2 Unix SMB/CIFS implementation.
4 trivial database library
6 Copyright (C) Andrew Tridgell 1999-2005
7 Copyright (C) Paul `Rusty' Russell 2000
8 Copyright (C) Jeremy Allison 2000-2003
10 ** NOTE! The following LGPL license applies to the tdb
11 ** library. This does NOT imply that all of Samba is released
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.
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.
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/>.
28 #include "tdb_private.h"
30 void tdb_setalarm_sigptr(struct tdb_context *tdb, volatile sig_atomic_t *ptr)
32 tdb->interrupt_sig_ptr = ptr;
35 static int fcntl_lock(struct tdb_context *tdb,
36 int rw, off_t off, off_t len, bool waitflag)
41 fl.l_whence = SEEK_SET;
47 return fcntl(tdb->fd, F_SETLKW, &fl);
49 return fcntl(tdb->fd, F_SETLK, &fl);
52 static int fcntl_unlock(struct tdb_context *tdb, int rw, off_t off, off_t len)
55 #if 0 /* Check they matched up locks and unlocks correctly. */
60 locks = fopen("/proc/locks", "r");
62 while (fgets(line, 80, locks)) {
66 /* eg. 1: FLOCK ADVISORY WRITE 2440 08:01:2180826 0 EOF */
67 p = strchr(line, ':') + 1;
68 if (strncmp(p, " POSIX ADVISORY ", strlen(" POSIX ADVISORY ")))
70 p += strlen(" FLOCK ADVISORY ");
71 if (strncmp(p, "READ ", strlen("READ ")) == 0)
73 else if (strncmp(p, "WRITE ", strlen("WRITE ")) == 0)
78 if (atoi(p) != getpid())
80 p = strchr(strchr(p, ' ') + 1, ' ') + 1;
82 p = strchr(p, ' ') + 1;
83 if (strncmp(p, "EOF", 3) == 0)
86 l = atoi(p) - start + 1;
90 fprintf(stderr, "Len %u should be %u: %s",
95 fprintf(stderr, "Type %s wrong: %s",
96 rw == F_RDLCK ? "READ" : "WRITE", line);
105 fprintf(stderr, "Unlock on %u@%u not found!\n",
114 fl.l_whence = SEEK_SET;
119 return fcntl(tdb->fd, F_SETLKW, &fl);
122 /* a byte range locking function - return 0 on success
123 this functions locks/unlocks 1 byte at the specified offset.
125 On error, errno is also set so that errors are passed back properly
128 note that a len of zero means lock to end of file
130 int tdb_brlock(struct tdb_context *tdb,
131 int rw_type, tdb_off_t offset, size_t len,
132 enum tdb_lock_flags flags)
136 if (tdb->flags & TDB_NOLOCK) {
140 if (flags & TDB_LOCK_MARK_ONLY) {
144 if ((rw_type == F_WRLCK) && (tdb->read_only || tdb->traverse_read)) {
145 tdb->ecode = TDB_ERR_RDONLY;
150 ret = fcntl_lock(tdb, rw_type, offset, len,
151 flags & TDB_LOCK_WAIT);
152 /* Check for a sigalarm break. */
153 if (ret == -1 && errno == EINTR &&
154 tdb->interrupt_sig_ptr &&
155 *tdb->interrupt_sig_ptr) {
158 } while (ret == -1 && errno == EINTR);
161 tdb->ecode = TDB_ERR_LOCK;
162 /* Generic lock error. errno set by fcntl.
163 * EAGAIN is an expected return from non-blocking
165 if (!(flags & TDB_LOCK_PROBE) && errno != EAGAIN) {
166 TDB_LOG((tdb, TDB_DEBUG_TRACE,"tdb_brlock failed (fd=%d) at offset %d rw_type=%d flags=%d len=%d\n",
167 tdb->fd, offset, rw_type, flags, (int)len));
174 int tdb_brunlock(struct tdb_context *tdb,
175 int rw_type, tdb_off_t offset, size_t len)
179 if (tdb->flags & TDB_NOLOCK) {
184 ret = fcntl_unlock(tdb, rw_type, offset, len);
185 } while (ret == -1 && errno == EINTR);
188 TDB_LOG((tdb, TDB_DEBUG_TRACE,"tdb_brunlock failed (fd=%d) at offset %d rw_type=%d len=%d\n",
189 tdb->fd, offset, rw_type, (int)len));
195 upgrade a read lock to a write lock. This needs to be handled in a
196 special way as some OSes (such as solaris) have too conservative
197 deadlock detection and claim a deadlock when progress can be
198 made. For those OSes we may loop for a while.
200 int tdb_brlock_upgrade(struct tdb_context *tdb, tdb_off_t offset, size_t len)
205 if (tdb_brlock(tdb, F_WRLCK, offset, len,
206 TDB_LOCK_WAIT|TDB_LOCK_PROBE) == 0) {
209 if (errno != EDEADLK) {
212 /* sleep for as short a time as we can - more portable than usleep() */
215 select(0, NULL, NULL, NULL, &tv);
217 TDB_LOG((tdb, TDB_DEBUG_TRACE,"tdb_brlock_upgrade failed at offset %d\n", offset));
221 /* list -1 is the alloc list, otherwise a hash chain. */
222 static tdb_off_t lock_offset(int list)
224 return FREELIST_TOP + 4*list;
227 static struct tdb_lock_type *find_nestlock(struct tdb_context *tdb,
232 for (i=0; i<tdb->num_lockrecs; i++) {
233 if (tdb->lockrecs[i].off == offset) {
234 return &tdb->lockrecs[i];
240 /* lock an offset in the database. */
241 int tdb_nest_lock(struct tdb_context *tdb, uint32_t offset, int ltype,
242 enum tdb_lock_flags flags)
244 struct tdb_lock_type *new_lck;
246 if (offset >= lock_offset(tdb->header.hash_size)) {
247 tdb->ecode = TDB_ERR_LOCK;
248 TDB_LOG((tdb, TDB_DEBUG_ERROR,"tdb_lock: invalid offset %u for ltype=%d\n",
252 if (tdb->flags & TDB_NOLOCK)
255 new_lck = find_nestlock(tdb, offset);
258 * Just increment the in-memory struct, posix locks
265 new_lck = (struct tdb_lock_type *)realloc(
267 sizeof(*tdb->lockrecs) * (tdb->num_lockrecs+1));
268 if (new_lck == NULL) {
272 tdb->lockrecs = new_lck;
274 /* Since fcntl locks don't nest, we do a lock for the first one,
275 and simply bump the count for future ones */
276 if (tdb->methods->brlock(tdb, ltype, offset, 1, flags)) {
280 tdb->lockrecs[tdb->num_lockrecs].off = offset;
281 tdb->lockrecs[tdb->num_lockrecs].count = 1;
282 tdb->lockrecs[tdb->num_lockrecs].ltype = ltype;
288 /* lock a list in the database. list -1 is the alloc list */
289 int tdb_lock(struct tdb_context *tdb, int list, int ltype)
293 /* a allrecord lock allows us to avoid per chain locks */
294 if (tdb->allrecord_lock.count &&
295 (ltype == tdb->allrecord_lock.ltype || ltype == F_RDLCK)) {
299 if (tdb->allrecord_lock.count) {
300 tdb->ecode = TDB_ERR_LOCK;
303 ret = tdb_nest_lock(tdb, lock_offset(list), ltype,
307 TDB_LOG((tdb, TDB_DEBUG_ERROR, "tdb_lock failed on list %d "
308 "ltype=%d (%s)\n", list, ltype, strerror(errno)));
313 /* lock a list in the database. list -1 is the alloc list. non-blocking lock */
314 int tdb_lock_nonblock(struct tdb_context *tdb, int list, int ltype)
316 /* a allrecord lock allows us to avoid per chain locks */
317 if (tdb->allrecord_lock.count &&
318 (ltype == tdb->allrecord_lock.ltype || ltype == F_RDLCK)) {
322 if (tdb->allrecord_lock.count) {
323 tdb->ecode = TDB_ERR_LOCK;
327 return tdb_nest_lock(tdb, lock_offset(list), ltype, TDB_LOCK_NOWAIT);
331 int tdb_nest_unlock(struct tdb_context *tdb, uint32_t offset, int ltype,
335 struct tdb_lock_type *lck;
337 if (tdb->flags & TDB_NOLOCK)
341 if (offset >= lock_offset(tdb->header.hash_size)) {
342 TDB_LOG((tdb, TDB_DEBUG_ERROR, "tdb_unlock: offset %u invalid (%d)\n", offset, tdb->header.hash_size));
346 lck = find_nestlock(tdb, offset);
347 if ((lck == NULL) || (lck->count == 0)) {
348 TDB_LOG((tdb, TDB_DEBUG_ERROR, "tdb_unlock: count is 0\n"));
352 if (lck->count > 1) {
358 * This lock has count==1 left, so we need to unlock it in the
359 * kernel. We don't bother with decrementing the in-memory array
360 * element, we're about to overwrite it with the last array element
367 ret = tdb->methods->brunlock(tdb, ltype, offset, 1);
371 * Shrink the array by overwriting the element just unlocked with the
372 * last array element.
374 *lck = tdb->lockrecs[--tdb->num_lockrecs];
377 * We don't bother with realloc when the array shrinks, but if we have
378 * a completely idle tdb we should get rid of the locked array.
381 if (tdb->num_lockrecs == 0) {
382 SAFE_FREE(tdb->lockrecs);
386 TDB_LOG((tdb, TDB_DEBUG_ERROR, "tdb_unlock: An error occurred unlocking!\n"));
390 int tdb_unlock(struct tdb_context *tdb, int list, int ltype)
392 /* a global lock allows us to avoid per chain locks */
393 if (tdb->allrecord_lock.count &&
394 (ltype == tdb->allrecord_lock.ltype || ltype == F_RDLCK)) {
398 if (tdb->allrecord_lock.count) {
399 tdb->ecode = TDB_ERR_LOCK;
403 return tdb_nest_unlock(tdb, lock_offset(list), ltype, false);
407 get the transaction lock
409 int tdb_transaction_lock(struct tdb_context *tdb, int ltype)
411 return tdb_nest_lock(tdb, TRANSACTION_LOCK, ltype, TDB_LOCK_WAIT);
415 release the transaction lock
417 int tdb_transaction_unlock(struct tdb_context *tdb, int ltype)
419 return tdb_nest_unlock(tdb, TRANSACTION_LOCK, ltype, false);
425 /* lock/unlock entire database */
426 static int _tdb_lockall(struct tdb_context *tdb, int ltype,
427 enum tdb_lock_flags flags)
429 /* There are no locks on read-only dbs */
430 if (tdb->read_only || tdb->traverse_read) {
431 tdb->ecode = TDB_ERR_LOCK;
435 if (tdb->allrecord_lock.count && tdb->allrecord_lock.ltype == ltype) {
436 tdb->allrecord_lock.count++;
440 if (tdb->allrecord_lock.count) {
441 /* a global lock of a different type exists */
442 tdb->ecode = TDB_ERR_LOCK;
446 if (tdb_have_extra_locks(tdb)) {
447 /* can't combine global and chain locks */
448 tdb->ecode = TDB_ERR_LOCK;
452 if (tdb->methods->brlock(tdb, ltype,
453 FREELIST_TOP, 4*tdb->header.hash_size,
455 if (flags & TDB_LOCK_WAIT) {
456 TDB_LOG((tdb, TDB_DEBUG_ERROR, "tdb_lockall failed (%s)\n", strerror(errno)));
461 tdb->allrecord_lock.count = 1;
462 tdb->allrecord_lock.ltype = ltype;
469 /* unlock entire db */
470 static int _tdb_unlockall(struct tdb_context *tdb, int ltype, bool mark_lock)
472 /* There are no locks on read-only dbs */
473 if (tdb->read_only || tdb->traverse_read) {
474 tdb->ecode = TDB_ERR_LOCK;
478 if (tdb->allrecord_lock.ltype != ltype || tdb->allrecord_lock.count == 0) {
479 tdb->ecode = TDB_ERR_LOCK;
483 if (tdb->allrecord_lock.count > 1) {
484 tdb->allrecord_lock.count--;
489 tdb->methods->brunlock(tdb, ltype,
490 FREELIST_TOP, 4*tdb->header.hash_size)) {
491 TDB_LOG((tdb, TDB_DEBUG_ERROR, "tdb_unlockall failed (%s)\n", strerror(errno)));
495 tdb->allrecord_lock.count = 0;
496 tdb->allrecord_lock.ltype = 0;
501 /* lock entire database with write lock */
502 int tdb_lockall(struct tdb_context *tdb)
504 tdb_trace(tdb, "tdb_lockall");
505 return _tdb_lockall(tdb, F_WRLCK, TDB_LOCK_WAIT);
508 /* lock entire database with write lock - mark only */
509 int tdb_lockall_mark(struct tdb_context *tdb)
511 tdb_trace(tdb, "tdb_lockall_mark");
512 return _tdb_lockall(tdb, F_WRLCK, TDB_LOCK_MARK_ONLY);
515 /* unlock entire database with write lock - unmark only */
516 int tdb_lockall_unmark(struct tdb_context *tdb)
518 tdb_trace(tdb, "tdb_lockall_unmark");
519 return _tdb_unlockall(tdb, F_WRLCK, true);
522 /* lock entire database with write lock - nonblocking varient */
523 int tdb_lockall_nonblock(struct tdb_context *tdb)
525 int ret = _tdb_lockall(tdb, F_WRLCK, TDB_LOCK_NOWAIT);
526 tdb_trace_ret(tdb, "tdb_lockall_nonblock", ret);
530 /* unlock entire database with write lock */
531 int tdb_unlockall(struct tdb_context *tdb)
533 tdb_trace(tdb, "tdb_unlockall");
534 return _tdb_unlockall(tdb, F_WRLCK, false);
537 /* lock entire database with read lock */
538 int tdb_lockall_read(struct tdb_context *tdb)
540 tdb_trace(tdb, "tdb_lockall_read");
541 return _tdb_lockall(tdb, F_RDLCK, TDB_LOCK_WAIT);
544 /* lock entire database with read lock - nonblock varient */
545 int tdb_lockall_read_nonblock(struct tdb_context *tdb)
547 int ret = _tdb_lockall(tdb, F_RDLCK, TDB_LOCK_NOWAIT);
548 tdb_trace_ret(tdb, "tdb_lockall_read_nonblock", ret);
552 /* unlock entire database with read lock */
553 int tdb_unlockall_read(struct tdb_context *tdb)
555 tdb_trace(tdb, "tdb_unlockall_read");
556 return _tdb_unlockall(tdb, F_RDLCK, false);
559 /* lock/unlock one hash chain. This is meant to be used to reduce
560 contention - it cannot guarantee how many records will be locked */
561 int tdb_chainlock(struct tdb_context *tdb, TDB_DATA key)
563 int ret = tdb_lock(tdb, BUCKET(tdb->hash_fn(&key)), F_WRLCK);
564 tdb_trace_1rec(tdb, "tdb_chainlock", key);
568 /* lock/unlock one hash chain, non-blocking. This is meant to be used
569 to reduce contention - it cannot guarantee how many records will be
571 int tdb_chainlock_nonblock(struct tdb_context *tdb, TDB_DATA key)
573 int ret = tdb_lock_nonblock(tdb, BUCKET(tdb->hash_fn(&key)), F_WRLCK);
574 tdb_trace_1rec_ret(tdb, "tdb_chainlock_nonblock", key, ret);
578 /* mark a chain as locked without actually locking it. Warning! use with great caution! */
579 int tdb_chainlock_mark(struct tdb_context *tdb, TDB_DATA key)
581 int ret = tdb_nest_lock(tdb, lock_offset(BUCKET(tdb->hash_fn(&key))),
582 F_WRLCK, TDB_LOCK_MARK_ONLY);
583 tdb_trace_1rec(tdb, "tdb_chainlock_mark", key);
587 /* unmark a chain as locked without actually locking it. Warning! use with great caution! */
588 int tdb_chainlock_unmark(struct tdb_context *tdb, TDB_DATA key)
590 tdb_trace_1rec(tdb, "tdb_chainlock_unmark", key);
591 return tdb_nest_unlock(tdb, lock_offset(BUCKET(tdb->hash_fn(&key))),
595 int tdb_chainunlock(struct tdb_context *tdb, TDB_DATA key)
597 tdb_trace_1rec(tdb, "tdb_chainunlock", key);
598 return tdb_unlock(tdb, BUCKET(tdb->hash_fn(&key)), F_WRLCK);
601 int tdb_chainlock_read(struct tdb_context *tdb, TDB_DATA key)
604 ret = tdb_lock(tdb, BUCKET(tdb->hash_fn(&key)), F_RDLCK);
605 tdb_trace_1rec(tdb, "tdb_chainlock_read", key);
609 int tdb_chainunlock_read(struct tdb_context *tdb, TDB_DATA key)
611 tdb_trace_1rec(tdb, "tdb_chainunlock_read", key);
612 return tdb_unlock(tdb, BUCKET(tdb->hash_fn(&key)), F_RDLCK);
617 /* record lock stops delete underneath */
618 int tdb_lock_record(struct tdb_context *tdb, tdb_off_t off)
620 if (tdb->allrecord_lock.count) {
623 return off ? tdb->methods->brlock(tdb, F_RDLCK, off, 1, TDB_LOCK_WAIT) : 0;
627 Write locks override our own fcntl readlocks, so check it here.
628 Note this is meant to be F_SETLK, *not* F_SETLKW, as it's not
629 an error to fail to get the lock here.
631 int tdb_write_lock_record(struct tdb_context *tdb, tdb_off_t off)
633 struct tdb_traverse_lock *i;
634 for (i = &tdb->travlocks; i; i = i->next)
637 return tdb->methods->brlock(tdb, F_WRLCK, off, 1, TDB_LOCK_NOWAIT|TDB_LOCK_PROBE);
640 int tdb_write_unlock_record(struct tdb_context *tdb, tdb_off_t off)
642 return tdb->methods->brunlock(tdb, F_WRLCK, off, 1);
645 /* fcntl locks don't stack: avoid unlocking someone else's */
646 int tdb_unlock_record(struct tdb_context *tdb, tdb_off_t off)
648 struct tdb_traverse_lock *i;
651 if (tdb->allrecord_lock.count) {
657 for (i = &tdb->travlocks; i; i = i->next)
660 return (count == 1 ? tdb->methods->brunlock(tdb, F_RDLCK, off, 1) : 0);
663 bool tdb_have_extra_locks(struct tdb_context *tdb)
665 unsigned int extra = tdb->num_lockrecs;
667 if (tdb->allrecord_lock.count) {
671 /* We always hold the active lock if CLEAR_IF_FIRST. */
672 if (find_nestlock(tdb, ACTIVE_LOCK)) {
676 /* In a transaction, we expect to hold the transaction lock */
677 if (tdb->transaction && find_nestlock(tdb, TRANSACTION_LOCK)) {
684 /* The transaction code uses this to remove all locks. Note that this
685 may include OPEN_LOCK. */
686 void tdb_release_extra_locks(struct tdb_context *tdb)
688 unsigned int i, extra = 0;
690 if (tdb->allrecord_lock.count != 0) {
691 tdb_brunlock(tdb, tdb->allrecord_lock.ltype,
692 FREELIST_TOP, 4*tdb->header.hash_size);
693 tdb->allrecord_lock.count = 0;
696 for (i=0;i<tdb->num_lockrecs;i++) {
697 struct tdb_lock_type *lck = &tdb->lockrecs[i];
699 /* Don't release transaction or active locks! */
700 if (tdb->transaction && lck->off == TRANSACTION_LOCK) {
701 tdb->lockrecs[extra++] = *lck;
702 } else if (lck->off == ACTIVE_LOCK) {
703 tdb->lockrecs[extra++] = *lck;
705 tdb_brunlock(tdb, lck->ltype, lck->off, 1);
708 tdb->num_lockrecs = extra;
709 if (tdb->num_lockrecs == 0) {
710 SAFE_FREE(tdb->lockrecs);