2 Unix SMB/CIFS implementation.
4 trivial database library
6 Copyright (C) Andrew Tridgell 2005
8 ** NOTE! The following LGPL license applies to the tdb
9 ** library. This does NOT imply that all of Samba is released
12 This library is free software; you can redistribute it and/or
13 modify it under the terms of the GNU Lesser General Public
14 License as published by the Free Software Foundation; either
15 version 3 of the License, or (at your option) any later version.
17 This library is distributed in the hope that it will be useful,
18 but WITHOUT ANY WARRANTY; without even the implied warranty of
19 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
20 Lesser General Public License for more details.
22 You should have received a copy of the GNU Lesser General Public
23 License along with this library; if not, see <http://www.gnu.org/licenses/>.
26 #include "tdb_private.h"
31 - only allow a single transaction at a time per database. This makes
32 using the transaction API simpler, as otherwise the caller would
33 have to cope with temporary failures in transactions that conflict
34 with other current transactions
36 - keep the transaction recovery information in the same file as the
37 database, using a special 'transaction recovery' record pointed at
38 by the header. This removes the need for extra journal files as
39 used by some other databases
41 - dynamically allocated the transaction recover record, re-using it
42 for subsequent transactions. If a larger record is needed then
43 tdb_free() the old record to place it on the normal tdb freelist
44 before allocating the new record
46 - during transactions, keep a linked list of writes all that have
47 been performed by intercepting all tdb_write() calls. The hooked
48 transaction versions of tdb_read() and tdb_write() check this
49 linked list and try to use the elements of the list in preference
52 - don't allow any locks to be held when a transaction starts,
53 otherwise we can end up with deadlock (plus lack of lock nesting
54 in posix locks would mean the lock is lost)
56 - if the caller gains a lock during the transaction but doesn't
57 release it then fail the commit
59 - allow for nested calls to tdb_transaction_start(), re-using the
60 existing transaction record. If the inner transaction is cancelled
61 then a subsequent commit will fail
63 - keep a mirrored copy of the tdb hash chain heads to allow for the
64 fast hash heads scan on traverse, updating the mirrored copy in
65 the transaction version of tdb_write
67 - allow callers to mix transaction and non-transaction use of tdb,
68 although once a transaction is started then an exclusive lock is
69 gained until the transaction is committed or cancelled
71 - the commit stategy involves first saving away all modified data
72 into a linearised buffer in the transaction recovery area, then
73 marking the transaction recovery area with a magic value to
74 indicate a valid recovery record. In total 4 fsync/msync calls are
75 needed per commit to prevent race conditions. It might be possible
76 to reduce this to 3 or even 2 with some more work.
78 - check for a valid recovery record on open of the tdb, while the
79 open lock is held. Automatically recover from the transaction
80 recovery area if needed, then continue with the open as
81 usual. This allows for smooth crash recovery with no administrator
84 - if TDB_NOSYNC is passed to flags in tdb_open then transactions are
85 still available, but no transaction recovery area is used and no
86 fsync/msync calls are made.
88 - if TDB_ALLOW_NESTING is passed to flags in tdb open, or added using
89 tdb_add_flags() transaction nesting is enabled.
90 It resets the TDB_DISALLOW_NESTING flag, as both cannot be used together.
91 The default is that transaction nesting is allowed.
92 Note: this default may change in future versions of tdb.
94 Beware. when transactions are nested a transaction successfully
95 completed with tdb_transaction_commit() can be silently unrolled later.
97 - if TDB_DISALLOW_NESTING is passed to flags in tdb open, or added using
98 tdb_add_flags() transaction nesting is disabled.
99 It resets the TDB_ALLOW_NESTING flag, as both cannot be used together.
100 An attempt create a nested transaction will fail with TDB_ERR_NESTING.
101 The default is that transaction nesting is allowed.
102 Note: this default may change in future versions of tdb.
107 hold the context of any current transaction
109 struct tdb_transaction {
110 /* we keep a mirrored copy of the tdb hash heads here so
111 tdb_next_hash_chain() can operate efficiently */
112 uint32_t *hash_heads;
114 /* the original io methods - used to do IOs to the real db */
115 const struct tdb_methods *io_methods;
117 /* the list of transaction blocks. When a block is first
118 written to, it gets created in this list */
121 uint32_t block_size; /* bytes in each block */
122 uint32_t last_block_size; /* number of valid bytes in the last block */
124 /* non-zero when an internal transaction error has
125 occurred. All write operations will then fail until the
126 transaction is ended */
127 int transaction_error;
129 /* when inside a transaction we need to keep track of any
130 nested tdb_transaction_start() calls, as these are allowed,
131 but don't create a new transaction */
134 /* set when a prepare has already occurred */
136 tdb_off_t magic_offset;
138 /* old file size before transaction */
139 tdb_len_t old_map_size;
141 /* we should re-pack on commit */
147 read while in a transaction. We need to check first if the data is in our list
148 of transaction elements, then if not do a real read
150 static int transaction_read(struct tdb_context *tdb, tdb_off_t off, void *buf,
151 tdb_len_t len, int cv)
155 /* break it down into block sized ops */
156 while (len + (off % tdb->transaction->block_size) > tdb->transaction->block_size) {
157 tdb_len_t len2 = tdb->transaction->block_size - (off % tdb->transaction->block_size);
158 if (transaction_read(tdb, off, buf, len2, cv) != 0) {
163 buf = (void *)(len2 + (char *)buf);
170 blk = off / tdb->transaction->block_size;
172 /* see if we have it in the block list */
173 if (tdb->transaction->num_blocks <= blk ||
174 tdb->transaction->blocks[blk] == NULL) {
175 /* nope, do a real read */
176 if (tdb->transaction->io_methods->tdb_read(tdb, off, buf, len, cv) != 0) {
182 /* it is in the block list. Now check for the last block */
183 if (blk == tdb->transaction->num_blocks-1) {
184 if (len > tdb->transaction->last_block_size) {
189 /* now copy it out of this block */
190 memcpy(buf, tdb->transaction->blocks[blk] + (off % tdb->transaction->block_size), len);
192 tdb_convert(buf, len);
197 TDB_LOG((tdb, TDB_DEBUG_FATAL, "transaction_read: failed at off=%d len=%d\n", off, len));
198 tdb->ecode = TDB_ERR_IO;
199 tdb->transaction->transaction_error = 1;
205 write while in a transaction
207 static int transaction_write(struct tdb_context *tdb, tdb_off_t off,
208 const void *buf, tdb_len_t len)
212 /* Only a commit is allowed on a prepared transaction */
213 if (tdb->transaction->prepared) {
214 tdb->ecode = TDB_ERR_EINVAL;
215 TDB_LOG((tdb, TDB_DEBUG_FATAL, "transaction_write: transaction already prepared, write not allowed\n"));
216 tdb->transaction->transaction_error = 1;
220 /* if the write is to a hash head, then update the transaction
222 if (len == sizeof(tdb_off_t) && off >= FREELIST_TOP &&
223 off < FREELIST_TOP+TDB_HASHTABLE_SIZE(tdb)) {
224 uint32_t chain = (off-FREELIST_TOP) / sizeof(tdb_off_t);
225 memcpy(&tdb->transaction->hash_heads[chain], buf, len);
228 /* break it up into block sized chunks */
229 while (len + (off % tdb->transaction->block_size) > tdb->transaction->block_size) {
230 tdb_len_t len2 = tdb->transaction->block_size - (off % tdb->transaction->block_size);
231 if (transaction_write(tdb, off, buf, len2) != 0) {
237 buf = (const void *)(len2 + (const char *)buf);
245 blk = off / tdb->transaction->block_size;
246 off = off % tdb->transaction->block_size;
248 if (tdb->transaction->num_blocks <= blk) {
249 uint8_t **new_blocks;
250 /* expand the blocks array */
251 if (tdb->transaction->blocks == NULL) {
252 new_blocks = (uint8_t **)malloc(
253 (blk+1)*sizeof(uint8_t *));
255 new_blocks = (uint8_t **)realloc(
256 tdb->transaction->blocks,
257 (blk+1)*sizeof(uint8_t *));
259 if (new_blocks == NULL) {
260 tdb->ecode = TDB_ERR_OOM;
263 memset(&new_blocks[tdb->transaction->num_blocks], 0,
264 (1+(blk - tdb->transaction->num_blocks))*sizeof(uint8_t *));
265 tdb->transaction->blocks = new_blocks;
266 tdb->transaction->num_blocks = blk+1;
267 tdb->transaction->last_block_size = 0;
270 /* allocate and fill a block? */
271 if (tdb->transaction->blocks[blk] == NULL) {
272 tdb->transaction->blocks[blk] = (uint8_t *)calloc(tdb->transaction->block_size, 1);
273 if (tdb->transaction->blocks[blk] == NULL) {
274 tdb->ecode = TDB_ERR_OOM;
275 tdb->transaction->transaction_error = 1;
278 if (tdb->transaction->old_map_size > blk * tdb->transaction->block_size) {
279 tdb_len_t len2 = tdb->transaction->block_size;
280 if (len2 + (blk * tdb->transaction->block_size) > tdb->transaction->old_map_size) {
281 len2 = tdb->transaction->old_map_size - (blk * tdb->transaction->block_size);
283 if (tdb->transaction->io_methods->tdb_read(tdb, blk * tdb->transaction->block_size,
284 tdb->transaction->blocks[blk],
286 SAFE_FREE(tdb->transaction->blocks[blk]);
287 tdb->ecode = TDB_ERR_IO;
290 if (blk == tdb->transaction->num_blocks-1) {
291 tdb->transaction->last_block_size = len2;
296 /* overwrite part of an existing block */
298 memset(tdb->transaction->blocks[blk] + off, 0, len);
300 memcpy(tdb->transaction->blocks[blk] + off, buf, len);
302 if (blk == tdb->transaction->num_blocks-1) {
303 if (len + off > tdb->transaction->last_block_size) {
304 tdb->transaction->last_block_size = len + off;
311 TDB_LOG((tdb, TDB_DEBUG_FATAL, "transaction_write: failed at off=%d len=%d\n",
312 (blk*tdb->transaction->block_size) + off, len));
313 tdb->transaction->transaction_error = 1;
319 write while in a transaction - this varient never expands the transaction blocks, it only
320 updates existing blocks. This means it cannot change the recovery size
322 static int transaction_write_existing(struct tdb_context *tdb, tdb_off_t off,
323 const void *buf, tdb_len_t len)
327 /* break it up into block sized chunks */
328 while (len + (off % tdb->transaction->block_size) > tdb->transaction->block_size) {
329 tdb_len_t len2 = tdb->transaction->block_size - (off % tdb->transaction->block_size);
330 if (transaction_write_existing(tdb, off, buf, len2) != 0) {
336 buf = (const void *)(len2 + (const char *)buf);
344 blk = off / tdb->transaction->block_size;
345 off = off % tdb->transaction->block_size;
347 if (tdb->transaction->num_blocks <= blk ||
348 tdb->transaction->blocks[blk] == NULL) {
352 if (blk == tdb->transaction->num_blocks-1 &&
353 off + len > tdb->transaction->last_block_size) {
354 if (off >= tdb->transaction->last_block_size) {
357 len = tdb->transaction->last_block_size - off;
360 /* overwrite part of an existing block */
361 memcpy(tdb->transaction->blocks[blk] + off, buf, len);
368 accelerated hash chain head search, using the cached hash heads
370 static void transaction_next_hash_chain(struct tdb_context *tdb, uint32_t *chain)
373 for (;h < tdb->header.hash_size;h++) {
374 /* the +1 takes account of the freelist */
375 if (0 != tdb->transaction->hash_heads[h+1]) {
383 out of bounds check during a transaction
385 static int transaction_oob(struct tdb_context *tdb, tdb_off_t len, int probe)
387 if (len <= tdb->map_size) {
390 tdb->ecode = TDB_ERR_IO;
395 transaction version of tdb_expand().
397 static int transaction_expand_file(struct tdb_context *tdb, tdb_off_t size,
400 /* add a write to the transaction elements, so subsequent
401 reads see the zero data */
402 if (transaction_write(tdb, size, NULL, addition) != 0) {
406 tdb->transaction->need_repack = true;
411 static const struct tdb_methods transaction_methods = {
414 transaction_next_hash_chain,
416 transaction_expand_file,
421 start a tdb transaction. No token is returned, as only a single
422 transaction is allowed to be pending per tdb_context
424 static int _tdb_transaction_start(struct tdb_context *tdb,
425 enum tdb_lock_flags lockflags)
427 /* some sanity checks */
428 if (tdb->read_only || (tdb->flags & TDB_INTERNAL) || tdb->traverse_read) {
429 TDB_LOG((tdb, TDB_DEBUG_ERROR, "tdb_transaction_start: cannot start a transaction on a read-only or internal db\n"));
430 tdb->ecode = TDB_ERR_EINVAL;
434 /* cope with nested tdb_transaction_start() calls */
435 if (tdb->transaction != NULL) {
436 if (!(tdb->flags & TDB_ALLOW_NESTING)) {
437 tdb->ecode = TDB_ERR_NESTING;
440 tdb->transaction->nesting++;
441 TDB_LOG((tdb, TDB_DEBUG_TRACE, "tdb_transaction_start: nesting %d\n",
442 tdb->transaction->nesting));
446 if (tdb_have_extra_locks(tdb)) {
447 /* the caller must not have any locks when starting a
448 transaction as otherwise we'll be screwed by lack
449 of nested locks in posix */
450 TDB_LOG((tdb, TDB_DEBUG_ERROR, "tdb_transaction_start: cannot start a transaction with locks held\n"));
451 tdb->ecode = TDB_ERR_LOCK;
455 if (tdb->travlocks.next != NULL) {
456 /* you cannot use transactions inside a traverse (although you can use
457 traverse inside a transaction) as otherwise you can end up with
459 TDB_LOG((tdb, TDB_DEBUG_ERROR, "tdb_transaction_start: cannot start a transaction within a traverse\n"));
460 tdb->ecode = TDB_ERR_LOCK;
464 tdb->transaction = (struct tdb_transaction *)
465 calloc(sizeof(struct tdb_transaction), 1);
466 if (tdb->transaction == NULL) {
467 tdb->ecode = TDB_ERR_OOM;
471 /* a page at a time seems like a reasonable compromise between compactness and efficiency */
472 tdb->transaction->block_size = tdb->page_size;
474 /* get the transaction write lock. This is a blocking lock. As
475 discussed with Volker, there are a number of ways we could
476 make this async, which we will probably do in the future */
477 if (tdb_transaction_lock(tdb, F_WRLCK, lockflags) == -1) {
478 SAFE_FREE(tdb->transaction->blocks);
479 SAFE_FREE(tdb->transaction);
480 if ((lockflags & TDB_LOCK_WAIT) == 0) {
481 tdb->ecode = TDB_ERR_NOLOCK;
486 /* get a read lock from the freelist to the end of file. This
487 is upgraded to a write lock during the commit */
488 if (tdb_allrecord_lock(tdb, F_RDLCK, TDB_LOCK_WAIT, true) == -1) {
489 TDB_LOG((tdb, TDB_DEBUG_ERROR, "tdb_transaction_start: failed to get hash locks\n"));
490 goto fail_allrecord_lock;
493 /* setup a copy of the hash table heads so the hash scan in
494 traverse can be fast */
495 tdb->transaction->hash_heads = (uint32_t *)
496 calloc(tdb->header.hash_size+1, sizeof(uint32_t));
497 if (tdb->transaction->hash_heads == NULL) {
498 tdb->ecode = TDB_ERR_OOM;
501 if (tdb->methods->tdb_read(tdb, FREELIST_TOP, tdb->transaction->hash_heads,
502 TDB_HASHTABLE_SIZE(tdb), 0) != 0) {
503 TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_transaction_start: failed to read hash heads\n"));
504 tdb->ecode = TDB_ERR_IO;
508 /* make sure we know about any file expansions already done by
510 tdb->methods->tdb_oob(tdb, tdb->map_size + 1, 1);
511 tdb->transaction->old_map_size = tdb->map_size;
513 /* finally hook the io methods, replacing them with
514 transaction specific methods */
515 tdb->transaction->io_methods = tdb->methods;
516 tdb->methods = &transaction_methods;
518 /* Trace at the end, so we get sequence number correct. */
519 tdb_trace(tdb, "tdb_transaction_start");
523 tdb_allrecord_unlock(tdb, F_RDLCK, false);
525 tdb_transaction_unlock(tdb, F_WRLCK);
526 SAFE_FREE(tdb->transaction->blocks);
527 SAFE_FREE(tdb->transaction->hash_heads);
528 SAFE_FREE(tdb->transaction);
532 int tdb_transaction_start(struct tdb_context *tdb)
534 return _tdb_transaction_start(tdb, TDB_LOCK_WAIT);
537 int tdb_transaction_start_nonblock(struct tdb_context *tdb)
539 return _tdb_transaction_start(tdb, TDB_LOCK_NOWAIT|TDB_LOCK_PROBE);
545 static int transaction_sync(struct tdb_context *tdb, tdb_off_t offset, tdb_len_t length)
547 if (tdb->flags & TDB_NOSYNC) {
551 if (fdatasync(tdb->fd) != 0) {
552 tdb->ecode = TDB_ERR_IO;
553 TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_transaction: fsync failed\n"));
558 tdb_off_t moffset = offset & ~(tdb->page_size-1);
559 if (msync(moffset + (char *)tdb->map_ptr,
560 length + (offset - moffset), MS_SYNC) != 0) {
561 tdb->ecode = TDB_ERR_IO;
562 TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_transaction: msync failed - %s\n",
572 static int _tdb_transaction_cancel(struct tdb_context *tdb)
576 if (tdb->transaction == NULL) {
577 TDB_LOG((tdb, TDB_DEBUG_ERROR, "tdb_transaction_cancel: no transaction\n"));
581 if (tdb->transaction->nesting != 0) {
582 tdb->transaction->transaction_error = 1;
583 tdb->transaction->nesting--;
587 tdb->map_size = tdb->transaction->old_map_size;
589 /* free all the transaction blocks */
590 for (i=0;i<tdb->transaction->num_blocks;i++) {
591 if (tdb->transaction->blocks[i] != NULL) {
592 free(tdb->transaction->blocks[i]);
595 SAFE_FREE(tdb->transaction->blocks);
597 if (tdb->transaction->magic_offset) {
598 const struct tdb_methods *methods = tdb->transaction->io_methods;
599 const uint32_t invalid = TDB_RECOVERY_INVALID_MAGIC;
601 /* remove the recovery marker */
602 if (methods->tdb_write(tdb, tdb->transaction->magic_offset, &invalid, 4) == -1 ||
603 transaction_sync(tdb, tdb->transaction->magic_offset, 4) == -1) {
604 TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_transaction_cancel: failed to remove recovery magic\n"));
609 /* This also removes the OPEN_LOCK, if we have it. */
610 tdb_release_transaction_locks(tdb);
612 /* restore the normal io methods */
613 tdb->methods = tdb->transaction->io_methods;
615 SAFE_FREE(tdb->transaction->hash_heads);
616 SAFE_FREE(tdb->transaction);
622 cancel the current transaction
624 int tdb_transaction_cancel(struct tdb_context *tdb)
626 tdb_trace(tdb, "tdb_transaction_cancel");
627 return _tdb_transaction_cancel(tdb);
631 work out how much space the linearised recovery data will consume
633 static tdb_len_t tdb_recovery_size(struct tdb_context *tdb)
635 tdb_len_t recovery_size = 0;
638 recovery_size = sizeof(uint32_t);
639 for (i=0;i<tdb->transaction->num_blocks;i++) {
640 if (i * tdb->transaction->block_size >= tdb->transaction->old_map_size) {
643 if (tdb->transaction->blocks[i] == NULL) {
646 recovery_size += 2*sizeof(tdb_off_t);
647 if (i == tdb->transaction->num_blocks-1) {
648 recovery_size += tdb->transaction->last_block_size;
650 recovery_size += tdb->transaction->block_size;
654 return recovery_size;
658 allocate the recovery area, or use an existing recovery area if it is
661 static int tdb_recovery_allocate(struct tdb_context *tdb,
662 tdb_len_t *recovery_size,
663 tdb_off_t *recovery_offset,
664 tdb_len_t *recovery_max_size)
666 struct tdb_record rec;
667 const struct tdb_methods *methods = tdb->transaction->io_methods;
668 tdb_off_t recovery_head;
670 if (tdb_ofs_read(tdb, TDB_RECOVERY_HEAD, &recovery_head) == -1) {
671 TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_recovery_allocate: failed to read recovery head\n"));
677 if (recovery_head != 0) {
678 if (methods->tdb_read(tdb, recovery_head, &rec, sizeof(rec), DOCONV()) == -1) {
679 TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_recovery_allocate: failed to read recovery record\n"));
682 /* ignore invalid recovery regions: can happen in crash */
683 if (rec.magic != TDB_RECOVERY_MAGIC &&
684 rec.magic != TDB_RECOVERY_INVALID_MAGIC) {
689 *recovery_size = tdb_recovery_size(tdb);
691 if (recovery_head != 0 && *recovery_size <= rec.rec_len) {
692 /* it fits in the existing area */
693 *recovery_max_size = rec.rec_len;
694 *recovery_offset = recovery_head;
698 /* we need to free up the old recovery area, then allocate a
699 new one at the end of the file. Note that we cannot use
700 tdb_allocate() to allocate the new one as that might return
701 us an area that is being currently used (as of the start of
703 if (recovery_head != 0) {
704 if (tdb_free(tdb, recovery_head, &rec) == -1) {
705 TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_recovery_allocate: failed to free previous recovery area\n"));
710 /* the tdb_free() call might have increased the recovery size */
711 *recovery_size = tdb_recovery_size(tdb);
713 /* round up to a multiple of page size */
714 *recovery_max_size = TDB_ALIGN(sizeof(rec) + *recovery_size, tdb->page_size) - sizeof(rec);
715 *recovery_offset = tdb->map_size;
716 recovery_head = *recovery_offset;
718 if (methods->tdb_expand_file(tdb, tdb->transaction->old_map_size,
719 (tdb->map_size - tdb->transaction->old_map_size) +
720 sizeof(rec) + *recovery_max_size) == -1) {
721 TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_recovery_allocate: failed to create recovery area\n"));
725 /* remap the file (if using mmap) */
726 methods->tdb_oob(tdb, tdb->map_size + 1, 1);
728 /* we have to reset the old map size so that we don't try to expand the file
729 again in the transaction commit, which would destroy the recovery area */
730 tdb->transaction->old_map_size = tdb->map_size;
732 /* write the recovery header offset and sync - we can sync without a race here
733 as the magic ptr in the recovery record has not been set */
734 CONVERT(recovery_head);
735 if (methods->tdb_write(tdb, TDB_RECOVERY_HEAD,
736 &recovery_head, sizeof(tdb_off_t)) == -1) {
737 TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_recovery_allocate: failed to write recovery head\n"));
740 if (transaction_write_existing(tdb, TDB_RECOVERY_HEAD, &recovery_head, sizeof(tdb_off_t)) == -1) {
741 TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_recovery_allocate: failed to write recovery head\n"));
750 setup the recovery data that will be used on a crash during commit
752 static int transaction_setup_recovery(struct tdb_context *tdb,
753 tdb_off_t *magic_offset)
755 tdb_len_t recovery_size;
756 unsigned char *data, *p;
757 const struct tdb_methods *methods = tdb->transaction->io_methods;
758 struct tdb_record *rec;
759 tdb_off_t recovery_offset, recovery_max_size;
760 tdb_off_t old_map_size = tdb->transaction->old_map_size;
761 uint32_t magic, tailer;
765 check that the recovery area has enough space
767 if (tdb_recovery_allocate(tdb, &recovery_size,
768 &recovery_offset, &recovery_max_size) == -1) {
772 data = (unsigned char *)malloc(recovery_size + sizeof(*rec));
774 tdb->ecode = TDB_ERR_OOM;
778 rec = (struct tdb_record *)data;
779 memset(rec, 0, sizeof(*rec));
781 rec->magic = TDB_RECOVERY_INVALID_MAGIC;
782 rec->data_len = recovery_size;
783 rec->rec_len = recovery_max_size;
784 rec->key_len = old_map_size;
787 /* build the recovery data into a single blob to allow us to do a single
788 large write, which should be more efficient */
789 p = data + sizeof(*rec);
790 for (i=0;i<tdb->transaction->num_blocks;i++) {
794 if (tdb->transaction->blocks[i] == NULL) {
798 offset = i * tdb->transaction->block_size;
799 length = tdb->transaction->block_size;
800 if (i == tdb->transaction->num_blocks-1) {
801 length = tdb->transaction->last_block_size;
804 if (offset >= old_map_size) {
807 if (offset + length > tdb->transaction->old_map_size) {
808 TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_transaction_setup_recovery: transaction data over new region boundary\n"));
810 tdb->ecode = TDB_ERR_CORRUPT;
813 memcpy(p, &offset, 4);
814 memcpy(p+4, &length, 4);
818 /* the recovery area contains the old data, not the
819 new data, so we have to call the original tdb_read
821 if (methods->tdb_read(tdb, offset, p + 8, length, 0) != 0) {
823 tdb->ecode = TDB_ERR_IO;
830 tailer = sizeof(*rec) + recovery_max_size;
831 memcpy(p, &tailer, 4);
834 /* write the recovery data to the recovery area */
835 if (methods->tdb_write(tdb, recovery_offset, data, sizeof(*rec) + recovery_size) == -1) {
836 TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_transaction_setup_recovery: failed to write recovery data\n"));
838 tdb->ecode = TDB_ERR_IO;
841 if (transaction_write_existing(tdb, recovery_offset, data, sizeof(*rec) + recovery_size) == -1) {
842 TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_transaction_setup_recovery: failed to write secondary recovery data\n"));
844 tdb->ecode = TDB_ERR_IO;
848 /* as we don't have ordered writes, we have to sync the recovery
849 data before we update the magic to indicate that the recovery
851 if (transaction_sync(tdb, recovery_offset, sizeof(*rec) + recovery_size) == -1) {
858 magic = TDB_RECOVERY_MAGIC;
861 *magic_offset = recovery_offset + offsetof(struct tdb_record, magic);
863 if (methods->tdb_write(tdb, *magic_offset, &magic, sizeof(magic)) == -1) {
864 TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_transaction_setup_recovery: failed to write recovery magic\n"));
865 tdb->ecode = TDB_ERR_IO;
868 if (transaction_write_existing(tdb, *magic_offset, &magic, sizeof(magic)) == -1) {
869 TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_transaction_setup_recovery: failed to write secondary recovery magic\n"));
870 tdb->ecode = TDB_ERR_IO;
874 /* ensure the recovery magic marker is on disk */
875 if (transaction_sync(tdb, *magic_offset, sizeof(magic)) == -1) {
882 static int _tdb_transaction_prepare_commit(struct tdb_context *tdb)
884 const struct tdb_methods *methods;
886 if (tdb->transaction == NULL) {
887 TDB_LOG((tdb, TDB_DEBUG_ERROR, "tdb_transaction_prepare_commit: no transaction\n"));
891 if (tdb->transaction->prepared) {
892 tdb->ecode = TDB_ERR_EINVAL;
893 _tdb_transaction_cancel(tdb);
894 TDB_LOG((tdb, TDB_DEBUG_ERROR, "tdb_transaction_prepare_commit: transaction already prepared\n"));
898 if (tdb->transaction->transaction_error) {
899 tdb->ecode = TDB_ERR_IO;
900 _tdb_transaction_cancel(tdb);
901 TDB_LOG((tdb, TDB_DEBUG_ERROR, "tdb_transaction_prepare_commit: transaction error pending\n"));
906 if (tdb->transaction->nesting != 0) {
910 /* check for a null transaction */
911 if (tdb->transaction->blocks == NULL) {
915 methods = tdb->transaction->io_methods;
917 /* if there are any locks pending then the caller has not
918 nested their locks properly, so fail the transaction */
919 if (tdb_have_extra_locks(tdb)) {
920 tdb->ecode = TDB_ERR_LOCK;
921 TDB_LOG((tdb, TDB_DEBUG_ERROR, "tdb_transaction_prepare_commit: locks pending on commit\n"));
922 _tdb_transaction_cancel(tdb);
926 /* upgrade the main transaction lock region to a write lock */
927 if (tdb_allrecord_upgrade(tdb) == -1) {
928 TDB_LOG((tdb, TDB_DEBUG_ERROR, "tdb_transaction_prepare_commit: failed to upgrade hash locks\n"));
929 _tdb_transaction_cancel(tdb);
933 /* get the open lock - this prevents new users attaching to the database
935 if (tdb_nest_lock(tdb, OPEN_LOCK, F_WRLCK, TDB_LOCK_WAIT) == -1) {
936 TDB_LOG((tdb, TDB_DEBUG_ERROR, "tdb_transaction_prepare_commit: failed to get open lock\n"));
937 _tdb_transaction_cancel(tdb);
941 if (!(tdb->flags & TDB_NOSYNC)) {
942 /* write the recovery data to the end of the file */
943 if (transaction_setup_recovery(tdb, &tdb->transaction->magic_offset) == -1) {
944 TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_transaction_prepare_commit: failed to setup recovery data\n"));
945 _tdb_transaction_cancel(tdb);
950 tdb->transaction->prepared = true;
952 /* expand the file to the new size if needed */
953 if (tdb->map_size != tdb->transaction->old_map_size) {
954 if (methods->tdb_expand_file(tdb, tdb->transaction->old_map_size,
956 tdb->transaction->old_map_size) == -1) {
957 tdb->ecode = TDB_ERR_IO;
958 TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_transaction_prepare_commit: expansion failed\n"));
959 _tdb_transaction_cancel(tdb);
962 tdb->map_size = tdb->transaction->old_map_size;
963 methods->tdb_oob(tdb, tdb->map_size + 1, 1);
966 /* Keep the open lock until the actual commit */
972 prepare to commit the current transaction
974 int tdb_transaction_prepare_commit(struct tdb_context *tdb)
976 tdb_trace(tdb, "tdb_transaction_prepare_commit");
977 return _tdb_transaction_prepare_commit(tdb);
981 commit the current transaction
983 int tdb_transaction_commit(struct tdb_context *tdb)
985 const struct tdb_methods *methods;
989 if (tdb->transaction == NULL) {
990 TDB_LOG((tdb, TDB_DEBUG_ERROR, "tdb_transaction_commit: no transaction\n"));
994 tdb_trace(tdb, "tdb_transaction_commit");
996 if (tdb->transaction->transaction_error) {
997 tdb->ecode = TDB_ERR_IO;
998 _tdb_transaction_cancel(tdb);
999 TDB_LOG((tdb, TDB_DEBUG_ERROR, "tdb_transaction_commit: transaction error pending\n"));
1004 if (tdb->transaction->nesting != 0) {
1005 tdb->transaction->nesting--;
1009 /* check for a null transaction */
1010 if (tdb->transaction->blocks == NULL) {
1011 _tdb_transaction_cancel(tdb);
1015 if (!tdb->transaction->prepared) {
1016 int ret = _tdb_transaction_prepare_commit(tdb);
1021 methods = tdb->transaction->io_methods;
1023 /* perform all the writes */
1024 for (i=0;i<tdb->transaction->num_blocks;i++) {
1028 if (tdb->transaction->blocks[i] == NULL) {
1032 offset = i * tdb->transaction->block_size;
1033 length = tdb->transaction->block_size;
1034 if (i == tdb->transaction->num_blocks-1) {
1035 length = tdb->transaction->last_block_size;
1038 if (methods->tdb_write(tdb, offset, tdb->transaction->blocks[i], length) == -1) {
1039 TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_transaction_commit: write failed during commit\n"));
1041 /* we've overwritten part of the data and
1042 possibly expanded the file, so we need to
1043 run the crash recovery code */
1044 tdb->methods = methods;
1045 tdb_transaction_recover(tdb);
1047 _tdb_transaction_cancel(tdb);
1049 TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_transaction_commit: write failed\n"));
1052 SAFE_FREE(tdb->transaction->blocks[i]);
1055 SAFE_FREE(tdb->transaction->blocks);
1056 tdb->transaction->num_blocks = 0;
1058 /* ensure the new data is on disk */
1059 if (transaction_sync(tdb, 0, tdb->map_size) == -1) {
1064 TODO: maybe write to some dummy hdr field, or write to magic
1065 offset without mmap, before the last sync, instead of the
1069 /* on some systems (like Linux 2.6.x) changes via mmap/msync
1070 don't change the mtime of the file, this means the file may
1071 not be backed up (as tdb rounding to block sizes means that
1072 file size changes are quite rare too). The following forces
1073 mtime changes when a transaction completes */
1075 utime(tdb->name, NULL);
1078 need_repack = tdb->transaction->need_repack;
1080 /* use a transaction cancel to free memory and remove the
1081 transaction locks */
1082 _tdb_transaction_cancel(tdb);
1085 return tdb_repack(tdb);
1093 recover from an aborted transaction. Must be called with exclusive
1094 database write access already established (including the open
1095 lock to prevent new processes attaching)
1097 int tdb_transaction_recover(struct tdb_context *tdb)
1099 tdb_off_t recovery_head, recovery_eof;
1100 unsigned char *data, *p;
1102 struct tdb_record rec;
1104 /* find the recovery area */
1105 if (tdb_ofs_read(tdb, TDB_RECOVERY_HEAD, &recovery_head) == -1) {
1106 TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_transaction_recover: failed to read recovery head\n"));
1107 tdb->ecode = TDB_ERR_IO;
1111 if (recovery_head == 0) {
1112 /* we have never allocated a recovery record */
1116 /* read the recovery record */
1117 if (tdb->methods->tdb_read(tdb, recovery_head, &rec,
1118 sizeof(rec), DOCONV()) == -1) {
1119 TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_transaction_recover: failed to read recovery record\n"));
1120 tdb->ecode = TDB_ERR_IO;
1124 if (rec.magic != TDB_RECOVERY_MAGIC) {
1125 /* there is no valid recovery data */
1129 if (tdb->read_only) {
1130 TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_transaction_recover: attempt to recover read only database\n"));
1131 tdb->ecode = TDB_ERR_CORRUPT;
1135 recovery_eof = rec.key_len;
1137 data = (unsigned char *)malloc(rec.data_len);
1139 TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_transaction_recover: failed to allocate recovery data\n"));
1140 tdb->ecode = TDB_ERR_OOM;
1144 /* read the full recovery data */
1145 if (tdb->methods->tdb_read(tdb, recovery_head + sizeof(rec), data,
1146 rec.data_len, 0) == -1) {
1147 TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_transaction_recover: failed to read recovery data\n"));
1148 tdb->ecode = TDB_ERR_IO;
1152 /* recover the file data */
1154 while (p+8 < data + rec.data_len) {
1160 memcpy(&len, p+4, 4);
1162 if (tdb->methods->tdb_write(tdb, ofs, p+8, len) == -1) {
1164 TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_transaction_recover: failed to recover %d bytes at offset %d\n", len, ofs));
1165 tdb->ecode = TDB_ERR_IO;
1173 if (transaction_sync(tdb, 0, tdb->map_size) == -1) {
1174 TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_transaction_recover: failed to sync recovery\n"));
1175 tdb->ecode = TDB_ERR_IO;
1179 /* if the recovery area is after the recovered eof then remove it */
1180 if (recovery_eof <= recovery_head) {
1181 if (tdb_ofs_write(tdb, TDB_RECOVERY_HEAD, &zero) == -1) {
1182 TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_transaction_recover: failed to remove recovery head\n"));
1183 tdb->ecode = TDB_ERR_IO;
1188 /* remove the recovery magic */
1189 if (tdb_ofs_write(tdb, recovery_head + offsetof(struct tdb_record, magic),
1191 TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_transaction_recover: failed to remove recovery magic\n"));
1192 tdb->ecode = TDB_ERR_IO;
1196 if (transaction_sync(tdb, 0, recovery_eof) == -1) {
1197 TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_transaction_recover: failed to sync2 recovery\n"));
1198 tdb->ecode = TDB_ERR_IO;
1202 TDB_LOG((tdb, TDB_DEBUG_TRACE, "tdb_transaction_recover: recovered %d byte database\n",
1209 /* Any I/O failures we say "needs recovery". */
1210 bool tdb_needs_recovery(struct tdb_context *tdb)
1212 tdb_off_t recovery_head;
1213 struct tdb_record rec;
1215 /* find the recovery area */
1216 if (tdb_ofs_read(tdb, TDB_RECOVERY_HEAD, &recovery_head) == -1) {
1220 if (recovery_head == 0) {
1221 /* we have never allocated a recovery record */
1225 /* read the recovery record */
1226 if (tdb->methods->tdb_read(tdb, recovery_head, &rec,
1227 sizeof(rec), DOCONV()) == -1) {
1231 return (rec.magic == TDB_RECOVERY_MAGIC);