ntdb);
416 if (berr != false) {
417 ntdb_brunlock(ntdb, ltype, offset, 1);
418
419 if (berr < 0)
420 return NTDB_OFF_TO_ERR(berr);
421 ecode = ntdb_lock_and_recover(ntdb);
422 if (ecode == NTDB_SUCCESS) {
423 ecode = ntdb_brlock(ntdb, ltype, offset, 1,
424 flags);
425 }
426 if (ecode != NTDB_SUCCESS) {
427 return ecode;
428 }
429 }
430 }
431
432 ntdb->file->lockrecs[ntdb->file->num_lockrecs].owner = ntdb;
433 ntdb->file->lockrecs[ntdb->file->num_lockrecs].off = offset;
434 ntdb->file->lockrecs[ntdb->file->num_lockrecs].count = 1;
435 ntdb->file->lockrecs[ntdb->file->num_lockrecs].ltype = ltype;
436 ntdb->file->num_lockrecs++;
437
438 return NTDB_SUCCESS;
439 }
440
441 static enum NTDB_ERROR ntdb_nest_unlock(struct ntdb_context *ntdb,
442 ntdb_off_t off, int ltype)
443 {
444 struct ntdb_lock *lck;
445 enum NTDB_ERROR ecode;
446
447 if (ntdb->flags & NTDB_NOLOCK)
448 return NTDB_SUCCESS;
449
450 lck = find_nestlock(ntdb, off, ntdb);
451 if ((lck == NULL) || (lck->count == 0)) {
452 return ntdb_logerr(ntdb, NTDB_ERR_LOCK, NTDB_LOG_ERROR,
453 "ntdb_nest_unlock: no lock for %zu",
454 (size_t)off);
455 }
456
457 if (lck->count > 1) {
458 lck->count--;
459 return NTDB_SUCCESS;
460 }
461
462 /*
463 * This lock has count==1 left, so we need to unlock it in the
464 * kernel. We don't bother with decrementing the in-memory array
465 * element, we're about to overwrite it with the last array element
466 * anyway.
467 */
468 ecode = ntdb_brunlock(ntdb, ltype, off, 1);
469
470 /*
471 * Shrink the array by overwriting the element just unlocked with the
472 * last array element.
473 */
474 *lck = ntdb->file->lockrecs[--ntdb->file->num_lockrecs];
475
476 return ecode;
477 }
478
479 /*
480 get the transaction lock
481 */
482 enum NTDB_ERROR ntdb_transaction_lock(struct ntdb_context *ntdb, int ltype)
483 {
484 return ntdb_nest_lock(ntdb, NTDB_TRANSACTION_LOCK, ltype, NTDB_LOCK_WAIT);
485 }
486
487 /*
488 release the transaction lock
489 */
490 void ntdb_transaction_unlock(struct ntdb_context *ntdb, int ltype)
491 {
492 ntdb_nest_unlock(ntdb, NTDB_TRANSACTION_LOCK, ltype);
493 }
494
495 /* We only need to lock individual bytes, but Linux merges consecutive locks
496 * so we lock in contiguous ranges. */
497 static enum NTDB_ERROR ntdb_lock_gradual(struct ntdb_context *ntdb,
498 int ltype, enum ntdb_lock_flags flags,
499 ntdb_off_t off, ntdb_off_t len)
500 {
501 enum NTDB_ERROR ecode;
502 enum ntdb_lock_flags nb_flags = (flags & ~NTDB_LOCK_WAIT);
503
504 if (len <= 1) {
505 /* 0 would mean to end-of-file... */
506 assert(len != 0);
507 /* Single hash. Just do blocking lock. */
508 return ntdb_brlock(ntdb, ltype, off, len, flags);
509 }
510
511 /* First we try non-blocking. */
512 ecode = ntdb_brlock(ntdb, ltype, off, len, nb_flags);
513 if (ecode != NTDB_ERR_LOCK) {
514 return ecode;
515 }
516
517 /* Try locking first half, then second. */
518 ecode = ntdb_lock_gradual(ntdb, ltype, flags, off, len / 2);
519 if (ecode != NTDB_SUCCESS)
520 return ecode;
521
522 ecode = ntdb_lock_gradual(ntdb, ltype, flags,
523 off + len / 2, len - len / 2);
524 if (ecode != NTDB_SUCCESS) {
525 ntdb_brunlock(ntdb, ltype, off, len / 2);
526 }
527 return ecode;
528 }
529
530 /* lock/unlock entire database. It can only be upgradable if you have some
531 * other way of guaranteeing exclusivity (ie. transaction write lock). */
532 enum NTDB_ERROR ntdb_allrecord_lock(struct ntdb_context *ntdb, int ltype,
533 enum ntdb_lock_flags flags, bool upgradable)
534 {
535 enum NTDB_ERROR ecode;
536 ntdb_bool_err berr;
537
538 if (ntdb->flags & NTDB_NOLOCK) {
539 return NTDB_SUCCESS;
540 }
541
542 if (!check_lock_pid(ntdb, "ntdb_allrecord_lock", true)) {
543 return NTDB_ERR_LOCK;
544 }
545
546 if (ntdb->file->allrecord_lock.count) {
547 if (ntdb->file->allrecord_lock.owner != ntdb) {
548 return owner_conflict(ntdb, "ntdb_allrecord_lock");
549 }
550
551 if (ltype == F_RDLCK
552 || ntdb->file->allrecord_lock.ltype == F_WRLCK) {
553 ntdb->file->allrecord_lock.count++;
554 return NTDB_SUCCESS;
555 }
556
557 /* a global lock of a different type exists */
558 return ntdb_logerr(ntdb, NTDB_ERR_LOCK, NTDB_LOG_USE_ERROR,
559 "ntdb_allrecord_lock: already have %s lock",
560 ntdb->file->allrecord_lock.ltype == F_RDLCK
561 ? "read" : "write");
562 }
563
564 if (ntdb_has_hash_locks(ntdb)) {
565 /* can't combine global and chain locks */
566 return ntdb_logerr(ntdb, NTDB_ERR_LOCK, NTDB_LOG_USE_ERROR,
567 "ntdb_allrecord_lock:"
568 " already have chain lock");
569 }
570
571 if (upgradable && ltype != F_RDLCK) {
572 /* ntdb error: you can't upgrade a write lock! */
573 return ntdb_logerr(ntdb, NTDB_ERR_LOCK, NTDB_LOG_ERROR,
574 "ntdb_allrecord_lock:"
575 " can't upgrade a write lock");
576 }
577
578 ntdb->stats.locks++;
579 again:
580 /* Lock hashes, gradually. */
581 ecode = ntdb_lock_gradual(ntdb, ltype, flags, NTDB_HASH_LOCK_START,
582 1 << ntdb->hash_bits);
583 if (ecode != NTDB_SUCCESS)
584 return ecode;
585
586 /* Lock free tables: there to end of file. */
587 ecode = ntdb_brlock(ntdb, ltype,
588 NTDB_HASH_LOCK_START + (1 << ntdb->hash_bits),
589 0, flags);
590 if (ecode != NTDB_SUCCESS) {
591 ntdb_brunlock(ntdb, ltype, NTDB_HASH_LOCK_START,
592 1 << ntdb->hash_bits);
593 return ecode;
594 }
595
596 ntdb->file->allrecord_lock.owner = ntdb;
597 ntdb->file->allrecord_lock.count = 1;
598 /* If it's upgradable, it's actually exclusive so we can treat
599 * it as a write lock. */
600 ntdb->file->allrecord_lock.ltype = upgradable ? F_WRLCK : ltype;
601 ntdb->file->allrecord_lock.off = upgradable;
602
603 /* Now check for needing recovery. */
604 if (flags & NTDB_LOCK_NOCHECK)
605 return NTDB_SUCCESS;
606
607 berr = ntdb_needs_recovery(ntdb);
608 if (likely(berr == false))
609 return NTDB_SUCCESS;
610
611 ntdb_allrecord_unlock(ntdb, ltype);
612 if (berr < 0)
613 return NTDB_OFF_TO_ERR(berr);
614 ecode = ntdb_lock_and_recover(ntdb);
615 if (ecode != NTDB_SUCCESS) {
616 return ecode;
617 }
618 goto again;
619 }
620
621 enum NTDB_ERROR ntdb_lock_open(struct ntdb_context *ntdb,
622 int ltype, enum ntdb_lock_flags flags)
623 {
624 return ntdb_nest_lock(ntdb, NTDB_OPEN_LOCK, ltype, flags);
625 }
626
627 void ntdb_unlock_open(struct ntdb_context *ntdb, int ltype)
628 {
629 ntdb_nest_unlock(ntdb, NTDB_OPEN_LOCK, ltype);
630 }
631
632 bool ntdb_has_open_lock(struct ntdb_context *ntdb)
633 {
634 return !(ntdb->flags & NTDB_NOLOCK)
635 && find_nestlock(ntdb, NTDB_OPEN_LOCK, ntdb) != NULL;
636 }
637
638 enum NTDB_ERROR ntdb_lock_expand(struct ntdb_context *ntdb, int ltype)
639 {
640 /* Lock doesn't protect data, so don't check (we recurse if we do!) */
641 return ntdb_nest_lock(ntdb, NTDB_EXPANSION_LOCK, ltype,
642 NTDB_LOCK_WAIT | NTDB_LOCK_NOCHECK);
643 }
644
645 void ntdb_unlock_expand(struct ntdb_context *ntdb, int ltype)
646 {
647 ntdb_nest_unlock(ntdb, NTDB_EXPANSION_LOCK, ltype);
648 }
649
650 /* unlock entire db */
651 void ntdb_allrecord_unlock(struct ntdb_context *ntdb, int ltype)
652 {
653 if (ntdb->flags & NTDB_NOLOCK)
654 return;
655
656 if (ntdb->file->allrecord_lock.count == 0) {
657 ntdb_logerr(ntdb, NTDB_ERR_LOCK, NTDB_LOG_USE_ERROR,
658 "ntdb_allrecord_unlock: not locked!");
659 return;
660 }
661
662 if (ntdb->file->allrecord_lock.owner != ntdb) {
663 ntdb_logerr(ntdb, NTDB_ERR_LOCK, NTDB_LOG_USE_ERROR,
664 "ntdb_allrecord_unlock: not locked by us!");
665 return;
666 }
667
668 /* Upgradable locks are marked as write locks. */
669 if (ntdb->file->allrecord_lock.ltype != ltype
670 && (!ntdb->file->allrecord_lock.off || ltype != F_RDLCK)) {
671 ntdb_logerr(ntdb, NTDB_ERR_LOCK, NTDB_LOG_ERROR,
672 "ntdb_allrecord_unlock: have %s lock",
673 ntdb->file->allrecord_lock.ltype == F_RDLCK
674 ? "read" : "write");
675 return;
676 }
677
678 if (ntdb->file->allrecord_lock.count > 1) {
679 ntdb->file->allrecord_lock.count--;
680 return;
681 }
682
683 ntdb->file->allrecord_lock.count = 0;
684 ntdb->file->allrecord_lock.ltype = 0;
685
686 ntdb_brunlock(ntdb, ltype, NTDB_HASH_LOCK_START, 0);
687 }
688
689 bool ntdb_has_expansion_lock(struct ntdb_context *ntdb)
690 {
691 return find_nestlock(ntdb, NTDB_EXPANSION_LOCK, ntdb) != NULL;
692 }
693
694 bool ntdb_has_hash_locks(struct ntdb_context *ntdb)
695 {
696 unsigned int i;
697
698 for (i=0; i<ntdb->file->num_lockrecs; i++) {
699 if (ntdb->file->lockrecs[i].off >= NTDB_HASH_LOCK_START
700 && ntdb->file->lockrecs[i].off < (NTDB_HASH_LOCK_START
701 + (1 << ntdb->hash_bits)))
702 return true;
703 }
704 return false;
705 }
706
707 static bool ntdb_has_free_lock(struct ntdb_context *ntdb)
708 {
709 unsigned int i;
710
711 if (ntdb->flags & NTDB_NOLOCK)
712 return false;
713
714 for (i=0; i<ntdb->file->num_lockrecs; i++) {
715 if (ntdb->file->lockrecs[i].off
716 > NTDB_HASH_LOCK_START + (1 << ntdb->hash_bits))
717 return true;
718 }
719 return false;
720 }
721
722 enum NTDB_ERROR ntdb_lock_hash(struct ntdb_context *ntdb,
723 unsigned int h,
724 int ltype)
725 {
726 unsigned l = NTDB_HASH_LOCK_START + h;
727
728 assert(h < (1 << ntdb->hash_bits));
729
730 /* a allrecord lock allows us to avoid per chain locks */
731 if (ntdb->file->allrecord_lock.count) {
732 if (!check_lock_pid(ntdb, "ntdb_lock_hashes", true))
733 return NTDB_ERR_LOCK;
734
735 if (ntdb->file->allrecord_lock.owner != ntdb)
736 return owner_conflict(ntdb, "ntdb_lock_hashes");
737 if (ltype == ntdb->file->allrecord_lock.ltype
738 || ltype == F_RDLCK) {
739 return NTDB_SUCCESS;
740 }
741
742 return ntdb_logerr(ntdb, NTDB_ERR_LOCK, NTDB_LOG_USE_ERROR,
743 "ntdb_lock_hashes:"
744 " already have %s allrecordlock",
745 ntdb->file->allrecord_lock.ltype == F_RDLCK
746 ? "read" : "write");
747 }
748
749 if (ntdb_has_free_lock(ntdb)) {
750 return ntdb_logerr(ntdb, NTDB_ERR_LOCK, NTDB_LOG_ERROR,
751 "ntdb_lock_hashes: already have free lock");
752 }
753
754 if (ntdb_has_expansion_lock(ntdb)) {
755 return ntdb_logerr(ntdb, NTDB_ERR_LOCK, NTDB_LOG_ERROR,
756 "ntdb_lock_hashes:"
757 " already have expansion lock");
758 }
759
760 return ntdb_nest_lock(ntdb, l, ltype, NTDB_LOCK_WAIT);
761 }
762
763 enum NTDB_ERROR ntdb_unlock_hash(struct ntdb_context *ntdb,
764 unsigned int h, int ltype)
765 {
766 unsigned l = NTDB_HASH_LOCK_START + (h & ((1 << ntdb->hash_bits)-1));
767
768 if (ntdb->flags & NTDB_NOLOCK)
769 return 0;
770
771 /* a allrecord lock allows us to avoid per chain locks */
772 if (ntdb->file->allrecord_lock.count) {
773 if (ntdb->file->allrecord_lock.ltype == F_RDLCK
774 && ltype == F_WRLCK) {
775 return ntdb_logerr(ntdb, NTDB_ERR_LOCK, NTDB_LOG_ERROR,
776 "ntdb_unlock_hashes RO allrecord!");
777 }
778 if (ntdb->file->allrecord_lock.owner != ntdb) {
779 return ntdb_logerr(ntdb, NTDB_ERR_LOCK, NTDB_LOG_USE_ERROR,
780 "ntdb_unlock_hashes:"
781 " not locked by us!");
782 }
783 return NTDB_SUCCESS;
784 }
785
786 return ntdb_nest_unlock(ntdb, l, ltype);
787 }
788
789 /* Hash locks use NTDB_HASH_LOCK_START + <number of hash entries>..
790 * Then we begin; bucket offsets are sizeof(ntdb_len_t) apart, so we divide.
791 * The result is that on 32 bit systems we don't use lock values > 2^31 on
792 * files that are less than 4GB.
793 */
794 static ntdb_off_t free_lock_off(const struct ntdb_context *ntdb,
795 ntdb_off_t b_off)
796 {
797 return NTDB_HASH_LOCK_START + (1 << ntdb->hash_bits)
798 + b_off / sizeof(ntdb_off_t);
799 }
800
801 enum NTDB_ERROR ntdb_lock_free_bucket(struct ntdb_context *ntdb, ntdb_off_t b_off,
802 enum ntdb_lock_flags waitflag)
803 {
804 assert(b_off >= sizeof(struct ntdb_header));
805
806 if (ntdb->flags & NTDB_NOLOCK)
807 return 0;
808
809 /* a allrecord lock allows us to avoid per chain locks */
810 if (ntdb->file->allrecord_lock.count) {
811 if (!check_lock_pid(ntdb, "ntdb_lock_free_bucket", true))
812 return NTDB_ERR_LOCK;
813
814 if (ntdb->file->allrecord_lock.owner != ntdb) {
815 return owner_conflict(ntdb, "ntdb_lock_free_bucket");
816 }
817
818 if (ntdb->file->allrecord_lock.ltype == F_WRLCK)
819 return 0;
820 return ntdb_logerr(ntdb, NTDB_ERR_LOCK, NTDB_LOG_ERROR,
821 "ntdb_lock_free_bucket with"
822 " read-only allrecordlock!");
823 }
824
825 #if 0 /* FIXME */
826 if (ntdb_has_expansion_lock(ntdb)) {
827 return ntdb_logerr(ntdb, NTDB_ERR_LOCK, NTDB_LOG_ERROR,
828 "ntdb_lock_free_bucket:"
829 " already have expansion lock");
830 }
831 #endif
832
833 return ntdb_nest_lock(ntdb, free_lock_off(ntdb, b_off), F_WRLCK,
834 waitflag);
835 }
836
837 void ntdb_unlock_free_bucket(struct ntdb_context *ntdb, ntdb_off_t b_off)
838 {
839 if (ntdb->file->allrecord_lock.count)
840 return;
841
842 ntdb_nest_unlock(ntdb, free_lock_off(ntdb, b_off), F_WRLCK);
843 }
844
845 _PUBLIC_ enum NTDB_ERROR ntdb_lockall(struct ntdb_context *ntdb)
846 {
847 return ntdb_allrecord_lock(ntdb, F_WRLCK, NTDB_LOCK_WAIT, false);
848 }
849
850 _PUBLIC_ void ntdb_unlockall(struct ntdb_context *ntdb)
851 {
852 ntdb_allrecord_unlock(ntdb, F_WRLCK);
853 }
854
855 _PUBLIC_ enum NTDB_ERROR ntdb_lockall_read(struct ntdb_context *ntdb)
856 {
857 return ntdb_allrecord_lock(ntdb, F_RDLCK, NTDB_LOCK_WAIT, false);
858 }
859
860 _PUBLIC_ void ntdb_unlockall_read(struct ntdb_context *ntdb)
861 {
862 ntdb_allrecord_unlock(ntdb, F_RDLCK);
863 }
864
865 void ntdb_lock_cleanup(struct ntdb_context *ntdb)
866 {
867 unsigned int i;
868
869 /* We don't want to warn: they're allowed to close ntdb after fork. */
870 if (!check_lock_pid(ntdb, "ntdb_close", false))
871 return;
872
873 while (ntdb->file->allrecord_lock.count
874 && ntdb->file->allrecord_lock.owner == ntdb) {
875 ntdb_allrecord_unlock(ntdb, ntdb->file->allrecord_lock.ltype);
876 }
877
878 for (i=0; i<ntdb->file->num_lockrecs; i++) {
879 if (ntdb->file->lockrecs[i].owner == ntdb) {
880 ntdb_nest_unlock(ntdb,
881 ntdb->file->lockrecs[i].off,
882 ntdb->file->lockrecs[i].ltype);
883 i--;
884 }
885 }
886 }
reg import