2 Unix SMB/CIFS implementation.
4 trivial database library
6 Copyright (C) Andrew Tridgell 2005
7 Copyright (C) Rusty Russell 2010
9 ** NOTE! The following LGPL license applies to the tdb
10 ** library. This does NOT imply that all of Samba is released
13 This library is free software; you can redistribute it and/or
14 modify it under the terms of the GNU Lesser General Public
15 License as published by the Free Software Foundation; either
16 version 3 of the License, or (at your option) any later version.
18 This library is distributed in the hope that it will be useful,
19 but WITHOUT ANY WARRANTY; without even the implied warranty of
20 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
21 Lesser General Public License for more details.
23 You should have received a copy of the GNU Lesser General Public
24 License along with this library; if not, see <http://www.gnu.org/licenses/>.
28 #define SAFE_FREE(x) do { if ((x) != NULL) {free(x); (x)=NULL;} } while(0)
33 - only allow a single transaction at a time per database. This makes
34 using the transaction API simpler, as otherwise the caller would
35 have to cope with temporary failures in transactions that conflict
36 with other current transactions
38 - keep the transaction recovery information in the same file as the
39 database, using a special 'transaction recovery' record pointed at
40 by the header. This removes the need for extra journal files as
41 used by some other databases
43 - dynamically allocated the transaction recover record, re-using it
44 for subsequent transactions. If a larger record is needed then
45 tdb_free() the old record to place it on the normal tdb freelist
46 before allocating the new record
48 - during transactions, keep a linked list of writes all that have
49 been performed by intercepting all tdb_write() calls. The hooked
50 transaction versions of tdb_read() and tdb_write() check this
51 linked list and try to use the elements of the list in preference
54 - don't allow any locks to be held when a transaction starts,
55 otherwise we can end up with deadlock (plus lack of lock nesting
56 in posix locks would mean the lock is lost)
58 - if the caller gains a lock during the transaction but doesn't
59 release it then fail the commit
61 - allow for nested calls to tdb_transaction_start(), re-using the
62 existing transaction record. If the inner transaction is cancelled
63 then a subsequent commit will fail
65 - keep a mirrored copy of the tdb hash chain heads to allow for the
66 fast hash heads scan on traverse, updating the mirrored copy in
67 the transaction version of tdb_write
69 - allow callers to mix transaction and non-transaction use of tdb,
70 although once a transaction is started then an exclusive lock is
71 gained until the transaction is committed or cancelled
73 - the commit stategy involves first saving away all modified data
74 into a linearised buffer in the transaction recovery area, then
75 marking the transaction recovery area with a magic value to
76 indicate a valid recovery record. In total 4 fsync/msync calls are
77 needed per commit to prevent race conditions. It might be possible
78 to reduce this to 3 or even 2 with some more work.
80 - check for a valid recovery record on open of the tdb, while the
81 open lock is held. Automatically recover from the transaction
82 recovery area if needed, then continue with the open as
83 usual. This allows for smooth crash recovery with no administrator
86 - if TDB_NOSYNC is passed to flags in tdb_open then transactions are
87 still available, but no transaction recovery area is used and no
88 fsync/msync calls are made.
93 hold the context of any current transaction
95 struct tdb_transaction {
96 /* the original io methods - used to do IOs to the real db */
97 const struct tdb_methods *io_methods;
99 /* the list of transaction blocks. When a block is first
100 written to, it gets created in this list */
103 size_t last_block_size; /* number of valid bytes in the last block */
105 /* non-zero when an internal transaction error has
106 occurred. All write operations will then fail until the
107 transaction is ended */
108 int transaction_error;
110 /* when inside a transaction we need to keep track of any
111 nested tdb_transaction_start() calls, as these are allowed,
112 but don't create a new transaction */
115 /* set when a prepare has already occurred */
117 tdb_off_t magic_offset;
119 /* old file size before transaction */
120 tdb_len_t old_map_size;
125 read while in a transaction. We need to check first if the data is in our list
126 of transaction elements, then if not do a real read
128 static int transaction_read(struct tdb_context *tdb, tdb_off_t off, void *buf,
133 /* break it down into block sized ops */
134 while (len + (off % getpagesize()) > getpagesize()) {
135 tdb_len_t len2 = getpagesize() - (off % getpagesize());
136 if (transaction_read(tdb, off, buf, len2) != 0) {
141 buf = (void *)(len2 + (char *)buf);
148 blk = off / getpagesize();
150 /* see if we have it in the block list */
151 if (tdb->transaction->num_blocks <= blk ||
152 tdb->transaction->blocks[blk] == NULL) {
153 /* nope, do a real read */
154 if (tdb->transaction->io_methods->tread(tdb, off, buf, len)
161 /* it is in the block list. Now check for the last block */
162 if (blk == tdb->transaction->num_blocks-1) {
163 if (len > tdb->transaction->last_block_size) {
168 /* now copy it out of this block */
169 memcpy(buf, tdb->transaction->blocks[blk] + (off % getpagesize()), len);
173 tdb_logerr(tdb, TDB_ERR_IO, TDB_DEBUG_FATAL,
174 "transaction_read: failed at off=%zu len=%zu",
175 (size_t)off, (size_t)len);
176 tdb->transaction->transaction_error = 1;
182 write while in a transaction
184 static int transaction_write(struct tdb_context *tdb, tdb_off_t off,
185 const void *buf, tdb_len_t len)
189 /* Only a commit is allowed on a prepared transaction */
190 if (tdb->transaction->prepared) {
191 tdb_logerr(tdb, TDB_ERR_EINVAL, TDB_DEBUG_FATAL,
192 "transaction_write: transaction already prepared,"
193 " write not allowed");
197 /* break it up into block sized chunks */
198 while (len + (off % getpagesize()) > getpagesize()) {
199 tdb_len_t len2 = getpagesize() - (off % getpagesize());
200 if (transaction_write(tdb, off, buf, len2) != 0) {
206 buf = (const void *)(len2 + (const char *)buf);
214 blk = off / getpagesize();
215 off = off % getpagesize();
217 if (tdb->transaction->num_blocks <= blk) {
218 uint8_t **new_blocks;
219 /* expand the blocks array */
220 if (tdb->transaction->blocks == NULL) {
221 new_blocks = (uint8_t **)malloc(
222 (blk+1)*sizeof(uint8_t *));
224 new_blocks = (uint8_t **)realloc(
225 tdb->transaction->blocks,
226 (blk+1)*sizeof(uint8_t *));
228 if (new_blocks == NULL) {
229 tdb_logerr(tdb, TDB_ERR_OOM, TDB_DEBUG_FATAL,
230 "transaction_write: failed to allocate");
233 memset(&new_blocks[tdb->transaction->num_blocks], 0,
234 (1+(blk - tdb->transaction->num_blocks))*sizeof(uint8_t *));
235 tdb->transaction->blocks = new_blocks;
236 tdb->transaction->num_blocks = blk+1;
237 tdb->transaction->last_block_size = 0;
240 /* allocate and fill a block? */
241 if (tdb->transaction->blocks[blk] == NULL) {
242 tdb->transaction->blocks[blk] = (uint8_t *)calloc(getpagesize(), 1);
243 if (tdb->transaction->blocks[blk] == NULL) {
244 tdb_logerr(tdb, TDB_ERR_OOM, TDB_DEBUG_FATAL,
245 "transaction_write: failed to allocate");
248 if (tdb->transaction->old_map_size > blk * getpagesize()) {
249 tdb_len_t len2 = getpagesize();
250 if (len2 + (blk * getpagesize()) > tdb->transaction->old_map_size) {
251 len2 = tdb->transaction->old_map_size - (blk * getpagesize());
253 if (tdb->transaction->io_methods->tread(tdb, blk * getpagesize(),
254 tdb->transaction->blocks[blk],
256 tdb_logerr(tdb, TDB_ERR_OOM, TDB_DEBUG_FATAL,
257 "transaction_write: failed to"
258 " read old block: %s",
260 SAFE_FREE(tdb->transaction->blocks[blk]);
263 if (blk == tdb->transaction->num_blocks-1) {
264 tdb->transaction->last_block_size = len2;
269 /* overwrite part of an existing block */
271 memset(tdb->transaction->blocks[blk] + off, 0, len);
273 memcpy(tdb->transaction->blocks[blk] + off, buf, len);
275 if (blk == tdb->transaction->num_blocks-1) {
276 if (len + off > tdb->transaction->last_block_size) {
277 tdb->transaction->last_block_size = len + off;
284 tdb->transaction->transaction_error = 1;
290 write while in a transaction - this varient never expands the transaction blocks, it only
291 updates existing blocks. This means it cannot change the recovery size
293 static void transaction_write_existing(struct tdb_context *tdb, tdb_off_t off,
294 const void *buf, tdb_len_t len)
298 /* break it up into block sized chunks */
299 while (len + (off % getpagesize()) > getpagesize()) {
300 tdb_len_t len2 = getpagesize() - (off % getpagesize());
301 transaction_write_existing(tdb, off, buf, len2);
305 buf = (const void *)(len2 + (const char *)buf);
313 blk = off / getpagesize();
314 off = off % getpagesize();
316 if (tdb->transaction->num_blocks <= blk ||
317 tdb->transaction->blocks[blk] == NULL) {
321 if (blk == tdb->transaction->num_blocks-1 &&
322 off + len > tdb->transaction->last_block_size) {
323 if (off >= tdb->transaction->last_block_size) {
326 len = tdb->transaction->last_block_size - off;
329 /* overwrite part of an existing block */
330 memcpy(tdb->transaction->blocks[blk] + off, buf, len);
335 out of bounds check during a transaction
337 static int transaction_oob(struct tdb_context *tdb, tdb_off_t len, bool probe)
339 if (len <= tdb->map_size) {
342 tdb->ecode = TDB_ERR_IO;
344 tdb_logerr(tdb, TDB_ERR_IO, TDB_DEBUG_FATAL,
345 "tdb_oob len %lld beyond transaction size %lld",
347 (long long)tdb->map_size);
353 transaction version of tdb_expand().
355 static int transaction_expand_file(struct tdb_context *tdb, tdb_off_t addition)
357 /* add a write to the transaction elements, so subsequent
358 reads see the zero data */
359 if (transaction_write(tdb, tdb->map_size, NULL, addition) != 0) {
362 tdb->map_size += addition;
366 static void *transaction_direct(struct tdb_context *tdb, tdb_off_t off,
367 size_t len, bool write_mode)
369 size_t blk = off / getpagesize(), end_blk;
371 /* This is wrong for zero-length blocks, but will fail gracefully */
372 end_blk = (off + len - 1) / getpagesize();
374 /* Can only do direct if in single block and we've already copied. */
378 if (blk >= tdb->transaction->num_blocks)
380 if (tdb->transaction->blocks[blk] == NULL)
382 return tdb->transaction->blocks[blk] + off % getpagesize();
385 /* Single which we have copied? */
387 && blk < tdb->transaction->num_blocks
388 && tdb->transaction->blocks[blk])
389 return tdb->transaction->blocks[blk] + off % getpagesize();
391 /* Otherwise must be all not copied. */
392 while (blk < end_blk) {
393 if (blk >= tdb->transaction->num_blocks)
395 if (tdb->transaction->blocks[blk])
399 return tdb->transaction->io_methods->direct(tdb, off, len, false);
402 static const struct tdb_methods transaction_methods = {
406 transaction_expand_file,
413 static int transaction_sync(struct tdb_context *tdb, tdb_off_t offset, tdb_len_t length)
415 if (tdb->flags & TDB_NOSYNC) {
419 if (fsync(tdb->fd) != 0) {
420 tdb_logerr(tdb, TDB_ERR_IO, TDB_DEBUG_FATAL,
421 "tdb_transaction: fsync failed: %s",
427 tdb_off_t moffset = offset & ~(getpagesize()-1);
428 if (msync(moffset + (char *)tdb->map_ptr,
429 length + (offset - moffset), MS_SYNC) != 0) {
430 tdb_logerr(tdb, TDB_ERR_IO, TDB_DEBUG_FATAL,
431 "tdb_transaction: msync failed: %s",
441 static void _tdb_transaction_cancel(struct tdb_context *tdb)
445 if (tdb->transaction == NULL) {
446 tdb_logerr(tdb, TDB_ERR_EINVAL, TDB_DEBUG_ERROR,
447 "tdb_transaction_cancel: no transaction");
451 if (tdb->transaction->nesting != 0) {
452 tdb->transaction->transaction_error = 1;
453 tdb->transaction->nesting--;
457 tdb->map_size = tdb->transaction->old_map_size;
459 /* free all the transaction blocks */
460 for (i=0;i<tdb->transaction->num_blocks;i++) {
461 if (tdb->transaction->blocks[i] != NULL) {
462 free(tdb->transaction->blocks[i]);
465 SAFE_FREE(tdb->transaction->blocks);
467 if (tdb->transaction->magic_offset) {
468 const struct tdb_methods *methods = tdb->transaction->io_methods;
469 uint64_t invalid = TDB_RECOVERY_INVALID_MAGIC;
471 /* remove the recovery marker */
472 if (methods->twrite(tdb, tdb->transaction->magic_offset,
473 &invalid, sizeof(invalid)) == -1 ||
474 transaction_sync(tdb, tdb->transaction->magic_offset,
475 sizeof(invalid)) == -1) {
476 tdb_logerr(tdb, tdb->ecode, TDB_DEBUG_FATAL,
477 "tdb_transaction_cancel: failed to remove"
482 if (tdb->allrecord_lock.count)
483 tdb_allrecord_unlock(tdb, tdb->allrecord_lock.ltype);
485 /* restore the normal io methods */
486 tdb->methods = tdb->transaction->io_methods;
488 tdb_transaction_unlock(tdb, F_WRLCK);
490 if (tdb_has_open_lock(tdb))
491 tdb_unlock_open(tdb);
493 SAFE_FREE(tdb->transaction);
497 start a tdb transaction. No token is returned, as only a single
498 transaction is allowed to be pending per tdb_context
500 int tdb_transaction_start(struct tdb_context *tdb)
502 /* some sanity checks */
503 if (tdb->read_only || (tdb->flags & TDB_INTERNAL)) {
504 tdb_logerr(tdb, TDB_ERR_EINVAL, TDB_DEBUG_ERROR,
505 "tdb_transaction_start: cannot start a transaction"
506 " on a read-only or internal db");
510 /* cope with nested tdb_transaction_start() calls */
511 if (tdb->transaction != NULL) {
512 tdb_logerr(tdb, TDB_ERR_NESTING, TDB_DEBUG_ERROR,
513 "tdb_transaction_start:"
514 " already inside transaction");
518 if (tdb_has_hash_locks(tdb)) {
519 /* the caller must not have any locks when starting a
520 transaction as otherwise we'll be screwed by lack
521 of nested locks in posix */
522 tdb_logerr(tdb, TDB_ERR_LOCK, TDB_DEBUG_ERROR,
523 "tdb_transaction_start: cannot start a transaction"
528 tdb->transaction = (struct tdb_transaction *)
529 calloc(sizeof(struct tdb_transaction), 1);
530 if (tdb->transaction == NULL) {
531 tdb_logerr(tdb, TDB_ERR_OOM, TDB_DEBUG_ERROR,
532 "tdb_transaction_start: cannot allocate");
536 /* get the transaction write lock. This is a blocking lock. As
537 discussed with Volker, there are a number of ways we could
538 make this async, which we will probably do in the future */
539 if (tdb_transaction_lock(tdb, F_WRLCK) == -1) {
540 SAFE_FREE(tdb->transaction->blocks);
541 SAFE_FREE(tdb->transaction);
545 /* get a read lock over entire file. This is upgraded to a write
546 lock during the commit */
547 if (tdb_allrecord_lock(tdb, F_RDLCK, TDB_LOCK_WAIT, true) == -1) {
548 goto fail_allrecord_lock;
551 /* make sure we know about any file expansions already done by
553 tdb->methods->oob(tdb, tdb->map_size + 1, true);
554 tdb->transaction->old_map_size = tdb->map_size;
556 /* finally hook the io methods, replacing them with
557 transaction specific methods */
558 tdb->transaction->io_methods = tdb->methods;
559 tdb->methods = &transaction_methods;
563 tdb_transaction_unlock(tdb, F_WRLCK);
564 SAFE_FREE(tdb->transaction->blocks);
565 SAFE_FREE(tdb->transaction);
571 cancel the current transaction
573 void tdb_transaction_cancel(struct tdb_context *tdb)
575 _tdb_transaction_cancel(tdb);
579 work out how much space the linearised recovery data will consume
581 static tdb_len_t tdb_recovery_size(struct tdb_context *tdb)
583 tdb_len_t recovery_size = 0;
586 recovery_size = sizeof(tdb_len_t);
587 for (i=0;i<tdb->transaction->num_blocks;i++) {
588 if (i * getpagesize() >= tdb->transaction->old_map_size) {
591 if (tdb->transaction->blocks[i] == NULL) {
594 recovery_size += 2*sizeof(tdb_off_t);
595 if (i == tdb->transaction->num_blocks-1) {
596 recovery_size += tdb->transaction->last_block_size;
598 recovery_size += getpagesize();
602 return recovery_size;
606 allocate the recovery area, or use an existing recovery area if it is
609 static int tdb_recovery_allocate(struct tdb_context *tdb,
610 tdb_len_t *recovery_size,
611 tdb_off_t *recovery_offset,
612 tdb_len_t *recovery_max_size)
614 struct tdb_recovery_record rec;
615 const struct tdb_methods *methods = tdb->transaction->io_methods;
616 tdb_off_t recovery_head;
619 recovery_head = tdb_read_off(tdb, offsetof(struct tdb_header,recovery));
620 if (recovery_head == TDB_OFF_ERR) {
621 tdb_logerr(tdb, tdb->ecode, TDB_DEBUG_FATAL,
622 "tdb_recovery_allocate:"
623 " failed to read recovery head");
627 if (recovery_head != 0) {
628 if (methods->tread(tdb, recovery_head, &rec, sizeof(rec))) {
629 tdb_logerr(tdb, tdb->ecode, TDB_DEBUG_FATAL,
630 "tdb_recovery_allocate:"
631 " failed to read recovery record");
634 tdb_convert(tdb, &rec, sizeof(rec));
635 /* ignore invalid recovery regions: can happen in crash */
636 if (rec.magic != TDB_RECOVERY_MAGIC &&
637 rec.magic != TDB_RECOVERY_INVALID_MAGIC) {
642 *recovery_size = tdb_recovery_size(tdb);
644 if (recovery_head != 0 && *recovery_size <= rec.max_len) {
645 /* it fits in the existing area */
646 *recovery_max_size = rec.max_len;
647 *recovery_offset = recovery_head;
651 /* we need to free up the old recovery area, then allocate a
652 new one at the end of the file. Note that we cannot use
653 normal allocation to allocate the new one as that might return
654 us an area that is being currently used (as of the start of
656 if (recovery_head != 0) {
657 add_stat(tdb, frees, 1);
658 if (add_free_record(tdb, recovery_head,
659 sizeof(rec) + rec.max_len) != 0) {
660 tdb_logerr(tdb, tdb->ecode, TDB_DEBUG_FATAL,
661 "tdb_recovery_allocate:"
662 " failed to free previous recovery area");
667 /* the tdb_free() call might have increased the recovery size */
668 *recovery_size = tdb_recovery_size(tdb);
670 /* round up to a multiple of page size */
672 = (((sizeof(rec) + *recovery_size) + getpagesize()-1)
673 & ~(getpagesize()-1))
675 *recovery_offset = tdb->map_size;
676 recovery_head = *recovery_offset;
678 /* Restore ->map_size before calling underlying expand_file.
679 Also so that we don't try to expand the file again in the
680 transaction commit, which would destroy the recovery
682 addition = (tdb->map_size - tdb->transaction->old_map_size) +
683 sizeof(rec) + *recovery_max_size;
684 tdb->map_size = tdb->transaction->old_map_size;
685 if (methods->expand_file(tdb, addition) == -1) {
686 tdb_logerr(tdb, tdb->ecode, TDB_DEBUG_FATAL,
687 "tdb_recovery_allocate:"
688 " failed to create recovery area");
692 /* we have to reset the old map size so that we don't try to
693 expand the file again in the transaction commit, which
694 would destroy the recovery area */
695 tdb->transaction->old_map_size = tdb->map_size;
697 /* write the recovery header offset and sync - we can sync without a race here
698 as the magic ptr in the recovery record has not been set */
699 tdb_convert(tdb, &recovery_head, sizeof(recovery_head));
700 if (methods->twrite(tdb, offsetof(struct tdb_header, recovery),
701 &recovery_head, sizeof(tdb_off_t)) == -1) {
702 tdb_logerr(tdb, tdb->ecode, TDB_DEBUG_FATAL,
703 "tdb_recovery_allocate:"
704 " failed to write recovery head");
707 transaction_write_existing(tdb, offsetof(struct tdb_header, recovery),
713 /* Set up header for the recovery record. */
714 static void set_recovery_header(struct tdb_recovery_record *rec,
716 uint64_t datalen, uint64_t actuallen,
720 rec->max_len = actuallen;
726 setup the recovery data that will be used on a crash during commit
728 static int transaction_setup_recovery(struct tdb_context *tdb,
729 tdb_off_t *magic_offset)
731 tdb_len_t recovery_size;
732 unsigned char *data, *p;
733 const struct tdb_methods *methods = tdb->transaction->io_methods;
734 struct tdb_recovery_record *rec;
735 tdb_off_t recovery_offset, recovery_max_size;
736 tdb_off_t old_map_size = tdb->transaction->old_map_size;
737 uint64_t magic, tailer;
741 check that the recovery area has enough space
743 if (tdb_recovery_allocate(tdb, &recovery_size,
744 &recovery_offset, &recovery_max_size) == -1) {
748 data = (unsigned char *)malloc(recovery_size + sizeof(*rec));
750 tdb_logerr(tdb, TDB_ERR_OOM, TDB_DEBUG_FATAL,
751 "transaction_setup_recovery: cannot allocate");
755 rec = (struct tdb_recovery_record *)data;
756 set_recovery_header(rec, TDB_RECOVERY_INVALID_MAGIC,
757 recovery_size, recovery_max_size, old_map_size);
758 tdb_convert(tdb, rec, sizeof(*rec));
760 /* build the recovery data into a single blob to allow us to do a single
761 large write, which should be more efficient */
762 p = data + sizeof(*rec);
763 for (i=0;i<tdb->transaction->num_blocks;i++) {
767 if (tdb->transaction->blocks[i] == NULL) {
771 offset = i * getpagesize();
772 length = getpagesize();
773 if (i == tdb->transaction->num_blocks-1) {
774 length = tdb->transaction->last_block_size;
777 if (offset >= old_map_size) {
780 if (offset + length > tdb->map_size) {
781 tdb_logerr(tdb, TDB_ERR_CORRUPT, TDB_DEBUG_FATAL,
782 "tdb_transaction_setup_recovery:"
783 " transaction data over new region boundary");
787 memcpy(p, &offset, sizeof(offset));
788 memcpy(p + sizeof(offset), &length, sizeof(length));
789 tdb_convert(tdb, p, sizeof(offset) + sizeof(length));
791 /* the recovery area contains the old data, not the
792 new data, so we have to call the original tdb_read
794 if (methods->tread(tdb, offset,
795 p + sizeof(offset) + sizeof(length),
800 p += sizeof(offset) + sizeof(length) + length;
804 tailer = sizeof(*rec) + recovery_max_size;
805 memcpy(p, &tailer, sizeof(tailer));
806 tdb_convert(tdb, p, sizeof(tailer));
808 /* write the recovery data to the recovery area */
809 if (methods->twrite(tdb, recovery_offset, data,
810 sizeof(*rec) + recovery_size) == -1) {
811 tdb_logerr(tdb, tdb->ecode, TDB_DEBUG_FATAL,
812 "tdb_transaction_setup_recovery:"
813 " failed to write recovery data");
817 transaction_write_existing(tdb, recovery_offset, data,
818 sizeof(*rec) + recovery_size);
820 /* as we don't have ordered writes, we have to sync the recovery
821 data before we update the magic to indicate that the recovery
823 if (transaction_sync(tdb, recovery_offset,
824 sizeof(*rec) + recovery_size) == -1) {
831 magic = TDB_RECOVERY_MAGIC;
832 tdb_convert(tdb, &magic, sizeof(magic));
834 *magic_offset = recovery_offset + offsetof(struct tdb_recovery_record,
837 if (methods->twrite(tdb, *magic_offset, &magic, sizeof(magic)) == -1) {
838 tdb_logerr(tdb, tdb->ecode, TDB_DEBUG_FATAL,
839 "tdb_transaction_setup_recovery:"
840 " failed to write recovery magic");
843 transaction_write_existing(tdb, *magic_offset, &magic, sizeof(magic));
845 /* ensure the recovery magic marker is on disk */
846 if (transaction_sync(tdb, *magic_offset, sizeof(magic)) == -1) {
853 static int _tdb_transaction_prepare_commit(struct tdb_context *tdb)
855 const struct tdb_methods *methods;
857 if (tdb->transaction == NULL) {
858 tdb_logerr(tdb, TDB_ERR_EINVAL, TDB_DEBUG_ERROR,
859 "tdb_transaction_prepare_commit: no transaction");
863 if (tdb->transaction->prepared) {
864 _tdb_transaction_cancel(tdb);
865 tdb_logerr(tdb, TDB_ERR_EINVAL, TDB_DEBUG_ERROR,
866 "tdb_transaction_prepare_commit:"
867 " transaction already prepared");
871 if (tdb->transaction->transaction_error) {
872 _tdb_transaction_cancel(tdb);
873 tdb_logerr(tdb, TDB_ERR_EINVAL, TDB_DEBUG_ERROR,
874 "tdb_transaction_prepare_commit:"
875 " transaction error pending");
880 if (tdb->transaction->nesting != 0) {
881 tdb->transaction->nesting--;
885 /* check for a null transaction */
886 if (tdb->transaction->blocks == NULL) {
890 methods = tdb->transaction->io_methods;
892 /* upgrade the main transaction lock region to a write lock */
893 if (tdb_allrecord_upgrade(tdb) == -1) {
894 tdb_logerr(tdb, tdb->ecode, TDB_DEBUG_ERROR,
895 "tdb_transaction_prepare_commit:"
896 " failed to upgrade hash locks");
897 _tdb_transaction_cancel(tdb);
901 /* get the open lock - this prevents new users attaching to the database
903 if (tdb_lock_open(tdb, TDB_LOCK_WAIT|TDB_LOCK_NOCHECK) == -1) {
904 tdb_logerr(tdb, tdb->ecode, TDB_DEBUG_ERROR,
905 "tdb_transaction_prepare_commit:"
906 " failed to get open lock");
907 _tdb_transaction_cancel(tdb);
911 /* Since we have whole db locked, we don't need the expansion lock. */
912 if (!(tdb->flags & TDB_NOSYNC)) {
913 /* write the recovery data to the end of the file */
914 if (transaction_setup_recovery(tdb, &tdb->transaction->magic_offset) == -1) {
915 tdb_logerr(tdb, tdb->ecode, TDB_DEBUG_FATAL,
916 "tdb_transaction_prepare_commit:"
917 " failed to setup recovery data");
918 _tdb_transaction_cancel(tdb);
923 tdb->transaction->prepared = true;
925 /* expand the file to the new size if needed */
926 if (tdb->map_size != tdb->transaction->old_map_size) {
927 tdb_len_t add = tdb->map_size - tdb->transaction->old_map_size;
928 /* Restore original map size for tdb_expand_file */
929 tdb->map_size = tdb->transaction->old_map_size;
930 if (methods->expand_file(tdb, add) == -1) {
931 tdb_logerr(tdb, tdb->ecode, TDB_DEBUG_ERROR,
932 "tdb_transaction_prepare_commit:"
933 " expansion failed");
934 _tdb_transaction_cancel(tdb);
939 /* Keep the open lock until the actual commit */
945 prepare to commit the current transaction
947 int tdb_transaction_prepare_commit(struct tdb_context *tdb)
949 return _tdb_transaction_prepare_commit(tdb);
953 commit the current transaction
955 int tdb_transaction_commit(struct tdb_context *tdb)
957 const struct tdb_methods *methods;
960 if (tdb->transaction == NULL) {
961 tdb_logerr(tdb, TDB_ERR_EINVAL, TDB_DEBUG_ERROR,
962 "tdb_transaction_commit: no transaction");
966 tdb_trace(tdb, "tdb_transaction_commit");
968 if (tdb->transaction->transaction_error) {
969 tdb_transaction_cancel(tdb);
970 tdb_logerr(tdb, TDB_ERR_IO, TDB_DEBUG_ERROR,
971 "tdb_transaction_commit:"
972 " transaction error pending");
977 if (tdb->transaction->nesting != 0) {
978 tdb->transaction->nesting--;
982 /* check for a null transaction */
983 if (tdb->transaction->blocks == NULL) {
984 _tdb_transaction_cancel(tdb);
988 if (!tdb->transaction->prepared) {
989 int ret = _tdb_transaction_prepare_commit(tdb);
994 methods = tdb->transaction->io_methods;
996 /* perform all the writes */
997 for (i=0;i<tdb->transaction->num_blocks;i++) {
1001 if (tdb->transaction->blocks[i] == NULL) {
1005 offset = i * getpagesize();
1006 length = getpagesize();
1007 if (i == tdb->transaction->num_blocks-1) {
1008 length = tdb->transaction->last_block_size;
1011 if (methods->twrite(tdb, offset, tdb->transaction->blocks[i],
1013 tdb_logerr(tdb, tdb->ecode, TDB_DEBUG_FATAL,
1014 "tdb_transaction_commit:"
1015 " write failed during commit");
1017 /* we've overwritten part of the data and
1018 possibly expanded the file, so we need to
1019 run the crash recovery code */
1020 tdb->methods = methods;
1021 tdb_transaction_recover(tdb);
1023 _tdb_transaction_cancel(tdb);
1027 SAFE_FREE(tdb->transaction->blocks[i]);
1030 SAFE_FREE(tdb->transaction->blocks);
1031 tdb->transaction->num_blocks = 0;
1033 /* ensure the new data is on disk */
1034 if (transaction_sync(tdb, 0, tdb->map_size) == -1) {
1039 TODO: maybe write to some dummy hdr field, or write to magic
1040 offset without mmap, before the last sync, instead of the
1044 /* on some systems (like Linux 2.6.x) changes via mmap/msync
1045 don't change the mtime of the file, this means the file may
1046 not be backed up (as tdb rounding to block sizes means that
1047 file size changes are quite rare too). The following forces
1048 mtime changes when a transaction completes */
1050 utime(tdb->name, NULL);
1053 /* use a transaction cancel to free memory and remove the
1054 transaction locks */
1055 _tdb_transaction_cancel(tdb);
1062 recover from an aborted transaction. Must be called with exclusive
1063 database write access already established (including the open
1064 lock to prevent new processes attaching)
1066 int tdb_transaction_recover(struct tdb_context *tdb)
1068 tdb_off_t recovery_head, recovery_eof;
1069 unsigned char *data, *p;
1070 struct tdb_recovery_record rec;
1072 /* find the recovery area */
1073 recovery_head = tdb_read_off(tdb, offsetof(struct tdb_header,recovery));
1074 if (recovery_head == TDB_OFF_ERR) {
1075 tdb_logerr(tdb, tdb->ecode, TDB_DEBUG_FATAL,
1076 "tdb_transaction_recover:"
1077 " failed to read recovery head");
1081 if (recovery_head == 0) {
1082 /* we have never allocated a recovery record */
1086 /* read the recovery record */
1087 if (tdb_read_convert(tdb, recovery_head, &rec, sizeof(rec)) == -1) {
1088 tdb_logerr(tdb, tdb->ecode, TDB_DEBUG_FATAL,
1089 "tdb_transaction_recover:"
1090 " failed to read recovery record");
1094 if (rec.magic != TDB_RECOVERY_MAGIC) {
1095 /* there is no valid recovery data */
1099 if (tdb->read_only) {
1100 tdb_logerr(tdb, TDB_ERR_CORRUPT, TDB_DEBUG_FATAL,
1101 "tdb_transaction_recover:"
1102 " attempt to recover read only database");
1106 recovery_eof = rec.eof;
1108 data = (unsigned char *)malloc(rec.len);
1110 tdb_logerr(tdb, TDB_ERR_OOM, TDB_DEBUG_FATAL,
1111 "tdb_transaction_recover:"
1112 " failed to allocate recovery data");
1116 /* read the full recovery data */
1117 if (tdb->methods->tread(tdb, recovery_head + sizeof(rec), data,
1119 tdb_logerr(tdb, tdb->ecode, TDB_DEBUG_FATAL,
1120 "tdb_transaction_recover:"
1121 " failed to read recovery data");
1125 /* recover the file data */
1127 while (p+sizeof(tdb_off_t)+sizeof(tdb_len_t) < data + rec.len) {
1130 tdb_convert(tdb, p, sizeof(ofs) + sizeof(len));
1131 memcpy(&ofs, p, sizeof(ofs));
1132 memcpy(&len, p + sizeof(ofs), sizeof(len));
1133 p += sizeof(ofs) + sizeof(len);
1135 if (tdb->methods->twrite(tdb, ofs, p, len) == -1) {
1137 tdb_logerr(tdb, tdb->ecode, TDB_DEBUG_FATAL,
1138 "tdb_transaction_recover:"
1139 " failed to recover %zu bytes at offset %zu",
1140 (size_t)len, (size_t)ofs);
1148 if (transaction_sync(tdb, 0, tdb->map_size) == -1) {
1149 tdb_logerr(tdb, tdb->ecode, TDB_DEBUG_FATAL,
1150 "tdb_transaction_recover: failed to sync recovery");
1154 /* if the recovery area is after the recovered eof then remove it */
1155 if (recovery_eof <= recovery_head) {
1156 if (tdb_write_off(tdb, offsetof(struct tdb_header,recovery), 0)
1158 tdb_logerr(tdb, tdb->ecode, TDB_DEBUG_FATAL,
1159 "tdb_transaction_recover:"
1160 " failed to remove recovery head");
1165 /* remove the recovery magic */
1166 if (tdb_write_off(tdb,
1168 + offsetof(struct tdb_recovery_record, magic),
1169 TDB_RECOVERY_INVALID_MAGIC) == -1) {
1170 tdb_logerr(tdb, tdb->ecode, TDB_DEBUG_FATAL,
1171 "tdb_transaction_recover:"
1172 " failed to remove recovery magic");
1176 if (transaction_sync(tdb, 0, recovery_eof) == -1) {
1177 tdb_logerr(tdb, tdb->ecode, TDB_DEBUG_FATAL,
1178 "tdb_transaction_recover: failed to sync2 recovery");
1182 tdb_logerr(tdb, TDB_SUCCESS, TDB_DEBUG_TRACE,
1183 "tdb_transaction_recover: recovered %zu byte database",
1184 (size_t)recovery_eof);
1190 /* Any I/O failures we say "needs recovery". */
1191 bool tdb_needs_recovery(struct tdb_context *tdb)
1193 tdb_off_t recovery_head;
1194 struct tdb_recovery_record rec;
1196 /* find the recovery area */
1197 recovery_head = tdb_read_off(tdb, offsetof(struct tdb_header,recovery));
1198 if (recovery_head == TDB_OFF_ERR) {
1202 if (recovery_head == 0) {
1203 /* we have never allocated a recovery record */
1207 /* read the recovery record */
1208 if (tdb_read_convert(tdb, recovery_head, &rec, sizeof(rec)) == -1) {
1212 return (rec.magic == TDB_RECOVERY_MAGIC);