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 global 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.
92 hold the context of any current transaction
94 struct tdb_transaction {
95 /* we keep a mirrored copy of the tdb hash heads here so
96 tdb_next_hash_chain() can operate efficiently */
99 /* the original io methods - used to do IOs to the real db */
100 const struct tdb_methods *io_methods;
102 /* the list of transaction blocks. When a block is first
103 written to, it gets created in this list */
106 uint32_t block_size; /* bytes in each block */
107 uint32_t last_block_size; /* number of valid bytes in the last block */
109 /* non-zero when an internal transaction error has
110 occurred. All write operations will then fail until the
111 transaction is ended */
112 int transaction_error;
114 /* when inside a transaction we need to keep track of any
115 nested tdb_transaction_start() calls, as these are allowed,
116 but don't create a new transaction */
119 /* set when a prepare has already occurred */
121 tdb_off_t magic_offset;
123 /* old file size before transaction */
124 tdb_len_t old_map_size;
126 /* we should re-pack on commit */
132 read while in a transaction. We need to check first if the data is in our list
133 of transaction elements, then if not do a real read
135 static int transaction_read(struct tdb_context *tdb, tdb_off_t off, void *buf,
136 tdb_len_t len, int cv)
140 /* break it down into block sized ops */
141 while (len + (off % tdb->transaction->block_size) > tdb->transaction->block_size) {
142 tdb_len_t len2 = tdb->transaction->block_size - (off % tdb->transaction->block_size);
143 if (transaction_read(tdb, off, buf, len2, cv) != 0) {
148 buf = (void *)(len2 + (char *)buf);
155 blk = off / tdb->transaction->block_size;
157 /* see if we have it in the block list */
158 if (tdb->transaction->num_blocks <= blk ||
159 tdb->transaction->blocks[blk] == NULL) {
160 /* nope, do a real read */
161 if (tdb->transaction->io_methods->tdb_read(tdb, off, buf, len, cv) != 0) {
167 /* it is in the block list. Now check for the last block */
168 if (blk == tdb->transaction->num_blocks-1) {
169 if (len > tdb->transaction->last_block_size) {
174 /* now copy it out of this block */
175 memcpy(buf, tdb->transaction->blocks[blk] + (off % tdb->transaction->block_size), len);
177 tdb_convert(buf, len);
182 TDB_LOG((tdb, TDB_DEBUG_FATAL, "transaction_read: failed at off=%d len=%d\n", off, len));
183 tdb->ecode = TDB_ERR_IO;
184 tdb->transaction->transaction_error = 1;
190 write while in a transaction
192 static int transaction_write(struct tdb_context *tdb, tdb_off_t off,
193 const void *buf, tdb_len_t len)
197 /* Only a commit is allowed on a prepared transaction */
198 if (tdb->transaction->prepared) {
199 tdb->ecode = TDB_ERR_EINVAL;
200 TDB_LOG((tdb, TDB_DEBUG_FATAL, "transaction_write: transaction already prepared, write not allowed\n"));
201 tdb->transaction->transaction_error = 1;
205 /* if the write is to a hash head, then update the transaction
207 if (len == sizeof(tdb_off_t) && off >= FREELIST_TOP &&
208 off < FREELIST_TOP+TDB_HASHTABLE_SIZE(tdb)) {
209 uint32_t chain = (off-FREELIST_TOP) / sizeof(tdb_off_t);
210 memcpy(&tdb->transaction->hash_heads[chain], buf, len);
213 /* break it up into block sized chunks */
214 while (len + (off % tdb->transaction->block_size) > tdb->transaction->block_size) {
215 tdb_len_t len2 = tdb->transaction->block_size - (off % tdb->transaction->block_size);
216 if (transaction_write(tdb, off, buf, len2) != 0) {
222 buf = (const void *)(len2 + (const char *)buf);
230 blk = off / tdb->transaction->block_size;
231 off = off % tdb->transaction->block_size;
233 if (tdb->transaction->num_blocks <= blk) {
234 uint8_t **new_blocks;
235 /* expand the blocks array */
236 if (tdb->transaction->blocks == NULL) {
237 new_blocks = (uint8_t **)malloc(
238 (blk+1)*sizeof(uint8_t *));
240 new_blocks = (uint8_t **)realloc(
241 tdb->transaction->blocks,
242 (blk+1)*sizeof(uint8_t *));
244 if (new_blocks == NULL) {
245 tdb->ecode = TDB_ERR_OOM;
248 memset(&new_blocks[tdb->transaction->num_blocks], 0,
249 (1+(blk - tdb->transaction->num_blocks))*sizeof(uint8_t *));
250 tdb->transaction->blocks = new_blocks;
251 tdb->transaction->num_blocks = blk+1;
252 tdb->transaction->last_block_size = 0;
255 /* allocate and fill a block? */
256 if (tdb->transaction->blocks[blk] == NULL) {
257 tdb->transaction->blocks[blk] = (uint8_t *)calloc(tdb->transaction->block_size, 1);
258 if (tdb->transaction->blocks[blk] == NULL) {
259 tdb->ecode = TDB_ERR_OOM;
260 tdb->transaction->transaction_error = 1;
263 if (tdb->transaction->old_map_size > blk * tdb->transaction->block_size) {
264 tdb_len_t len2 = tdb->transaction->block_size;
265 if (len2 + (blk * tdb->transaction->block_size) > tdb->transaction->old_map_size) {
266 len2 = tdb->transaction->old_map_size - (blk * tdb->transaction->block_size);
268 if (tdb->transaction->io_methods->tdb_read(tdb, blk * tdb->transaction->block_size,
269 tdb->transaction->blocks[blk],
271 SAFE_FREE(tdb->transaction->blocks[blk]);
272 tdb->ecode = TDB_ERR_IO;
275 if (blk == tdb->transaction->num_blocks-1) {
276 tdb->transaction->last_block_size = len2;
281 /* overwrite part of an existing block */
283 memset(tdb->transaction->blocks[blk] + off, 0, len);
285 memcpy(tdb->transaction->blocks[blk] + off, buf, len);
287 if (blk == tdb->transaction->num_blocks-1) {
288 if (len + off > tdb->transaction->last_block_size) {
289 tdb->transaction->last_block_size = len + off;
296 TDB_LOG((tdb, TDB_DEBUG_FATAL, "transaction_write: failed at off=%d len=%d\n",
297 (blk*tdb->transaction->block_size) + off, len));
298 tdb->transaction->transaction_error = 1;
304 write while in a transaction - this varient never expands the transaction blocks, it only
305 updates existing blocks. This means it cannot change the recovery size
307 static int transaction_write_existing(struct tdb_context *tdb, tdb_off_t off,
308 const void *buf, tdb_len_t len)
312 /* break it up into block sized chunks */
313 while (len + (off % tdb->transaction->block_size) > tdb->transaction->block_size) {
314 tdb_len_t len2 = tdb->transaction->block_size - (off % tdb->transaction->block_size);
315 if (transaction_write_existing(tdb, off, buf, len2) != 0) {
321 buf = (const void *)(len2 + (const char *)buf);
329 blk = off / tdb->transaction->block_size;
330 off = off % tdb->transaction->block_size;
332 if (tdb->transaction->num_blocks <= blk ||
333 tdb->transaction->blocks[blk] == NULL) {
337 if (blk == tdb->transaction->num_blocks-1 &&
338 off + len > tdb->transaction->last_block_size) {
339 if (off >= tdb->transaction->last_block_size) {
342 len = tdb->transaction->last_block_size - off;
345 /* overwrite part of an existing block */
346 memcpy(tdb->transaction->blocks[blk] + off, buf, len);
353 accelerated hash chain head search, using the cached hash heads
355 static void transaction_next_hash_chain(struct tdb_context *tdb, uint32_t *chain)
358 for (;h < tdb->header.hash_size;h++) {
359 /* the +1 takes account of the freelist */
360 if (0 != tdb->transaction->hash_heads[h+1]) {
368 out of bounds check during a transaction
370 static int transaction_oob(struct tdb_context *tdb, tdb_off_t len, int probe)
372 if (len <= tdb->map_size) {
375 tdb->ecode = TDB_ERR_IO;
380 transaction version of tdb_expand().
382 static int transaction_expand_file(struct tdb_context *tdb, tdb_off_t size,
385 /* add a write to the transaction elements, so subsequent
386 reads see the zero data */
387 if (transaction_write(tdb, size, NULL, addition) != 0) {
391 tdb->transaction->need_repack = true;
397 brlock during a transaction - ignore them
399 static int transaction_brlock(struct tdb_context *tdb, tdb_off_t offset,
400 int rw_type, int lck_type, int probe, size_t len)
405 static const struct tdb_methods transaction_methods = {
408 transaction_next_hash_chain,
410 transaction_expand_file,
416 start a tdb transaction. No token is returned, as only a single
417 transaction is allowed to be pending per tdb_context
419 int tdb_transaction_start(struct tdb_context *tdb)
421 /* some sanity checks */
422 if (tdb->read_only || (tdb->flags & TDB_INTERNAL) || tdb->traverse_read) {
423 TDB_LOG((tdb, TDB_DEBUG_ERROR, "tdb_transaction_start: cannot start a transaction on a read-only or internal db\n"));
424 tdb->ecode = TDB_ERR_EINVAL;
428 /* cope with nested tdb_transaction_start() calls */
429 if (tdb->transaction != NULL) {
430 tdb->transaction->nesting++;
431 TDB_LOG((tdb, TDB_DEBUG_TRACE, "tdb_transaction_start: nesting %d\n",
432 tdb->transaction->nesting));
436 if (tdb->num_locks != 0 || tdb->global_lock.count) {
437 /* the caller must not have any locks when starting a
438 transaction as otherwise we'll be screwed by lack
439 of nested locks in posix */
440 TDB_LOG((tdb, TDB_DEBUG_ERROR, "tdb_transaction_start: cannot start a transaction with locks held\n"));
441 tdb->ecode = TDB_ERR_LOCK;
445 if (tdb->travlocks.next != NULL) {
446 /* you cannot use transactions inside a traverse (although you can use
447 traverse inside a transaction) as otherwise you can end up with
449 TDB_LOG((tdb, TDB_DEBUG_ERROR, "tdb_transaction_start: cannot start a transaction within a traverse\n"));
450 tdb->ecode = TDB_ERR_LOCK;
454 tdb->transaction = (struct tdb_transaction *)
455 calloc(sizeof(struct tdb_transaction), 1);
456 if (tdb->transaction == NULL) {
457 tdb->ecode = TDB_ERR_OOM;
461 /* a page at a time seems like a reasonable compromise between compactness and efficiency */
462 tdb->transaction->block_size = tdb->page_size;
464 /* get the transaction write lock. This is a blocking lock. As
465 discussed with Volker, there are a number of ways we could
466 make this async, which we will probably do in the future */
467 if (tdb_transaction_lock(tdb, F_WRLCK) == -1) {
468 SAFE_FREE(tdb->transaction->blocks);
469 SAFE_FREE(tdb->transaction);
473 /* get a read lock from the freelist to the end of file. This
474 is upgraded to a write lock during the commit */
475 if (tdb_brlock(tdb, FREELIST_TOP, F_RDLCK, F_SETLKW, 0, 0) == -1) {
476 TDB_LOG((tdb, TDB_DEBUG_ERROR, "tdb_transaction_start: failed to get hash locks\n"));
477 tdb->ecode = TDB_ERR_LOCK;
481 /* setup a copy of the hash table heads so the hash scan in
482 traverse can be fast */
483 tdb->transaction->hash_heads = (uint32_t *)
484 calloc(tdb->header.hash_size+1, sizeof(uint32_t));
485 if (tdb->transaction->hash_heads == NULL) {
486 tdb->ecode = TDB_ERR_OOM;
489 if (tdb->methods->tdb_read(tdb, FREELIST_TOP, tdb->transaction->hash_heads,
490 TDB_HASHTABLE_SIZE(tdb), 0) != 0) {
491 TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_transaction_start: failed to read hash heads\n"));
492 tdb->ecode = TDB_ERR_IO;
496 /* make sure we know about any file expansions already done by
498 tdb->methods->tdb_oob(tdb, tdb->map_size + 1, 1);
499 tdb->transaction->old_map_size = tdb->map_size;
501 /* finally hook the io methods, replacing them with
502 transaction specific methods */
503 tdb->transaction->io_methods = tdb->methods;
504 tdb->methods = &transaction_methods;
506 /* Trace at the end, so we get sequence number correct. */
507 tdb_trace(tdb, "tdb_transaction_start");
511 tdb_brlock(tdb, FREELIST_TOP, F_UNLCK, F_SETLKW, 0, 0);
512 tdb_transaction_unlock(tdb);
513 SAFE_FREE(tdb->transaction->blocks);
514 SAFE_FREE(tdb->transaction->hash_heads);
515 SAFE_FREE(tdb->transaction);
523 static int transaction_sync(struct tdb_context *tdb, tdb_off_t offset, tdb_len_t length)
525 if (tdb->flags & TDB_NOSYNC) {
529 if (fsync(tdb->fd) != 0) {
530 tdb->ecode = TDB_ERR_IO;
531 TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_transaction: fsync failed\n"));
536 tdb_off_t moffset = offset & ~(tdb->page_size-1);
537 if (msync(moffset + (char *)tdb->map_ptr,
538 length + (offset - moffset), MS_SYNC) != 0) {
539 tdb->ecode = TDB_ERR_IO;
540 TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_transaction: msync failed - %s\n",
550 int _tdb_transaction_cancel(struct tdb_context *tdb)
554 if (tdb->transaction == NULL) {
555 TDB_LOG((tdb, TDB_DEBUG_ERROR, "tdb_transaction_cancel: no transaction\n"));
559 if (tdb->transaction->nesting != 0) {
560 tdb->transaction->transaction_error = 1;
561 tdb->transaction->nesting--;
565 tdb->map_size = tdb->transaction->old_map_size;
567 /* free all the transaction blocks */
568 for (i=0;i<tdb->transaction->num_blocks;i++) {
569 if (tdb->transaction->blocks[i] != NULL) {
570 free(tdb->transaction->blocks[i]);
573 SAFE_FREE(tdb->transaction->blocks);
575 if (tdb->transaction->magic_offset) {
576 const struct tdb_methods *methods = tdb->transaction->io_methods;
579 /* remove the recovery marker */
580 if (methods->tdb_write(tdb, tdb->transaction->magic_offset, &zero, 4) == -1 ||
581 transaction_sync(tdb, tdb->transaction->magic_offset, 4) == -1) {
582 TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_transaction_cancel: failed to remove recovery magic\n"));
587 /* remove any global lock created during the transaction */
588 if (tdb->global_lock.count != 0) {
589 tdb_brlock(tdb, FREELIST_TOP, F_UNLCK, F_SETLKW, 0, 4*tdb->header.hash_size);
590 tdb->global_lock.count = 0;
593 /* remove any locks created during the transaction */
594 if (tdb->num_locks != 0) {
595 for (i=0;i<tdb->num_lockrecs;i++) {
596 tdb_brlock(tdb,FREELIST_TOP+4*tdb->lockrecs[i].list,
597 F_UNLCK,F_SETLKW, 0, 1);
600 tdb->num_lockrecs = 0;
601 SAFE_FREE(tdb->lockrecs);
604 /* restore the normal io methods */
605 tdb->methods = tdb->transaction->io_methods;
607 tdb_brlock(tdb, FREELIST_TOP, F_UNLCK, F_SETLKW, 0, 0);
608 tdb_transaction_unlock(tdb);
609 SAFE_FREE(tdb->transaction->hash_heads);
610 SAFE_FREE(tdb->transaction);
616 cancel the current transaction
618 int tdb_transaction_cancel(struct tdb_context *tdb)
620 tdb_trace(tdb, "tdb_transaction_cancel");
621 return _tdb_transaction_cancel(tdb);
625 work out how much space the linearised recovery data will consume
627 static tdb_len_t tdb_recovery_size(struct tdb_context *tdb)
629 tdb_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(tdb_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;
652 allocate the recovery area, or use an existing recovery area if it is
655 static int tdb_recovery_allocate(struct tdb_context *tdb,
656 tdb_len_t *recovery_size,
657 tdb_off_t *recovery_offset,
658 tdb_len_t *recovery_max_size)
660 struct list_struct rec;
661 const struct tdb_methods *methods = tdb->transaction->io_methods;
662 tdb_off_t recovery_head;
664 if (tdb_ofs_read(tdb, TDB_RECOVERY_HEAD, &recovery_head) == -1) {
665 TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_recovery_allocate: failed to read recovery head\n"));
671 if (recovery_head != 0 &&
672 methods->tdb_read(tdb, recovery_head, &rec, sizeof(rec), DOCONV()) == -1) {
673 TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_recovery_allocate: failed to read recovery record\n"));
677 *recovery_size = tdb_recovery_size(tdb);
679 if (recovery_head != 0 && *recovery_size <= rec.rec_len) {
680 /* it fits in the existing area */
681 *recovery_max_size = rec.rec_len;
682 *recovery_offset = recovery_head;
686 /* we need to free up the old recovery area, then allocate a
687 new one at the end of the file. Note that we cannot use
688 tdb_allocate() to allocate the new one as that might return
689 us an area that is being currently used (as of the start of
691 if (recovery_head != 0) {
692 if (tdb_free(tdb, recovery_head, &rec) == -1) {
693 TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_recovery_allocate: failed to free previous recovery area\n"));
698 /* the tdb_free() call might have increased the recovery size */
699 *recovery_size = tdb_recovery_size(tdb);
701 /* round up to a multiple of page size */
702 *recovery_max_size = TDB_ALIGN(sizeof(rec) + *recovery_size, tdb->page_size) - sizeof(rec);
703 *recovery_offset = tdb->map_size;
704 recovery_head = *recovery_offset;
706 if (methods->tdb_expand_file(tdb, tdb->transaction->old_map_size,
707 (tdb->map_size - tdb->transaction->old_map_size) +
708 sizeof(rec) + *recovery_max_size) == -1) {
709 TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_recovery_allocate: failed to create recovery area\n"));
713 /* remap the file (if using mmap) */
714 methods->tdb_oob(tdb, tdb->map_size + 1, 1);
716 /* we have to reset the old map size so that we don't try to expand the file
717 again in the transaction commit, which would destroy the recovery area */
718 tdb->transaction->old_map_size = tdb->map_size;
720 /* write the recovery header offset and sync - we can sync without a race here
721 as the magic ptr in the recovery record has not been set */
722 CONVERT(recovery_head);
723 if (methods->tdb_write(tdb, TDB_RECOVERY_HEAD,
724 &recovery_head, sizeof(tdb_off_t)) == -1) {
725 TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_recovery_allocate: failed to write recovery head\n"));
728 if (transaction_write_existing(tdb, TDB_RECOVERY_HEAD, &recovery_head, sizeof(tdb_off_t)) == -1) {
729 TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_recovery_allocate: failed to write recovery head\n"));
738 setup the recovery data that will be used on a crash during commit
740 static int transaction_setup_recovery(struct tdb_context *tdb,
741 tdb_off_t *magic_offset)
743 tdb_len_t recovery_size;
744 unsigned char *data, *p;
745 const struct tdb_methods *methods = tdb->transaction->io_methods;
746 struct list_struct *rec;
747 tdb_off_t recovery_offset, recovery_max_size;
748 tdb_off_t old_map_size = tdb->transaction->old_map_size;
749 uint32_t magic, tailer;
753 check that the recovery area has enough space
755 if (tdb_recovery_allocate(tdb, &recovery_size,
756 &recovery_offset, &recovery_max_size) == -1) {
760 data = (unsigned char *)malloc(recovery_size + sizeof(*rec));
762 tdb->ecode = TDB_ERR_OOM;
766 rec = (struct list_struct *)data;
767 memset(rec, 0, sizeof(*rec));
770 rec->data_len = recovery_size;
771 rec->rec_len = recovery_max_size;
772 rec->key_len = old_map_size;
775 /* build the recovery data into a single blob to allow us to do a single
776 large write, which should be more efficient */
777 p = data + sizeof(*rec);
778 for (i=0;i<tdb->transaction->num_blocks;i++) {
782 if (tdb->transaction->blocks[i] == NULL) {
786 offset = i * tdb->transaction->block_size;
787 length = tdb->transaction->block_size;
788 if (i == tdb->transaction->num_blocks-1) {
789 length = tdb->transaction->last_block_size;
792 if (offset >= old_map_size) {
795 if (offset + length > tdb->transaction->old_map_size) {
796 TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_transaction_setup_recovery: transaction data over new region boundary\n"));
798 tdb->ecode = TDB_ERR_CORRUPT;
801 memcpy(p, &offset, 4);
802 memcpy(p+4, &length, 4);
806 /* the recovery area contains the old data, not the
807 new data, so we have to call the original tdb_read
809 if (methods->tdb_read(tdb, offset, p + 8, length, 0) != 0) {
811 tdb->ecode = TDB_ERR_IO;
818 tailer = sizeof(*rec) + recovery_max_size;
819 memcpy(p, &tailer, 4);
822 /* write the recovery data to the recovery area */
823 if (methods->tdb_write(tdb, recovery_offset, data, sizeof(*rec) + recovery_size) == -1) {
824 TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_transaction_setup_recovery: failed to write recovery data\n"));
826 tdb->ecode = TDB_ERR_IO;
829 if (transaction_write_existing(tdb, recovery_offset, data, sizeof(*rec) + recovery_size) == -1) {
830 TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_transaction_setup_recovery: failed to write secondary recovery data\n"));
832 tdb->ecode = TDB_ERR_IO;
836 /* as we don't have ordered writes, we have to sync the recovery
837 data before we update the magic to indicate that the recovery
839 if (transaction_sync(tdb, recovery_offset, sizeof(*rec) + recovery_size) == -1) {
846 magic = TDB_RECOVERY_MAGIC;
849 *magic_offset = recovery_offset + offsetof(struct list_struct, magic);
851 if (methods->tdb_write(tdb, *magic_offset, &magic, sizeof(magic)) == -1) {
852 TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_transaction_setup_recovery: failed to write recovery magic\n"));
853 tdb->ecode = TDB_ERR_IO;
856 if (transaction_write_existing(tdb, *magic_offset, &magic, sizeof(magic)) == -1) {
857 TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_transaction_setup_recovery: failed to write secondary recovery magic\n"));
858 tdb->ecode = TDB_ERR_IO;
862 /* ensure the recovery magic marker is on disk */
863 if (transaction_sync(tdb, *magic_offset, sizeof(magic)) == -1) {
870 static int _tdb_transaction_prepare_commit(struct tdb_context *tdb)
872 const struct tdb_methods *methods;
874 if (tdb->transaction == NULL) {
875 TDB_LOG((tdb, TDB_DEBUG_ERROR, "tdb_transaction_prepare_commit: no transaction\n"));
879 if (tdb->transaction->prepared) {
880 tdb->ecode = TDB_ERR_EINVAL;
881 _tdb_transaction_cancel(tdb);
882 TDB_LOG((tdb, TDB_DEBUG_ERROR, "tdb_transaction_prepare_commit: transaction already prepared\n"));
886 if (tdb->transaction->transaction_error) {
887 tdb->ecode = TDB_ERR_IO;
888 _tdb_transaction_cancel(tdb);
889 TDB_LOG((tdb, TDB_DEBUG_ERROR, "tdb_transaction_prepare_commit: transaction error pending\n"));
894 if (tdb->transaction->nesting != 0) {
898 /* check for a null transaction */
899 if (tdb->transaction->blocks == NULL) {
903 methods = tdb->transaction->io_methods;
905 /* if there are any locks pending then the caller has not
906 nested their locks properly, so fail the transaction */
907 if (tdb->num_locks || tdb->global_lock.count) {
908 tdb->ecode = TDB_ERR_LOCK;
909 TDB_LOG((tdb, TDB_DEBUG_ERROR, "tdb_transaction_prepare_commit: locks pending on commit\n"));
910 _tdb_transaction_cancel(tdb);
914 /* upgrade the main transaction lock region to a write lock */
915 if (tdb_brlock_upgrade(tdb, FREELIST_TOP, 0) == -1) {
916 TDB_LOG((tdb, TDB_DEBUG_ERROR, "tdb_transaction_prepare_commit: failed to upgrade hash locks\n"));
917 tdb->ecode = TDB_ERR_LOCK;
918 _tdb_transaction_cancel(tdb);
922 /* get the global lock - this prevents new users attaching to the database
924 if (tdb_brlock(tdb, GLOBAL_LOCK, F_WRLCK, F_SETLKW, 0, 1) == -1) {
925 TDB_LOG((tdb, TDB_DEBUG_ERROR, "tdb_transaction_prepare_commit: failed to get global lock\n"));
926 tdb->ecode = TDB_ERR_LOCK;
927 _tdb_transaction_cancel(tdb);
931 if (!(tdb->flags & TDB_NOSYNC)) {
932 /* write the recovery data to the end of the file */
933 if (transaction_setup_recovery(tdb, &tdb->transaction->magic_offset) == -1) {
934 TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_transaction_prepare_commit: failed to setup recovery data\n"));
935 tdb_brlock(tdb, GLOBAL_LOCK, F_UNLCK, F_SETLKW, 0, 1);
936 _tdb_transaction_cancel(tdb);
941 tdb->transaction->prepared = true;
943 /* expand the file to the new size if needed */
944 if (tdb->map_size != tdb->transaction->old_map_size) {
945 if (methods->tdb_expand_file(tdb, tdb->transaction->old_map_size,
947 tdb->transaction->old_map_size) == -1) {
948 tdb->ecode = TDB_ERR_IO;
949 TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_transaction_prepare_commit: expansion failed\n"));
950 tdb_brlock(tdb, GLOBAL_LOCK, F_UNLCK, F_SETLKW, 0, 1);
951 _tdb_transaction_cancel(tdb);
954 tdb->map_size = tdb->transaction->old_map_size;
955 methods->tdb_oob(tdb, tdb->map_size + 1, 1);
958 /* Keep the global lock until the actual commit */
964 prepare to commit the current transaction
966 int tdb_transaction_prepare_commit(struct tdb_context *tdb)
968 tdb_trace(tdb, "tdb_transaction_prepare_commit");
969 return _tdb_transaction_prepare_commit(tdb);
973 commit the current transaction
975 int tdb_transaction_commit(struct tdb_context *tdb)
977 const struct tdb_methods *methods;
981 if (tdb->transaction == NULL) {
982 TDB_LOG((tdb, TDB_DEBUG_ERROR, "tdb_transaction_commit: no transaction\n"));
986 tdb_trace(tdb, "tdb_transaction_commit");
988 if (tdb->transaction->transaction_error) {
989 tdb->ecode = TDB_ERR_IO;
990 _tdb_transaction_cancel(tdb);
991 TDB_LOG((tdb, TDB_DEBUG_ERROR, "tdb_transaction_commit: transaction error pending\n"));
996 if (tdb->transaction->nesting != 0) {
997 tdb->transaction->nesting--;
1001 /* check for a null transaction */
1002 if (tdb->transaction->blocks == NULL) {
1003 _tdb_transaction_cancel(tdb);
1007 if (!tdb->transaction->prepared) {
1008 int ret = _tdb_transaction_prepare_commit(tdb);
1013 methods = tdb->transaction->io_methods;
1015 /* perform all the writes */
1016 for (i=0;i<tdb->transaction->num_blocks;i++) {
1020 if (tdb->transaction->blocks[i] == NULL) {
1024 offset = i * tdb->transaction->block_size;
1025 length = tdb->transaction->block_size;
1026 if (i == tdb->transaction->num_blocks-1) {
1027 length = tdb->transaction->last_block_size;
1030 if (methods->tdb_write(tdb, offset, tdb->transaction->blocks[i], length) == -1) {
1031 TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_transaction_commit: write failed during commit\n"));
1033 /* we've overwritten part of the data and
1034 possibly expanded the file, so we need to
1035 run the crash recovery code */
1036 tdb->methods = methods;
1037 tdb_transaction_recover(tdb);
1039 _tdb_transaction_cancel(tdb);
1040 tdb_brlock(tdb, GLOBAL_LOCK, F_UNLCK, F_SETLKW, 0, 1);
1042 TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_transaction_commit: write failed\n"));
1045 SAFE_FREE(tdb->transaction->blocks[i]);
1048 SAFE_FREE(tdb->transaction->blocks);
1049 tdb->transaction->num_blocks = 0;
1051 /* ensure the new data is on disk */
1052 if (transaction_sync(tdb, 0, tdb->map_size) == -1) {
1056 tdb_brlock(tdb, GLOBAL_LOCK, F_UNLCK, F_SETLKW, 0, 1);
1059 TODO: maybe write to some dummy hdr field, or write to magic
1060 offset without mmap, before the last sync, instead of the
1064 /* on some systems (like Linux 2.6.x) changes via mmap/msync
1065 don't change the mtime of the file, this means the file may
1066 not be backed up (as tdb rounding to block sizes means that
1067 file size changes are quite rare too). The following forces
1068 mtime changes when a transaction completes */
1070 utime(tdb->name, NULL);
1073 need_repack = tdb->transaction->need_repack;
1075 /* use a transaction cancel to free memory and remove the
1076 transaction locks */
1077 _tdb_transaction_cancel(tdb);
1080 return tdb_repack(tdb);
1088 recover from an aborted transaction. Must be called with exclusive
1089 database write access already established (including the global
1090 lock to prevent new processes attaching)
1092 int tdb_transaction_recover(struct tdb_context *tdb)
1094 tdb_off_t recovery_head, recovery_eof;
1095 unsigned char *data, *p;
1097 struct list_struct rec;
1099 /* find the recovery area */
1100 if (tdb_ofs_read(tdb, TDB_RECOVERY_HEAD, &recovery_head) == -1) {
1101 TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_transaction_recover: failed to read recovery head\n"));
1102 tdb->ecode = TDB_ERR_IO;
1106 if (recovery_head == 0) {
1107 /* we have never allocated a recovery record */
1111 /* read the recovery record */
1112 if (tdb->methods->tdb_read(tdb, recovery_head, &rec,
1113 sizeof(rec), DOCONV()) == -1) {
1114 TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_transaction_recover: failed to read recovery record\n"));
1115 tdb->ecode = TDB_ERR_IO;
1119 if (rec.magic != TDB_RECOVERY_MAGIC) {
1120 /* there is no valid recovery data */
1124 if (tdb->read_only) {
1125 TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_transaction_recover: attempt to recover read only database\n"));
1126 tdb->ecode = TDB_ERR_CORRUPT;
1130 recovery_eof = rec.key_len;
1132 data = (unsigned char *)malloc(rec.data_len);
1134 TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_transaction_recover: failed to allocate recovery data\n"));
1135 tdb->ecode = TDB_ERR_OOM;
1139 /* read the full recovery data */
1140 if (tdb->methods->tdb_read(tdb, recovery_head + sizeof(rec), data,
1141 rec.data_len, 0) == -1) {
1142 TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_transaction_recover: failed to read recovery data\n"));
1143 tdb->ecode = TDB_ERR_IO;
1147 /* recover the file data */
1149 while (p+8 < data + rec.data_len) {
1155 memcpy(&len, p+4, 4);
1157 if (tdb->methods->tdb_write(tdb, ofs, p+8, len) == -1) {
1159 TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_transaction_recover: failed to recover %d bytes at offset %d\n", len, ofs));
1160 tdb->ecode = TDB_ERR_IO;
1168 if (transaction_sync(tdb, 0, tdb->map_size) == -1) {
1169 TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_transaction_recover: failed to sync recovery\n"));
1170 tdb->ecode = TDB_ERR_IO;
1174 /* if the recovery area is after the recovered eof then remove it */
1175 if (recovery_eof <= recovery_head) {
1176 if (tdb_ofs_write(tdb, TDB_RECOVERY_HEAD, &zero) == -1) {
1177 TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_transaction_recover: failed to remove recovery head\n"));
1178 tdb->ecode = TDB_ERR_IO;
1183 /* remove the recovery magic */
1184 if (tdb_ofs_write(tdb, recovery_head + offsetof(struct list_struct, magic),
1186 TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_transaction_recover: failed to remove recovery magic\n"));
1187 tdb->ecode = TDB_ERR_IO;
1191 /* reduce the file size to the old size */
1193 if (ftruncate(tdb->fd, recovery_eof) != 0) {
1194 TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_transaction_recover: failed to reduce to recovery size\n"));
1195 tdb->ecode = TDB_ERR_IO;
1198 tdb->map_size = recovery_eof;
1201 if (transaction_sync(tdb, 0, recovery_eof) == -1) {
1202 TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_transaction_recover: failed to sync2 recovery\n"));
1203 tdb->ecode = TDB_ERR_IO;
1207 TDB_LOG((tdb, TDB_DEBUG_TRACE, "tdb_transaction_recover: recovered %d byte database\n",