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;
412 brlock during a transaction - ignore them
414 static int transaction_brlock(struct tdb_context *tdb,
415 int rw_type, tdb_off_t offset, size_t len,
416 enum tdb_lock_flags flags)
418 /* FIXME: We actually grab the open lock during a transaction. */
419 if (offset == OPEN_LOCK)
420 return tdb_brlock(tdb, rw_type, offset, len, flags);
424 static int transaction_brunlock(struct tdb_context *tdb,
425 int rw_type, tdb_off_t offset, size_t len)
430 static const struct tdb_methods transaction_methods = {
433 transaction_next_hash_chain,
435 transaction_expand_file,
442 start a tdb transaction. No token is returned, as only a single
443 transaction is allowed to be pending per tdb_context
445 int tdb_transaction_start(struct tdb_context *tdb)
447 /* some sanity checks */
448 if (tdb->read_only || (tdb->flags & TDB_INTERNAL) || tdb->traverse_read) {
449 TDB_LOG((tdb, TDB_DEBUG_ERROR, "tdb_transaction_start: cannot start a transaction on a read-only or internal db\n"));
450 tdb->ecode = TDB_ERR_EINVAL;
454 /* cope with nested tdb_transaction_start() calls */
455 if (tdb->transaction != NULL) {
456 if (!(tdb->flags & TDB_ALLOW_NESTING)) {
457 tdb->ecode = TDB_ERR_NESTING;
460 tdb->transaction->nesting++;
461 TDB_LOG((tdb, TDB_DEBUG_TRACE, "tdb_transaction_start: nesting %d\n",
462 tdb->transaction->nesting));
466 if (tdb_have_extra_locks(tdb)) {
467 /* the caller must not have any locks when starting a
468 transaction as otherwise we'll be screwed by lack
469 of nested locks in posix */
470 TDB_LOG((tdb, TDB_DEBUG_ERROR, "tdb_transaction_start: cannot start a transaction with locks held\n"));
471 tdb->ecode = TDB_ERR_LOCK;
475 if (tdb->travlocks.next != NULL) {
476 /* you cannot use transactions inside a traverse (although you can use
477 traverse inside a transaction) as otherwise you can end up with
479 TDB_LOG((tdb, TDB_DEBUG_ERROR, "tdb_transaction_start: cannot start a transaction within a traverse\n"));
480 tdb->ecode = TDB_ERR_LOCK;
484 tdb->transaction = (struct tdb_transaction *)
485 calloc(sizeof(struct tdb_transaction), 1);
486 if (tdb->transaction == NULL) {
487 tdb->ecode = TDB_ERR_OOM;
491 /* a page at a time seems like a reasonable compromise between compactness and efficiency */
492 tdb->transaction->block_size = tdb->page_size;
494 /* get the transaction write lock. This is a blocking lock. As
495 discussed with Volker, there are a number of ways we could
496 make this async, which we will probably do in the future */
497 if (tdb_transaction_lock(tdb, F_WRLCK) == -1) {
498 SAFE_FREE(tdb->transaction->blocks);
499 SAFE_FREE(tdb->transaction);
503 /* get a read lock from the freelist to the end of file. This
504 is upgraded to a write lock during the commit */
505 if (tdb_brlock(tdb, F_RDLCK, FREELIST_TOP, 0, TDB_LOCK_WAIT) == -1) {
506 TDB_LOG((tdb, TDB_DEBUG_ERROR, "tdb_transaction_start: failed to get hash locks\n"));
507 tdb->ecode = TDB_ERR_LOCK;
511 /* setup a copy of the hash table heads so the hash scan in
512 traverse can be fast */
513 tdb->transaction->hash_heads = (uint32_t *)
514 calloc(tdb->header.hash_size+1, sizeof(uint32_t));
515 if (tdb->transaction->hash_heads == NULL) {
516 tdb->ecode = TDB_ERR_OOM;
519 if (tdb->methods->tdb_read(tdb, FREELIST_TOP, tdb->transaction->hash_heads,
520 TDB_HASHTABLE_SIZE(tdb), 0) != 0) {
521 TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_transaction_start: failed to read hash heads\n"));
522 tdb->ecode = TDB_ERR_IO;
526 /* make sure we know about any file expansions already done by
528 tdb->methods->tdb_oob(tdb, tdb->map_size + 1, 1);
529 tdb->transaction->old_map_size = tdb->map_size;
531 /* finally hook the io methods, replacing them with
532 transaction specific methods */
533 tdb->transaction->io_methods = tdb->methods;
534 tdb->methods = &transaction_methods;
536 /* Trace at the end, so we get sequence number correct. */
537 tdb_trace(tdb, "tdb_transaction_start");
541 tdb_brunlock(tdb, F_RDLCK, FREELIST_TOP, 0);
542 tdb_transaction_unlock(tdb, F_WRLCK);
543 SAFE_FREE(tdb->transaction->blocks);
544 SAFE_FREE(tdb->transaction->hash_heads);
545 SAFE_FREE(tdb->transaction);
553 static int transaction_sync(struct tdb_context *tdb, tdb_off_t offset, tdb_len_t length)
555 if (tdb->flags & TDB_NOSYNC) {
559 if (fdatasync(tdb->fd) != 0) {
560 tdb->ecode = TDB_ERR_IO;
561 TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_transaction: fsync failed\n"));
566 tdb_off_t moffset = offset & ~(tdb->page_size-1);
567 if (msync(moffset + (char *)tdb->map_ptr,
568 length + (offset - moffset), MS_SYNC) != 0) {
569 tdb->ecode = TDB_ERR_IO;
570 TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_transaction: msync failed - %s\n",
580 /* ltype is F_WRLCK after prepare. */
581 static int _tdb_transaction_cancel(struct tdb_context *tdb, int ltype)
585 if (tdb->transaction == NULL) {
586 TDB_LOG((tdb, TDB_DEBUG_ERROR, "tdb_transaction_cancel: no transaction\n"));
590 if (tdb->transaction->nesting != 0) {
591 tdb->transaction->transaction_error = 1;
592 tdb->transaction->nesting--;
596 tdb->map_size = tdb->transaction->old_map_size;
598 /* free all the transaction blocks */
599 for (i=0;i<tdb->transaction->num_blocks;i++) {
600 if (tdb->transaction->blocks[i] != NULL) {
601 free(tdb->transaction->blocks[i]);
604 SAFE_FREE(tdb->transaction->blocks);
606 if (tdb->transaction->magic_offset) {
607 const struct tdb_methods *methods = tdb->transaction->io_methods;
608 const uint32_t invalid = TDB_RECOVERY_INVALID_MAGIC;
610 /* remove the recovery marker */
611 if (methods->tdb_write(tdb, tdb->transaction->magic_offset, &invalid, 4) == -1 ||
612 transaction_sync(tdb, tdb->transaction->magic_offset, 4) == -1) {
613 TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_transaction_cancel: failed to remove recovery magic\n"));
618 /* This also removes the OPEN_LOCK, if we have it. */
619 tdb_release_extra_locks(tdb);
621 /* restore the normal io methods */
622 tdb->methods = tdb->transaction->io_methods;
624 tdb_brunlock(tdb, ltype, FREELIST_TOP, 0);
625 tdb_transaction_unlock(tdb, F_WRLCK);
626 SAFE_FREE(tdb->transaction->hash_heads);
627 SAFE_FREE(tdb->transaction);
633 cancel the current transaction
635 int tdb_transaction_cancel(struct tdb_context *tdb)
638 tdb_trace(tdb, "tdb_transaction_cancel");
639 if (tdb->transaction && tdb->transaction->prepared)
641 return _tdb_transaction_cancel(tdb, ltype);
645 work out how much space the linearised recovery data will consume
647 static tdb_len_t tdb_recovery_size(struct tdb_context *tdb)
649 tdb_len_t recovery_size = 0;
652 recovery_size = sizeof(uint32_t);
653 for (i=0;i<tdb->transaction->num_blocks;i++) {
654 if (i * tdb->transaction->block_size >= tdb->transaction->old_map_size) {
657 if (tdb->transaction->blocks[i] == NULL) {
660 recovery_size += 2*sizeof(tdb_off_t);
661 if (i == tdb->transaction->num_blocks-1) {
662 recovery_size += tdb->transaction->last_block_size;
664 recovery_size += tdb->transaction->block_size;
668 return recovery_size;
672 allocate the recovery area, or use an existing recovery area if it is
675 static int tdb_recovery_allocate(struct tdb_context *tdb,
676 tdb_len_t *recovery_size,
677 tdb_off_t *recovery_offset,
678 tdb_len_t *recovery_max_size)
680 struct tdb_record rec;
681 const struct tdb_methods *methods = tdb->transaction->io_methods;
682 tdb_off_t recovery_head;
684 if (tdb_ofs_read(tdb, TDB_RECOVERY_HEAD, &recovery_head) == -1) {
685 TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_recovery_allocate: failed to read recovery head\n"));
691 if (recovery_head != 0) {
692 if (methods->tdb_read(tdb, recovery_head, &rec, sizeof(rec), DOCONV()) == -1) {
693 TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_recovery_allocate: failed to read recovery record\n"));
696 /* ignore invalid recovery regions: can happen in crash */
697 if (rec.magic != TDB_RECOVERY_MAGIC &&
698 rec.magic != TDB_RECOVERY_INVALID_MAGIC) {
703 *recovery_size = tdb_recovery_size(tdb);
705 if (recovery_head != 0 && *recovery_size <= rec.rec_len) {
706 /* it fits in the existing area */
707 *recovery_max_size = rec.rec_len;
708 *recovery_offset = recovery_head;
712 /* we need to free up the old recovery area, then allocate a
713 new one at the end of the file. Note that we cannot use
714 tdb_allocate() to allocate the new one as that might return
715 us an area that is being currently used (as of the start of
717 if (recovery_head != 0) {
718 if (tdb_free(tdb, recovery_head, &rec) == -1) {
719 TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_recovery_allocate: failed to free previous recovery area\n"));
724 /* the tdb_free() call might have increased the recovery size */
725 *recovery_size = tdb_recovery_size(tdb);
727 /* round up to a multiple of page size */
728 *recovery_max_size = TDB_ALIGN(sizeof(rec) + *recovery_size, tdb->page_size) - sizeof(rec);
729 *recovery_offset = tdb->map_size;
730 recovery_head = *recovery_offset;
732 if (methods->tdb_expand_file(tdb, tdb->transaction->old_map_size,
733 (tdb->map_size - tdb->transaction->old_map_size) +
734 sizeof(rec) + *recovery_max_size) == -1) {
735 TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_recovery_allocate: failed to create recovery area\n"));
739 /* remap the file (if using mmap) */
740 methods->tdb_oob(tdb, tdb->map_size + 1, 1);
742 /* we have to reset the old map size so that we don't try to expand the file
743 again in the transaction commit, which would destroy the recovery area */
744 tdb->transaction->old_map_size = tdb->map_size;
746 /* write the recovery header offset and sync - we can sync without a race here
747 as the magic ptr in the recovery record has not been set */
748 CONVERT(recovery_head);
749 if (methods->tdb_write(tdb, TDB_RECOVERY_HEAD,
750 &recovery_head, sizeof(tdb_off_t)) == -1) {
751 TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_recovery_allocate: failed to write recovery head\n"));
754 if (transaction_write_existing(tdb, TDB_RECOVERY_HEAD, &recovery_head, sizeof(tdb_off_t)) == -1) {
755 TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_recovery_allocate: failed to write recovery head\n"));
764 setup the recovery data that will be used on a crash during commit
766 static int transaction_setup_recovery(struct tdb_context *tdb,
767 tdb_off_t *magic_offset)
769 tdb_len_t recovery_size;
770 unsigned char *data, *p;
771 const struct tdb_methods *methods = tdb->transaction->io_methods;
772 struct tdb_record *rec;
773 tdb_off_t recovery_offset, recovery_max_size;
774 tdb_off_t old_map_size = tdb->transaction->old_map_size;
775 uint32_t magic, tailer;
779 check that the recovery area has enough space
781 if (tdb_recovery_allocate(tdb, &recovery_size,
782 &recovery_offset, &recovery_max_size) == -1) {
786 data = (unsigned char *)malloc(recovery_size + sizeof(*rec));
788 tdb->ecode = TDB_ERR_OOM;
792 rec = (struct tdb_record *)data;
793 memset(rec, 0, sizeof(*rec));
795 rec->magic = TDB_RECOVERY_INVALID_MAGIC;
796 rec->data_len = recovery_size;
797 rec->rec_len = recovery_max_size;
798 rec->key_len = old_map_size;
801 /* build the recovery data into a single blob to allow us to do a single
802 large write, which should be more efficient */
803 p = data + sizeof(*rec);
804 for (i=0;i<tdb->transaction->num_blocks;i++) {
808 if (tdb->transaction->blocks[i] == NULL) {
812 offset = i * tdb->transaction->block_size;
813 length = tdb->transaction->block_size;
814 if (i == tdb->transaction->num_blocks-1) {
815 length = tdb->transaction->last_block_size;
818 if (offset >= old_map_size) {
821 if (offset + length > tdb->transaction->old_map_size) {
822 TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_transaction_setup_recovery: transaction data over new region boundary\n"));
824 tdb->ecode = TDB_ERR_CORRUPT;
827 memcpy(p, &offset, 4);
828 memcpy(p+4, &length, 4);
832 /* the recovery area contains the old data, not the
833 new data, so we have to call the original tdb_read
835 if (methods->tdb_read(tdb, offset, p + 8, length, 0) != 0) {
837 tdb->ecode = TDB_ERR_IO;
844 tailer = sizeof(*rec) + recovery_max_size;
845 memcpy(p, &tailer, 4);
848 /* write the recovery data to the recovery area */
849 if (methods->tdb_write(tdb, recovery_offset, data, sizeof(*rec) + recovery_size) == -1) {
850 TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_transaction_setup_recovery: failed to write recovery data\n"));
852 tdb->ecode = TDB_ERR_IO;
855 if (transaction_write_existing(tdb, recovery_offset, data, sizeof(*rec) + recovery_size) == -1) {
856 TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_transaction_setup_recovery: failed to write secondary recovery data\n"));
858 tdb->ecode = TDB_ERR_IO;
862 /* as we don't have ordered writes, we have to sync the recovery
863 data before we update the magic to indicate that the recovery
865 if (transaction_sync(tdb, recovery_offset, sizeof(*rec) + recovery_size) == -1) {
872 magic = TDB_RECOVERY_MAGIC;
875 *magic_offset = recovery_offset + offsetof(struct tdb_record, magic);
877 if (methods->tdb_write(tdb, *magic_offset, &magic, sizeof(magic)) == -1) {
878 TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_transaction_setup_recovery: failed to write recovery magic\n"));
879 tdb->ecode = TDB_ERR_IO;
882 if (transaction_write_existing(tdb, *magic_offset, &magic, sizeof(magic)) == -1) {
883 TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_transaction_setup_recovery: failed to write secondary recovery magic\n"));
884 tdb->ecode = TDB_ERR_IO;
888 /* ensure the recovery magic marker is on disk */
889 if (transaction_sync(tdb, *magic_offset, sizeof(magic)) == -1) {
896 static int _tdb_transaction_prepare_commit(struct tdb_context *tdb)
898 const struct tdb_methods *methods;
900 if (tdb->transaction == NULL) {
901 TDB_LOG((tdb, TDB_DEBUG_ERROR, "tdb_transaction_prepare_commit: no transaction\n"));
905 if (tdb->transaction->prepared) {
906 tdb->ecode = TDB_ERR_EINVAL;
907 _tdb_transaction_cancel(tdb, F_WRLCK);
908 TDB_LOG((tdb, TDB_DEBUG_ERROR, "tdb_transaction_prepare_commit: transaction already prepared\n"));
912 if (tdb->transaction->transaction_error) {
913 tdb->ecode = TDB_ERR_IO;
914 _tdb_transaction_cancel(tdb, F_RDLCK);
915 TDB_LOG((tdb, TDB_DEBUG_ERROR, "tdb_transaction_prepare_commit: transaction error pending\n"));
920 if (tdb->transaction->nesting != 0) {
924 /* check for a null transaction */
925 if (tdb->transaction->blocks == NULL) {
929 methods = tdb->transaction->io_methods;
931 /* if there are any locks pending then the caller has not
932 nested their locks properly, so fail the transaction */
933 if (tdb_have_extra_locks(tdb)) {
934 tdb->ecode = TDB_ERR_LOCK;
935 TDB_LOG((tdb, TDB_DEBUG_ERROR, "tdb_transaction_prepare_commit: locks pending on commit\n"));
936 _tdb_transaction_cancel(tdb, F_RDLCK);
940 /* upgrade the main transaction lock region to a write lock */
941 if (tdb_brlock_upgrade(tdb, FREELIST_TOP, 0) == -1) {
942 TDB_LOG((tdb, TDB_DEBUG_ERROR, "tdb_transaction_prepare_commit: failed to upgrade hash locks\n"));
943 tdb->ecode = TDB_ERR_LOCK;
944 _tdb_transaction_cancel(tdb, F_RDLCK);
948 /* get the open lock - this prevents new users attaching to the database
950 if (tdb_nest_lock(tdb, OPEN_LOCK, F_WRLCK, TDB_LOCK_WAIT) == -1) {
951 TDB_LOG((tdb, TDB_DEBUG_ERROR, "tdb_transaction_prepare_commit: failed to get open lock\n"));
952 _tdb_transaction_cancel(tdb, F_WRLCK);
956 if (!(tdb->flags & TDB_NOSYNC)) {
957 /* write the recovery data to the end of the file */
958 if (transaction_setup_recovery(tdb, &tdb->transaction->magic_offset) == -1) {
959 TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_transaction_prepare_commit: failed to setup recovery data\n"));
960 _tdb_transaction_cancel(tdb, F_WRLCK);
965 tdb->transaction->prepared = true;
967 /* expand the file to the new size if needed */
968 if (tdb->map_size != tdb->transaction->old_map_size) {
969 if (methods->tdb_expand_file(tdb, tdb->transaction->old_map_size,
971 tdb->transaction->old_map_size) == -1) {
972 tdb->ecode = TDB_ERR_IO;
973 TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_transaction_prepare_commit: expansion failed\n"));
974 _tdb_transaction_cancel(tdb, F_WRLCK);
977 tdb->map_size = tdb->transaction->old_map_size;
978 methods->tdb_oob(tdb, tdb->map_size + 1, 1);
981 /* Keep the open lock until the actual commit */
987 prepare to commit the current transaction
989 int tdb_transaction_prepare_commit(struct tdb_context *tdb)
991 tdb_trace(tdb, "tdb_transaction_prepare_commit");
992 return _tdb_transaction_prepare_commit(tdb);
996 commit the current transaction
998 int tdb_transaction_commit(struct tdb_context *tdb)
1000 const struct tdb_methods *methods;
1004 if (tdb->transaction == NULL) {
1005 TDB_LOG((tdb, TDB_DEBUG_ERROR, "tdb_transaction_commit: no transaction\n"));
1009 tdb_trace(tdb, "tdb_transaction_commit");
1011 if (tdb->transaction->transaction_error) {
1012 tdb->ecode = TDB_ERR_IO;
1013 _tdb_transaction_cancel(tdb, F_RDLCK);
1014 TDB_LOG((tdb, TDB_DEBUG_ERROR, "tdb_transaction_commit: transaction error pending\n"));
1019 if (tdb->transaction->nesting != 0) {
1020 tdb->transaction->nesting--;
1024 /* check for a null transaction */
1025 if (tdb->transaction->blocks == NULL) {
1026 _tdb_transaction_cancel(tdb, F_RDLCK);
1030 if (!tdb->transaction->prepared) {
1031 int ret = _tdb_transaction_prepare_commit(tdb);
1036 methods = tdb->transaction->io_methods;
1038 /* perform all the writes */
1039 for (i=0;i<tdb->transaction->num_blocks;i++) {
1043 if (tdb->transaction->blocks[i] == NULL) {
1047 offset = i * tdb->transaction->block_size;
1048 length = tdb->transaction->block_size;
1049 if (i == tdb->transaction->num_blocks-1) {
1050 length = tdb->transaction->last_block_size;
1053 if (methods->tdb_write(tdb, offset, tdb->transaction->blocks[i], length) == -1) {
1054 TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_transaction_commit: write failed during commit\n"));
1056 /* we've overwritten part of the data and
1057 possibly expanded the file, so we need to
1058 run the crash recovery code */
1059 tdb->methods = methods;
1060 tdb_transaction_recover(tdb);
1062 _tdb_transaction_cancel(tdb, F_WRLCK);
1064 TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_transaction_commit: write failed\n"));
1067 SAFE_FREE(tdb->transaction->blocks[i]);
1070 SAFE_FREE(tdb->transaction->blocks);
1071 tdb->transaction->num_blocks = 0;
1073 /* ensure the new data is on disk */
1074 if (transaction_sync(tdb, 0, tdb->map_size) == -1) {
1079 TODO: maybe write to some dummy hdr field, or write to magic
1080 offset without mmap, before the last sync, instead of the
1084 /* on some systems (like Linux 2.6.x) changes via mmap/msync
1085 don't change the mtime of the file, this means the file may
1086 not be backed up (as tdb rounding to block sizes means that
1087 file size changes are quite rare too). The following forces
1088 mtime changes when a transaction completes */
1090 utime(tdb->name, NULL);
1093 need_repack = tdb->transaction->need_repack;
1095 /* use a transaction cancel to free memory and remove the
1096 transaction locks */
1097 _tdb_transaction_cancel(tdb, F_WRLCK);
1100 return tdb_repack(tdb);
1108 recover from an aborted transaction. Must be called with exclusive
1109 database write access already established (including the open
1110 lock to prevent new processes attaching)
1112 int tdb_transaction_recover(struct tdb_context *tdb)
1114 tdb_off_t recovery_head, recovery_eof;
1115 unsigned char *data, *p;
1117 struct tdb_record rec;
1119 /* find the recovery area */
1120 if (tdb_ofs_read(tdb, TDB_RECOVERY_HEAD, &recovery_head) == -1) {
1121 TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_transaction_recover: failed to read recovery head\n"));
1122 tdb->ecode = TDB_ERR_IO;
1126 if (recovery_head == 0) {
1127 /* we have never allocated a recovery record */
1131 /* read the recovery record */
1132 if (tdb->methods->tdb_read(tdb, recovery_head, &rec,
1133 sizeof(rec), DOCONV()) == -1) {
1134 TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_transaction_recover: failed to read recovery record\n"));
1135 tdb->ecode = TDB_ERR_IO;
1139 if (rec.magic != TDB_RECOVERY_MAGIC) {
1140 /* there is no valid recovery data */
1144 if (tdb->read_only) {
1145 TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_transaction_recover: attempt to recover read only database\n"));
1146 tdb->ecode = TDB_ERR_CORRUPT;
1150 recovery_eof = rec.key_len;
1152 data = (unsigned char *)malloc(rec.data_len);
1154 TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_transaction_recover: failed to allocate recovery data\n"));
1155 tdb->ecode = TDB_ERR_OOM;
1159 /* read the full recovery data */
1160 if (tdb->methods->tdb_read(tdb, recovery_head + sizeof(rec), data,
1161 rec.data_len, 0) == -1) {
1162 TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_transaction_recover: failed to read recovery data\n"));
1163 tdb->ecode = TDB_ERR_IO;
1167 /* recover the file data */
1169 while (p+8 < data + rec.data_len) {
1175 memcpy(&len, p+4, 4);
1177 if (tdb->methods->tdb_write(tdb, ofs, p+8, len) == -1) {
1179 TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_transaction_recover: failed to recover %d bytes at offset %d\n", len, ofs));
1180 tdb->ecode = TDB_ERR_IO;
1188 if (transaction_sync(tdb, 0, tdb->map_size) == -1) {
1189 TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_transaction_recover: failed to sync recovery\n"));
1190 tdb->ecode = TDB_ERR_IO;
1194 /* if the recovery area is after the recovered eof then remove it */
1195 if (recovery_eof <= recovery_head) {
1196 if (tdb_ofs_write(tdb, TDB_RECOVERY_HEAD, &zero) == -1) {
1197 TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_transaction_recover: failed to remove recovery head\n"));
1198 tdb->ecode = TDB_ERR_IO;
1203 /* remove the recovery magic */
1204 if (tdb_ofs_write(tdb, recovery_head + offsetof(struct tdb_record, magic),
1206 TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_transaction_recover: failed to remove recovery magic\n"));
1207 tdb->ecode = TDB_ERR_IO;
1211 /* reduce the file size to the old size */
1213 if (ftruncate(tdb->fd, recovery_eof) != 0) {
1214 TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_transaction_recover: failed to reduce to recovery size\n"));
1215 tdb->ecode = TDB_ERR_IO;
1218 tdb->map_size = recovery_eof;
1221 if (transaction_sync(tdb, 0, recovery_eof) == -1) {
1222 TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_transaction_recover: failed to sync2 recovery\n"));
1223 tdb->ecode = TDB_ERR_IO;
1227 TDB_LOG((tdb, TDB_DEBUG_TRACE, "tdb_transaction_recover: recovered %d byte database\n",