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 /* set when the OPEN_LOCK has been taken */
139 bool open_lock_taken;
141 /* old file size before transaction */
142 tdb_len_t old_map_size;
144 /* we should re-pack on commit */
150 read while in a transaction. We need to check first if the data is in our list
151 of transaction elements, then if not do a real read
153 static int transaction_read(struct tdb_context *tdb, tdb_off_t off, void *buf,
154 tdb_len_t len, int cv)
158 /* break it down into block sized ops */
159 while (len + (off % tdb->transaction->block_size) > tdb->transaction->block_size) {
160 tdb_len_t len2 = tdb->transaction->block_size - (off % tdb->transaction->block_size);
161 if (transaction_read(tdb, off, buf, len2, cv) != 0) {
166 buf = (void *)(len2 + (char *)buf);
173 blk = off / tdb->transaction->block_size;
175 /* see if we have it in the block list */
176 if (tdb->transaction->num_blocks <= blk ||
177 tdb->transaction->blocks[blk] == NULL) {
178 /* nope, do a real read */
179 if (tdb->transaction->io_methods->tdb_read(tdb, off, buf, len, cv) != 0) {
185 /* it is in the block list. Now check for the last block */
186 if (blk == tdb->transaction->num_blocks-1) {
187 if (len > tdb->transaction->last_block_size) {
192 /* now copy it out of this block */
193 memcpy(buf, tdb->transaction->blocks[blk] + (off % tdb->transaction->block_size), len);
195 tdb_convert(buf, len);
200 TDB_LOG((tdb, TDB_DEBUG_FATAL, "transaction_read: failed at off=%d len=%d\n", off, len));
201 tdb->ecode = TDB_ERR_IO;
202 tdb->transaction->transaction_error = 1;
208 write while in a transaction
210 static int transaction_write(struct tdb_context *tdb, tdb_off_t off,
211 const void *buf, tdb_len_t len)
215 /* Only a commit is allowed on a prepared transaction */
216 if (tdb->transaction->prepared) {
217 tdb->ecode = TDB_ERR_EINVAL;
218 TDB_LOG((tdb, TDB_DEBUG_FATAL, "transaction_write: transaction already prepared, write not allowed\n"));
219 tdb->transaction->transaction_error = 1;
223 /* if the write is to a hash head, then update the transaction
225 if (len == sizeof(tdb_off_t) && off >= FREELIST_TOP &&
226 off < FREELIST_TOP+TDB_HASHTABLE_SIZE(tdb)) {
227 uint32_t chain = (off-FREELIST_TOP) / sizeof(tdb_off_t);
228 memcpy(&tdb->transaction->hash_heads[chain], buf, len);
231 /* break it up into block sized chunks */
232 while (len + (off % tdb->transaction->block_size) > tdb->transaction->block_size) {
233 tdb_len_t len2 = tdb->transaction->block_size - (off % tdb->transaction->block_size);
234 if (transaction_write(tdb, off, buf, len2) != 0) {
240 buf = (const void *)(len2 + (const char *)buf);
248 blk = off / tdb->transaction->block_size;
249 off = off % tdb->transaction->block_size;
251 if (tdb->transaction->num_blocks <= blk) {
252 uint8_t **new_blocks;
253 /* expand the blocks array */
254 if (tdb->transaction->blocks == NULL) {
255 new_blocks = (uint8_t **)malloc(
256 (blk+1)*sizeof(uint8_t *));
258 new_blocks = (uint8_t **)realloc(
259 tdb->transaction->blocks,
260 (blk+1)*sizeof(uint8_t *));
262 if (new_blocks == NULL) {
263 tdb->ecode = TDB_ERR_OOM;
266 memset(&new_blocks[tdb->transaction->num_blocks], 0,
267 (1+(blk - tdb->transaction->num_blocks))*sizeof(uint8_t *));
268 tdb->transaction->blocks = new_blocks;
269 tdb->transaction->num_blocks = blk+1;
270 tdb->transaction->last_block_size = 0;
273 /* allocate and fill a block? */
274 if (tdb->transaction->blocks[blk] == NULL) {
275 tdb->transaction->blocks[blk] = (uint8_t *)calloc(tdb->transaction->block_size, 1);
276 if (tdb->transaction->blocks[blk] == NULL) {
277 tdb->ecode = TDB_ERR_OOM;
278 tdb->transaction->transaction_error = 1;
281 if (tdb->transaction->old_map_size > blk * tdb->transaction->block_size) {
282 tdb_len_t len2 = tdb->transaction->block_size;
283 if (len2 + (blk * tdb->transaction->block_size) > tdb->transaction->old_map_size) {
284 len2 = tdb->transaction->old_map_size - (blk * tdb->transaction->block_size);
286 if (tdb->transaction->io_methods->tdb_read(tdb, blk * tdb->transaction->block_size,
287 tdb->transaction->blocks[blk],
289 SAFE_FREE(tdb->transaction->blocks[blk]);
290 tdb->ecode = TDB_ERR_IO;
293 if (blk == tdb->transaction->num_blocks-1) {
294 tdb->transaction->last_block_size = len2;
299 /* overwrite part of an existing block */
301 memset(tdb->transaction->blocks[blk] + off, 0, len);
303 memcpy(tdb->transaction->blocks[blk] + off, buf, len);
305 if (blk == tdb->transaction->num_blocks-1) {
306 if (len + off > tdb->transaction->last_block_size) {
307 tdb->transaction->last_block_size = len + off;
314 TDB_LOG((tdb, TDB_DEBUG_FATAL, "transaction_write: failed at off=%d len=%d\n",
315 (blk*tdb->transaction->block_size) + off, len));
316 tdb->transaction->transaction_error = 1;
322 write while in a transaction - this varient never expands the transaction blocks, it only
323 updates existing blocks. This means it cannot change the recovery size
325 static int transaction_write_existing(struct tdb_context *tdb, tdb_off_t off,
326 const void *buf, tdb_len_t len)
330 /* break it up into block sized chunks */
331 while (len + (off % tdb->transaction->block_size) > tdb->transaction->block_size) {
332 tdb_len_t len2 = tdb->transaction->block_size - (off % tdb->transaction->block_size);
333 if (transaction_write_existing(tdb, off, buf, len2) != 0) {
339 buf = (const void *)(len2 + (const char *)buf);
347 blk = off / tdb->transaction->block_size;
348 off = off % tdb->transaction->block_size;
350 if (tdb->transaction->num_blocks <= blk ||
351 tdb->transaction->blocks[blk] == NULL) {
355 if (blk == tdb->transaction->num_blocks-1 &&
356 off + len > tdb->transaction->last_block_size) {
357 if (off >= tdb->transaction->last_block_size) {
360 len = tdb->transaction->last_block_size - off;
363 /* overwrite part of an existing block */
364 memcpy(tdb->transaction->blocks[blk] + off, buf, len);
371 accelerated hash chain head search, using the cached hash heads
373 static void transaction_next_hash_chain(struct tdb_context *tdb, uint32_t *chain)
376 for (;h < tdb->header.hash_size;h++) {
377 /* the +1 takes account of the freelist */
378 if (0 != tdb->transaction->hash_heads[h+1]) {
386 out of bounds check during a transaction
388 static int transaction_oob(struct tdb_context *tdb, tdb_off_t len, int probe)
390 if (len <= tdb->map_size) {
393 tdb->ecode = TDB_ERR_IO;
398 transaction version of tdb_expand().
400 static int transaction_expand_file(struct tdb_context *tdb, tdb_off_t size,
403 /* add a write to the transaction elements, so subsequent
404 reads see the zero data */
405 if (transaction_write(tdb, size, NULL, addition) != 0) {
409 tdb->transaction->need_repack = true;
415 brlock during a transaction - ignore them
417 static int transaction_brlock(struct tdb_context *tdb,
418 int rw_type, tdb_off_t offset, size_t len,
419 enum tdb_lock_flags 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,
443 static int transaction_sync(struct tdb_context *tdb, tdb_off_t offset, tdb_len_t length)
445 if (tdb->flags & TDB_NOSYNC) {
449 if (fsync(tdb->fd) != 0) {
450 tdb->ecode = TDB_ERR_IO;
451 TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_transaction: fsync failed\n"));
456 tdb_off_t moffset = offset & ~(tdb->page_size-1);
457 if (msync(moffset + (char *)tdb->map_ptr,
458 length + (offset - moffset), MS_SYNC) != 0) {
459 tdb->ecode = TDB_ERR_IO;
460 TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_transaction: msync failed - %s\n",
469 /* ltype is F_WRLCK after prepare. */
470 int _tdb_transaction_cancel(struct tdb_context *tdb, int ltype)
474 if (tdb->transaction == NULL) {
475 TDB_LOG((tdb, TDB_DEBUG_ERROR, "tdb_transaction_cancel: no transaction\n"));
479 if (tdb->transaction->nesting != 0) {
480 tdb->transaction->transaction_error = 1;
481 tdb->transaction->nesting--;
485 tdb->map_size = tdb->transaction->old_map_size;
487 /* free all the transaction blocks */
488 for (i=0;i<tdb->transaction->num_blocks;i++) {
489 if (tdb->transaction->blocks[i] != NULL) {
490 free(tdb->transaction->blocks[i]);
493 SAFE_FREE(tdb->transaction->blocks);
495 if (tdb->transaction->magic_offset) {
496 const struct tdb_methods *methods = tdb->transaction->io_methods;
497 uint32_t invalid = TDB_RECOVERY_INVALID_MAGIC;
499 /* remove the recovery marker */
500 if (methods->tdb_write(tdb, tdb->transaction->magic_offset, &invalid, 4) == -1 ||
501 transaction_sync(tdb, tdb->transaction->magic_offset, 4) == -1) {
502 TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_transaction_cancel: failed to remove recovery magic\n"));
507 if (tdb->transaction->open_lock_taken) {
508 tdb_brunlock(tdb, F_WRLCK, OPEN_LOCK, 1);
509 tdb->transaction->open_lock_taken = false;
512 tdb_release_extra_locks(tdb);
514 /* restore the normal io methods */
515 tdb->methods = tdb->transaction->io_methods;
517 tdb_brunlock(tdb, ltype, FREELIST_TOP, 0);
518 tdb_transaction_unlock(tdb, F_WRLCK);
519 SAFE_FREE(tdb->transaction->hash_heads);
520 SAFE_FREE(tdb->transaction);
526 start a tdb transaction. No token is returned, as only a single
527 transaction is allowed to be pending per tdb_context
529 int tdb_transaction_start(struct tdb_context *tdb)
531 /* some sanity checks */
532 if (tdb->read_only || (tdb->flags & TDB_INTERNAL) || tdb->traverse_read) {
533 TDB_LOG((tdb, TDB_DEBUG_ERROR, "tdb_transaction_start: cannot start a transaction on a read-only or internal db\n"));
534 tdb->ecode = TDB_ERR_EINVAL;
538 /* cope with nested tdb_transaction_start() calls */
539 if (tdb->transaction != NULL) {
540 if (!(tdb->flags & TDB_ALLOW_NESTING)) {
541 tdb->ecode = TDB_ERR_NESTING;
544 tdb_trace(tdb, "tdb_transaction_start");
545 tdb->transaction->nesting++;
546 TDB_LOG((tdb, TDB_DEBUG_TRACE, "tdb_transaction_start: nesting %d\n",
547 tdb->transaction->nesting));
551 if (tdb_have_extra_locks(tdb)) {
552 /* the caller must not have any locks when starting a
553 transaction as otherwise we'll be screwed by lack
554 of nested locks in posix */
555 TDB_LOG((tdb, TDB_DEBUG_ERROR, "tdb_transaction_start: cannot start a transaction with locks held\n"));
556 tdb->ecode = TDB_ERR_LOCK;
560 if (tdb->travlocks.next != NULL) {
561 /* you cannot use transactions inside a traverse (although you can use
562 traverse inside a transaction) as otherwise you can end up with
564 TDB_LOG((tdb, TDB_DEBUG_ERROR, "tdb_transaction_start: cannot start a transaction within a traverse\n"));
565 tdb->ecode = TDB_ERR_LOCK;
569 tdb->transaction = (struct tdb_transaction *)
570 calloc(sizeof(struct tdb_transaction), 1);
571 if (tdb->transaction == NULL) {
572 tdb->ecode = TDB_ERR_OOM;
576 /* a page at a time seems like a reasonable compromise between compactness and efficiency */
577 tdb->transaction->block_size = tdb->page_size;
579 /* get the transaction write lock. This is a blocking lock. As
580 discussed with Volker, there are a number of ways we could
581 make this async, which we will probably do in the future */
582 if (tdb_transaction_lock(tdb, F_WRLCK) == -1) {
583 SAFE_FREE(tdb->transaction->blocks);
584 SAFE_FREE(tdb->transaction);
588 /* get a read lock from the freelist to the end of file. This
589 is upgraded to a write lock during the commit */
590 if (tdb_brlock(tdb, F_RDLCK, FREELIST_TOP, 0, TDB_LOCK_WAIT) == -1) {
591 TDB_LOG((tdb, TDB_DEBUG_ERROR, "tdb_transaction_start: failed to get hash locks\n"));
592 tdb->ecode = TDB_ERR_LOCK;
596 /* setup a copy of the hash table heads so the hash scan in
597 traverse can be fast */
598 tdb->transaction->hash_heads = (uint32_t *)
599 calloc(tdb->header.hash_size+1, sizeof(uint32_t));
600 if (tdb->transaction->hash_heads == NULL) {
601 tdb->ecode = TDB_ERR_OOM;
604 if (tdb->methods->tdb_read(tdb, FREELIST_TOP, tdb->transaction->hash_heads,
605 TDB_HASHTABLE_SIZE(tdb), 0) != 0) {
606 TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_transaction_start: failed to read hash heads\n"));
607 tdb->ecode = TDB_ERR_IO;
611 /* make sure we know about any file expansions already done by
613 tdb->methods->tdb_oob(tdb, tdb->map_size + 1, 1);
614 tdb->transaction->old_map_size = tdb->map_size;
616 /* finally hook the io methods, replacing them with
617 transaction specific methods */
618 tdb->transaction->io_methods = tdb->methods;
619 tdb->methods = &transaction_methods;
621 /* Trace at the end, so we get sequence number correct. */
622 tdb_trace(tdb, "tdb_transaction_start");
626 tdb_brunlock(tdb, F_RDLCK, FREELIST_TOP, 0);
627 tdb_transaction_unlock(tdb, F_WRLCK);
628 SAFE_FREE(tdb->transaction->blocks);
629 SAFE_FREE(tdb->transaction->hash_heads);
630 SAFE_FREE(tdb->transaction);
636 cancel the current transaction
638 int tdb_transaction_cancel(struct tdb_context *tdb)
641 tdb_trace(tdb, "tdb_transaction_cancel");
642 if (tdb->transaction && tdb->transaction->prepared)
644 return _tdb_transaction_cancel(tdb, ltype);
648 work out how much space the linearised recovery data will consume
650 static tdb_len_t tdb_recovery_size(struct tdb_context *tdb)
652 tdb_len_t recovery_size = 0;
655 recovery_size = sizeof(uint32_t);
656 for (i=0;i<tdb->transaction->num_blocks;i++) {
657 if (i * tdb->transaction->block_size >= tdb->transaction->old_map_size) {
660 if (tdb->transaction->blocks[i] == NULL) {
663 recovery_size += 2*sizeof(tdb_off_t);
664 if (i == tdb->transaction->num_blocks-1) {
665 recovery_size += tdb->transaction->last_block_size;
667 recovery_size += tdb->transaction->block_size;
671 return recovery_size;
675 allocate the recovery area, or use an existing recovery area if it is
678 static int tdb_recovery_allocate(struct tdb_context *tdb,
679 tdb_len_t *recovery_size,
680 tdb_off_t *recovery_offset,
681 tdb_len_t *recovery_max_size)
683 struct tdb_record rec;
684 const struct tdb_methods *methods = tdb->transaction->io_methods;
685 tdb_off_t recovery_head;
687 if (tdb_ofs_read(tdb, TDB_RECOVERY_HEAD, &recovery_head) == -1) {
688 TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_recovery_allocate: failed to read recovery head\n"));
694 if (recovery_head != 0 &&
695 methods->tdb_read(tdb, recovery_head, &rec, sizeof(rec), DOCONV()) == -1) {
696 TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_recovery_allocate: failed to read recovery record\n"));
700 *recovery_size = tdb_recovery_size(tdb);
702 if (recovery_head != 0 && *recovery_size <= rec.rec_len) {
703 /* it fits in the existing area */
704 *recovery_max_size = rec.rec_len;
705 *recovery_offset = recovery_head;
709 /* we need to free up the old recovery area, then allocate a
710 new one at the end of the file. Note that we cannot use
711 tdb_allocate() to allocate the new one as that might return
712 us an area that is being currently used (as of the start of
714 if (recovery_head != 0) {
715 if (tdb_free(tdb, recovery_head, &rec) == -1) {
716 TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_recovery_allocate: failed to free previous recovery area\n"));
721 /* the tdb_free() call might have increased the recovery size */
722 *recovery_size = tdb_recovery_size(tdb);
724 /* round up to a multiple of page size */
725 *recovery_max_size = TDB_ALIGN(sizeof(rec) + *recovery_size, tdb->page_size) - sizeof(rec);
726 *recovery_offset = tdb->map_size;
727 recovery_head = *recovery_offset;
729 if (methods->tdb_expand_file(tdb, tdb->transaction->old_map_size,
730 (tdb->map_size - tdb->transaction->old_map_size) +
731 sizeof(rec) + *recovery_max_size) == -1) {
732 TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_recovery_allocate: failed to create recovery area\n"));
736 /* remap the file (if using mmap) */
737 methods->tdb_oob(tdb, tdb->map_size + 1, 1);
739 /* we have to reset the old map size so that we don't try to expand the file
740 again in the transaction commit, which would destroy the recovery area */
741 tdb->transaction->old_map_size = tdb->map_size;
743 /* write the recovery header offset and sync - we can sync without a race here
744 as the magic ptr in the recovery record has not been set */
745 CONVERT(recovery_head);
746 if (methods->tdb_write(tdb, TDB_RECOVERY_HEAD,
747 &recovery_head, sizeof(tdb_off_t)) == -1) {
748 TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_recovery_allocate: failed to write recovery head\n"));
751 if (transaction_write_existing(tdb, TDB_RECOVERY_HEAD, &recovery_head, sizeof(tdb_off_t)) == -1) {
752 TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_recovery_allocate: failed to write recovery head\n"));
761 setup the recovery data that will be used on a crash during commit
763 static int transaction_setup_recovery(struct tdb_context *tdb,
764 tdb_off_t *magic_offset)
766 tdb_len_t recovery_size;
767 unsigned char *data, *p;
768 const struct tdb_methods *methods = tdb->transaction->io_methods;
769 struct tdb_record *rec;
770 tdb_off_t recovery_offset, recovery_max_size;
771 tdb_off_t old_map_size = tdb->transaction->old_map_size;
772 uint32_t magic, tailer;
776 check that the recovery area has enough space
778 if (tdb_recovery_allocate(tdb, &recovery_size,
779 &recovery_offset, &recovery_max_size) == -1) {
783 data = (unsigned char *)malloc(recovery_size + sizeof(*rec));
785 tdb->ecode = TDB_ERR_OOM;
789 rec = (struct tdb_record *)data;
790 memset(rec, 0, sizeof(*rec));
792 rec->magic = TDB_RECOVERY_INVALID_MAGIC;
793 rec->data_len = recovery_size;
794 rec->rec_len = recovery_max_size;
795 rec->key_len = old_map_size;
798 /* build the recovery data into a single blob to allow us to do a single
799 large write, which should be more efficient */
800 p = data + sizeof(*rec);
801 for (i=0;i<tdb->transaction->num_blocks;i++) {
805 if (tdb->transaction->blocks[i] == NULL) {
809 offset = i * tdb->transaction->block_size;
810 length = tdb->transaction->block_size;
811 if (i == tdb->transaction->num_blocks-1) {
812 length = tdb->transaction->last_block_size;
815 if (offset >= old_map_size) {
818 if (offset + length > tdb->transaction->old_map_size) {
819 TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_transaction_setup_recovery: transaction data over new region boundary\n"));
821 tdb->ecode = TDB_ERR_CORRUPT;
824 memcpy(p, &offset, 4);
825 memcpy(p+4, &length, 4);
829 /* the recovery area contains the old data, not the
830 new data, so we have to call the original tdb_read
832 if (methods->tdb_read(tdb, offset, p + 8, length, 0) != 0) {
834 tdb->ecode = TDB_ERR_IO;
841 tailer = sizeof(*rec) + recovery_max_size;
842 memcpy(p, &tailer, 4);
845 /* write the recovery data to the recovery area */
846 if (methods->tdb_write(tdb, recovery_offset, data, sizeof(*rec) + recovery_size) == -1) {
847 TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_transaction_setup_recovery: failed to write recovery data\n"));
849 tdb->ecode = TDB_ERR_IO;
852 if (transaction_write_existing(tdb, recovery_offset, data, sizeof(*rec) + recovery_size) == -1) {
853 TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_transaction_setup_recovery: failed to write secondary recovery data\n"));
855 tdb->ecode = TDB_ERR_IO;
859 /* as we don't have ordered writes, we have to sync the recovery
860 data before we update the magic to indicate that the recovery
862 if (transaction_sync(tdb, recovery_offset, sizeof(*rec) + recovery_size) == -1) {
869 magic = TDB_RECOVERY_MAGIC;
872 *magic_offset = recovery_offset + offsetof(struct tdb_record, magic);
874 if (methods->tdb_write(tdb, *magic_offset, &magic, sizeof(magic)) == -1) {
875 TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_transaction_setup_recovery: failed to write recovery magic\n"));
876 tdb->ecode = TDB_ERR_IO;
879 if (transaction_write_existing(tdb, *magic_offset, &magic, sizeof(magic)) == -1) {
880 TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_transaction_setup_recovery: failed to write secondary recovery magic\n"));
881 tdb->ecode = TDB_ERR_IO;
885 /* ensure the recovery magic marker is on disk */
886 if (transaction_sync(tdb, *magic_offset, sizeof(magic)) == -1) {
893 static int _tdb_transaction_prepare_commit(struct tdb_context *tdb)
895 const struct tdb_methods *methods;
897 if (tdb->transaction == NULL) {
898 TDB_LOG((tdb, TDB_DEBUG_ERROR, "tdb_transaction_prepare_commit: no transaction\n"));
902 if (tdb->transaction->prepared) {
903 tdb->ecode = TDB_ERR_EINVAL;
904 _tdb_transaction_cancel(tdb, F_WRLCK);
905 TDB_LOG((tdb, TDB_DEBUG_ERROR, "tdb_transaction_prepare_commit: transaction already prepared\n"));
909 if (tdb->transaction->transaction_error) {
910 tdb->ecode = TDB_ERR_IO;
911 _tdb_transaction_cancel(tdb, F_RDLCK);
912 TDB_LOG((tdb, TDB_DEBUG_ERROR, "tdb_transaction_prepare_commit: transaction error pending\n"));
917 if (tdb->transaction->nesting != 0) {
918 tdb->transaction->nesting--;
922 /* check for a null transaction */
923 if (tdb->transaction->blocks == NULL) {
927 methods = tdb->transaction->io_methods;
929 /* if there are any locks pending then the caller has not
930 nested their locks properly, so fail the transaction */
931 if (tdb_have_extra_locks(tdb)) {
932 tdb->ecode = TDB_ERR_LOCK;
933 TDB_LOG((tdb, TDB_DEBUG_ERROR, "tdb_transaction_prepare_commit: locks pending on commit\n"));
934 _tdb_transaction_cancel(tdb, F_RDLCK);
938 /* upgrade the main transaction lock region to a write lock */
939 if (tdb_brlock_upgrade(tdb, FREELIST_TOP, 0) == -1) {
940 TDB_LOG((tdb, TDB_DEBUG_ERROR, "tdb_transaction_prepare_commit: failed to upgrade hash locks\n"));
941 tdb->ecode = TDB_ERR_LOCK;
942 _tdb_transaction_cancel(tdb, F_RDLCK);
946 /* get the open lock - this prevents new users attaching to the database
948 if (tdb_brlock(tdb, F_WRLCK, OPEN_LOCK, 1, TDB_LOCK_WAIT) == -1) {
949 TDB_LOG((tdb, TDB_DEBUG_ERROR, "tdb_transaction_prepare_commit: failed to get open lock\n"));
950 tdb->ecode = TDB_ERR_LOCK;
951 _tdb_transaction_cancel(tdb, F_WRLCK);
955 tdb->transaction->open_lock_taken = true;
957 if (!(tdb->flags & TDB_NOSYNC)) {
958 /* write the recovery data to the end of the file */
959 if (transaction_setup_recovery(tdb, &tdb->transaction->magic_offset) == -1) {
960 TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_transaction_prepare_commit: failed to setup recovery data\n"));
961 _tdb_transaction_cancel(tdb, F_WRLCK);
966 tdb->transaction->prepared = true;
968 /* expand the file to the new size if needed */
969 if (tdb->map_size != tdb->transaction->old_map_size) {
970 if (methods->tdb_expand_file(tdb, tdb->transaction->old_map_size,
972 tdb->transaction->old_map_size) == -1) {
973 tdb->ecode = TDB_ERR_IO;
974 TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_transaction_prepare_commit: expansion failed\n"));
975 _tdb_transaction_cancel(tdb, F_WRLCK);
978 tdb->map_size = tdb->transaction->old_map_size;
979 methods->tdb_oob(tdb, tdb->map_size + 1, 1);
982 /* Keep the open lock until the actual commit */
988 prepare to commit the current transaction
990 int tdb_transaction_prepare_commit(struct tdb_context *tdb)
992 tdb_trace(tdb, "tdb_transaction_prepare_commit");
993 return _tdb_transaction_prepare_commit(tdb);
997 commit the current transaction
999 int tdb_transaction_commit(struct tdb_context *tdb)
1001 const struct tdb_methods *methods;
1005 if (tdb->transaction == NULL) {
1006 TDB_LOG((tdb, TDB_DEBUG_ERROR, "tdb_transaction_commit: no transaction\n"));
1010 tdb_trace(tdb, "tdb_transaction_commit");
1012 if (tdb->transaction->transaction_error) {
1013 tdb->ecode = TDB_ERR_IO;
1014 tdb_transaction_cancel(tdb);
1015 TDB_LOG((tdb, TDB_DEBUG_ERROR, "tdb_transaction_commit: transaction error pending\n"));
1020 if (tdb->transaction->nesting != 0) {
1021 tdb->transaction->nesting--;
1025 /* check for a null transaction */
1026 if (tdb->transaction->blocks == NULL) {
1027 _tdb_transaction_cancel(tdb, F_RDLCK);
1031 if (!tdb->transaction->prepared) {
1032 int ret = _tdb_transaction_prepare_commit(tdb);
1037 methods = tdb->transaction->io_methods;
1039 /* perform all the writes */
1040 for (i=0;i<tdb->transaction->num_blocks;i++) {
1044 if (tdb->transaction->blocks[i] == NULL) {
1048 offset = i * tdb->transaction->block_size;
1049 length = tdb->transaction->block_size;
1050 if (i == tdb->transaction->num_blocks-1) {
1051 length = tdb->transaction->last_block_size;
1054 if (methods->tdb_write(tdb, offset, tdb->transaction->blocks[i], length) == -1) {
1055 TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_transaction_commit: write failed during commit\n"));
1057 /* we've overwritten part of the data and
1058 possibly expanded the file, so we need to
1059 run the crash recovery code */
1060 tdb->methods = methods;
1061 tdb_transaction_recover(tdb);
1063 _tdb_transaction_cancel(tdb, F_WRLCK);
1065 TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_transaction_commit: write failed\n"));
1068 SAFE_FREE(tdb->transaction->blocks[i]);
1071 SAFE_FREE(tdb->transaction->blocks);
1072 tdb->transaction->num_blocks = 0;
1074 /* ensure the new data is on disk */
1075 if (transaction_sync(tdb, 0, tdb->map_size) == -1) {
1080 TODO: maybe write to some dummy hdr field, or write to magic
1081 offset without mmap, before the last sync, instead of the
1085 /* on some systems (like Linux 2.6.x) changes via mmap/msync
1086 don't change the mtime of the file, this means the file may
1087 not be backed up (as tdb rounding to block sizes means that
1088 file size changes are quite rare too). The following forces
1089 mtime changes when a transaction completes */
1091 utime(tdb->name, NULL);
1094 need_repack = tdb->transaction->need_repack;
1096 /* use a transaction cancel to free memory and remove the
1097 transaction locks */
1098 _tdb_transaction_cancel(tdb, F_WRLCK);
1101 return tdb_repack(tdb);
1109 recover from an aborted transaction. Must be called with exclusive
1110 database write access already established (including the open
1111 lock to prevent new processes attaching)
1113 int tdb_transaction_recover(struct tdb_context *tdb)
1115 tdb_off_t recovery_head, recovery_eof;
1116 unsigned char *data, *p;
1118 struct tdb_record rec;
1120 /* find the recovery area */
1121 if (tdb_ofs_read(tdb, TDB_RECOVERY_HEAD, &recovery_head) == -1) {
1122 TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_transaction_recover: failed to read recovery head\n"));
1123 tdb->ecode = TDB_ERR_IO;
1127 if (recovery_head == 0) {
1128 /* we have never allocated a recovery record */
1132 /* read the recovery record */
1133 if (tdb->methods->tdb_read(tdb, recovery_head, &rec,
1134 sizeof(rec), DOCONV()) == -1) {
1135 TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_transaction_recover: failed to read recovery record\n"));
1136 tdb->ecode = TDB_ERR_IO;
1140 if (rec.magic != TDB_RECOVERY_MAGIC) {
1141 /* there is no valid recovery data */
1145 if (tdb->read_only) {
1146 TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_transaction_recover: attempt to recover read only database\n"));
1147 tdb->ecode = TDB_ERR_CORRUPT;
1151 recovery_eof = rec.key_len;
1153 data = (unsigned char *)malloc(rec.data_len);
1155 TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_transaction_recover: failed to allocate recovery data\n"));
1156 tdb->ecode = TDB_ERR_OOM;
1160 /* read the full recovery data */
1161 if (tdb->methods->tdb_read(tdb, recovery_head + sizeof(rec), data,
1162 rec.data_len, 0) == -1) {
1163 TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_transaction_recover: failed to read recovery data\n"));
1164 tdb->ecode = TDB_ERR_IO;
1168 /* recover the file data */
1170 while (p+8 < data + rec.data_len) {
1176 memcpy(&len, p+4, 4);
1178 if (tdb->methods->tdb_write(tdb, ofs, p+8, len) == -1) {
1180 TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_transaction_recover: failed to recover %d bytes at offset %d\n", len, ofs));
1181 tdb->ecode = TDB_ERR_IO;
1189 if (transaction_sync(tdb, 0, tdb->map_size) == -1) {
1190 TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_transaction_recover: failed to sync recovery\n"));
1191 tdb->ecode = TDB_ERR_IO;
1195 /* if the recovery area is after the recovered eof then remove it */
1196 if (recovery_eof <= recovery_head) {
1197 if (tdb_ofs_write(tdb, TDB_RECOVERY_HEAD, &zero) == -1) {
1198 TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_transaction_recover: failed to remove recovery head\n"));
1199 tdb->ecode = TDB_ERR_IO;
1204 /* remove the recovery magic */
1205 if (tdb_ofs_write(tdb, recovery_head + offsetof(struct tdb_record, magic),
1207 TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_transaction_recover: failed to remove recovery magic\n"));
1208 tdb->ecode = TDB_ERR_IO;
1212 /* reduce the file size to the old size */
1214 if (ftruncate(tdb->fd, recovery_eof) != 0) {
1215 TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_transaction_recover: failed to reduce to recovery size\n"));
1216 tdb->ecode = TDB_ERR_IO;
1219 tdb->map_size = recovery_eof;
1222 if (transaction_sync(tdb, 0, recovery_eof) == -1) {
1223 TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_transaction_recover: failed to sync2 recovery\n"));
1224 tdb->ecode = TDB_ERR_IO;
1228 TDB_LOG((tdb, TDB_DEBUG_TRACE, "tdb_transaction_recover: recovered %d byte database\n",