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 "tdb1_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 tdb1_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 tdb1_write() calls. The hooked
48 transaction versions of tdb1_read() and tdb1_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 tdb1_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 tdb1_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 tdb1_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 tdb1_add_flags() transaction nesting is enabled.
90 The default is that transaction nesting is NOT allowed.
92 Beware. when transactions are nested a transaction successfully
93 completed with tdb1_transaction_commit() can be silently unrolled later.
98 hold the context of any current transaction
100 struct tdb1_transaction {
101 /* we keep a mirrored copy of the tdb hash heads here so
102 tdb1_next_hash_chain() can operate efficiently */
103 uint32_t *hash_heads;
105 /* the original io methods - used to do IOs to the real db */
106 const struct tdb1_methods *io_methods;
108 /* the list of transaction blocks. When a block is first
109 written to, it gets created in this list */
112 uint32_t block_size; /* bytes in each block */
113 uint32_t last_block_size; /* number of valid bytes in the last block */
115 /* non-zero when an internal transaction error has
116 occurred. All write operations will then fail until the
117 transaction is ended */
118 int transaction_error;
120 /* when inside a transaction we need to keep track of any
121 nested tdb1_transaction_start() calls, as these are allowed,
122 but don't create a new transaction */
125 /* set when a prepare has already occurred */
127 tdb1_off_t magic_offset;
129 /* old file size before transaction */
130 tdb1_len_t old_map_size;
132 /* did we expand in this transaction */
138 read while in a transaction. We need to check first if the data is in our list
139 of transaction elements, then if not do a real read
141 static int transaction1_read(struct tdb1_context *tdb, tdb1_off_t off, void *buf,
142 tdb1_len_t len, int cv)
146 /* break it down into block sized ops */
147 while (len + (off % tdb->transaction->block_size) > tdb->transaction->block_size) {
148 tdb1_len_t len2 = tdb->transaction->block_size - (off % tdb->transaction->block_size);
149 if (transaction1_read(tdb, off, buf, len2, cv) != 0) {
154 buf = (void *)(len2 + (char *)buf);
161 blk = off / tdb->transaction->block_size;
163 /* see if we have it in the block list */
164 if (tdb->transaction->num_blocks <= blk ||
165 tdb->transaction->blocks[blk] == NULL) {
166 /* nope, do a real read */
167 if (tdb->transaction->io_methods->tdb1_read(tdb, off, buf, len, cv) != 0) {
173 /* it is in the block list. Now check for the last block */
174 if (blk == tdb->transaction->num_blocks-1) {
175 if (len > tdb->transaction->last_block_size) {
180 /* now copy it out of this block */
181 memcpy(buf, tdb->transaction->blocks[blk] + (off % tdb->transaction->block_size), len);
183 tdb1_convert(buf, len);
188 tdb->last_error = tdb_logerr(tdb, TDB_ERR_IO, TDB_LOG_ERROR,
189 "transaction_read: failed at off=%d len=%d",
191 tdb->transaction->transaction_error = 1;
197 write while in a transaction
199 static int transaction1_write(struct tdb1_context *tdb, tdb1_off_t off,
200 const void *buf, tdb1_len_t len)
204 /* Only a commit is allowed on a prepared transaction */
205 if (tdb->transaction->prepared) {
206 tdb->last_error = tdb_logerr(tdb, TDB_ERR_EINVAL, TDB_LOG_USE_ERROR,
207 "transaction_write: transaction already"
208 " prepared, write not allowed");
209 tdb->transaction->transaction_error = 1;
213 /* if the write is to a hash head, then update the transaction
215 if (len == sizeof(tdb1_off_t) && off >= TDB1_FREELIST_TOP &&
216 off < TDB1_FREELIST_TOP+TDB1_HASHTABLE_SIZE(tdb)) {
217 uint32_t chain = (off-TDB1_FREELIST_TOP) / sizeof(tdb1_off_t);
218 memcpy(&tdb->transaction->hash_heads[chain], buf, len);
221 /* break it up into block sized chunks */
222 while (len + (off % tdb->transaction->block_size) > tdb->transaction->block_size) {
223 tdb1_len_t len2 = tdb->transaction->block_size - (off % tdb->transaction->block_size);
224 if (transaction1_write(tdb, off, buf, len2) != 0) {
230 buf = (const void *)(len2 + (const char *)buf);
238 blk = off / tdb->transaction->block_size;
239 off = off % tdb->transaction->block_size;
241 if (tdb->transaction->num_blocks <= blk) {
242 uint8_t **new_blocks;
243 /* expand the blocks array */
244 if (tdb->transaction->blocks == NULL) {
245 new_blocks = (uint8_t **)malloc(
246 (blk+1)*sizeof(uint8_t *));
248 new_blocks = (uint8_t **)realloc(
249 tdb->transaction->blocks,
250 (blk+1)*sizeof(uint8_t *));
252 if (new_blocks == NULL) {
253 tdb->last_error = TDB_ERR_OOM;
256 memset(&new_blocks[tdb->transaction->num_blocks], 0,
257 (1+(blk - tdb->transaction->num_blocks))*sizeof(uint8_t *));
258 tdb->transaction->blocks = new_blocks;
259 tdb->transaction->num_blocks = blk+1;
260 tdb->transaction->last_block_size = 0;
263 /* allocate and fill a block? */
264 if (tdb->transaction->blocks[blk] == NULL) {
265 tdb->transaction->blocks[blk] = (uint8_t *)calloc(tdb->transaction->block_size, 1);
266 if (tdb->transaction->blocks[blk] == NULL) {
267 tdb->last_error = TDB_ERR_OOM;
268 tdb->transaction->transaction_error = 1;
271 if (tdb->transaction->old_map_size > blk * tdb->transaction->block_size) {
272 tdb1_len_t len2 = tdb->transaction->block_size;
273 if (len2 + (blk * tdb->transaction->block_size) > tdb->transaction->old_map_size) {
274 len2 = tdb->transaction->old_map_size - (blk * tdb->transaction->block_size);
276 if (tdb->transaction->io_methods->tdb1_read(tdb, blk * tdb->transaction->block_size,
277 tdb->transaction->blocks[blk],
279 SAFE_FREE(tdb->transaction->blocks[blk]);
280 tdb->last_error = TDB_ERR_IO;
283 if (blk == tdb->transaction->num_blocks-1) {
284 tdb->transaction->last_block_size = len2;
289 /* overwrite part of an existing block */
291 memset(tdb->transaction->blocks[blk] + off, 0, len);
293 memcpy(tdb->transaction->blocks[blk] + off, buf, len);
295 if (blk == tdb->transaction->num_blocks-1) {
296 if (len + off > tdb->transaction->last_block_size) {
297 tdb->transaction->last_block_size = len + off;
304 tdb_logerr(tdb, tdb->last_error, TDB_LOG_ERROR,
305 "transaction_write: failed at off=%d len=%d",
306 (blk*tdb->transaction->block_size) + off, len);
307 tdb->transaction->transaction_error = 1;
313 write while in a transaction - this varient never expands the transaction blocks, it only
314 updates existing blocks. This means it cannot change the recovery size
316 static int transaction1_write_existing(struct tdb1_context *tdb, tdb1_off_t off,
317 const void *buf, tdb1_len_t len)
321 /* break it up into block sized chunks */
322 while (len + (off % tdb->transaction->block_size) > tdb->transaction->block_size) {
323 tdb1_len_t len2 = tdb->transaction->block_size - (off % tdb->transaction->block_size);
324 if (transaction1_write_existing(tdb, off, buf, len2) != 0) {
330 buf = (const void *)(len2 + (const char *)buf);
338 blk = off / tdb->transaction->block_size;
339 off = off % tdb->transaction->block_size;
341 if (tdb->transaction->num_blocks <= blk ||
342 tdb->transaction->blocks[blk] == NULL) {
346 if (blk == tdb->transaction->num_blocks-1 &&
347 off + len > tdb->transaction->last_block_size) {
348 if (off >= tdb->transaction->last_block_size) {
351 len = tdb->transaction->last_block_size - off;
354 /* overwrite part of an existing block */
355 memcpy(tdb->transaction->blocks[blk] + off, buf, len);
362 accelerated hash chain head search, using the cached hash heads
364 static void transaction1_next_hash_chain(struct tdb1_context *tdb, uint32_t *chain)
367 for (;h < tdb->header.hash_size;h++) {
368 /* the +1 takes account of the freelist */
369 if (0 != tdb->transaction->hash_heads[h+1]) {
377 out of bounds check during a transaction
379 static int transaction1_oob(struct tdb1_context *tdb, tdb1_off_t len, int probe)
381 if (len <= tdb->file->map_size) {
384 tdb->last_error = TDB_ERR_IO;
389 transaction version of tdb1_expand().
391 static int transaction1_expand_file(struct tdb1_context *tdb, tdb1_off_t size,
394 /* add a write to the transaction elements, so subsequent
395 reads see the zero data */
396 if (transaction1_write(tdb, size, NULL, addition) != 0) {
400 tdb->transaction->expanded = true;
405 static const struct tdb1_methods transaction1_methods = {
408 transaction1_next_hash_chain,
410 transaction1_expand_file,
415 start a tdb transaction. No token is returned, as only a single
416 transaction is allowed to be pending per tdb1_context
418 static int _tdb1_transaction_start(struct tdb1_context *tdb)
420 /* some sanity checks */
421 if (tdb->read_only || (tdb->flags & TDB_INTERNAL) || tdb->traverse_read) {
422 tdb->last_error = tdb_logerr(tdb, TDB_ERR_EINVAL, TDB_LOG_USE_ERROR,
423 "tdb1_transaction_start: cannot start a"
424 " transaction on a read-only or"
429 /* cope with nested tdb1_transaction_start() calls */
430 if (tdb->transaction != NULL) {
431 if (!(tdb->flags & TDB_ALLOW_NESTING)) {
432 tdb->last_error = TDB_ERR_EINVAL;
435 tdb->transaction->nesting++;
439 if (tdb1_have_extra_locks(tdb)) {
440 /* the caller must not have any locks when starting a
441 transaction as otherwise we'll be screwed by lack
442 of nested locks in posix */
443 tdb->last_error = tdb_logerr(tdb, TDB_ERR_LOCK, TDB_LOG_USE_ERROR,
444 "tdb1_transaction_start: cannot start a"
445 " transaction with locks held");
449 if (tdb->travlocks.next != NULL) {
450 /* you cannot use transactions inside a traverse (although you can use
451 traverse inside a transaction) as otherwise you can end up with
453 tdb->last_error = tdb_logerr(tdb, TDB_ERR_LOCK, TDB_LOG_USE_ERROR,
454 "tdb1_transaction_start: cannot start a"
455 " transaction within a traverse");
459 tdb->transaction = (struct tdb1_transaction *)
460 calloc(sizeof(struct tdb1_transaction), 1);
461 if (tdb->transaction == NULL) {
462 tdb->last_error = TDB_ERR_OOM;
466 /* a page at a time seems like a reasonable compromise between compactness and efficiency */
467 tdb->transaction->block_size = tdb->page_size;
469 /* get the transaction write lock. This is a blocking lock. As
470 discussed with Volker, there are a number of ways we could
471 make this async, which we will probably do in the future */
472 if (tdb1_transaction_lock(tdb, F_WRLCK, TDB_LOCK_WAIT) == -1) {
473 SAFE_FREE(tdb->transaction->blocks);
474 SAFE_FREE(tdb->transaction);
478 /* get a read lock from the freelist to the end of file. This
479 is upgraded to a write lock during the commit */
480 if (tdb1_allrecord_lock(tdb, F_RDLCK, TDB_LOCK_WAIT, true) == -1) {
481 tdb_logerr(tdb, tdb->last_error, TDB_LOG_ERROR,
482 "tdb1_transaction_start: failed to get hash locks");
483 goto fail_allrecord_lock;
486 /* setup a copy of the hash table heads so the hash scan in
487 traverse can be fast */
488 tdb->transaction->hash_heads = (uint32_t *)
489 calloc(tdb->header.hash_size+1, sizeof(uint32_t));
490 if (tdb->transaction->hash_heads == NULL) {
491 tdb->last_error = TDB_ERR_OOM;
494 if (tdb->methods->tdb1_read(tdb, TDB1_FREELIST_TOP, tdb->transaction->hash_heads,
495 TDB1_HASHTABLE_SIZE(tdb), 0) != 0) {
496 tdb_logerr(tdb, tdb->last_error, TDB_LOG_ERROR,
497 "tdb1_transaction_start: failed to read hash heads");
501 /* make sure we know about any file expansions already done by
503 tdb->methods->tdb1_oob(tdb, tdb->file->map_size + 1, 1);
504 tdb->transaction->old_map_size = tdb->file->map_size;
506 /* finally hook the io methods, replacing them with
507 transaction specific methods */
508 tdb->transaction->io_methods = tdb->methods;
509 tdb->methods = &transaction1_methods;
514 tdb1_allrecord_unlock(tdb, F_RDLCK);
516 tdb1_transaction_unlock(tdb, F_WRLCK);
517 SAFE_FREE(tdb->transaction->blocks);
518 SAFE_FREE(tdb->transaction->hash_heads);
519 SAFE_FREE(tdb->transaction);
523 int tdb1_transaction_start(struct tdb1_context *tdb)
525 return _tdb1_transaction_start(tdb);
531 static int transaction1_sync(struct tdb1_context *tdb, tdb1_off_t offset, tdb1_len_t length)
533 if (tdb->flags & TDB_NOSYNC) {
538 if (fdatasync(tdb->file->fd) != 0) {
540 if (fsync(tdb->file->fd) != 0) {
542 tdb->last_error = tdb_logerr(tdb, TDB_ERR_IO, TDB_LOG_ERROR,
543 "tdb1_transaction: fsync failed");
547 if (tdb->file->map_ptr) {
548 tdb1_off_t moffset = offset & ~(tdb->page_size-1);
549 if (msync(moffset + (char *)tdb->file->map_ptr,
550 length + (offset - moffset), MS_SYNC) != 0) {
551 tdb->last_error = tdb_logerr(tdb, TDB_ERR_IO, TDB_LOG_ERROR,
553 " msync failed - %s",
563 static int _tdb1_transaction_cancel(struct tdb1_context *tdb)
567 if (tdb->transaction == NULL) {
568 tdb->last_error = tdb_logerr(tdb, TDB_ERR_EINVAL, TDB_LOG_USE_ERROR,
569 "tdb1_transaction_cancel:"
574 if (tdb->transaction->nesting != 0) {
575 tdb->transaction->transaction_error = 1;
576 tdb->transaction->nesting--;
580 tdb->file->map_size = tdb->transaction->old_map_size;
582 /* free all the transaction blocks */
583 for (i=0;i<tdb->transaction->num_blocks;i++) {
584 if (tdb->transaction->blocks[i] != NULL) {
585 free(tdb->transaction->blocks[i]);
588 SAFE_FREE(tdb->transaction->blocks);
590 if (tdb->transaction->magic_offset) {
591 const struct tdb1_methods *methods = tdb->transaction->io_methods;
592 const uint32_t invalid = TDB1_RECOVERY_INVALID_MAGIC;
594 /* remove the recovery marker */
595 if (methods->tdb1_write(tdb, tdb->transaction->magic_offset, &invalid, 4) == -1 ||
596 transaction1_sync(tdb, tdb->transaction->magic_offset, 4) == -1) {
597 tdb_logerr(tdb, tdb->last_error, TDB_LOG_ERROR,
598 "tdb1_transaction_cancel: failed to"
599 " remove recovery magic");
604 /* This also removes the OPEN_LOCK, if we have it. */
605 tdb1_release_transaction_locks(tdb);
607 /* restore the normal io methods */
608 tdb->methods = tdb->transaction->io_methods;
610 SAFE_FREE(tdb->transaction->hash_heads);
611 SAFE_FREE(tdb->transaction);
617 cancel the current transaction
619 int tdb1_transaction_cancel(struct tdb1_context *tdb)
621 return _tdb1_transaction_cancel(tdb);
625 work out how much space the linearised recovery data will consume
627 static tdb1_len_t tdb1_recovery_size(struct tdb1_context *tdb)
629 tdb1_len_t recovery_size = 0;
632 recovery_size = sizeof(uint32_t);
633 for (i=0;i<tdb->transaction->num_blocks;i++) {
634 if (i * tdb->transaction->block_size >= tdb->transaction->old_map_size) {
637 if (tdb->transaction->blocks[i] == NULL) {
640 recovery_size += 2*sizeof(tdb1_off_t);
641 if (i == tdb->transaction->num_blocks-1) {
642 recovery_size += tdb->transaction->last_block_size;
644 recovery_size += tdb->transaction->block_size;
648 return recovery_size;
651 int tdb1_recovery_area(struct tdb1_context *tdb,
652 const struct tdb1_methods *methods,
653 tdb1_off_t *recovery_offset,
654 struct tdb1_record *rec)
656 if (tdb1_ofs_read(tdb, TDB1_RECOVERY_HEAD, recovery_offset) == -1) {
660 if (*recovery_offset == 0) {
665 if (methods->tdb1_read(tdb, *recovery_offset, rec, sizeof(*rec),
666 TDB1_DOCONV()) == -1) {
670 /* ignore invalid recovery regions: can happen in crash */
671 if (rec->magic != TDB1_RECOVERY_MAGIC &&
672 rec->magic != TDB1_RECOVERY_INVALID_MAGIC) {
673 *recovery_offset = 0;
680 allocate the recovery area, or use an existing recovery area if it is
683 static int tdb1_recovery_allocate(struct tdb1_context *tdb,
684 tdb1_len_t *recovery_size,
685 tdb1_off_t *recovery_offset,
686 tdb1_len_t *recovery_max_size)
688 struct tdb1_record rec;
689 const struct tdb1_methods *methods = tdb->transaction->io_methods;
690 tdb1_off_t recovery_head;
692 if (tdb1_recovery_area(tdb, methods, &recovery_head, &rec) == -1) {
693 tdb_logerr(tdb, tdb->last_error, TDB_LOG_ERROR,
694 "tdb1_recovery_allocate:"
695 " failed to read recovery head");
699 *recovery_size = tdb1_recovery_size(tdb);
701 if (recovery_head != 0 && *recovery_size <= rec.rec_len) {
702 /* it fits in the existing area */
703 *recovery_max_size = rec.rec_len;
704 *recovery_offset = recovery_head;
708 /* we need to free up the old recovery area, then allocate a
709 new one at the end of the file. Note that we cannot use
710 tdb1_allocate() to allocate the new one as that might return
711 us an area that is being currently used (as of the start of
713 if (recovery_head != 0) {
714 if (tdb1_free(tdb, recovery_head, &rec) == -1) {
715 tdb_logerr(tdb, tdb->last_error, TDB_LOG_ERROR,
716 "tdb1_recovery_allocate: failed to free"
717 " previous recovery area");
722 /* the tdb1_free() call might have increased the recovery size */
723 *recovery_size = tdb1_recovery_size(tdb);
725 /* round up to a multiple of page size */
726 *recovery_max_size = TDB1_ALIGN(sizeof(rec) + *recovery_size, tdb->page_size) - sizeof(rec);
727 *recovery_offset = tdb->file->map_size;
728 recovery_head = *recovery_offset;
730 if (methods->tdb1_expand_file(tdb, tdb->transaction->old_map_size,
731 (tdb->file->map_size - tdb->transaction->old_map_size) +
732 sizeof(rec) + *recovery_max_size) == -1) {
733 tdb_logerr(tdb, tdb->last_error, TDB_LOG_ERROR,
734 "tdb1_recovery_allocate:"
735 " failed to create recovery area");
739 /* remap the file (if using mmap) */
740 methods->tdb1_oob(tdb, tdb->file->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->file->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 TDB1_CONV(recovery_head);
749 if (methods->tdb1_write(tdb, TDB1_RECOVERY_HEAD,
750 &recovery_head, sizeof(tdb1_off_t)) == -1) {
751 tdb_logerr(tdb, tdb->last_error, TDB_LOG_ERROR,
752 "tdb1_recovery_allocate:"
753 " failed to write recovery head");
756 if (transaction1_write_existing(tdb, TDB1_RECOVERY_HEAD, &recovery_head, sizeof(tdb1_off_t)) == -1) {
757 tdb_logerr(tdb, tdb->last_error, TDB_LOG_ERROR,
758 "tdb1_recovery_allocate:"
759 " failed to write recovery head");
768 setup the recovery data that will be used on a crash during commit
770 static int transaction1_setup_recovery(struct tdb1_context *tdb,
771 tdb1_off_t *magic_offset)
773 tdb1_len_t recovery_size;
774 unsigned char *data, *p;
775 const struct tdb1_methods *methods = tdb->transaction->io_methods;
776 struct tdb1_record *rec;
777 tdb1_off_t recovery_offset, recovery_max_size;
778 tdb1_off_t old_map_size = tdb->transaction->old_map_size;
779 uint32_t magic, tailer;
783 check that the recovery area has enough space
785 if (tdb1_recovery_allocate(tdb, &recovery_size,
786 &recovery_offset, &recovery_max_size) == -1) {
790 data = (unsigned char *)malloc(recovery_size + sizeof(*rec));
792 tdb->last_error = TDB_ERR_OOM;
796 rec = (struct tdb1_record *)data;
797 memset(rec, 0, sizeof(*rec));
799 rec->magic = TDB1_RECOVERY_INVALID_MAGIC;
800 rec->data_len = recovery_size;
801 rec->rec_len = recovery_max_size;
802 rec->key_len = old_map_size;
805 /* build the recovery data into a single blob to allow us to do a single
806 large write, which should be more efficient */
807 p = data + sizeof(*rec);
808 for (i=0;i<tdb->transaction->num_blocks;i++) {
812 if (tdb->transaction->blocks[i] == NULL) {
816 offset = i * tdb->transaction->block_size;
817 length = tdb->transaction->block_size;
818 if (i == tdb->transaction->num_blocks-1) {
819 length = tdb->transaction->last_block_size;
822 if (offset >= old_map_size) {
825 if (offset + length > tdb->transaction->old_map_size) {
826 tdb->last_error = tdb_logerr(tdb, TDB_ERR_CORRUPT,
828 "tdb1_transaction_setup_recovery: transaction data over new region boundary");
832 memcpy(p, &offset, 4);
833 memcpy(p+4, &length, 4);
837 /* the recovery area contains the old data, not the
838 new data, so we have to call the original tdb1_read
840 if (methods->tdb1_read(tdb, offset, p + 8, length, 0) != 0) {
842 tdb->last_error = TDB_ERR_IO;
849 tailer = sizeof(*rec) + recovery_max_size;
850 memcpy(p, &tailer, 4);
855 /* write the recovery data to the recovery area */
856 if (methods->tdb1_write(tdb, recovery_offset, data, sizeof(*rec) + recovery_size) == -1) {
857 tdb_logerr(tdb, tdb->last_error, TDB_LOG_ERROR,
858 "tdb1_transaction_setup_recovery:"
859 " failed to write recovery data");
863 if (transaction1_write_existing(tdb, recovery_offset, data, sizeof(*rec) + recovery_size) == -1) {
864 tdb_logerr(tdb, tdb->last_error, TDB_LOG_ERROR,
865 "tdb1_transaction_setup_recovery: failed to write"
866 " secondary recovery data");
871 /* as we don't have ordered writes, we have to sync the recovery
872 data before we update the magic to indicate that the recovery
874 if (transaction1_sync(tdb, recovery_offset, sizeof(*rec) + recovery_size) == -1) {
881 magic = TDB1_RECOVERY_MAGIC;
884 *magic_offset = recovery_offset + offsetof(struct tdb1_record, magic);
886 if (methods->tdb1_write(tdb, *magic_offset, &magic, sizeof(magic)) == -1) {
887 tdb_logerr(tdb, tdb->last_error, TDB_LOG_ERROR,
888 "tdb1_transaction_setup_recovery:"
889 " failed to write recovery magic");
892 if (transaction1_write_existing(tdb, *magic_offset, &magic, sizeof(magic)) == -1) {
893 tdb_logerr(tdb, tdb->last_error, TDB_LOG_ERROR,
894 "tdb1_transaction_setup_recovery:"
895 " failed to write secondary recovery magic");
899 /* ensure the recovery magic marker is on disk */
900 if (transaction1_sync(tdb, *magic_offset, sizeof(magic)) == -1) {
907 static int _tdb1_transaction_prepare_commit(struct tdb1_context *tdb)
909 const struct tdb1_methods *methods;
911 if (tdb->transaction == NULL) {
912 tdb->last_error = tdb_logerr(tdb, TDB_ERR_EINVAL, TDB_LOG_USE_ERROR,
913 "tdb1_transaction_prepare_commit:"
918 if (tdb->transaction->prepared) {
919 tdb->last_error = tdb_logerr(tdb, TDB_ERR_EINVAL, TDB_LOG_USE_ERROR,
920 "tdb1_transaction_prepare_commit:"
921 " transaction already prepared");
922 _tdb1_transaction_cancel(tdb);
926 if (tdb->transaction->transaction_error) {
927 tdb->last_error = tdb_logerr(tdb, TDB_ERR_IO, TDB_LOG_ERROR,
928 "tdb1_transaction_prepare_commit:"
929 " transaction error pending");
930 _tdb1_transaction_cancel(tdb);
935 if (tdb->transaction->nesting != 0) {
939 /* check for a null transaction */
940 if (tdb->transaction->blocks == NULL) {
944 methods = tdb->transaction->io_methods;
946 /* if there are any locks pending then the caller has not
947 nested their locks properly, so fail the transaction */
948 if (tdb1_have_extra_locks(tdb)) {
949 tdb->last_error = tdb_logerr(tdb, TDB_ERR_LOCK, TDB_LOG_USE_ERROR,
950 "tdb1_transaction_prepare_commit:"
951 " locks pending on commit");
952 _tdb1_transaction_cancel(tdb);
956 /* upgrade the main transaction lock region to a write lock */
957 if (tdb1_allrecord_upgrade(tdb) == -1) {
958 tdb_logerr(tdb, tdb->last_error, TDB_LOG_ERROR,
959 "tdb1_transaction_prepare_commit:"
960 " failed to upgrade hash locks");
961 _tdb1_transaction_cancel(tdb);
965 /* get the open lock - this prevents new users attaching to the database
967 if (tdb1_nest_lock(tdb, TDB1_OPEN_LOCK, F_WRLCK, TDB_LOCK_WAIT) == -1) {
968 tdb_logerr(tdb, tdb->last_error, TDB_LOG_ERROR,
969 "tdb1_transaction_prepare_commit:"
970 " failed to get open lock");
971 _tdb1_transaction_cancel(tdb);
975 if (!(tdb->flags & TDB_NOSYNC)) {
976 /* write the recovery data to the end of the file */
977 if (transaction1_setup_recovery(tdb, &tdb->transaction->magic_offset) == -1) {
978 tdb_logerr(tdb, tdb->last_error, TDB_LOG_ERROR,
979 "tdb1_transaction_prepare_commit:"
980 " failed to setup recovery data");
981 _tdb1_transaction_cancel(tdb);
986 tdb->transaction->prepared = true;
988 /* expand the file to the new size if needed */
989 if (tdb->file->map_size != tdb->transaction->old_map_size) {
990 if (methods->tdb1_expand_file(tdb, tdb->transaction->old_map_size,
991 tdb->file->map_size -
992 tdb->transaction->old_map_size) == -1) {
993 tdb_logerr(tdb, tdb->last_error, TDB_LOG_ERROR,
994 "tdb1_transaction_prepare_commit:"
995 " expansion failed");
996 _tdb1_transaction_cancel(tdb);
999 tdb->file->map_size = tdb->transaction->old_map_size;
1000 methods->tdb1_oob(tdb, tdb->file->map_size + 1, 1);
1003 /* Keep the open lock until the actual commit */
1009 prepare to commit the current transaction
1011 int tdb1_transaction_prepare_commit(struct tdb1_context *tdb)
1013 return _tdb1_transaction_prepare_commit(tdb);
1016 /* A repack is worthwhile if the largest is less than half total free. */
1017 static bool repack_worthwhile(struct tdb1_context *tdb)
1020 struct tdb1_record rec;
1021 tdb1_len_t total = 0, largest = 0;
1023 if (tdb1_ofs_read(tdb, TDB1_FREELIST_TOP, &ptr) == -1) {
1027 while (ptr != 0 && tdb1_rec_free_read(tdb, ptr, &rec) == 0) {
1028 total += rec.rec_len;
1029 if (rec.rec_len > largest) {
1030 largest = rec.rec_len;
1035 return total > largest * 2;
1039 commit the current transaction
1041 int tdb1_transaction_commit(struct tdb1_context *tdb)
1043 const struct tdb1_methods *methods;
1045 bool need_repack = false;
1047 if (tdb->transaction == NULL) {
1048 tdb->last_error = tdb_logerr(tdb, TDB_ERR_EINVAL, TDB_LOG_USE_ERROR,
1049 "tdb1_transaction_commit:"
1054 if (tdb->transaction->transaction_error) {
1055 tdb->last_error = tdb_logerr(tdb, TDB_ERR_IO, TDB_LOG_ERROR,
1056 "tdb1_transaction_commit:"
1057 " transaction error pending");
1058 _tdb1_transaction_cancel(tdb);
1063 if (tdb->transaction->nesting != 0) {
1064 tdb->transaction->nesting--;
1068 /* check for a null transaction */
1069 if (tdb->transaction->blocks == NULL) {
1070 _tdb1_transaction_cancel(tdb);
1074 if (!tdb->transaction->prepared) {
1075 int ret = _tdb1_transaction_prepare_commit(tdb);
1080 methods = tdb->transaction->io_methods;
1082 /* perform all the writes */
1083 for (i=0;i<tdb->transaction->num_blocks;i++) {
1087 if (tdb->transaction->blocks[i] == NULL) {
1091 offset = i * tdb->transaction->block_size;
1092 length = tdb->transaction->block_size;
1093 if (i == tdb->transaction->num_blocks-1) {
1094 length = tdb->transaction->last_block_size;
1097 if (methods->tdb1_write(tdb, offset, tdb->transaction->blocks[i], length) == -1) {
1098 tdb_logerr(tdb, tdb->last_error, TDB_LOG_ERROR,
1099 "tdb1_transaction_commit:"
1100 " write failed during commit");
1102 /* we've overwritten part of the data and
1103 possibly expanded the file, so we need to
1104 run the crash recovery code */
1105 tdb->methods = methods;
1106 tdb1_transaction_recover(tdb);
1108 _tdb1_transaction_cancel(tdb);
1110 tdb_logerr(tdb, tdb->last_error, TDB_LOG_ERROR,
1111 "tdb1_transaction_commit: write failed");
1114 SAFE_FREE(tdb->transaction->blocks[i]);
1117 /* Do this before we drop lock or blocks. */
1118 if (tdb->transaction->expanded) {
1119 need_repack = repack_worthwhile(tdb);
1122 SAFE_FREE(tdb->transaction->blocks);
1123 tdb->transaction->num_blocks = 0;
1125 /* ensure the new data is on disk */
1126 if (transaction1_sync(tdb, 0, tdb->file->map_size) == -1) {
1131 TODO: maybe write to some dummy hdr field, or write to magic
1132 offset without mmap, before the last sync, instead of the
1136 /* on some systems (like Linux 2.6.x) changes via mmap/msync
1137 don't change the mtime of the file, this means the file may
1138 not be backed up (as tdb rounding to block sizes means that
1139 file size changes are quite rare too). The following forces
1140 mtime changes when a transaction completes */
1142 utime(tdb->name, NULL);
1145 /* use a transaction cancel to free memory and remove the
1146 transaction locks */
1147 _tdb1_transaction_cancel(tdb);
1150 return tdb1_repack(tdb);
1158 recover from an aborted transaction. Must be called with exclusive
1159 database write access already established (including the open
1160 lock to prevent new processes attaching)
1162 int tdb1_transaction_recover(struct tdb1_context *tdb)
1164 tdb1_off_t recovery_head, recovery_eof;
1165 unsigned char *data, *p;
1167 struct tdb1_record rec;
1169 /* find the recovery area */
1170 if (tdb1_ofs_read(tdb, TDB1_RECOVERY_HEAD, &recovery_head) == -1) {
1171 tdb_logerr(tdb, tdb->last_error, TDB_LOG_ERROR,
1172 "tdb1_transaction_recover:"
1173 " failed to read recovery head");
1177 if (recovery_head == 0) {
1178 /* we have never allocated a recovery record */
1182 /* read the recovery record */
1183 if (tdb->methods->tdb1_read(tdb, recovery_head, &rec,
1184 sizeof(rec), TDB1_DOCONV()) == -1) {
1185 tdb_logerr(tdb, tdb->last_error, TDB_LOG_ERROR,
1186 "tdb1_transaction_recover:"
1187 " failed to read recovery record");
1191 if (rec.magic != TDB1_RECOVERY_MAGIC) {
1192 /* there is no valid recovery data */
1196 if (tdb->read_only) {
1197 tdb->last_error = tdb_logerr(tdb, TDB_ERR_CORRUPT, TDB_LOG_ERROR,
1198 "tdb1_transaction_recover:"
1199 " attempt to recover read only"
1204 recovery_eof = rec.key_len;
1206 data = (unsigned char *)malloc(rec.data_len);
1208 tdb->last_error = tdb_logerr(tdb, TDB_ERR_OOM, TDB_LOG_ERROR,
1209 "tdb1_transaction_recover:"
1210 " failed to allocate recovery data");
1214 /* read the full recovery data */
1215 if (tdb->methods->tdb1_read(tdb, recovery_head + sizeof(rec), data,
1216 rec.data_len, 0) == -1) {
1217 tdb_logerr(tdb, tdb->last_error, TDB_LOG_ERROR,
1218 "tdb1_transaction_recover:"
1219 " failed to read recovery data");
1223 /* recover the file data */
1225 while (p+8 < data + rec.data_len) {
1227 if (TDB1_DOCONV()) {
1231 memcpy(&len, p+4, 4);
1233 if (tdb->methods->tdb1_write(tdb, ofs, p+8, len) == -1) {
1235 tdb_logerr(tdb, tdb->last_error, TDB_LOG_ERROR,
1236 "tdb1_transaction_recover: failed to recover"
1237 " %d bytes at offset %d", len, ofs);
1245 if (transaction1_sync(tdb, 0, tdb->file->map_size) == -1) {
1246 tdb_logerr(tdb, tdb->last_error, TDB_LOG_ERROR,
1247 "tdb1_transaction_recover: failed to sync recovery");
1251 /* if the recovery area is after the recovered eof then remove it */
1252 if (recovery_eof <= recovery_head) {
1253 if (tdb1_ofs_write(tdb, TDB1_RECOVERY_HEAD, &zero) == -1) {
1254 tdb_logerr(tdb, tdb->last_error, TDB_LOG_ERROR,
1255 "tdb1_transaction_recover: failed to remove"
1261 /* remove the recovery magic */
1262 if (tdb1_ofs_write(tdb, recovery_head + offsetof(struct tdb1_record, magic),
1264 tdb_logerr(tdb, tdb->last_error, TDB_LOG_ERROR,
1265 "tdb1_transaction_recover: failed to remove"
1270 if (transaction1_sync(tdb, 0, recovery_eof) == -1) {
1271 tdb_logerr(tdb, tdb->last_error, TDB_LOG_ERROR,
1272 "tdb1_transaction_recover:"
1273 " failed to sync2 recovery");
1277 tdb_logerr(tdb, TDB_SUCCESS, TDB_LOG_WARNING,
1278 "tdb1_transaction_recover: recovered %d byte database",
1285 /* Any I/O failures we say "needs recovery". */
1286 bool tdb1_needs_recovery(struct tdb1_context *tdb)
1288 tdb1_off_t recovery_head;
1289 struct tdb1_record rec;
1291 /* find the recovery area */
1292 if (tdb1_ofs_read(tdb, TDB1_RECOVERY_HEAD, &recovery_head) == -1) {
1296 if (recovery_head == 0) {
1297 /* we have never allocated a recovery record */
1301 /* read the recovery record */
1302 if (tdb->methods->tdb1_read(tdb, recovery_head, &rec,
1303 sizeof(rec), TDB1_DOCONV()) == -1) {
1307 return (rec.magic == TDB1_RECOVERY_MAGIC);