2 Unix SMB/CIFS implementation.
4 trivial database library
6 Copyright (C) Andrew Tridgell 2005
7 Copyright (C) Rusty Russell 2010
9 ** NOTE! The following LGPL license applies to the tdb
10 ** library. This does NOT imply that all of Samba is released
13 This library is free software; you can redistribute it and/or
14 modify it under the terms of the GNU Lesser General Public
15 License as published by the Free Software Foundation; either
16 version 3 of the License, or (at your option) any later version.
18 This library is distributed in the hope that it will be useful,
19 but WITHOUT ANY WARRANTY; without even the implied warranty of
20 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
21 Lesser General Public License for more details.
23 You should have received a copy of the GNU Lesser General Public
24 License along with this library; if not, see <http://www.gnu.org/licenses/>.
28 #define SAFE_FREE(x) do { if ((x) != NULL) {free(x); (x)=NULL;} } while(0)
33 - only allow a single transaction at a time per database. This makes
34 using the transaction API simpler, as otherwise the caller would
35 have to cope with temporary failures in transactions that conflict
36 with other current transactions
38 - keep the transaction recovery information in the same file as the
39 database, using a special 'transaction recovery' record pointed at
40 by the header. This removes the need for extra journal files as
41 used by some other databases
43 - dynamically allocated the transaction recover record, re-using it
44 for subsequent transactions. If a larger record is needed then
45 tdb_free() the old record to place it on the normal tdb freelist
46 before allocating the new record
48 - during transactions, keep a linked list of writes all that have
49 been performed by intercepting all tdb_write() calls. The hooked
50 transaction versions of tdb_read() and tdb_write() check this
51 linked list and try to use the elements of the list in preference
54 - don't allow any locks to be held when a transaction starts,
55 otherwise we can end up with deadlock (plus lack of lock nesting
56 in POSIX locks would mean the lock is lost)
58 - if the caller gains a lock during the transaction but doesn't
59 release it then fail the commit
61 - allow for nested calls to tdb_transaction_start(), re-using the
62 existing transaction record. If the inner transaction is canceled
63 then a subsequent commit will fail
65 - keep a mirrored copy of the tdb hash chain heads to allow for the
66 fast hash heads scan on traverse, updating the mirrored copy in
67 the transaction version of tdb_write
69 - allow callers to mix transaction and non-transaction use of tdb,
70 although once a transaction is started then an exclusive lock is
71 gained until the transaction is committed or canceled
73 - the commit stategy involves first saving away all modified data
74 into a linearised buffer in the transaction recovery area, then
75 marking the transaction recovery area with a magic value to
76 indicate a valid recovery record. In total 4 fsync/msync calls are
77 needed per commit to prevent race conditions. It might be possible
78 to reduce this to 3 or even 2 with some more work.
80 - check for a valid recovery record on open of the tdb, while the
81 open lock is held. Automatically recover from the transaction
82 recovery area if needed, then continue with the open as
83 usual. This allows for smooth crash recovery with no administrator
86 - if TDB_NOSYNC is passed to flags in tdb_open then transactions are
87 still available, but no transaction recovery area is used and no
88 fsync/msync calls are made.
93 hold the context of any current transaction
95 struct tdb_transaction {
96 /* the original io methods - used to do IOs to the real db */
97 const struct tdb_methods *io_methods;
99 /* the list of transaction blocks. When a block is first
100 written to, it gets created in this list */
103 size_t last_block_size; /* number of valid bytes in the last block */
105 /* non-zero when an internal transaction error has
106 occurred. All write operations will then fail until the
107 transaction is ended */
108 int transaction_error;
110 /* when inside a transaction we need to keep track of any
111 nested tdb_transaction_start() calls, as these are allowed,
112 but don't create a new transaction */
115 /* set when a prepare has already occurred */
117 tdb_off_t magic_offset;
119 /* old file size before transaction */
120 tdb_len_t old_map_size;
125 read while in a transaction. We need to check first if the data is in our list
126 of transaction elements, then if not do a real read
128 static enum TDB_ERROR transaction_read(struct tdb_context *tdb, tdb_off_t off,
129 void *buf, tdb_len_t len)
132 enum TDB_ERROR ecode;
134 /* break it down into block sized ops */
135 while (len + (off % getpagesize()) > getpagesize()) {
136 tdb_len_t len2 = getpagesize() - (off % getpagesize());
137 ecode = transaction_read(tdb, off, buf, len2);
138 if (ecode != TDB_SUCCESS) {
143 buf = (void *)(len2 + (char *)buf);
150 blk = off / getpagesize();
152 /* see if we have it in the block list */
153 if (tdb->transaction->num_blocks <= blk ||
154 tdb->transaction->blocks[blk] == NULL) {
155 /* nope, do a real read */
156 ecode = tdb->transaction->io_methods->tread(tdb, off, buf, len);
157 if (ecode != TDB_SUCCESS) {
163 /* it is in the block list. Now check for the last block */
164 if (blk == tdb->transaction->num_blocks-1) {
165 if (len > tdb->transaction->last_block_size) {
171 /* now copy it out of this block */
172 memcpy(buf, tdb->transaction->blocks[blk] + (off % getpagesize()), len);
176 tdb->transaction->transaction_error = 1;
177 return tdb_logerr(tdb, ecode, TDB_LOG_ERROR,
178 "transaction_read: failed at off=%zu len=%zu",
179 (size_t)off, (size_t)len);
184 write while in a transaction
186 static enum TDB_ERROR transaction_write(struct tdb_context *tdb, tdb_off_t off,
187 const void *buf, tdb_len_t len)
190 enum TDB_ERROR ecode;
192 /* Only a commit is allowed on a prepared transaction */
193 if (tdb->transaction->prepared) {
194 ecode = tdb_logerr(tdb, TDB_ERR_EINVAL, TDB_LOG_ERROR,
195 "transaction_write: transaction already"
196 " prepared, write not allowed");
200 /* break it up into block sized chunks */
201 while (len + (off % getpagesize()) > getpagesize()) {
202 tdb_len_t len2 = getpagesize() - (off % getpagesize());
203 ecode = transaction_write(tdb, off, buf, len2);
204 if (ecode != TDB_SUCCESS) {
210 buf = (const void *)(len2 + (const char *)buf);
218 blk = off / getpagesize();
219 off = off % getpagesize();
221 if (tdb->transaction->num_blocks <= blk) {
222 uint8_t **new_blocks;
223 /* expand the blocks array */
224 if (tdb->transaction->blocks == NULL) {
225 new_blocks = (uint8_t **)malloc(
226 (blk+1)*sizeof(uint8_t *));
228 new_blocks = (uint8_t **)realloc(
229 tdb->transaction->blocks,
230 (blk+1)*sizeof(uint8_t *));
232 if (new_blocks == NULL) {
233 ecode = tdb_logerr(tdb, TDB_ERR_OOM, TDB_LOG_ERROR,
235 " failed to allocate");
238 memset(&new_blocks[tdb->transaction->num_blocks], 0,
239 (1+(blk - tdb->transaction->num_blocks))*sizeof(uint8_t *));
240 tdb->transaction->blocks = new_blocks;
241 tdb->transaction->num_blocks = blk+1;
242 tdb->transaction->last_block_size = 0;
245 /* allocate and fill a block? */
246 if (tdb->transaction->blocks[blk] == NULL) {
247 tdb->transaction->blocks[blk] = (uint8_t *)calloc(getpagesize(), 1);
248 if (tdb->transaction->blocks[blk] == NULL) {
249 ecode = tdb_logerr(tdb, TDB_ERR_OOM, TDB_LOG_ERROR,
251 " failed to allocate");
254 if (tdb->transaction->old_map_size > blk * getpagesize()) {
255 tdb_len_t len2 = getpagesize();
256 if (len2 + (blk * getpagesize()) > tdb->transaction->old_map_size) {
257 len2 = tdb->transaction->old_map_size - (blk * getpagesize());
259 ecode = tdb->transaction->io_methods->tread(tdb,
261 tdb->transaction->blocks[blk],
263 if (ecode != TDB_SUCCESS) {
264 ecode = tdb_logerr(tdb, ecode,
268 " read old block: %s",
270 SAFE_FREE(tdb->transaction->blocks[blk]);
273 if (blk == tdb->transaction->num_blocks-1) {
274 tdb->transaction->last_block_size = len2;
279 /* overwrite part of an existing block */
281 memset(tdb->transaction->blocks[blk] + off, 0, len);
283 memcpy(tdb->transaction->blocks[blk] + off, buf, len);
285 if (blk == tdb->transaction->num_blocks-1) {
286 if (len + off > tdb->transaction->last_block_size) {
287 tdb->transaction->last_block_size = len + off;
294 tdb->transaction->transaction_error = 1;
300 write while in a transaction - this variant never expands the transaction blocks, it only
301 updates existing blocks. This means it cannot change the recovery size
303 static void transaction_write_existing(struct tdb_context *tdb, tdb_off_t off,
304 const void *buf, tdb_len_t len)
308 /* break it up into block sized chunks */
309 while (len + (off % getpagesize()) > getpagesize()) {
310 tdb_len_t len2 = getpagesize() - (off % getpagesize());
311 transaction_write_existing(tdb, off, buf, len2);
315 buf = (const void *)(len2 + (const char *)buf);
323 blk = off / getpagesize();
324 off = off % getpagesize();
326 if (tdb->transaction->num_blocks <= blk ||
327 tdb->transaction->blocks[blk] == NULL) {
331 if (blk == tdb->transaction->num_blocks-1 &&
332 off + len > tdb->transaction->last_block_size) {
333 if (off >= tdb->transaction->last_block_size) {
336 len = tdb->transaction->last_block_size - off;
339 /* overwrite part of an existing block */
340 memcpy(tdb->transaction->blocks[blk] + off, buf, len);
345 out of bounds check during a transaction
347 static enum TDB_ERROR transaction_oob(struct tdb_context *tdb, tdb_off_t len,
350 if (len <= tdb->file->map_size) {
354 tdb_logerr(tdb, TDB_ERR_IO, TDB_LOG_ERROR,
355 "tdb_oob len %lld beyond transaction size %lld",
357 (long long)tdb->file->map_size);
363 transaction version of tdb_expand().
365 static enum TDB_ERROR transaction_expand_file(struct tdb_context *tdb,
368 enum TDB_ERROR ecode;
370 /* add a write to the transaction elements, so subsequent
371 reads see the zero data */
372 ecode = transaction_write(tdb, tdb->file->map_size, NULL, addition);
373 if (ecode == TDB_SUCCESS) {
374 tdb->file->map_size += addition;
379 static void *transaction_direct(struct tdb_context *tdb, tdb_off_t off,
380 size_t len, bool write_mode)
382 size_t blk = off / getpagesize(), end_blk;
384 /* This is wrong for zero-length blocks, but will fail gracefully */
385 end_blk = (off + len - 1) / getpagesize();
387 /* Can only do direct if in single block and we've already copied. */
391 if (blk >= tdb->transaction->num_blocks)
393 if (tdb->transaction->blocks[blk] == NULL)
395 return tdb->transaction->blocks[blk] + off % getpagesize();
398 /* Single which we have copied? */
400 && blk < tdb->transaction->num_blocks
401 && tdb->transaction->blocks[blk])
402 return tdb->transaction->blocks[blk] + off % getpagesize();
404 /* Otherwise must be all not copied. */
405 while (blk < end_blk) {
406 if (blk >= tdb->transaction->num_blocks)
408 if (tdb->transaction->blocks[blk])
412 return tdb->transaction->io_methods->direct(tdb, off, len, false);
415 static const struct tdb_methods transaction_methods = {
419 transaction_expand_file,
426 static enum TDB_ERROR transaction_sync(struct tdb_context *tdb,
427 tdb_off_t offset, tdb_len_t length)
429 if (tdb->flags & TDB_NOSYNC) {
433 if (fsync(tdb->file->fd) != 0) {
434 return tdb_logerr(tdb, TDB_ERR_IO, TDB_LOG_ERROR,
435 "tdb_transaction: fsync failed: %s",
439 if (tdb->file->map_ptr) {
440 tdb_off_t moffset = offset & ~(getpagesize()-1);
441 if (msync(moffset + (char *)tdb->file->map_ptr,
442 length + (offset - moffset), MS_SYNC) != 0) {
443 return tdb_logerr(tdb, TDB_ERR_IO, TDB_LOG_ERROR,
444 "tdb_transaction: msync failed: %s",
453 static void _tdb_transaction_cancel(struct tdb_context *tdb)
456 enum TDB_ERROR ecode;
458 if (tdb->transaction == NULL) {
459 tdb_logerr(tdb, TDB_ERR_EINVAL, TDB_LOG_USE_ERROR,
460 "tdb_transaction_cancel: no transaction");
464 if (tdb->transaction->nesting != 0) {
465 tdb->transaction->transaction_error = 1;
466 tdb->transaction->nesting--;
470 tdb->file->map_size = tdb->transaction->old_map_size;
472 /* free all the transaction blocks */
473 for (i=0;i<tdb->transaction->num_blocks;i++) {
474 if (tdb->transaction->blocks[i] != NULL) {
475 free(tdb->transaction->blocks[i]);
478 SAFE_FREE(tdb->transaction->blocks);
480 if (tdb->transaction->magic_offset) {
481 const struct tdb_methods *methods = tdb->transaction->io_methods;
482 uint64_t invalid = TDB_RECOVERY_INVALID_MAGIC;
484 /* remove the recovery marker */
485 ecode = methods->twrite(tdb, tdb->transaction->magic_offset,
486 &invalid, sizeof(invalid));
487 if (ecode == TDB_SUCCESS)
488 ecode = transaction_sync(tdb,
489 tdb->transaction->magic_offset,
491 if (ecode != TDB_SUCCESS) {
492 tdb_logerr(tdb, ecode, TDB_LOG_ERROR,
493 "tdb_transaction_cancel: failed to remove"
498 if (tdb->file->allrecord_lock.count)
499 tdb_allrecord_unlock(tdb, tdb->file->allrecord_lock.ltype);
501 /* restore the normal io methods */
502 tdb->methods = tdb->transaction->io_methods;
504 tdb_transaction_unlock(tdb, F_WRLCK);
506 if (tdb_has_open_lock(tdb))
507 tdb_unlock_open(tdb);
509 SAFE_FREE(tdb->transaction);
513 start a tdb transaction. No token is returned, as only a single
514 transaction is allowed to be pending per tdb_context
516 enum TDB_ERROR tdb_transaction_start(struct tdb_context *tdb)
518 enum TDB_ERROR ecode;
520 /* some sanity checks */
521 if (tdb->read_only || (tdb->flags & TDB_INTERNAL)) {
522 return tdb->last_error = tdb_logerr(tdb, TDB_ERR_EINVAL,
524 "tdb_transaction_start:"
527 "read-only or internal db");
530 /* cope with nested tdb_transaction_start() calls */
531 if (tdb->transaction != NULL) {
532 return tdb->last_error = tdb_logerr(tdb, TDB_ERR_IO,
534 "tdb_transaction_start:"
539 if (tdb_has_hash_locks(tdb)) {
540 /* the caller must not have any locks when starting a
541 transaction as otherwise we'll be screwed by lack
542 of nested locks in POSIX */
543 return tdb->last_error = tdb_logerr(tdb, TDB_ERR_LOCK,
545 "tdb_transaction_start:"
547 " transaction with locks"
551 tdb->transaction = (struct tdb_transaction *)
552 calloc(sizeof(struct tdb_transaction), 1);
553 if (tdb->transaction == NULL) {
554 return tdb->last_error = tdb_logerr(tdb, TDB_ERR_OOM,
556 "tdb_transaction_start:"
560 /* get the transaction write lock. This is a blocking lock. As
561 discussed with Volker, there are a number of ways we could
562 make this async, which we will probably do in the future */
563 ecode = tdb_transaction_lock(tdb, F_WRLCK);
564 if (ecode != TDB_SUCCESS) {
565 SAFE_FREE(tdb->transaction->blocks);
566 SAFE_FREE(tdb->transaction);
567 return tdb->last_error = ecode;
570 /* get a read lock over entire file. This is upgraded to a write
571 lock during the commit */
572 ecode = tdb_allrecord_lock(tdb, F_RDLCK, TDB_LOCK_WAIT, true);
573 if (ecode != TDB_SUCCESS) {
574 goto fail_allrecord_lock;
577 /* make sure we know about any file expansions already done by
579 tdb->methods->oob(tdb, tdb->file->map_size + 1, true);
580 tdb->transaction->old_map_size = tdb->file->map_size;
582 /* finally hook the io methods, replacing them with
583 transaction specific methods */
584 tdb->transaction->io_methods = tdb->methods;
585 tdb->methods = &transaction_methods;
586 return tdb->last_error = TDB_SUCCESS;
589 tdb_transaction_unlock(tdb, F_WRLCK);
590 SAFE_FREE(tdb->transaction->blocks);
591 SAFE_FREE(tdb->transaction);
592 return tdb->last_error = ecode;
597 cancel the current transaction
599 void tdb_transaction_cancel(struct tdb_context *tdb)
601 _tdb_transaction_cancel(tdb);
605 work out how much space the linearised recovery data will consume
607 static tdb_len_t tdb_recovery_size(struct tdb_context *tdb)
609 tdb_len_t recovery_size = 0;
612 recovery_size = sizeof(tdb_len_t);
613 for (i=0;i<tdb->transaction->num_blocks;i++) {
614 if (i * getpagesize() >= tdb->transaction->old_map_size) {
617 if (tdb->transaction->blocks[i] == NULL) {
620 recovery_size += 2*sizeof(tdb_off_t);
621 if (i == tdb->transaction->num_blocks-1) {
622 recovery_size += tdb->transaction->last_block_size;
624 recovery_size += getpagesize();
628 return recovery_size;
632 allocate the recovery area, or use an existing recovery area if it is
635 static enum TDB_ERROR tdb_recovery_allocate(struct tdb_context *tdb,
636 tdb_len_t *recovery_size,
637 tdb_off_t *recovery_offset,
638 tdb_len_t *recovery_max_size)
640 struct tdb_recovery_record rec;
641 const struct tdb_methods *methods = tdb->transaction->io_methods;
642 tdb_off_t recovery_head;
644 enum TDB_ERROR ecode;
646 recovery_head = tdb_read_off(tdb, offsetof(struct tdb_header,recovery));
647 if (TDB_OFF_IS_ERR(recovery_head)) {
648 return tdb_logerr(tdb, recovery_head, TDB_LOG_ERROR,
649 "tdb_recovery_allocate:"
650 " failed to read recovery head");
653 if (recovery_head != 0) {
654 ecode = methods->tread(tdb, recovery_head, &rec, sizeof(rec));
655 if (ecode != TDB_SUCCESS) {
656 return tdb_logerr(tdb, ecode, TDB_LOG_ERROR,
657 "tdb_recovery_allocate:"
658 " failed to read recovery record");
660 tdb_convert(tdb, &rec, sizeof(rec));
661 /* ignore invalid recovery regions: can happen in crash */
662 if (rec.magic != TDB_RECOVERY_MAGIC &&
663 rec.magic != TDB_RECOVERY_INVALID_MAGIC) {
668 *recovery_size = tdb_recovery_size(tdb);
670 if (recovery_head != 0 && *recovery_size <= rec.max_len) {
671 /* it fits in the existing area */
672 *recovery_max_size = rec.max_len;
673 *recovery_offset = recovery_head;
677 /* we need to free up the old recovery area, then allocate a
678 new one at the end of the file. Note that we cannot use
679 normal allocation to allocate the new one as that might return
680 us an area that is being currently used (as of the start of
682 if (recovery_head != 0) {
683 add_stat(tdb, frees, 1);
684 ecode = add_free_record(tdb, recovery_head,
685 sizeof(rec) + rec.max_len);
686 if (ecode != TDB_SUCCESS) {
687 return tdb_logerr(tdb, ecode, TDB_LOG_ERROR,
688 "tdb_recovery_allocate:"
689 " failed to free previous"
694 /* the tdb_free() call might have increased the recovery size */
695 *recovery_size = tdb_recovery_size(tdb);
697 /* round up to a multiple of page size */
699 = (((sizeof(rec) + *recovery_size) + getpagesize()-1)
700 & ~(getpagesize()-1))
702 *recovery_offset = tdb->file->map_size;
703 recovery_head = *recovery_offset;
705 /* Restore ->map_size before calling underlying expand_file.
706 Also so that we don't try to expand the file again in the
707 transaction commit, which would destroy the recovery
709 addition = (tdb->file->map_size - tdb->transaction->old_map_size) +
710 sizeof(rec) + *recovery_max_size;
711 tdb->file->map_size = tdb->transaction->old_map_size;
712 ecode = methods->expand_file(tdb, addition);
713 if (ecode != TDB_SUCCESS) {
714 return tdb_logerr(tdb, ecode, TDB_LOG_ERROR,
715 "tdb_recovery_allocate:"
716 " failed to create recovery area");
719 /* we have to reset the old map size so that we don't try to
720 expand the file again in the transaction commit, which
721 would destroy the recovery area */
722 tdb->transaction->old_map_size = tdb->file->map_size;
724 /* write the recovery header offset and sync - we can sync without a race here
725 as the magic ptr in the recovery record has not been set */
726 tdb_convert(tdb, &recovery_head, sizeof(recovery_head));
727 ecode = methods->twrite(tdb, offsetof(struct tdb_header, recovery),
728 &recovery_head, sizeof(tdb_off_t));
729 if (ecode != TDB_SUCCESS) {
730 return tdb_logerr(tdb, ecode, TDB_LOG_ERROR,
731 "tdb_recovery_allocate:"
732 " failed to write recovery head");
734 transaction_write_existing(tdb, offsetof(struct tdb_header, recovery),
740 /* Set up header for the recovery record. */
741 static void set_recovery_header(struct tdb_recovery_record *rec,
743 uint64_t datalen, uint64_t actuallen,
747 rec->max_len = actuallen;
753 setup the recovery data that will be used on a crash during commit
755 static enum TDB_ERROR transaction_setup_recovery(struct tdb_context *tdb,
756 tdb_off_t *magic_offset)
758 /* Initialized for GCC's 4.4.5 overzealous uninitialized warnings. */
759 tdb_len_t recovery_size = 0;
760 tdb_off_t recovery_offset = 0, recovery_max_size = 0;
761 unsigned char *data, *p;
762 const struct tdb_methods *methods = tdb->transaction->io_methods;
763 struct tdb_recovery_record *rec;
764 tdb_off_t old_map_size = tdb->transaction->old_map_size;
765 uint64_t magic, tailer;
767 enum TDB_ERROR ecode;
770 check that the recovery area has enough space
772 ecode = tdb_recovery_allocate(tdb, &recovery_size,
773 &recovery_offset, &recovery_max_size);
774 if (ecode != TDB_SUCCESS) {
778 data = (unsigned char *)malloc(recovery_size + sizeof(*rec));
780 return tdb_logerr(tdb, TDB_ERR_OOM, TDB_LOG_ERROR,
781 "transaction_setup_recovery:"
785 rec = (struct tdb_recovery_record *)data;
786 set_recovery_header(rec, TDB_RECOVERY_INVALID_MAGIC,
787 recovery_size, recovery_max_size, old_map_size);
788 tdb_convert(tdb, rec, sizeof(*rec));
790 /* build the recovery data into a single blob to allow us to do a single
791 large write, which should be more efficient */
792 p = data + sizeof(*rec);
793 for (i=0;i<tdb->transaction->num_blocks;i++) {
797 if (tdb->transaction->blocks[i] == NULL) {
801 offset = i * getpagesize();
802 length = getpagesize();
803 if (i == tdb->transaction->num_blocks-1) {
804 length = tdb->transaction->last_block_size;
807 if (offset >= old_map_size) {
810 if (offset + length > tdb->file->map_size) {
812 return tdb_logerr(tdb, TDB_ERR_CORRUPT, TDB_LOG_ERROR,
813 "tdb_transaction_setup_recovery:"
814 " transaction data over new region"
817 memcpy(p, &offset, sizeof(offset));
818 memcpy(p + sizeof(offset), &length, sizeof(length));
819 tdb_convert(tdb, p, sizeof(offset) + sizeof(length));
821 /* the recovery area contains the old data, not the
822 new data, so we have to call the original tdb_read
824 ecode = methods->tread(tdb, offset,
825 p + sizeof(offset) + sizeof(length),
827 if (ecode != TDB_SUCCESS) {
831 p += sizeof(offset) + sizeof(length) + length;
835 tailer = sizeof(*rec) + recovery_max_size;
836 memcpy(p, &tailer, sizeof(tailer));
837 tdb_convert(tdb, p, sizeof(tailer));
839 /* write the recovery data to the recovery area */
840 ecode = methods->twrite(tdb, recovery_offset, data,
841 sizeof(*rec) + recovery_size);
842 if (ecode != TDB_SUCCESS) {
844 return tdb_logerr(tdb, ecode, TDB_LOG_ERROR,
845 "tdb_transaction_setup_recovery:"
846 " failed to write recovery data");
848 transaction_write_existing(tdb, recovery_offset, data,
849 sizeof(*rec) + recovery_size);
851 /* as we don't have ordered writes, we have to sync the recovery
852 data before we update the magic to indicate that the recovery
854 ecode = transaction_sync(tdb, recovery_offset,
855 sizeof(*rec) + recovery_size);
856 if (ecode != TDB_SUCCESS) {
863 magic = TDB_RECOVERY_MAGIC;
864 tdb_convert(tdb, &magic, sizeof(magic));
866 *magic_offset = recovery_offset + offsetof(struct tdb_recovery_record,
869 ecode = methods->twrite(tdb, *magic_offset, &magic, sizeof(magic));
870 if (ecode != TDB_SUCCESS) {
871 return tdb_logerr(tdb, ecode, TDB_LOG_ERROR,
872 "tdb_transaction_setup_recovery:"
873 " failed to write recovery magic");
875 transaction_write_existing(tdb, *magic_offset, &magic, sizeof(magic));
877 /* ensure the recovery magic marker is on disk */
878 return transaction_sync(tdb, *magic_offset, sizeof(magic));
881 static enum TDB_ERROR _tdb_transaction_prepare_commit(struct tdb_context *tdb)
883 const struct tdb_methods *methods;
884 enum TDB_ERROR ecode;
886 if (tdb->transaction == NULL) {
887 return tdb_logerr(tdb, TDB_ERR_EINVAL, TDB_LOG_USE_ERROR,
888 "tdb_transaction_prepare_commit:"
892 if (tdb->transaction->prepared) {
893 _tdb_transaction_cancel(tdb);
894 return tdb_logerr(tdb, TDB_ERR_EINVAL, TDB_LOG_USE_ERROR,
895 "tdb_transaction_prepare_commit:"
896 " transaction already prepared");
899 if (tdb->transaction->transaction_error) {
900 _tdb_transaction_cancel(tdb);
901 return tdb_logerr(tdb, TDB_ERR_EINVAL, TDB_LOG_ERROR,
902 "tdb_transaction_prepare_commit:"
903 " transaction error pending");
907 if (tdb->transaction->nesting != 0) {
908 tdb->transaction->nesting--;
912 /* check for a null transaction */
913 if (tdb->transaction->blocks == NULL) {
917 methods = tdb->transaction->io_methods;
919 /* upgrade the main transaction lock region to a write lock */
920 ecode = tdb_allrecord_upgrade(tdb);
921 if (ecode != TDB_SUCCESS) {
922 tdb_logerr(tdb, ecode, TDB_LOG_ERROR,
923 "tdb_transaction_prepare_commit:"
924 " failed to upgrade hash locks");
925 _tdb_transaction_cancel(tdb);
929 /* get the open lock - this prevents new users attaching to the database
931 ecode = tdb_lock_open(tdb, TDB_LOCK_WAIT|TDB_LOCK_NOCHECK);
932 if (ecode != TDB_SUCCESS) {
933 tdb_logerr(tdb, ecode, TDB_LOG_ERROR,
934 "tdb_transaction_prepare_commit:"
935 " failed to get open lock");
936 _tdb_transaction_cancel(tdb);
940 /* Since we have whole db locked, we don't need the expansion lock. */
941 if (!(tdb->flags & TDB_NOSYNC)) {
942 /* write the recovery data to the end of the file */
943 ecode = transaction_setup_recovery(tdb,
946 if (ecode != TDB_SUCCESS) {
947 tdb_logerr(tdb, ecode, TDB_LOG_ERROR,
948 "tdb_transaction_prepare_commit:"
949 " failed to setup recovery data");
950 _tdb_transaction_cancel(tdb);
955 tdb->transaction->prepared = true;
957 /* expand the file to the new size if needed */
958 if (tdb->file->map_size != tdb->transaction->old_map_size) {
961 add = tdb->file->map_size - tdb->transaction->old_map_size;
962 /* Restore original map size for tdb_expand_file */
963 tdb->file->map_size = tdb->transaction->old_map_size;
964 ecode = methods->expand_file(tdb, add);
965 if (ecode != TDB_SUCCESS) {
966 tdb_logerr(tdb, ecode, TDB_LOG_ERROR,
967 "tdb_transaction_prepare_commit:"
968 " expansion failed");
969 _tdb_transaction_cancel(tdb);
974 /* Keep the open lock until the actual commit */
979 prepare to commit the current transaction
981 enum TDB_ERROR tdb_transaction_prepare_commit(struct tdb_context *tdb)
983 return _tdb_transaction_prepare_commit(tdb);
987 commit the current transaction
989 enum TDB_ERROR tdb_transaction_commit(struct tdb_context *tdb)
991 const struct tdb_methods *methods;
993 enum TDB_ERROR ecode;
995 if (tdb->transaction == NULL) {
996 return tdb->last_error = tdb_logerr(tdb, TDB_ERR_EINVAL,
998 "tdb_transaction_commit:"
1002 tdb_trace(tdb, "tdb_transaction_commit");
1004 if (tdb->transaction->nesting != 0) {
1005 tdb->transaction->nesting--;
1006 return tdb->last_error = TDB_SUCCESS;
1009 /* check for a null transaction */
1010 if (tdb->transaction->blocks == NULL) {
1011 _tdb_transaction_cancel(tdb);
1012 return tdb->last_error = TDB_SUCCESS;
1015 if (!tdb->transaction->prepared) {
1016 ecode = _tdb_transaction_prepare_commit(tdb);
1017 if (ecode != TDB_SUCCESS)
1018 return tdb->last_error = ecode;
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 * getpagesize();
1033 length = getpagesize();
1034 if (i == tdb->transaction->num_blocks-1) {
1035 length = tdb->transaction->last_block_size;
1038 ecode = methods->twrite(tdb, offset,
1039 tdb->transaction->blocks[i], length);
1040 if (ecode != TDB_SUCCESS) {
1041 tdb_logerr(tdb, ecode, TDB_LOG_ERROR,
1042 "tdb_transaction_commit:"
1043 " write failed during commit");
1045 /* we've overwritten part of the data and
1046 possibly expanded the file, so we need to
1047 run the crash recovery code */
1048 tdb->methods = methods;
1049 tdb_transaction_recover(tdb);
1051 _tdb_transaction_cancel(tdb);
1053 return tdb->last_error = ecode;
1055 SAFE_FREE(tdb->transaction->blocks[i]);
1058 SAFE_FREE(tdb->transaction->blocks);
1059 tdb->transaction->num_blocks = 0;
1061 /* ensure the new data is on disk */
1062 ecode = transaction_sync(tdb, 0, tdb->file->map_size);
1063 if (ecode != TDB_SUCCESS) {
1064 return tdb->last_error = ecode;
1068 TODO: maybe write to some dummy hdr field, or write to magic
1069 offset without mmap, before the last sync, instead of the
1073 /* on some systems (like Linux 2.6.x) changes via mmap/msync
1074 don't change the mtime of the file, this means the file may
1075 not be backed up (as tdb rounding to block sizes means that
1076 file size changes are quite rare too). The following forces
1077 mtime changes when a transaction completes */
1079 utime(tdb->name, NULL);
1082 /* use a transaction cancel to free memory and remove the
1083 transaction locks */
1084 _tdb_transaction_cancel(tdb);
1086 return tdb->last_error = TDB_SUCCESS;
1091 recover from an aborted transaction. Must be called with exclusive
1092 database write access already established (including the open
1093 lock to prevent new processes attaching)
1095 enum TDB_ERROR tdb_transaction_recover(struct tdb_context *tdb)
1097 tdb_off_t recovery_head, recovery_eof;
1098 unsigned char *data, *p;
1099 struct tdb_recovery_record rec;
1100 enum TDB_ERROR ecode;
1102 /* find the recovery area */
1103 recovery_head = tdb_read_off(tdb, offsetof(struct tdb_header,recovery));
1104 if (TDB_OFF_IS_ERR(recovery_head)) {
1105 return tdb_logerr(tdb, recovery_head, TDB_LOG_ERROR,
1106 "tdb_transaction_recover:"
1107 " failed to read recovery head");
1110 if (recovery_head == 0) {
1111 /* we have never allocated a recovery record */
1115 /* read the recovery record */
1116 ecode = tdb_read_convert(tdb, recovery_head, &rec, sizeof(rec));
1117 if (ecode != TDB_SUCCESS) {
1118 return tdb_logerr(tdb, ecode, TDB_LOG_ERROR,
1119 "tdb_transaction_recover:"
1120 " failed to read recovery record");
1123 if (rec.magic != TDB_RECOVERY_MAGIC) {
1124 /* there is no valid recovery data */
1128 if (tdb->read_only) {
1129 return tdb_logerr(tdb, TDB_ERR_CORRUPT, TDB_LOG_ERROR,
1130 "tdb_transaction_recover:"
1131 " attempt to recover read only database");
1134 recovery_eof = rec.eof;
1136 data = (unsigned char *)malloc(rec.len);
1138 return tdb_logerr(tdb, TDB_ERR_OOM, TDB_LOG_ERROR,
1139 "tdb_transaction_recover:"
1140 " failed to allocate recovery data");
1143 /* read the full recovery data */
1144 ecode = tdb->methods->tread(tdb, recovery_head + sizeof(rec), data,
1146 if (ecode != TDB_SUCCESS) {
1147 return tdb_logerr(tdb, ecode, TDB_LOG_ERROR,
1148 "tdb_transaction_recover:"
1149 " failed to read recovery data");
1152 /* recover the file data */
1154 while (p+sizeof(tdb_off_t)+sizeof(tdb_len_t) < data + rec.len) {
1157 tdb_convert(tdb, p, sizeof(ofs) + sizeof(len));
1158 memcpy(&ofs, p, sizeof(ofs));
1159 memcpy(&len, p + sizeof(ofs), sizeof(len));
1160 p += sizeof(ofs) + sizeof(len);
1162 ecode = tdb->methods->twrite(tdb, ofs, p, len);
1163 if (ecode != TDB_SUCCESS) {
1165 return tdb_logerr(tdb, ecode, TDB_LOG_ERROR,
1166 "tdb_transaction_recover:"
1167 " failed to recover %zu bytes"
1169 (size_t)len, (size_t)ofs);
1176 ecode = transaction_sync(tdb, 0, tdb->file->map_size);
1177 if (ecode != TDB_SUCCESS) {
1178 return tdb_logerr(tdb, ecode, TDB_LOG_ERROR,
1179 "tdb_transaction_recover:"
1180 " failed to sync recovery");
1183 /* if the recovery area is after the recovered eof then remove it */
1184 if (recovery_eof <= recovery_head) {
1185 ecode = tdb_write_off(tdb, offsetof(struct tdb_header,
1188 if (ecode != TDB_SUCCESS) {
1189 return tdb_logerr(tdb, ecode, TDB_LOG_ERROR,
1190 "tdb_transaction_recover:"
1191 " failed to remove recovery head");
1195 /* remove the recovery magic */
1196 ecode = tdb_write_off(tdb,
1198 + offsetof(struct tdb_recovery_record, magic),
1199 TDB_RECOVERY_INVALID_MAGIC);
1200 if (ecode != TDB_SUCCESS) {
1201 return tdb_logerr(tdb, ecode, TDB_LOG_ERROR,
1202 "tdb_transaction_recover:"
1203 " failed to remove recovery magic");
1206 ecode = transaction_sync(tdb, 0, recovery_eof);
1207 if (ecode != TDB_SUCCESS) {
1208 return tdb_logerr(tdb, ecode, TDB_LOG_ERROR,
1209 "tdb_transaction_recover:"
1210 " failed to sync2 recovery");
1213 tdb_logerr(tdb, TDB_SUCCESS, TDB_LOG_WARNING,
1214 "tdb_transaction_recover: recovered %zu byte database",
1215 (size_t)recovery_eof);
1221 tdb_bool_err tdb_needs_recovery(struct tdb_context *tdb)
1223 tdb_off_t recovery_head;
1224 struct tdb_recovery_record rec;
1225 enum TDB_ERROR ecode;
1227 /* find the recovery area */
1228 recovery_head = tdb_read_off(tdb, offsetof(struct tdb_header,recovery));
1229 if (TDB_OFF_IS_ERR(recovery_head)) {
1230 return recovery_head;
1233 if (recovery_head == 0) {
1234 /* we have never allocated a recovery record */
1238 /* read the recovery record */
1239 ecode = tdb_read_convert(tdb, recovery_head, &rec, sizeof(rec));
1240 if (ecode != TDB_SUCCESS) {
1244 return (rec.magic == TDB_RECOVERY_MAGIC);