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libcli/smb: add basic session->smb2.channel_sequence handling
[Samba/gebeck_regimport.git] / lib / ntdb / lock.c
blob4517e2556857865c605dad7c50ef3b27c06385b6
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, ntdb->file->locker, getpid());
57 }
58 return false;
59 }
60
61 int ntdb_fcntl_lock(int fd, int rw, off_t off, off_t len, bool waitflag,
62 void *unused)
63 {
64 struct flock fl;
65 int ret;
66
67 do {
68 fl.l_type = rw;
69 fl.l_whence = SEEK_SET;
70 fl.l_start = off;
71 fl.l_len = len;
72
73 if (waitflag)
74 ret = fcntl(fd, F_SETLKW, &fl);
75 else
76 ret = fcntl(fd, F_SETLK, &fl);
77 } while (ret != 0 && errno == EINTR);
78 return ret;
79 }
80
81 int ntdb_fcntl_unlock(int fd, int rw, off_t off, off_t len, void *unused)
82 {
83 struct flock fl;
84 int ret;
85
86 do {
87 fl.l_type = F_UNLCK;
88 fl.l_whence = SEEK_SET;
89 fl.l_start = off;
90 fl.l_len = len;
91
92 ret = fcntl(fd, F_SETLKW, &fl);
93 } while (ret != 0 && errno == EINTR);
94 return ret;
95 }
96
97 static int lock(struct ntdb_context *ntdb,
98 int rw, off_t off, off_t len, bool waitflag)
99 {
100 int ret;
101 if (ntdb->file->allrecord_lock.count == 0
102 && ntdb->file->num_lockrecs == 0) {
103 ntdb->file->locker = getpid();
104 }
105
106 ntdb->stats.lock_lowlevel++;
107 ret = ntdb->lock_fn(ntdb->file->fd, rw, off, len, waitflag,
108 ntdb->lock_data);
109 if (!waitflag) {
110 ntdb->stats.lock_nonblock++;
111 if (ret != 0)
112 ntdb->stats.lock_nonblock_fail++;
113 }
114 return ret;
115 }
116
117 static int unlock(struct ntdb_context *ntdb, int rw, off_t off, off_t len)
118 {
119 #if 0 /* Check they matched up locks and unlocks correctly. */
120 char line[80];
121 FILE *locks;
122 bool found = false;
123
124 locks = fopen("/proc/locks", "r");
125
126 while (fgets(line, 80, locks)) {
127 char *p;
128 int type, start, l;
129
130 /* eg. 1: FLOCK ADVISORY WRITE 2440 08:01:2180826 0 EOF */
131 p = strchr(line, ':') + 1;
132 if (strncmp(p, " POSIX ADVISORY ", strlen(" POSIX ADVISORY ")))
133 continue;
134 p += strlen(" FLOCK ADVISORY ");
135 if (strncmp(p, "READ ", strlen("READ ")) == 0)
136 type = F_RDLCK;
137 else if (strncmp(p, "WRITE ", strlen("WRITE ")) == 0)
138 type = F_WRLCK;
139 else
140 abort();
141 p += 6;
142 if (atoi(p) != getpid())
143 continue;
144 p = strchr(strchr(p, ' ') + 1, ' ') + 1;
145 start = atoi(p);
146 p = strchr(p, ' ') + 1;
147 if (strncmp(p, "EOF", 3) == 0)
148 l = 0;
149 else
150 l = atoi(p) - start + 1;
151
152 if (off == start) {
153 if (len != l) {
154 fprintf(stderr, "Len %u should be %u: %s",
155 (int)len, l, line);
156 abort();
157 }
158 if (type != rw) {
159 fprintf(stderr, "Type %s wrong: %s",
160 rw == F_RDLCK ? "READ" : "WRITE", line);
161 abort();
162 }
163 found = true;
164 break;
165 }
166 }
167
168 if (!found) {
169 fprintf(stderr, "Unlock on %u@%u not found!",
170 (int)off, (int)len);
171 abort();
172 }
173
174 fclose(locks);
175 #endif
176
177 return ntdb->unlock_fn(ntdb->file->fd, rw, off, len, ntdb->lock_data);
178 }
179
180 /* a byte range locking function - return 0 on success
181 this functions locks len bytes at the specified offset.
182
183 note that a len of zero means lock to end of file
184 */
185 static enum NTDB_ERROR ntdb_brlock(struct ntdb_context *ntdb,
186 int rw_type, ntdb_off_t offset, ntdb_off_t len,
187 enum ntdb_lock_flags flags)
188 {
189 int ret;
190
191 if (rw_type == F_WRLCK && (ntdb->flags & NTDB_RDONLY)) {
192 return ntdb_logerr(ntdb, NTDB_ERR_RDONLY, NTDB_LOG_USE_ERROR,
193 "Write lock attempted on read-only database");
194 }
195
196 if (ntdb->flags & NTDB_NOLOCK) {
197 return NTDB_SUCCESS;
198 }
199
200 /* A 32 bit system cannot open a 64-bit file, but it could have
201 * expanded since then: check here. */
202 if ((size_t)(offset + len) != offset + len) {
203 return ntdb_logerr(ntdb, NTDB_ERR_IO, NTDB_LOG_ERROR,
204 "ntdb_brlock: lock on giant offset %llu",
205 (long long)(offset + len));
206 }
207
208 ret = lock(ntdb, rw_type, offset, len, flags & NTDB_LOCK_WAIT);
209 if (ret != 0) {
210 /* Generic lock error. errno set by fcntl.
211 * EAGAIN is an expected return from non-blocking
212 * locks. */
213 if (!(flags & NTDB_LOCK_PROBE)
214 && (errno != EAGAIN && errno != EINTR)) {
215 ntdb_logerr(ntdb, NTDB_ERR_LOCK, NTDB_LOG_ERROR,
216 "ntdb_brlock failed (fd=%d) at"
217 " offset %zu rw_type=%d flags=%d len=%zu:"
218 " %s",
219 ntdb->file->fd, (size_t)offset, rw_type,
220 flags, (size_t)len, strerror(errno));
221 }
222 return NTDB_ERR_LOCK;
223 }
224 return NTDB_SUCCESS;
225 }
226
227 static enum NTDB_ERROR ntdb_brunlock(struct ntdb_context *ntdb,
228 int rw_type, ntdb_off_t offset, size_t len)
229 {
230 if (ntdb->flags & NTDB_NOLOCK) {
231 return NTDB_SUCCESS;
232 }
233
234 if (!check_lock_pid(ntdb, "ntdb_brunlock", false))
235 return NTDB_ERR_LOCK;
236
237 if (unlock(ntdb, rw_type, offset, len) == -1) {
238 return ntdb_logerr(ntdb, NTDB_ERR_LOCK, NTDB_LOG_ERROR,
239 "ntdb_brunlock failed (fd=%d) at offset %zu"
240 " rw_type=%d len=%zu: %s",
241 ntdb->file->fd, (size_t)offset, rw_type,
242 (size_t)len, strerror(errno));
243 }
244 return NTDB_SUCCESS;
245 }
246
247 /*
248 upgrade a read lock to a write lock. This needs to be handled in a
249 special way as some OSes (such as solaris) have too conservative
250 deadlock detection and claim a deadlock when progress can be
251 made. For those OSes we may loop for a while.
252 */
253 enum NTDB_ERROR ntdb_allrecord_upgrade(struct ntdb_context *ntdb, off_t start)
254 {
255 int count = 1000;
256
257 if (!check_lock_pid(ntdb, "ntdb_transaction_prepare_commit", true))
258 return NTDB_ERR_LOCK;
259
260 if (ntdb->file->allrecord_lock.count != 1) {
261 return ntdb_logerr(ntdb, NTDB_ERR_LOCK, NTDB_LOG_ERROR,
262 "ntdb_allrecord_upgrade failed:"
263 " count %u too high",
264 ntdb->file->allrecord_lock.count);
265 }
266
267 if (ntdb->file->allrecord_lock.off != 1) {
268 return ntdb_logerr(ntdb, NTDB_ERR_LOCK, NTDB_LOG_ERROR,
269 "ntdb_allrecord_upgrade failed:"
270 " already upgraded?");
271 }
272
273 if (ntdb->file->allrecord_lock.owner != ntdb) {
274 return owner_conflict(ntdb, "ntdb_allrecord_upgrade");
275 }
276
277 while (count--) {
278 struct timeval tv;
279 if (ntdb_brlock(ntdb, F_WRLCK, start, 0,
280 NTDB_LOCK_WAIT|NTDB_LOCK_PROBE) == NTDB_SUCCESS) {
281 ntdb->file->allrecord_lock.ltype = F_WRLCK;
282 ntdb->file->allrecord_lock.off = 0;
283 return NTDB_SUCCESS;
284 }
285 if (errno != EDEADLK) {
286 break;
287 }
288 /* sleep for as short a time as we can - more portable than usleep() */
289 tv.tv_sec = 0;
290 tv.tv_usec = 1;
291 select(0, NULL, NULL, NULL, &tv);
292 }
293
294 if (errno != EAGAIN && errno != EINTR)
295 ntdb_logerr(ntdb, NTDB_ERR_LOCK, NTDB_LOG_ERROR,
296 "ntdb_allrecord_upgrade failed");
297 return NTDB_ERR_LOCK;
298 }
299
300 static struct ntdb_lock *find_nestlock(struct ntdb_context *ntdb, ntdb_off_t offset,
301 const struct ntdb_context *owner)
302 {
303 unsigned int i;
304
305 for (i=0; i<ntdb->file->num_lockrecs; i++) {
306 if (ntdb->file->lockrecs[i].off == offset) {
307 if (owner && ntdb->file->lockrecs[i].owner != owner)
308 return NULL;
309 return &ntdb->file->lockrecs[i];
310 }
311 }
312 return NULL;
313 }
314
315 enum NTDB_ERROR ntdb_lock_and_recover(struct ntdb_context *ntdb)
316 {
317 enum NTDB_ERROR ecode;
318
319 if (!check_lock_pid(ntdb, "ntdb_transaction_prepare_commit", true))
320 return NTDB_ERR_LOCK;
321
322 ecode = ntdb_allrecord_lock(ntdb, F_WRLCK, NTDB_LOCK_WAIT|NTDB_LOCK_NOCHECK,
323 false);
324 if (ecode != NTDB_SUCCESS) {
325 return ecode;
326 }
327
328 ecode = ntdb_lock_open(ntdb, F_WRLCK, NTDB_LOCK_WAIT|NTDB_LOCK_NOCHECK);
329 if (ecode != NTDB_SUCCESS) {
330 ntdb_allrecord_unlock(ntdb, F_WRLCK);
331 return ecode;
332 }
333 ecode = ntdb_transaction_recover(ntdb);
334 ntdb_unlock_open(ntdb, F_WRLCK);
335 ntdb_allrecord_unlock(ntdb, F_WRLCK);
336
337 return ecode;
338 }
339
340 /* lock an offset in the database. */
341 static enum NTDB_ERROR ntdb_nest_lock(struct ntdb_context *ntdb,
342 ntdb_off_t offset, int ltype,
343 enum ntdb_lock_flags flags)
344 {
345 struct ntdb_lock *new_lck;
346 enum NTDB_ERROR ecode;
347
348 assert(offset <= (NTDB_HASH_LOCK_START + (1 << ntdb->hash_bits)
349 + ntdb->file->map_size / 8));
350
351 if (ntdb->flags & NTDB_NOLOCK)
352 return NTDB_SUCCESS;
353
354 if (!check_lock_pid(ntdb, "ntdb_nest_lock", true)) {
355 return NTDB_ERR_LOCK;
356 }
357
358 ntdb->stats.locks++;
359
360 new_lck = find_nestlock(ntdb, offset, NULL);
361 if (new_lck) {
362 if (new_lck->owner != ntdb) {
363 return owner_conflict(ntdb, "ntdb_nest_lock");
364 }
365
366 if (new_lck->ltype == F_RDLCK && ltype == F_WRLCK) {
367 return ntdb_logerr(ntdb, NTDB_ERR_LOCK, NTDB_LOG_ERROR,
368 "ntdb_nest_lock:"
369 " offset %zu has read lock",
370 (size_t)offset);
371 }
372 /* Just increment the struct, posix locks don't stack. */
373 new_lck->count++;
374 return NTDB_SUCCESS;
375 }
376
377 #if 0
378 if (ntdb->file->num_lockrecs
379 && offset >= NTDB_HASH_LOCK_START
380 && offset < NTDB_HASH_LOCK_START + NTDB_HASH_LOCK_RANGE) {
381 return ntdb_logerr(ntdb, NTDB_ERR_LOCK, NTDB_LOG_ERROR,
382 "ntdb_nest_lock: already have a hash lock?");
383 }
384 #endif
385 if (ntdb->file->lockrecs == NULL) {
386 new_lck = ntdb->alloc_fn(ntdb->file, sizeof(*ntdb->file->lockrecs),
387 ntdb->alloc_data);
388 } else {
389 new_lck = (struct ntdb_lock *)ntdb->expand_fn(
390 ntdb->file->lockrecs,
391 sizeof(*ntdb->file->lockrecs)
392 * (ntdb->file->num_lockrecs+1),
393 ntdb->alloc_data);
394 }
395 if (new_lck == NULL) {
396 return ntdb_logerr(ntdb, NTDB_ERR_OOM, NTDB_LOG_ERROR,
397 "ntdb_nest_lock:"
398 " unable to allocate %zu lock struct",
399 ntdb->file->num_lockrecs + 1);
400 }
401 ntdb->file->lockrecs = new_lck;
402
403 /* Since fcntl locks don't nest, we do a lock for the first one,
404 and simply bump the count for future ones */
405 ecode = ntdb_brlock(ntdb, ltype, offset, 1, flags);
406 if (ecode != NTDB_SUCCESS) {
407 return ecode;
408 }
409
410 /* First time we grab a lock, perhaps someone died in commit? */
411 if (!(flags & NTDB_LOCK_NOCHECK)
412 && ntdb->file->num_lockrecs == 0) {
413 ntdb_bool_err berr = ntdb_needs_recovery(ntdb);
414 if (berr != false) {
415 ntdb_brunlock(ntdb, ltype, offset, 1);
416
417 if (berr < 0)
418 return NTDB_OFF_TO_ERR(berr);
419 ecode = ntdb_lock_and_recover(ntdb);
420 if (ecode == NTDB_SUCCESS) {
421 ecode = ntdb_brlock(ntdb, ltype, offset, 1,
422 flags);
423 }
424 if (ecode != NTDB_SUCCESS) {
425 return ecode;
426 }
427 }
428 }
429
430 ntdb->file->lockrecs[ntdb->file->num_lockrecs].owner = ntdb;
431 ntdb->file->lockrecs[ntdb->file->num_lockrecs].off = offset;
432 ntdb->file->lockrecs[ntdb->file->num_lockrecs].count = 1;
433 ntdb->file->lockrecs[ntdb->file->num_lockrecs].ltype = ltype;
434 ntdb->file->num_lockrecs++;
435
436 return NTDB_SUCCESS;
437 }
438
439 static enum NTDB_ERROR ntdb_nest_unlock(struct ntdb_context *ntdb,
440 ntdb_off_t off, int ltype)
441 {
442 struct ntdb_lock *lck;
443 enum NTDB_ERROR ecode;
444
445 if (ntdb->flags & NTDB_NOLOCK)
446 return NTDB_SUCCESS;
447
448 lck = find_nestlock(ntdb, off, ntdb);
449 if ((lck == NULL) || (lck->count == 0)) {
450 return ntdb_logerr(ntdb, NTDB_ERR_LOCK, NTDB_LOG_ERROR,
451 "ntdb_nest_unlock: no lock for %zu",
452 (size_t)off);
453 }
454
455 if (lck->count > 1) {
456 lck->count--;
457 return NTDB_SUCCESS;
458 }
459
460 /*
461 * This lock has count==1 left, so we need to unlock it in the
462 * kernel. We don't bother with decrementing the in-memory array
463 * element, we're about to overwrite it with the last array element
464 * anyway.
465 */
466 ecode = ntdb_brunlock(ntdb, ltype, off, 1);
467
468 /*
469 * Shrink the array by overwriting the element just unlocked with the
470 * last array element.
471 */
472 *lck = ntdb->file->lockrecs[--ntdb->file->num_lockrecs];
473
474 return ecode;
475 }
476
477 /*
478 get the transaction lock
479 */
480 enum NTDB_ERROR ntdb_transaction_lock(struct ntdb_context *ntdb, int ltype)
481 {
482 return ntdb_nest_lock(ntdb, NTDB_TRANSACTION_LOCK, ltype, NTDB_LOCK_WAIT);
483 }
484
485 /*
486 release the transaction lock
487 */
488 void ntdb_transaction_unlock(struct ntdb_context *ntdb, int ltype)
489 {
490 ntdb_nest_unlock(ntdb, NTDB_TRANSACTION_LOCK, ltype);
491 }
492
493 /* We only need to lock individual bytes, but Linux merges consecutive locks
494 * so we lock in contiguous ranges. */
495 static enum NTDB_ERROR ntdb_lock_gradual(struct ntdb_context *ntdb,
496 int ltype, enum ntdb_lock_flags flags,
497 ntdb_off_t off, ntdb_off_t len)
498 {
499 enum NTDB_ERROR ecode;
500 enum ntdb_lock_flags nb_flags = (flags & ~NTDB_LOCK_WAIT);
501
502 if (len <= 1) {
503 /* 0 would mean to end-of-file... */
504 assert(len != 0);
505 /* Single hash. Just do blocking lock. */
506 return ntdb_brlock(ntdb, ltype, off, len, flags);
507 }
508
509 /* First we try non-blocking. */
510 ecode = ntdb_brlock(ntdb, ltype, off, len, nb_flags);
511 if (ecode != NTDB_ERR_LOCK) {
512 return ecode;
513 }
514
515 /* Try locking first half, then second. */
516 ecode = ntdb_lock_gradual(ntdb, ltype, flags, off, len / 2);
517 if (ecode != NTDB_SUCCESS)
518 return ecode;
519
520 ecode = ntdb_lock_gradual(ntdb, ltype, flags,
521 off + len / 2, len - len / 2);
522 if (ecode != NTDB_SUCCESS) {
523 ntdb_brunlock(ntdb, ltype, off, len / 2);
524 }
525 return ecode;
526 }
527
528 /* lock/unlock entire database. It can only be upgradable if you have some
529 * other way of guaranteeing exclusivity (ie. transaction write lock). */
530 enum NTDB_ERROR ntdb_allrecord_lock(struct ntdb_context *ntdb, int ltype,
531 enum ntdb_lock_flags flags, bool upgradable)
532 {
533 enum NTDB_ERROR ecode;
534 ntdb_bool_err berr;
535
536 if (ntdb->flags & NTDB_NOLOCK) {
537 return NTDB_SUCCESS;
538 }
539
540 if (!check_lock_pid(ntdb, "ntdb_allrecord_lock", true)) {
541 return NTDB_ERR_LOCK;
542 }
543
544 if (ntdb->file->allrecord_lock.count) {
545 if (ntdb->file->allrecord_lock.owner != ntdb) {
546 return owner_conflict(ntdb, "ntdb_allrecord_lock");
547 }
548
549 if (ltype == F_RDLCK
550 || ntdb->file->allrecord_lock.ltype == F_WRLCK) {
551 ntdb->file->allrecord_lock.count++;
552 return NTDB_SUCCESS;
553 }
554
555 /* a global lock of a different type exists */
556 return ntdb_logerr(ntdb, NTDB_ERR_LOCK, NTDB_LOG_USE_ERROR,
557 "ntdb_allrecord_lock: already have %s lock",
558 ntdb->file->allrecord_lock.ltype == F_RDLCK
559 ? "read" : "write");
560 }
561
562 if (ntdb_has_hash_locks(ntdb)) {
563 /* can't combine global and chain locks */
564 return ntdb_logerr(ntdb, NTDB_ERR_LOCK, NTDB_LOG_USE_ERROR,
565 "ntdb_allrecord_lock:"
566 " already have chain lock");
567 }
568
569 if (upgradable && ltype != F_RDLCK) {
570 /* ntdb error: you can't upgrade a write lock! */
571 return ntdb_logerr(ntdb, NTDB_ERR_LOCK, NTDB_LOG_ERROR,
572 "ntdb_allrecord_lock:"
573 " can't upgrade a write lock");
574 }
575
576 ntdb->stats.locks++;
577 again:
578 /* Lock hashes, gradually. */
579 ecode = ntdb_lock_gradual(ntdb, ltype, flags, NTDB_HASH_LOCK_START,
580 1 << ntdb->hash_bits);
581 if (ecode != NTDB_SUCCESS)
582 return ecode;
583
584 /* Lock free tables: there to end of file. */
585 ecode = ntdb_brlock(ntdb, ltype,
586 NTDB_HASH_LOCK_START + (1 << ntdb->hash_bits),
587 0, flags);
588 if (ecode != NTDB_SUCCESS) {
589 ntdb_brunlock(ntdb, ltype, NTDB_HASH_LOCK_START,
590 1 << ntdb->hash_bits);
591 return ecode;
592 }
593
594 ntdb->file->allrecord_lock.owner = ntdb;
595 ntdb->file->allrecord_lock.count = 1;
596 /* If it's upgradable, it's actually exclusive so we can treat
597 * it as a write lock. */
598 ntdb->file->allrecord_lock.ltype = upgradable ? F_WRLCK : ltype;
599 ntdb->file->allrecord_lock.off = upgradable;
600
601 /* Now check for needing recovery. */
602 if (flags & NTDB_LOCK_NOCHECK)
603 return NTDB_SUCCESS;
604
605 berr = ntdb_needs_recovery(ntdb);
606 if (likely(berr == false))
607 return NTDB_SUCCESS;
608
609 ntdb_allrecord_unlock(ntdb, ltype);
610 if (berr < 0)
611 return NTDB_OFF_TO_ERR(berr);
612 ecode = ntdb_lock_and_recover(ntdb);
613 if (ecode != NTDB_SUCCESS) {
614 return ecode;
615 }
616 goto again;
617 }
618
619 enum NTDB_ERROR ntdb_lock_open(struct ntdb_context *ntdb,
620 int ltype, enum ntdb_lock_flags flags)
621 {
622 return ntdb_nest_lock(ntdb, NTDB_OPEN_LOCK, ltype, flags);
623 }
624
625 void ntdb_unlock_open(struct ntdb_context *ntdb, int ltype)
626 {
627 ntdb_nest_unlock(ntdb, NTDB_OPEN_LOCK, ltype);
628 }
629
630 bool ntdb_has_open_lock(struct ntdb_context *ntdb)
631 {
632 return !(ntdb->flags & NTDB_NOLOCK)
633 && find_nestlock(ntdb, NTDB_OPEN_LOCK, ntdb) != NULL;
634 }
635
636 enum NTDB_ERROR ntdb_lock_expand(struct ntdb_context *ntdb, int ltype)
637 {
638 /* Lock doesn't protect data, so don't check (we recurse if we do!) */
639 return ntdb_nest_lock(ntdb, NTDB_EXPANSION_LOCK, ltype,
640 NTDB_LOCK_WAIT | NTDB_LOCK_NOCHECK);
641 }
642
643 void ntdb_unlock_expand(struct ntdb_context *ntdb, int ltype)
644 {
645 ntdb_nest_unlock(ntdb, NTDB_EXPANSION_LOCK, ltype);
646 }
647
648 /* unlock entire db */
649 void ntdb_allrecord_unlock(struct ntdb_context *ntdb, int ltype)
650 {
651 if (ntdb->flags & NTDB_NOLOCK)
652 return;
653
654 if (ntdb->file->allrecord_lock.count == 0) {
655 ntdb_logerr(ntdb, NTDB_ERR_LOCK, NTDB_LOG_USE_ERROR,
656 "ntdb_allrecord_unlock: not locked!");
657 return;
658 }
659
660 if (ntdb->file->allrecord_lock.owner != ntdb) {
661 ntdb_logerr(ntdb, NTDB_ERR_LOCK, NTDB_LOG_USE_ERROR,
662 "ntdb_allrecord_unlock: not locked by us!");
663 return;
664 }
665
666 /* Upgradable locks are marked as write locks. */
667 if (ntdb->file->allrecord_lock.ltype != ltype
668 && (!ntdb->file->allrecord_lock.off || ltype != F_RDLCK)) {
669 ntdb_logerr(ntdb, NTDB_ERR_LOCK, NTDB_LOG_ERROR,
670 "ntdb_allrecord_unlock: have %s lock",
671 ntdb->file->allrecord_lock.ltype == F_RDLCK
672 ? "read" : "write");
673 return;
674 }
675
676 if (ntdb->file->allrecord_lock.count > 1) {
677 ntdb->file->allrecord_lock.count--;
678 return;
679 }
680
681 ntdb->file->allrecord_lock.count = 0;
682 ntdb->file->allrecord_lock.ltype = 0;
683
684 ntdb_brunlock(ntdb, ltype, NTDB_HASH_LOCK_START, 0);
685 }
686
687 bool ntdb_has_expansion_lock(struct ntdb_context *ntdb)
688 {
689 return find_nestlock(ntdb, NTDB_EXPANSION_LOCK, ntdb) != NULL;
690 }
691
692 bool ntdb_has_hash_locks(struct ntdb_context *ntdb)
693 {
694 unsigned int i;
695
696 for (i=0; i<ntdb->file->num_lockrecs; i++) {
697 if (ntdb->file->lockrecs[i].off >= NTDB_HASH_LOCK_START
698 && ntdb->file->lockrecs[i].off < (NTDB_HASH_LOCK_START
699 + (1 << ntdb->hash_bits)))
700 return true;
701 }
702 return false;
703 }
704
705 static bool ntdb_has_free_lock(struct ntdb_context *ntdb)
706 {
707 unsigned int i;
708
709 if (ntdb->flags & NTDB_NOLOCK)
710 return false;
711
712 for (i=0; i<ntdb->file->num_lockrecs; i++) {
713 if (ntdb->file->lockrecs[i].off
714 > NTDB_HASH_LOCK_START + (1 << ntdb->hash_bits))
715 return true;
716 }
717 return false;
718 }
719
720 enum NTDB_ERROR ntdb_lock_hash(struct ntdb_context *ntdb,
721 unsigned int h,
722 int ltype)
723 {
724 unsigned l = NTDB_HASH_LOCK_START + h;
725
726 assert(h < (1 << ntdb->hash_bits));
727
728 /* a allrecord lock allows us to avoid per chain locks */
729 if (ntdb->file->allrecord_lock.count) {
730 if (!check_lock_pid(ntdb, "ntdb_lock_hashes", true))
731 return NTDB_ERR_LOCK;
732
733 if (ntdb->file->allrecord_lock.owner != ntdb)
734 return owner_conflict(ntdb, "ntdb_lock_hashes");
735 if (ltype == ntdb->file->allrecord_lock.ltype
736 || ltype == F_RDLCK) {
737 return NTDB_SUCCESS;
738 }
739
740 return ntdb_logerr(ntdb, NTDB_ERR_LOCK, NTDB_LOG_USE_ERROR,
741 "ntdb_lock_hashes:"
742 " already have %s allrecordlock",
743 ntdb->file->allrecord_lock.ltype == F_RDLCK
744 ? "read" : "write");
745 }
746
747 if (ntdb_has_free_lock(ntdb)) {
748 return ntdb_logerr(ntdb, NTDB_ERR_LOCK, NTDB_LOG_ERROR,
749 "ntdb_lock_hashes: already have free lock");
750 }
751
752 if (ntdb_has_expansion_lock(ntdb)) {
753 return ntdb_logerr(ntdb, NTDB_ERR_LOCK, NTDB_LOG_ERROR,
754 "ntdb_lock_hashes:"
755 " already have expansion lock");
756 }
757
758 return ntdb_nest_lock(ntdb, l, ltype, NTDB_LOCK_WAIT);
759 }
760
761 enum NTDB_ERROR ntdb_unlock_hash(struct ntdb_context *ntdb,
762 unsigned int h, int ltype)
763 {
764 unsigned l = NTDB_HASH_LOCK_START + (h & ((1 << ntdb->hash_bits)-1));
765
766 if (ntdb->flags & NTDB_NOLOCK)
767 return 0;
768
769 /* a allrecord lock allows us to avoid per chain locks */
770 if (ntdb->file->allrecord_lock.count) {
771 if (ntdb->file->allrecord_lock.ltype == F_RDLCK
772 && ltype == F_WRLCK) {
773 return ntdb_logerr(ntdb, NTDB_ERR_LOCK, NTDB_LOG_ERROR,
774 "ntdb_unlock_hashes RO allrecord!");
775 }
776 if (ntdb->file->allrecord_lock.owner != ntdb) {
777 return ntdb_logerr(ntdb, NTDB_ERR_LOCK, NTDB_LOG_USE_ERROR,
778 "ntdb_unlock_hashes:"
779 " not locked by us!");
780 }
781 return NTDB_SUCCESS;
782 }
783
784 return ntdb_nest_unlock(ntdb, l, ltype);
785 }
786
787 /* Hash locks use NTDB_HASH_LOCK_START + <number of hash entries>..
788 * Then we begin; bucket offsets are sizeof(ntdb_len_t) apart, so we divide.
789 * The result is that on 32 bit systems we don't use lock values > 2^31 on
790 * files that are less than 4GB.
791 */
792 static ntdb_off_t free_lock_off(const struct ntdb_context *ntdb,
793 ntdb_off_t b_off)
794 {
795 return NTDB_HASH_LOCK_START + (1 << ntdb->hash_bits)
796 + b_off / sizeof(ntdb_off_t);
797 }
798
799 enum NTDB_ERROR ntdb_lock_free_bucket(struct ntdb_context *ntdb, ntdb_off_t b_off,
800 enum ntdb_lock_flags waitflag)
801 {
802 assert(b_off >= sizeof(struct ntdb_header));
803
804 if (ntdb->flags & NTDB_NOLOCK)
805 return 0;
806
807 /* a allrecord lock allows us to avoid per chain locks */
808 if (ntdb->file->allrecord_lock.count) {
809 if (!check_lock_pid(ntdb, "ntdb_lock_free_bucket", true))
810 return NTDB_ERR_LOCK;
811
812 if (ntdb->file->allrecord_lock.owner != ntdb) {
813 return owner_conflict(ntdb, "ntdb_lock_free_bucket");
814 }
815
816 if (ntdb->file->allrecord_lock.ltype == F_WRLCK)
817 return 0;
818 return ntdb_logerr(ntdb, NTDB_ERR_LOCK, NTDB_LOG_ERROR,
819 "ntdb_lock_free_bucket with"
820 " read-only allrecordlock!");
821 }
822
823 #if 0 /* FIXME */
824 if (ntdb_has_expansion_lock(ntdb)) {
825 return ntdb_logerr(ntdb, NTDB_ERR_LOCK, NTDB_LOG_ERROR,
826 "ntdb_lock_free_bucket:"
827 " already have expansion lock");
828 }
829 #endif
830
831 return ntdb_nest_lock(ntdb, free_lock_off(ntdb, b_off), F_WRLCK,
832 waitflag);
833 }
834
835 void ntdb_unlock_free_bucket(struct ntdb_context *ntdb, ntdb_off_t b_off)
836 {
837 if (ntdb->file->allrecord_lock.count)
838 return;
839
840 ntdb_nest_unlock(ntdb, free_lock_off(ntdb, b_off), F_WRLCK);
841 }
842
843 _PUBLIC_ enum NTDB_ERROR ntdb_lockall(struct ntdb_context *ntdb)
844 {
845 return ntdb_allrecord_lock(ntdb, F_WRLCK, NTDB_LOCK_WAIT, false);
846 }
847
848 _PUBLIC_ void ntdb_unlockall(struct ntdb_context *ntdb)
849 {
850 ntdb_allrecord_unlock(ntdb, F_WRLCK);
851 }
852
853 _PUBLIC_ enum NTDB_ERROR ntdb_lockall_read(struct ntdb_context *ntdb)
854 {
855 return ntdb_allrecord_lock(ntdb, F_RDLCK, NTDB_LOCK_WAIT, false);
856 }
857
858 _PUBLIC_ void ntdb_unlockall_read(struct ntdb_context *ntdb)
859 {
860 ntdb_allrecord_unlock(ntdb, F_RDLCK);
861 }
862
863 void ntdb_lock_cleanup(struct ntdb_context *ntdb)
864 {
865 unsigned int i;
866
867 /* We don't want to warn: they're allowed to close ntdb after fork. */
868 if (!check_lock_pid(ntdb, "ntdb_close", false))
869 return;
870
871 while (ntdb->file->allrecord_lock.count
872 && ntdb->file->allrecord_lock.owner == ntdb) {
873 ntdb_allrecord_unlock(ntdb, ntdb->file->allrecord_lock.ltype);
874 }
875
876 for (i=0; i<ntdb->file->num_lockrecs; i++) {
877 if (ntdb->file->lockrecs[i].owner == ntdb) {
878 ntdb_nest_unlock(ntdb,
879 ntdb->file->lockrecs[i].off,
880 ntdb->file->lockrecs[i].ltype);
881 i--;
882 }
883 }
884 }
reg import