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;
129 read while in a transaction. We need to check first if the data is in our list
130 of transaction elements, then if not do a real read
132 static int transaction_read(struct tdb_context *tdb, tdb_off_t off, void *buf,
133 tdb_len_t len, int cv)
137 /* Only a commit is allowed on a prepared transaction */
138 if (tdb->transaction->prepared) {
139 tdb->ecode = TDB_ERR_EINVAL;
140 TDB_LOG((tdb, TDB_DEBUG_FATAL, "transaction_read: transaction already prepared, read not allowed\n"));
141 tdb->transaction->transaction_error = 1;
145 /* break it down into block sized ops */
146 while (len + (off % tdb->transaction->block_size) > tdb->transaction->block_size) {
147 tdb_len_t len2 = tdb->transaction->block_size - (off % tdb->transaction->block_size);
148 if (transaction_read(tdb, off, buf, len2, cv) != 0) {
153 buf = (void *)(len2 + (char *)buf);
160 blk = off / tdb->transaction->block_size;
162 /* see if we have it in the block list */
163 if (tdb->transaction->num_blocks <= blk ||
164 tdb->transaction->blocks[blk] == NULL) {
165 /* nope, do a real read */
166 if (tdb->transaction->io_methods->tdb_read(tdb, off, buf, len, cv) != 0) {
172 /* it is in the block list. Now check for the last block */
173 if (blk == tdb->transaction->num_blocks-1) {
174 if (len > tdb->transaction->last_block_size) {
179 /* now copy it out of this block */
180 memcpy(buf, tdb->transaction->blocks[blk] + (off % tdb->transaction->block_size), len);
182 tdb_convert(buf, len);
187 TDB_LOG((tdb, TDB_DEBUG_FATAL, "transaction_read: failed at off=%d len=%d\n", off, len));
188 tdb->ecode = TDB_ERR_IO;
189 tdb->transaction->transaction_error = 1;
195 write while in a transaction
197 static int transaction_write(struct tdb_context *tdb, tdb_off_t off,
198 const void *buf, tdb_len_t len)
202 /* Only a commit is allowed on a prepared transaction */
203 if (tdb->transaction->prepared) {
204 tdb->ecode = TDB_ERR_EINVAL;
205 TDB_LOG((tdb, TDB_DEBUG_FATAL, "transaction_write: transaction already prepared, write not allowed\n"));
206 tdb->transaction->transaction_error = 1;
210 /* if the write is to a hash head, then update the transaction
212 if (len == sizeof(tdb_off_t) && off >= FREELIST_TOP &&
213 off < FREELIST_TOP+TDB_HASHTABLE_SIZE(tdb)) {
214 uint32_t chain = (off-FREELIST_TOP) / sizeof(tdb_off_t);
215 memcpy(&tdb->transaction->hash_heads[chain], buf, len);
218 /* break it up into block sized chunks */
219 while (len + (off % tdb->transaction->block_size) > tdb->transaction->block_size) {
220 tdb_len_t len2 = tdb->transaction->block_size - (off % tdb->transaction->block_size);
221 if (transaction_write(tdb, off, buf, len2) != 0) {
227 buf = (const void *)(len2 + (const char *)buf);
235 blk = off / tdb->transaction->block_size;
236 off = off % tdb->transaction->block_size;
238 if (tdb->transaction->num_blocks <= blk) {
239 uint8_t **new_blocks;
240 /* expand the blocks array */
241 if (tdb->transaction->blocks == NULL) {
242 new_blocks = (uint8_t **)malloc(
243 (blk+1)*sizeof(uint8_t *));
245 new_blocks = (uint8_t **)realloc(
246 tdb->transaction->blocks,
247 (blk+1)*sizeof(uint8_t *));
249 if (new_blocks == NULL) {
250 tdb->ecode = TDB_ERR_OOM;
253 memset(&new_blocks[tdb->transaction->num_blocks], 0,
254 (1+(blk - tdb->transaction->num_blocks))*sizeof(uint8_t *));
255 tdb->transaction->blocks = new_blocks;
256 tdb->transaction->num_blocks = blk+1;
257 tdb->transaction->last_block_size = 0;
260 /* allocate and fill a block? */
261 if (tdb->transaction->blocks[blk] == NULL) {
262 tdb->transaction->blocks[blk] = (uint8_t *)calloc(tdb->transaction->block_size, 1);
263 if (tdb->transaction->blocks[blk] == NULL) {
264 tdb->ecode = TDB_ERR_OOM;
265 tdb->transaction->transaction_error = 1;
268 if (tdb->transaction->old_map_size > blk * tdb->transaction->block_size) {
269 tdb_len_t len2 = tdb->transaction->block_size;
270 if (len2 + (blk * tdb->transaction->block_size) > tdb->transaction->old_map_size) {
271 len2 = tdb->transaction->old_map_size - (blk * tdb->transaction->block_size);
273 if (tdb->transaction->io_methods->tdb_read(tdb, blk * tdb->transaction->block_size,
274 tdb->transaction->blocks[blk],
276 SAFE_FREE(tdb->transaction->blocks[blk]);
277 tdb->ecode = TDB_ERR_IO;
280 if (blk == tdb->transaction->num_blocks-1) {
281 tdb->transaction->last_block_size = len2;
286 /* overwrite part of an existing block */
288 memset(tdb->transaction->blocks[blk] + off, 0, len);
290 memcpy(tdb->transaction->blocks[blk] + off, buf, len);
292 if (blk == tdb->transaction->num_blocks-1) {
293 if (len + off > tdb->transaction->last_block_size) {
294 tdb->transaction->last_block_size = len + off;
301 TDB_LOG((tdb, TDB_DEBUG_FATAL, "transaction_write: failed at off=%d len=%d\n",
302 (blk*tdb->transaction->block_size) + off, len));
303 tdb->transaction->transaction_error = 1;
309 write while in a transaction - this varient never expands the transaction blocks, it only
310 updates existing blocks. This means it cannot change the recovery size
312 static int transaction_write_existing(struct tdb_context *tdb, tdb_off_t off,
313 const void *buf, tdb_len_t len)
317 /* break it up into block sized chunks */
318 while (len + (off % tdb->transaction->block_size) > tdb->transaction->block_size) {
319 tdb_len_t len2 = tdb->transaction->block_size - (off % tdb->transaction->block_size);
320 if (transaction_write_existing(tdb, off, buf, len2) != 0) {
326 buf = (const void *)(len2 + (const char *)buf);
334 blk = off / tdb->transaction->block_size;
335 off = off % tdb->transaction->block_size;
337 if (tdb->transaction->num_blocks <= blk ||
338 tdb->transaction->blocks[blk] == NULL) {
342 if (blk == tdb->transaction->num_blocks-1 &&
343 off + len > tdb->transaction->last_block_size) {
344 if (off >= tdb->transaction->last_block_size) {
347 len = tdb->transaction->last_block_size - off;
350 /* overwrite part of an existing block */
351 memcpy(tdb->transaction->blocks[blk] + off, buf, len);
358 accelerated hash chain head search, using the cached hash heads
360 static void transaction_next_hash_chain(struct tdb_context *tdb, uint32_t *chain)
363 for (;h < tdb->header.hash_size;h++) {
364 /* the +1 takes account of the freelist */
365 if (0 != tdb->transaction->hash_heads[h+1]) {
373 out of bounds check during a transaction
375 static int transaction_oob(struct tdb_context *tdb, tdb_off_t len, int probe)
377 if (len <= tdb->map_size) {
380 return TDB_ERRCODE(TDB_ERR_IO, -1);
384 transaction version of tdb_expand().
386 static int transaction_expand_file(struct tdb_context *tdb, tdb_off_t size,
389 /* add a write to the transaction elements, so subsequent
390 reads see the zero data */
391 if (transaction_write(tdb, size, NULL, addition) != 0) {
399 brlock during a transaction - ignore them
401 static int transaction_brlock(struct tdb_context *tdb, tdb_off_t offset,
402 int rw_type, int lck_type, int probe, size_t len)
407 static const struct tdb_methods transaction_methods = {
410 transaction_next_hash_chain,
412 transaction_expand_file,
418 start a tdb transaction. No token is returned, as only a single
419 transaction is allowed to be pending per tdb_context
421 int tdb_transaction_start(struct tdb_context *tdb)
423 /* some sanity checks */
424 if (tdb->read_only || (tdb->flags & TDB_INTERNAL) || tdb->traverse_read) {
425 TDB_LOG((tdb, TDB_DEBUG_ERROR, "tdb_transaction_start: cannot start a transaction on a read-only or internal db\n"));
426 tdb->ecode = TDB_ERR_EINVAL;
430 /* cope with nested tdb_transaction_start() calls */
431 if (tdb->transaction != NULL) {
432 tdb->transaction->nesting++;
433 TDB_LOG((tdb, TDB_DEBUG_TRACE, "tdb_transaction_start: nesting %d\n",
434 tdb->transaction->nesting));
438 if (tdb->num_locks != 0 || tdb->global_lock.count) {
439 /* the caller must not have any locks when starting a
440 transaction as otherwise we'll be screwed by lack
441 of nested locks in posix */
442 TDB_LOG((tdb, TDB_DEBUG_ERROR, "tdb_transaction_start: cannot start a transaction with locks held\n"));
443 tdb->ecode = TDB_ERR_LOCK;
447 if (tdb->travlocks.next != NULL) {
448 /* you cannot use transactions inside a traverse (although you can use
449 traverse inside a transaction) as otherwise you can end up with
451 TDB_LOG((tdb, TDB_DEBUG_ERROR, "tdb_transaction_start: cannot start a transaction within a traverse\n"));
452 tdb->ecode = TDB_ERR_LOCK;
456 tdb->transaction = (struct tdb_transaction *)
457 calloc(sizeof(struct tdb_transaction), 1);
458 if (tdb->transaction == NULL) {
459 tdb->ecode = TDB_ERR_OOM;
463 /* a page at a time seems like a reasonable compromise between compactness and efficiency */
464 tdb->transaction->block_size = tdb->page_size;
466 /* get the transaction write lock. This is a blocking lock. As
467 discussed with Volker, there are a number of ways we could
468 make this async, which we will probably do in the future */
469 if (tdb_transaction_lock(tdb, F_WRLCK) == -1) {
470 SAFE_FREE(tdb->transaction->blocks);
471 SAFE_FREE(tdb->transaction);
475 /* get a read lock from the freelist to the end of file. This
476 is upgraded to a write lock during the commit */
477 if (tdb_brlock(tdb, FREELIST_TOP, F_RDLCK, F_SETLKW, 0, 0) == -1) {
478 TDB_LOG((tdb, TDB_DEBUG_ERROR, "tdb_transaction_start: failed to get hash locks\n"));
479 tdb->ecode = TDB_ERR_LOCK;
483 /* setup a copy of the hash table heads so the hash scan in
484 traverse can be fast */
485 tdb->transaction->hash_heads = (uint32_t *)
486 calloc(tdb->header.hash_size+1, sizeof(uint32_t));
487 if (tdb->transaction->hash_heads == NULL) {
488 tdb->ecode = TDB_ERR_OOM;
491 if (tdb->methods->tdb_read(tdb, FREELIST_TOP, tdb->transaction->hash_heads,
492 TDB_HASHTABLE_SIZE(tdb), 0) != 0) {
493 TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_transaction_start: failed to read hash heads\n"));
494 tdb->ecode = TDB_ERR_IO;
498 /* make sure we know about any file expansions already done by
500 tdb->methods->tdb_oob(tdb, tdb->map_size + 1, 1);
501 tdb->transaction->old_map_size = tdb->map_size;
503 /* finally hook the io methods, replacing them with
504 transaction specific methods */
505 tdb->transaction->io_methods = tdb->methods;
506 tdb->methods = &transaction_methods;
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 (fsync(tdb->fd) != 0) {
526 tdb->ecode = TDB_ERR_IO;
527 TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_transaction: fsync failed\n"));
532 tdb_off_t moffset = offset & ~(tdb->page_size-1);
533 if (msync(moffset + (char *)tdb->map_ptr,
534 length + (offset - moffset), MS_SYNC) != 0) {
535 tdb->ecode = TDB_ERR_IO;
536 TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_transaction: msync failed - %s\n",
547 cancel the current transaction
549 int tdb_transaction_cancel(struct tdb_context *tdb)
553 if (tdb->transaction == NULL) {
554 TDB_LOG((tdb, TDB_DEBUG_ERROR, "tdb_transaction_cancel: no transaction\n"));
558 if (tdb->transaction->nesting != 0) {
559 tdb->transaction->transaction_error = 1;
560 tdb->transaction->nesting--;
564 tdb->map_size = tdb->transaction->old_map_size;
566 /* free all the transaction blocks */
567 for (i=0;i<tdb->transaction->num_blocks;i++) {
568 if (tdb->transaction->blocks[i] != NULL) {
569 free(tdb->transaction->blocks[i]);
572 SAFE_FREE(tdb->transaction->blocks);
574 if (tdb->transaction->magic_offset) {
575 const struct tdb_methods *methods = tdb->transaction->io_methods;
578 /* remove the recovery marker */
579 if (methods->tdb_write(tdb, tdb->transaction->magic_offset, &zero, 4) == -1 ||
580 transaction_sync(tdb, tdb->transaction->magic_offset, 4) == -1) {
581 TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_transaction_cancel: failed to remove recovery magic\n"));
586 /* remove any global lock created during the transaction */
587 if (tdb->global_lock.count != 0) {
588 tdb_brlock(tdb, FREELIST_TOP, F_UNLCK, F_SETLKW, 0, 4*tdb->header.hash_size);
589 tdb->global_lock.count = 0;
592 /* remove any locks created during the transaction */
593 if (tdb->num_locks != 0) {
594 for (i=0;i<tdb->num_lockrecs;i++) {
595 tdb_brlock(tdb,FREELIST_TOP+4*tdb->lockrecs[i].list,
596 F_UNLCK,F_SETLKW, 0, 1);
599 tdb->num_lockrecs = 0;
600 SAFE_FREE(tdb->lockrecs);
603 /* restore the normal io methods */
604 tdb->methods = tdb->transaction->io_methods;
606 tdb_brlock(tdb, FREELIST_TOP, F_UNLCK, F_SETLKW, 0, 0);
607 tdb_transaction_unlock(tdb);
608 SAFE_FREE(tdb->transaction->hash_heads);
609 SAFE_FREE(tdb->transaction);
616 work out how much space the linearised recovery data will consume
618 static tdb_len_t tdb_recovery_size(struct tdb_context *tdb)
620 tdb_len_t recovery_size = 0;
623 recovery_size = sizeof(uint32_t);
624 for (i=0;i<tdb->transaction->num_blocks;i++) {
625 if (i * tdb->transaction->block_size >= tdb->transaction->old_map_size) {
628 if (tdb->transaction->blocks[i] == NULL) {
631 recovery_size += 2*sizeof(tdb_off_t);
632 if (i == tdb->transaction->num_blocks-1) {
633 recovery_size += tdb->transaction->last_block_size;
635 recovery_size += tdb->transaction->block_size;
639 return recovery_size;
643 allocate the recovery area, or use an existing recovery area if it is
646 static int tdb_recovery_allocate(struct tdb_context *tdb,
647 tdb_len_t *recovery_size,
648 tdb_off_t *recovery_offset,
649 tdb_len_t *recovery_max_size)
651 struct list_struct rec;
652 const struct tdb_methods *methods = tdb->transaction->io_methods;
653 tdb_off_t recovery_head;
655 if (tdb_ofs_read(tdb, TDB_RECOVERY_HEAD, &recovery_head) == -1) {
656 TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_recovery_allocate: failed to read recovery head\n"));
662 if (recovery_head != 0 &&
663 methods->tdb_read(tdb, recovery_head, &rec, sizeof(rec), DOCONV()) == -1) {
664 TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_recovery_allocate: failed to read recovery record\n"));
668 *recovery_size = tdb_recovery_size(tdb);
670 if (recovery_head != 0 && *recovery_size <= rec.rec_len) {
671 /* it fits in the existing area */
672 *recovery_max_size = rec.rec_len;
673 *recovery_offset = recovery_head;
677 /* we need to free up the old recovery area, then allocate a
678 new one at the end of the file. Note that we cannot use
679 tdb_allocate() to allocate the new one as that might return
680 us an area that is being currently used (as of the start of
682 if (recovery_head != 0) {
683 if (tdb_free(tdb, recovery_head, &rec) == -1) {
684 TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_recovery_allocate: failed to free previous recovery area\n"));
689 /* the tdb_free() call might have increased the recovery size */
690 *recovery_size = tdb_recovery_size(tdb);
692 /* round up to a multiple of page size */
693 *recovery_max_size = TDB_ALIGN(sizeof(rec) + *recovery_size, tdb->page_size) - sizeof(rec);
694 *recovery_offset = tdb->map_size;
695 recovery_head = *recovery_offset;
697 if (methods->tdb_expand_file(tdb, tdb->transaction->old_map_size,
698 (tdb->map_size - tdb->transaction->old_map_size) +
699 sizeof(rec) + *recovery_max_size) == -1) {
700 TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_recovery_allocate: failed to create recovery area\n"));
704 /* remap the file (if using mmap) */
705 methods->tdb_oob(tdb, tdb->map_size + 1, 1);
707 /* we have to reset the old map size so that we don't try to expand the file
708 again in the transaction commit, which would destroy the recovery area */
709 tdb->transaction->old_map_size = tdb->map_size;
711 /* write the recovery header offset and sync - we can sync without a race here
712 as the magic ptr in the recovery record has not been set */
713 CONVERT(recovery_head);
714 if (methods->tdb_write(tdb, TDB_RECOVERY_HEAD,
715 &recovery_head, sizeof(tdb_off_t)) == -1) {
716 TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_recovery_allocate: failed to write recovery head\n"));
719 if (transaction_write_existing(tdb, TDB_RECOVERY_HEAD, &recovery_head, sizeof(tdb_off_t)) == -1) {
720 TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_recovery_allocate: failed to write recovery head\n"));
729 setup the recovery data that will be used on a crash during commit
731 static int transaction_setup_recovery(struct tdb_context *tdb,
732 tdb_off_t *magic_offset)
734 tdb_len_t recovery_size;
735 unsigned char *data, *p;
736 const struct tdb_methods *methods = tdb->transaction->io_methods;
737 struct list_struct *rec;
738 tdb_off_t recovery_offset, recovery_max_size;
739 tdb_off_t old_map_size = tdb->transaction->old_map_size;
740 uint32_t magic, tailer;
744 check that the recovery area has enough space
746 if (tdb_recovery_allocate(tdb, &recovery_size,
747 &recovery_offset, &recovery_max_size) == -1) {
751 data = (unsigned char *)malloc(recovery_size + sizeof(*rec));
753 tdb->ecode = TDB_ERR_OOM;
757 rec = (struct list_struct *)data;
758 memset(rec, 0, sizeof(*rec));
761 rec->data_len = recovery_size;
762 rec->rec_len = recovery_max_size;
763 rec->key_len = old_map_size;
766 /* build the recovery data into a single blob to allow us to do a single
767 large write, which should be more efficient */
768 p = data + sizeof(*rec);
769 for (i=0;i<tdb->transaction->num_blocks;i++) {
773 if (tdb->transaction->blocks[i] == NULL) {
777 offset = i * tdb->transaction->block_size;
778 length = tdb->transaction->block_size;
779 if (i == tdb->transaction->num_blocks-1) {
780 length = tdb->transaction->last_block_size;
783 if (offset >= old_map_size) {
786 if (offset + length > tdb->transaction->old_map_size) {
787 TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_transaction_setup_recovery: transaction data over new region boundary\n"));
789 tdb->ecode = TDB_ERR_CORRUPT;
792 memcpy(p, &offset, 4);
793 memcpy(p+4, &length, 4);
797 /* the recovery area contains the old data, not the
798 new data, so we have to call the original tdb_read
800 if (methods->tdb_read(tdb, offset, p + 8, length, 0) != 0) {
802 tdb->ecode = TDB_ERR_IO;
809 tailer = sizeof(*rec) + recovery_max_size;
810 memcpy(p, &tailer, 4);
813 /* write the recovery data to the recovery area */
814 if (methods->tdb_write(tdb, recovery_offset, data, sizeof(*rec) + recovery_size) == -1) {
815 TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_transaction_setup_recovery: failed to write recovery data\n"));
817 tdb->ecode = TDB_ERR_IO;
820 if (transaction_write_existing(tdb, recovery_offset, data, sizeof(*rec) + recovery_size) == -1) {
821 TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_transaction_setup_recovery: failed to write secondary recovery data\n"));
823 tdb->ecode = TDB_ERR_IO;
827 /* as we don't have ordered writes, we have to sync the recovery
828 data before we update the magic to indicate that the recovery
830 if (transaction_sync(tdb, recovery_offset, sizeof(*rec) + recovery_size) == -1) {
837 magic = TDB_RECOVERY_MAGIC;
840 *magic_offset = recovery_offset + offsetof(struct list_struct, magic);
842 if (methods->tdb_write(tdb, *magic_offset, &magic, sizeof(magic)) == -1) {
843 TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_transaction_setup_recovery: failed to write recovery magic\n"));
844 tdb->ecode = TDB_ERR_IO;
847 if (transaction_write_existing(tdb, *magic_offset, &magic, sizeof(magic)) == -1) {
848 TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_transaction_setup_recovery: failed to write secondary recovery magic\n"));
849 tdb->ecode = TDB_ERR_IO;
853 /* ensure the recovery magic marker is on disk */
854 if (transaction_sync(tdb, *magic_offset, sizeof(magic)) == -1) {
862 prepare to commit the current transaction
864 int tdb_transaction_prepare_commit(struct tdb_context *tdb)
866 const struct tdb_methods *methods;
868 if (tdb->transaction == NULL) {
869 TDB_LOG((tdb, TDB_DEBUG_ERROR, "tdb_transaction_prepare_commit: no transaction\n"));
873 if (tdb->transaction->prepared) {
874 tdb->ecode = TDB_ERR_EINVAL;
875 tdb_transaction_cancel(tdb);
876 TDB_LOG((tdb, TDB_DEBUG_ERROR, "tdb_transaction_prepare_commit: transaction already prepared\n"));
880 if (tdb->transaction->transaction_error) {
881 tdb->ecode = TDB_ERR_IO;
882 tdb_transaction_cancel(tdb);
883 TDB_LOG((tdb, TDB_DEBUG_ERROR, "tdb_transaction_prepare_commit: transaction error pending\n"));
888 if (tdb->transaction->nesting != 0) {
892 /* check for a null transaction */
893 if (tdb->transaction->blocks == NULL) {
897 methods = tdb->transaction->io_methods;
899 /* if there are any locks pending then the caller has not
900 nested their locks properly, so fail the transaction */
901 if (tdb->num_locks || tdb->global_lock.count) {
902 tdb->ecode = TDB_ERR_LOCK;
903 TDB_LOG((tdb, TDB_DEBUG_ERROR, "tdb_transaction_prepare_commit: locks pending on commit\n"));
904 tdb_transaction_cancel(tdb);
908 /* upgrade the main transaction lock region to a write lock */
909 if (tdb_brlock_upgrade(tdb, FREELIST_TOP, 0) == -1) {
910 TDB_LOG((tdb, TDB_DEBUG_ERROR, "tdb_transaction_prepare_commit: failed to upgrade hash locks\n"));
911 tdb->ecode = TDB_ERR_LOCK;
912 tdb_transaction_cancel(tdb);
916 /* get the global lock - this prevents new users attaching to the database
918 if (tdb_brlock(tdb, GLOBAL_LOCK, F_WRLCK, F_SETLKW, 0, 1) == -1) {
919 TDB_LOG((tdb, TDB_DEBUG_ERROR, "tdb_transaction_prepare_commit: failed to get global lock\n"));
920 tdb->ecode = TDB_ERR_LOCK;
921 tdb_transaction_cancel(tdb);
925 if (!(tdb->flags & TDB_NOSYNC)) {
926 /* write the recovery data to the end of the file */
927 if (transaction_setup_recovery(tdb, &tdb->transaction->magic_offset) == -1) {
928 TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_transaction_prepare_commit: failed to setup recovery data\n"));
929 tdb_brlock(tdb, GLOBAL_LOCK, F_UNLCK, F_SETLKW, 0, 1);
930 tdb_transaction_cancel(tdb);
935 tdb->transaction->prepared = true;
937 /* expand the file to the new size if needed */
938 if (tdb->map_size != tdb->transaction->old_map_size) {
939 if (methods->tdb_expand_file(tdb, tdb->transaction->old_map_size,
941 tdb->transaction->old_map_size) == -1) {
942 tdb->ecode = TDB_ERR_IO;
943 TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_transaction_prepare_commit: expansion failed\n"));
944 tdb_brlock(tdb, GLOBAL_LOCK, F_UNLCK, F_SETLKW, 0, 1);
945 tdb_transaction_cancel(tdb);
948 tdb->map_size = tdb->transaction->old_map_size;
949 methods->tdb_oob(tdb, tdb->map_size + 1, 1);
952 /* Keep the global lock until the actual commit */
958 commit the current transaction
960 int tdb_transaction_commit(struct tdb_context *tdb)
962 const struct tdb_methods *methods;
965 if (tdb->transaction == NULL) {
966 TDB_LOG((tdb, TDB_DEBUG_ERROR, "tdb_transaction_commit: no transaction\n"));
970 if (tdb->transaction->transaction_error) {
971 tdb->ecode = TDB_ERR_IO;
972 tdb_transaction_cancel(tdb);
973 TDB_LOG((tdb, TDB_DEBUG_ERROR, "tdb_transaction_commit: transaction error pending\n"));
978 if (tdb->transaction->nesting != 0) {
979 tdb->transaction->nesting--;
983 /* check for a null transaction */
984 if (tdb->transaction->blocks == NULL) {
985 tdb_transaction_cancel(tdb);
989 if (!tdb->transaction->prepared) {
990 int ret = tdb_transaction_prepare_commit(tdb);
995 methods = tdb->transaction->io_methods;
997 /* perform all the writes */
998 for (i=0;i<tdb->transaction->num_blocks;i++) {
1002 if (tdb->transaction->blocks[i] == NULL) {
1006 offset = i * tdb->transaction->block_size;
1007 length = tdb->transaction->block_size;
1008 if (i == tdb->transaction->num_blocks-1) {
1009 length = tdb->transaction->last_block_size;
1012 if (methods->tdb_write(tdb, offset, tdb->transaction->blocks[i], length) == -1) {
1013 TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_transaction_commit: write failed during commit\n"));
1015 /* we've overwritten part of the data and
1016 possibly expanded the file, so we need to
1017 run the crash recovery code */
1018 tdb->methods = methods;
1019 tdb_transaction_recover(tdb);
1021 tdb_transaction_cancel(tdb);
1022 tdb_brlock(tdb, GLOBAL_LOCK, F_UNLCK, F_SETLKW, 0, 1);
1024 TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_transaction_commit: write failed\n"));
1027 SAFE_FREE(tdb->transaction->blocks[i]);
1030 SAFE_FREE(tdb->transaction->blocks);
1031 tdb->transaction->num_blocks = 0;
1033 if (!(tdb->flags & TDB_NOSYNC)) {
1034 /* ensure the new data is on disk */
1035 if (transaction_sync(tdb, 0, tdb->map_size) == -1) {
1040 tdb_brlock(tdb, GLOBAL_LOCK, F_UNLCK, F_SETLKW, 0, 1);
1043 TODO: maybe write to some dummy hdr field, or write to magic
1044 offset without mmap, before the last sync, instead of the
1048 /* on some systems (like Linux 2.6.x) changes via mmap/msync
1049 don't change the mtime of the file, this means the file may
1050 not be backed up (as tdb rounding to block sizes means that
1051 file size changes are quite rare too). The following forces
1052 mtime changes when a transaction completes */
1054 utime(tdb->name, NULL);
1057 /* use a transaction cancel to free memory and remove the
1058 transaction locks */
1059 tdb_transaction_cancel(tdb);
1066 recover from an aborted transaction. Must be called with exclusive
1067 database write access already established (including the global
1068 lock to prevent new processes attaching)
1070 int tdb_transaction_recover(struct tdb_context *tdb)
1072 tdb_off_t recovery_head, recovery_eof;
1073 unsigned char *data, *p;
1075 struct list_struct rec;
1077 /* find the recovery area */
1078 if (tdb_ofs_read(tdb, TDB_RECOVERY_HEAD, &recovery_head) == -1) {
1079 TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_transaction_recover: failed to read recovery head\n"));
1080 tdb->ecode = TDB_ERR_IO;
1084 if (recovery_head == 0) {
1085 /* we have never allocated a recovery record */
1089 /* read the recovery record */
1090 if (tdb->methods->tdb_read(tdb, recovery_head, &rec,
1091 sizeof(rec), DOCONV()) == -1) {
1092 TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_transaction_recover: failed to read recovery record\n"));
1093 tdb->ecode = TDB_ERR_IO;
1097 if (rec.magic != TDB_RECOVERY_MAGIC) {
1098 /* there is no valid recovery data */
1102 if (tdb->read_only) {
1103 TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_transaction_recover: attempt to recover read only database\n"));
1104 tdb->ecode = TDB_ERR_CORRUPT;
1108 recovery_eof = rec.key_len;
1110 data = (unsigned char *)malloc(rec.data_len);
1112 TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_transaction_recover: failed to allocate recovery data\n"));
1113 tdb->ecode = TDB_ERR_OOM;
1117 /* read the full recovery data */
1118 if (tdb->methods->tdb_read(tdb, recovery_head + sizeof(rec), data,
1119 rec.data_len, 0) == -1) {
1120 TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_transaction_recover: failed to read recovery data\n"));
1121 tdb->ecode = TDB_ERR_IO;
1125 /* recover the file data */
1127 while (p+8 < data + rec.data_len) {
1133 memcpy(&len, p+4, 4);
1135 if (tdb->methods->tdb_write(tdb, ofs, p+8, len) == -1) {
1137 TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_transaction_recover: failed to recover %d bytes at offset %d\n", len, ofs));
1138 tdb->ecode = TDB_ERR_IO;
1146 if (transaction_sync(tdb, 0, tdb->map_size) == -1) {
1147 TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_transaction_recover: failed to sync recovery\n"));
1148 tdb->ecode = TDB_ERR_IO;
1152 /* if the recovery area is after the recovered eof then remove it */
1153 if (recovery_eof <= recovery_head) {
1154 if (tdb_ofs_write(tdb, TDB_RECOVERY_HEAD, &zero) == -1) {
1155 TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_transaction_recover: failed to remove recovery head\n"));
1156 tdb->ecode = TDB_ERR_IO;
1161 /* remove the recovery magic */
1162 if (tdb_ofs_write(tdb, recovery_head + offsetof(struct list_struct, magic),
1164 TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_transaction_recover: failed to remove recovery magic\n"));
1165 tdb->ecode = TDB_ERR_IO;
1169 /* reduce the file size to the old size */
1171 if (ftruncate(tdb->fd, recovery_eof) != 0) {
1172 TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_transaction_recover: failed to reduce to recovery size\n"));
1173 tdb->ecode = TDB_ERR_IO;
1176 tdb->map_size = recovery_eof;
1179 if (transaction_sync(tdb, 0, recovery_eof) == -1) {
1180 TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_transaction_recover: failed to sync2 recovery\n"));
1181 tdb->ecode = TDB_ERR_IO;
1185 TDB_LOG((tdb, TDB_DEBUG_TRACE, "tdb_transaction_recover: recovered %d byte database\n",