+++ /dev/null
- /*
- Unix SMB/CIFS implementation.
-
- trivial database library
-
- Copyright (C) Andrew Tridgell 2005
-
- ** NOTE! The following LGPL license applies to the tdb
- ** library. This does NOT imply that all of Samba is released
- ** under the LGPL
-
- This library is free software; you can redistribute it and/or
- modify it under the terms of the GNU Lesser General Public
- License as published by the Free Software Foundation; either
- version 3 of the License, or (at your option) any later version.
-
- This library is distributed in the hope that it will be useful,
- but WITHOUT ANY WARRANTY; without even the implied warranty of
- MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
- Lesser General Public License for more details.
-
- You should have received a copy of the GNU Lesser General Public
- License along with this library; if not, see <http://www.gnu.org/licenses/>.
-*/
-
-#include "tdb_private.h"
-
-/*
- transaction design:
-
- - only allow a single transaction at a time per database. This makes
- using the transaction API simpler, as otherwise the caller would
- have to cope with temporary failures in transactions that conflict
- with other current transactions
-
- - keep the transaction recovery information in the same file as the
- database, using a special 'transaction recovery' record pointed at
- by the header. This removes the need for extra journal files as
- used by some other databases
-
- - dynamically allocated the transaction recover record, re-using it
- for subsequent transactions. If a larger record is needed then
- tdb_free() the old record to place it on the normal tdb freelist
- before allocating the new record
-
- - during transactions, keep a linked list of writes all that have
- been performed by intercepting all tdb_write() calls. The hooked
- transaction versions of tdb_read() and tdb_write() check this
- linked list and try to use the elements of the list in preference
- to the real database.
-
- - don't allow any locks to be held when a transaction starts,
- otherwise we can end up with deadlock (plus lack of lock nesting
- in posix locks would mean the lock is lost)
-
- - if the caller gains a lock during the transaction but doesn't
- release it then fail the commit
-
- - allow for nested calls to tdb_transaction_start(), re-using the
- existing transaction record. If the inner transaction is cancelled
- then a subsequent commit will fail
-
- - keep a mirrored copy of the tdb hash chain heads to allow for the
- fast hash heads scan on traverse, updating the mirrored copy in
- the transaction version of tdb_write
-
- - allow callers to mix transaction and non-transaction use of tdb,
- although once a transaction is started then an exclusive lock is
- gained until the transaction is committed or cancelled
-
- - the commit stategy involves first saving away all modified data
- into a linearised buffer in the transaction recovery area, then
- marking the transaction recovery area with a magic value to
- indicate a valid recovery record. In total 4 fsync/msync calls are
- needed per commit to prevent race conditions. It might be possible
- to reduce this to 3 or even 2 with some more work.
-
- - check for a valid recovery record on open of the tdb, while the
- open lock is held. Automatically recover from the transaction
- recovery area if needed, then continue with the open as
- usual. This allows for smooth crash recovery with no administrator
- intervention.
-
- - if TDB_NOSYNC is passed to flags in tdb_open then transactions are
- still available, but no transaction recovery area is used and no
- fsync/msync calls are made.
-
- - if TDB_ALLOW_NESTING is passed to flags in tdb open, or added using
- tdb_add_flags() transaction nesting is enabled.
- It resets the TDB_DISALLOW_NESTING flag, as both cannot be used together.
- The default is that transaction nesting is allowed.
- Note: this default may change in future versions of tdb.
-
- Beware. when transactions are nested a transaction successfully
- completed with tdb_transaction_commit() can be silently unrolled later.
-
- - if TDB_DISALLOW_NESTING is passed to flags in tdb open, or added using
- tdb_add_flags() transaction nesting is disabled.
- It resets the TDB_ALLOW_NESTING flag, as both cannot be used together.
- An attempt create a nested transaction will fail with TDB_ERR_NESTING.
- The default is that transaction nesting is allowed.
- Note: this default may change in future versions of tdb.
-*/
-
-
-/*
- hold the context of any current transaction
-*/
-struct tdb_transaction {
- /* we keep a mirrored copy of the tdb hash heads here so
- tdb_next_hash_chain() can operate efficiently */
- uint32_t *hash_heads;
-
- /* the original io methods - used to do IOs to the real db */
- const struct tdb_methods *io_methods;
-
- /* the list of transaction blocks. When a block is first
- written to, it gets created in this list */
- uint8_t **blocks;
- uint32_t num_blocks;
- uint32_t block_size; /* bytes in each block */
- uint32_t last_block_size; /* number of valid bytes in the last block */
-
- /* non-zero when an internal transaction error has
- occurred. All write operations will then fail until the
- transaction is ended */
- int transaction_error;
-
- /* when inside a transaction we need to keep track of any
- nested tdb_transaction_start() calls, as these are allowed,
- but don't create a new transaction */
- int nesting;
-
- /* set when a prepare has already occurred */
- bool prepared;
- tdb_off_t magic_offset;
-
- /* old file size before transaction */
- tdb_len_t old_map_size;
-
- /* we should re-pack on commit */
- bool need_repack;
-};
-
-
-/*
- read while in a transaction. We need to check first if the data is in our list
- of transaction elements, then if not do a real read
-*/
-static int transaction_read(struct tdb_context *tdb, tdb_off_t off, void *buf,
- tdb_len_t len, int cv)
-{
- uint32_t blk;
-
- /* break it down into block sized ops */
- while (len + (off % tdb->transaction->block_size) > tdb->transaction->block_size) {
- tdb_len_t len2 = tdb->transaction->block_size - (off % tdb->transaction->block_size);
- if (transaction_read(tdb, off, buf, len2, cv) != 0) {
- return -1;
- }
- len -= len2;
- off += len2;
- buf = (void *)(len2 + (char *)buf);
- }
-
- if (len == 0) {
- return 0;
- }
-
- blk = off / tdb->transaction->block_size;
-
- /* see if we have it in the block list */
- if (tdb->transaction->num_blocks <= blk ||
- tdb->transaction->blocks[blk] == NULL) {
- /* nope, do a real read */
- if (tdb->transaction->io_methods->tdb_read(tdb, off, buf, len, cv) != 0) {
- goto fail;
- }
- return 0;
- }
-
- /* it is in the block list. Now check for the last block */
- if (blk == tdb->transaction->num_blocks-1) {
- if (len > tdb->transaction->last_block_size) {
- goto fail;
- }
- }
-
- /* now copy it out of this block */
- memcpy(buf, tdb->transaction->blocks[blk] + (off % tdb->transaction->block_size), len);
- if (cv) {
- tdb_convert(buf, len);
- }
- return 0;
-
-fail:
- TDB_LOG((tdb, TDB_DEBUG_FATAL, "transaction_read: failed at off=%d len=%d\n", off, len));
- tdb->ecode = TDB_ERR_IO;
- tdb->transaction->transaction_error = 1;
- return -1;
-}
-
-
-/*
- write while in a transaction
-*/
-static int transaction_write(struct tdb_context *tdb, tdb_off_t off,
- const void *buf, tdb_len_t len)
-{
- uint32_t blk;
-
- /* Only a commit is allowed on a prepared transaction */
- if (tdb->transaction->prepared) {
- tdb->ecode = TDB_ERR_EINVAL;
- TDB_LOG((tdb, TDB_DEBUG_FATAL, "transaction_write: transaction already prepared, write not allowed\n"));
- tdb->transaction->transaction_error = 1;
- return -1;
- }
-
- /* if the write is to a hash head, then update the transaction
- hash heads */
- if (len == sizeof(tdb_off_t) && off >= FREELIST_TOP &&
- off < FREELIST_TOP+TDB_HASHTABLE_SIZE(tdb)) {
- uint32_t chain = (off-FREELIST_TOP) / sizeof(tdb_off_t);
- memcpy(&tdb->transaction->hash_heads[chain], buf, len);
- }
-
- /* break it up into block sized chunks */
- while (len + (off % tdb->transaction->block_size) > tdb->transaction->block_size) {
- tdb_len_t len2 = tdb->transaction->block_size - (off % tdb->transaction->block_size);
- if (transaction_write(tdb, off, buf, len2) != 0) {
- return -1;
- }
- len -= len2;
- off += len2;
- if (buf != NULL) {
- buf = (const void *)(len2 + (const char *)buf);
- }
- }
-
- if (len == 0) {
- return 0;
- }
-
- blk = off / tdb->transaction->block_size;
- off = off % tdb->transaction->block_size;
-
- if (tdb->transaction->num_blocks <= blk) {
- uint8_t **new_blocks;
- /* expand the blocks array */
- if (tdb->transaction->blocks == NULL) {
- new_blocks = (uint8_t **)malloc(
- (blk+1)*sizeof(uint8_t *));
- } else {
- new_blocks = (uint8_t **)realloc(
- tdb->transaction->blocks,
- (blk+1)*sizeof(uint8_t *));
- }
- if (new_blocks == NULL) {
- tdb->ecode = TDB_ERR_OOM;
- goto fail;
- }
- memset(&new_blocks[tdb->transaction->num_blocks], 0,
- (1+(blk - tdb->transaction->num_blocks))*sizeof(uint8_t *));
- tdb->transaction->blocks = new_blocks;
- tdb->transaction->num_blocks = blk+1;
- tdb->transaction->last_block_size = 0;
- }
-
- /* allocate and fill a block? */
- if (tdb->transaction->blocks[blk] == NULL) {
- tdb->transaction->blocks[blk] = (uint8_t *)calloc(tdb->transaction->block_size, 1);
- if (tdb->transaction->blocks[blk] == NULL) {
- tdb->ecode = TDB_ERR_OOM;
- tdb->transaction->transaction_error = 1;
- return -1;
- }
- if (tdb->transaction->old_map_size > blk * tdb->transaction->block_size) {
- tdb_len_t len2 = tdb->transaction->block_size;
- if (len2 + (blk * tdb->transaction->block_size) > tdb->transaction->old_map_size) {
- len2 = tdb->transaction->old_map_size - (blk * tdb->transaction->block_size);
- }
- if (tdb->transaction->io_methods->tdb_read(tdb, blk * tdb->transaction->block_size,
- tdb->transaction->blocks[blk],
- len2, 0) != 0) {
- SAFE_FREE(tdb->transaction->blocks[blk]);
- tdb->ecode = TDB_ERR_IO;
- goto fail;
- }
- if (blk == tdb->transaction->num_blocks-1) {
- tdb->transaction->last_block_size = len2;
- }
- }
- }
-
- /* overwrite part of an existing block */
- if (buf == NULL) {
- memset(tdb->transaction->blocks[blk] + off, 0, len);
- } else {
- memcpy(tdb->transaction->blocks[blk] + off, buf, len);
- }
- if (blk == tdb->transaction->num_blocks-1) {
- if (len + off > tdb->transaction->last_block_size) {
- tdb->transaction->last_block_size = len + off;
- }
- }
-
- return 0;
-
-fail:
- TDB_LOG((tdb, TDB_DEBUG_FATAL, "transaction_write: failed at off=%d len=%d\n",
- (blk*tdb->transaction->block_size) + off, len));
- tdb->transaction->transaction_error = 1;
- return -1;
-}
-
-
-/*
- write while in a transaction - this varient never expands the transaction blocks, it only
- updates existing blocks. This means it cannot change the recovery size
-*/
-static int transaction_write_existing(struct tdb_context *tdb, tdb_off_t off,
- const void *buf, tdb_len_t len)
-{
- uint32_t blk;
-
- /* break it up into block sized chunks */
- while (len + (off % tdb->transaction->block_size) > tdb->transaction->block_size) {
- tdb_len_t len2 = tdb->transaction->block_size - (off % tdb->transaction->block_size);
- if (transaction_write_existing(tdb, off, buf, len2) != 0) {
- return -1;
- }
- len -= len2;
- off += len2;
- if (buf != NULL) {
- buf = (const void *)(len2 + (const char *)buf);
- }
- }
-
- if (len == 0) {
- return 0;
- }
-
- blk = off / tdb->transaction->block_size;
- off = off % tdb->transaction->block_size;
-
- if (tdb->transaction->num_blocks <= blk ||
- tdb->transaction->blocks[blk] == NULL) {
- return 0;
- }
-
- if (blk == tdb->transaction->num_blocks-1 &&
- off + len > tdb->transaction->last_block_size) {
- if (off >= tdb->transaction->last_block_size) {
- return 0;
- }
- len = tdb->transaction->last_block_size - off;
- }
-
- /* overwrite part of an existing block */
- memcpy(tdb->transaction->blocks[blk] + off, buf, len);
-
- return 0;
-}
-
-
-/*
- accelerated hash chain head search, using the cached hash heads
-*/
-static void transaction_next_hash_chain(struct tdb_context *tdb, uint32_t *chain)
-{
- uint32_t h = *chain;
- for (;h < tdb->header.hash_size;h++) {
- /* the +1 takes account of the freelist */
- if (0 != tdb->transaction->hash_heads[h+1]) {
- break;
- }
- }
- (*chain) = h;
-}
-
-/*
- out of bounds check during a transaction
-*/
-static int transaction_oob(struct tdb_context *tdb, tdb_off_t len, int probe)
-{
- if (len <= tdb->map_size) {
- return 0;
- }
- tdb->ecode = TDB_ERR_IO;
- return -1;
-}
-
-/*
- transaction version of tdb_expand().
-*/
-static int transaction_expand_file(struct tdb_context *tdb, tdb_off_t size,
- tdb_off_t addition)
-{
- /* add a write to the transaction elements, so subsequent
- reads see the zero data */
- if (transaction_write(tdb, size, NULL, addition) != 0) {
- return -1;
- }
-
- tdb->transaction->need_repack = true;
-
- return 0;
-}
-
-static const struct tdb_methods transaction_methods = {
- transaction_read,
- transaction_write,
- transaction_next_hash_chain,
- transaction_oob,
- transaction_expand_file,
-};
-
-/*
- sync to disk
-*/
-static int transaction_sync(struct tdb_context *tdb, tdb_off_t offset, tdb_len_t length)
-{
- if (tdb->flags & TDB_NOSYNC) {
- return 0;
- }
-
- if (fsync(tdb->fd) != 0) {
- tdb->ecode = TDB_ERR_IO;
- TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_transaction: fsync failed\n"));
- return -1;
- }
-#ifdef MS_SYNC
- if (tdb->map_ptr) {
- tdb_off_t moffset = offset & ~(tdb->page_size-1);
- if (msync(moffset + (char *)tdb->map_ptr,
- length + (offset - moffset), MS_SYNC) != 0) {
- tdb->ecode = TDB_ERR_IO;
- TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_transaction: msync failed - %s\n",
- strerror(errno)));
- return -1;
- }
- }
-#endif
- return 0;
-}
-
-
-static int _tdb_transaction_cancel(struct tdb_context *tdb)
-{
- int i, ret = 0;
-
- if (tdb->transaction == NULL) {
- TDB_LOG((tdb, TDB_DEBUG_ERROR, "tdb_transaction_cancel: no transaction\n"));
- return -1;
- }
-
- if (tdb->transaction->nesting != 0) {
- tdb->transaction->transaction_error = 1;
- tdb->transaction->nesting--;
- return 0;
- }
-
- tdb->map_size = tdb->transaction->old_map_size;
-
- /* free all the transaction blocks */
- for (i=0;i<tdb->transaction->num_blocks;i++) {
- if (tdb->transaction->blocks[i] != NULL) {
- free(tdb->transaction->blocks[i]);
- }
- }
- SAFE_FREE(tdb->transaction->blocks);
-
- if (tdb->transaction->magic_offset) {
- const struct tdb_methods *methods = tdb->transaction->io_methods;
- uint32_t invalid = TDB_RECOVERY_INVALID_MAGIC;
-
- /* remove the recovery marker */
- if (methods->tdb_write(tdb, tdb->transaction->magic_offset, &invalid, 4) == -1 ||
- transaction_sync(tdb, tdb->transaction->magic_offset, 4) == -1) {
- TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_transaction_cancel: failed to remove recovery magic\n"));
- ret = -1;
- }
- }
-
- /* This also removes the OPEN_LOCK, if we have it. */
- tdb_release_extra_locks(tdb);
-
- /* restore the normal io methods */
- tdb->methods = tdb->transaction->io_methods;
-
- tdb_transaction_unlock(tdb, F_WRLCK);
- SAFE_FREE(tdb->transaction->hash_heads);
- SAFE_FREE(tdb->transaction);
-
- return ret;
-}
-
-/*
- start a tdb transaction. No token is returned, as only a single
- transaction is allowed to be pending per tdb_context
-*/
-int tdb_transaction_start(struct tdb_context *tdb)
-{
- /* some sanity checks */
- if (tdb->read_only || (tdb->flags & TDB_INTERNAL) || tdb->traverse_read) {
- TDB_LOG((tdb, TDB_DEBUG_ERROR, "tdb_transaction_start: cannot start a transaction on a read-only or internal db\n"));
- tdb->ecode = TDB_ERR_EINVAL;
- return -1;
- }
-
- /* cope with nested tdb_transaction_start() calls */
- if (tdb->transaction != NULL) {
- if (!(tdb->flags & TDB_ALLOW_NESTING)) {
- tdb->ecode = TDB_ERR_NESTING;
- return -1;
- }
- tdb_trace(tdb, "tdb_transaction_start");
- tdb->transaction->nesting++;
- TDB_LOG((tdb, TDB_DEBUG_TRACE, "tdb_transaction_start: nesting %d\n",
- tdb->transaction->nesting));
- return 0;
- }
-
- if (tdb_have_extra_locks(tdb)) {
- /* the caller must not have any locks when starting a
- transaction as otherwise we'll be screwed by lack
- of nested locks in posix */
- TDB_LOG((tdb, TDB_DEBUG_ERROR, "tdb_transaction_start: cannot start a transaction with locks held\n"));
- tdb->ecode = TDB_ERR_LOCK;
- return -1;
- }
-
- if (tdb->travlocks.next != NULL) {
- /* you cannot use transactions inside a traverse (although you can use
- traverse inside a transaction) as otherwise you can end up with
- deadlock */
- TDB_LOG((tdb, TDB_DEBUG_ERROR, "tdb_transaction_start: cannot start a transaction within a traverse\n"));
- tdb->ecode = TDB_ERR_LOCK;
- return -1;
- }
-
- tdb->transaction = (struct tdb_transaction *)
- calloc(sizeof(struct tdb_transaction), 1);
- if (tdb->transaction == NULL) {
- tdb->ecode = TDB_ERR_OOM;
- return -1;
- }
-
- /* a page at a time seems like a reasonable compromise between compactness and efficiency */
- tdb->transaction->block_size = tdb->page_size;
-
- /* get the transaction write lock. This is a blocking lock. As
- discussed with Volker, there are a number of ways we could
- make this async, which we will probably do in the future */
- if (tdb_transaction_lock(tdb, F_WRLCK) == -1) {
- SAFE_FREE(tdb->transaction->blocks);
- SAFE_FREE(tdb->transaction);
- return -1;
- }
-
- /* get a read lock from the freelist to the end of file. This
- is upgraded to a write lock during the commit */
- if (tdb_allrecord_lock(tdb, F_RDLCK, TDB_LOCK_WAIT, true) == -1) {
- TDB_LOG((tdb, TDB_DEBUG_ERROR, "tdb_transaction_start: failed to get hash locks\n"));
- goto fail_allrecord_lock;
- }
-
- /* setup a copy of the hash table heads so the hash scan in
- traverse can be fast */
- tdb->transaction->hash_heads = (uint32_t *)
- calloc(tdb->header.hash_size+1, sizeof(uint32_t));
- if (tdb->transaction->hash_heads == NULL) {
- tdb->ecode = TDB_ERR_OOM;
- goto fail;
- }
- if (tdb->methods->tdb_read(tdb, FREELIST_TOP, tdb->transaction->hash_heads,
- TDB_HASHTABLE_SIZE(tdb), 0) != 0) {
- TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_transaction_start: failed to read hash heads\n"));
- tdb->ecode = TDB_ERR_IO;
- goto fail;
- }
-
- /* make sure we know about any file expansions already done by
- anyone else */
- tdb->methods->tdb_oob(tdb, tdb->map_size + 1, 1);
- tdb->transaction->old_map_size = tdb->map_size;
-
- /* finally hook the io methods, replacing them with
- transaction specific methods */
- tdb->transaction->io_methods = tdb->methods;
- tdb->methods = &transaction_methods;
-
- /* Trace at the end, so we get sequence number correct. */
- tdb_trace(tdb, "tdb_transaction_start");
- return 0;
-
-fail:
- tdb_allrecord_unlock(tdb, F_RDLCK, false);
-fail_allrecord_lock:
- tdb_transaction_unlock(tdb, F_WRLCK);
- SAFE_FREE(tdb->transaction->blocks);
- SAFE_FREE(tdb->transaction->hash_heads);
- SAFE_FREE(tdb->transaction);
- return -1;
-}
-
-
-/*
- cancel the current transaction
-*/
-int tdb_transaction_cancel(struct tdb_context *tdb)
-{
- tdb_trace(tdb, "tdb_transaction_cancel");
- return _tdb_transaction_cancel(tdb);
-}
-
-/*
- work out how much space the linearised recovery data will consume
-*/
-static tdb_len_t tdb_recovery_size(struct tdb_context *tdb)
-{
- tdb_len_t recovery_size = 0;
- int i;
-
- recovery_size = sizeof(uint32_t);
- for (i=0;i<tdb->transaction->num_blocks;i++) {
- if (i * tdb->transaction->block_size >= tdb->transaction->old_map_size) {
- break;
- }
- if (tdb->transaction->blocks[i] == NULL) {
- continue;
- }
- recovery_size += 2*sizeof(tdb_off_t);
- if (i == tdb->transaction->num_blocks-1) {
- recovery_size += tdb->transaction->last_block_size;
- } else {
- recovery_size += tdb->transaction->block_size;
- }
- }
-
- return recovery_size;
-}
-
-/*
- allocate the recovery area, or use an existing recovery area if it is
- large enough
-*/
-static int tdb_recovery_allocate(struct tdb_context *tdb,
- tdb_len_t *recovery_size,
- tdb_off_t *recovery_offset,
- tdb_len_t *recovery_max_size)
-{
- struct tdb_record rec;
- const struct tdb_methods *methods = tdb->transaction->io_methods;
- tdb_off_t recovery_head, new_end;
-
- if (tdb_ofs_read(tdb, TDB_RECOVERY_HEAD, &recovery_head) == -1) {
- TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_recovery_allocate: failed to read recovery head\n"));
- return -1;
- }
-
- rec.rec_len = 0;
-
- if (recovery_head != 0) {
- if (methods->tdb_read(tdb, recovery_head, &rec, sizeof(rec), DOCONV()) == -1) {
- TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_recovery_allocate: failed to read recovery record\n"));
- return -1;
- }
- /* ignore invalid recovery regions: can happen in crash */
- if (rec.magic != TDB_RECOVERY_MAGIC &&
- rec.magic != TDB_RECOVERY_INVALID_MAGIC) {
- recovery_head = 0;
- }
- }
-
- *recovery_size = tdb_recovery_size(tdb);
-
- /* Existing recovery area? */
- if (recovery_head != 0 && *recovery_size <= rec.rec_len) {
- /* it fits in the existing area */
- *recovery_max_size = rec.rec_len;
- *recovery_offset = recovery_head;
- return 0;
- }
-
- /* If recovery area in middle of file, we need a new one. */
- if (recovery_head == 0
- || recovery_head + sizeof(rec) + rec.rec_len != tdb->map_size) {
- /* we need to free up the old recovery area, then allocate a
- new one at the end of the file. Note that we cannot use
- tdb_allocate() to allocate the new one as that might return
- us an area that is being currently used (as of the start of
- the transaction) */
- if (recovery_head) {
- if (tdb_free(tdb, recovery_head, &rec) == -1) {
- TDB_LOG((tdb, TDB_DEBUG_FATAL,
- "tdb_recovery_allocate: failed to"
- " free previous recovery area\n"));
- return -1;
- }
-
- /* the tdb_free() call might have increased
- * the recovery size */
- *recovery_size = tdb_recovery_size(tdb);
- }
-
- /* New head will be at end of file. */
- recovery_head = tdb->map_size;
- }
-
- /* Now we know where it will be. */
- *recovery_offset = recovery_head;
-
- /* Expand by more than we need, so we don't do it often. */
- *recovery_max_size = tdb_expand_adjust(tdb->map_size,
- *recovery_size,
- tdb->page_size)
- - sizeof(rec);
-
- new_end = recovery_head + sizeof(rec) + *recovery_max_size;
-
- if (methods->tdb_expand_file(tdb, tdb->transaction->old_map_size,
- new_end - tdb->transaction->old_map_size)
- == -1) {
- TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_recovery_allocate: failed to create recovery area\n"));
- return -1;
- }
-
- /* remap the file (if using mmap) */
- methods->tdb_oob(tdb, tdb->map_size + 1, 1);
-
- /* we have to reset the old map size so that we don't try to expand the file
- again in the transaction commit, which would destroy the recovery area */
- tdb->transaction->old_map_size = tdb->map_size;
-
- /* write the recovery header offset and sync - we can sync without a race here
- as the magic ptr in the recovery record has not been set */
- CONVERT(recovery_head);
- if (methods->tdb_write(tdb, TDB_RECOVERY_HEAD,
- &recovery_head, sizeof(tdb_off_t)) == -1) {
- TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_recovery_allocate: failed to write recovery head\n"));
- return -1;
- }
- if (transaction_write_existing(tdb, TDB_RECOVERY_HEAD, &recovery_head, sizeof(tdb_off_t)) == -1) {
- TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_recovery_allocate: failed to write recovery head\n"));
- return -1;
- }
-
- return 0;
-}
-
-
-/*
- setup the recovery data that will be used on a crash during commit
-*/
-static int transaction_setup_recovery(struct tdb_context *tdb,
- tdb_off_t *magic_offset)
-{
- tdb_len_t recovery_size;
- unsigned char *data, *p;
- const struct tdb_methods *methods = tdb->transaction->io_methods;
- struct tdb_record *rec;
- tdb_off_t recovery_offset, recovery_max_size;
- tdb_off_t old_map_size = tdb->transaction->old_map_size;
- uint32_t magic, tailer;
- int i;
-
- /*
- check that the recovery area has enough space
- */
- if (tdb_recovery_allocate(tdb, &recovery_size,
- &recovery_offset, &recovery_max_size) == -1) {
- return -1;
- }
-
- data = (unsigned char *)malloc(recovery_size + sizeof(*rec));
- if (data == NULL) {
- tdb->ecode = TDB_ERR_OOM;
- return -1;
- }
-
- rec = (struct tdb_record *)data;
- memset(rec, 0, sizeof(*rec));
-
- rec->magic = TDB_RECOVERY_INVALID_MAGIC;
- rec->data_len = recovery_size;
- rec->rec_len = recovery_max_size;
- rec->key_len = old_map_size;
- CONVERT(rec);
-
- /* build the recovery data into a single blob to allow us to do a single
- large write, which should be more efficient */
- p = data + sizeof(*rec);
- for (i=0;i<tdb->transaction->num_blocks;i++) {
- tdb_off_t offset;
- tdb_len_t length;
-
- if (tdb->transaction->blocks[i] == NULL) {
- continue;
- }
-
- offset = i * tdb->transaction->block_size;
- length = tdb->transaction->block_size;
- if (i == tdb->transaction->num_blocks-1) {
- length = tdb->transaction->last_block_size;
- }
-
- if (offset >= old_map_size) {
- continue;
- }
- if (offset + length > tdb->transaction->old_map_size) {
- TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_transaction_setup_recovery: transaction data over new region boundary\n"));
- free(data);
- tdb->ecode = TDB_ERR_CORRUPT;
- return -1;
- }
- memcpy(p, &offset, 4);
- memcpy(p+4, &length, 4);
- if (DOCONV()) {
- tdb_convert(p, 8);
- }
- /* the recovery area contains the old data, not the
- new data, so we have to call the original tdb_read
- method to get it */
- if (methods->tdb_read(tdb, offset, p + 8, length, 0) != 0) {
- free(data);
- tdb->ecode = TDB_ERR_IO;
- return -1;
- }
- p += 8 + length;
- }
-
- /* and the tailer */
- tailer = sizeof(*rec) + recovery_max_size;
- memcpy(p, &tailer, 4);
- CONVERT(p);
-
- /* write the recovery data to the recovery area */
- if (methods->tdb_write(tdb, recovery_offset, data, sizeof(*rec) + recovery_size) == -1) {
- TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_transaction_setup_recovery: failed to write recovery data\n"));
- free(data);
- tdb->ecode = TDB_ERR_IO;
- return -1;
- }
- if (transaction_write_existing(tdb, recovery_offset, data, sizeof(*rec) + recovery_size) == -1) {
- TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_transaction_setup_recovery: failed to write secondary recovery data\n"));
- free(data);
- tdb->ecode = TDB_ERR_IO;
- return -1;
- }
-
- /* as we don't have ordered writes, we have to sync the recovery
- data before we update the magic to indicate that the recovery
- data is present */
- if (transaction_sync(tdb, recovery_offset, sizeof(*rec) + recovery_size) == -1) {
- free(data);
- return -1;
- }
-
- free(data);
-
- magic = TDB_RECOVERY_MAGIC;
- CONVERT(magic);
-
- *magic_offset = recovery_offset + offsetof(struct tdb_record, magic);
-
- if (methods->tdb_write(tdb, *magic_offset, &magic, sizeof(magic)) == -1) {
- TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_transaction_setup_recovery: failed to write recovery magic\n"));
- tdb->ecode = TDB_ERR_IO;
- return -1;
- }
- if (transaction_write_existing(tdb, *magic_offset, &magic, sizeof(magic)) == -1) {
- TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_transaction_setup_recovery: failed to write secondary recovery magic\n"));
- tdb->ecode = TDB_ERR_IO;
- return -1;
- }
-
- /* ensure the recovery magic marker is on disk */
- if (transaction_sync(tdb, *magic_offset, sizeof(magic)) == -1) {
- return -1;
- }
-
- return 0;
-}
-
-static int _tdb_transaction_prepare_commit(struct tdb_context *tdb)
-{
- const struct tdb_methods *methods;
-
- if (tdb->transaction == NULL) {
- TDB_LOG((tdb, TDB_DEBUG_ERROR, "tdb_transaction_prepare_commit: no transaction\n"));
- return -1;
- }
-
- if (tdb->transaction->prepared) {
- tdb->ecode = TDB_ERR_EINVAL;
- _tdb_transaction_cancel(tdb);
- TDB_LOG((tdb, TDB_DEBUG_ERROR, "tdb_transaction_prepare_commit: transaction already prepared\n"));
- return -1;
- }
-
- if (tdb->transaction->transaction_error) {
- tdb->ecode = TDB_ERR_IO;
- _tdb_transaction_cancel(tdb);
- TDB_LOG((tdb, TDB_DEBUG_ERROR, "tdb_transaction_prepare_commit: transaction error pending\n"));
- return -1;
- }
-
-
- if (tdb->transaction->nesting != 0) {
- tdb->transaction->nesting--;
- return 0;
- }
-
- /* check for a null transaction */
- if (tdb->transaction->blocks == NULL) {
- return 0;
- }
-
- methods = tdb->transaction->io_methods;
-
- /* if there are any locks pending then the caller has not
- nested their locks properly, so fail the transaction */
- if (tdb_have_extra_locks(tdb)) {
- tdb->ecode = TDB_ERR_LOCK;
- TDB_LOG((tdb, TDB_DEBUG_ERROR, "tdb_transaction_prepare_commit: locks pending on commit\n"));
- _tdb_transaction_cancel(tdb);
- return -1;
- }
-
- /* upgrade the main transaction lock region to a write lock */
- if (tdb_allrecord_upgrade(tdb) == -1) {
- TDB_LOG((tdb, TDB_DEBUG_ERROR, "tdb_transaction_prepare_commit: failed to upgrade hash locks\n"));
- _tdb_transaction_cancel(tdb);
- return -1;
- }
-
- /* get the open lock - this prevents new users attaching to the database
- during the commit */
- if (tdb_nest_lock(tdb, OPEN_LOCK, F_WRLCK, TDB_LOCK_WAIT) == -1) {
- TDB_LOG((tdb, TDB_DEBUG_ERROR, "tdb_transaction_prepare_commit: failed to get open lock\n"));
- _tdb_transaction_cancel(tdb);
- return -1;
- }
-
- if (!(tdb->flags & TDB_NOSYNC)) {
- /* write the recovery data to the end of the file */
- if (transaction_setup_recovery(tdb, &tdb->transaction->magic_offset) == -1) {
- TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_transaction_prepare_commit: failed to setup recovery data\n"));
- _tdb_transaction_cancel(tdb);
- return -1;
- }
- }
-
- tdb->transaction->prepared = true;
-
- /* expand the file to the new size if needed */
- if (tdb->map_size != tdb->transaction->old_map_size) {
- if (methods->tdb_expand_file(tdb, tdb->transaction->old_map_size,
- tdb->map_size -
- tdb->transaction->old_map_size) == -1) {
- tdb->ecode = TDB_ERR_IO;
- TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_transaction_prepare_commit: expansion failed\n"));
- _tdb_transaction_cancel(tdb);
- return -1;
- }
- tdb->map_size = tdb->transaction->old_map_size;
- methods->tdb_oob(tdb, tdb->map_size + 1, 1);
- }
-
- /* Keep the open lock until the actual commit */
-
- return 0;
-}
-
-/*
- prepare to commit the current transaction
-*/
-int tdb_transaction_prepare_commit(struct tdb_context *tdb)
-{
- tdb_trace(tdb, "tdb_transaction_prepare_commit");
- return _tdb_transaction_prepare_commit(tdb);
-}
-
-/*
- commit the current transaction
-*/
-int tdb_transaction_commit(struct tdb_context *tdb)
-{
- const struct tdb_methods *methods;
- int i;
- bool need_repack;
-
- if (tdb->transaction == NULL) {
- TDB_LOG((tdb, TDB_DEBUG_ERROR, "tdb_transaction_commit: no transaction\n"));
- return -1;
- }
-
- tdb_trace(tdb, "tdb_transaction_commit");
-
- if (tdb->transaction->transaction_error) {
- tdb->ecode = TDB_ERR_IO;
- tdb_transaction_cancel(tdb);
- TDB_LOG((tdb, TDB_DEBUG_ERROR, "tdb_transaction_commit: transaction error pending\n"));
- return -1;
- }
-
-
- if (tdb->transaction->nesting != 0) {
- tdb->transaction->nesting--;
- return 0;
- }
-
- /* check for a null transaction */
- if (tdb->transaction->blocks == NULL) {
- _tdb_transaction_cancel(tdb);
- return 0;
- }
-
- if (!tdb->transaction->prepared) {
- int ret = _tdb_transaction_prepare_commit(tdb);
- if (ret)
- return ret;
- }
-
- methods = tdb->transaction->io_methods;
-
- /* perform all the writes */
- for (i=0;i<tdb->transaction->num_blocks;i++) {
- tdb_off_t offset;
- tdb_len_t length;
-
- if (tdb->transaction->blocks[i] == NULL) {
- continue;
- }
-
- offset = i * tdb->transaction->block_size;
- length = tdb->transaction->block_size;
- if (i == tdb->transaction->num_blocks-1) {
- length = tdb->transaction->last_block_size;
- }
-
- if (methods->tdb_write(tdb, offset, tdb->transaction->blocks[i], length) == -1) {
- TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_transaction_commit: write failed during commit\n"));
-
- /* we've overwritten part of the data and
- possibly expanded the file, so we need to
- run the crash recovery code */
- tdb->methods = methods;
- tdb_transaction_recover(tdb);
-
- _tdb_transaction_cancel(tdb);
-
- TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_transaction_commit: write failed\n"));
- return -1;
- }
- SAFE_FREE(tdb->transaction->blocks[i]);
- }
-
- SAFE_FREE(tdb->transaction->blocks);
- tdb->transaction->num_blocks = 0;
-
- /* ensure the new data is on disk */
- if (transaction_sync(tdb, 0, tdb->map_size) == -1) {
- return -1;
- }
-
- /*
- TODO: maybe write to some dummy hdr field, or write to magic
- offset without mmap, before the last sync, instead of the
- utime() call
- */
-
- /* on some systems (like Linux 2.6.x) changes via mmap/msync
- don't change the mtime of the file, this means the file may
- not be backed up (as tdb rounding to block sizes means that
- file size changes are quite rare too). The following forces
- mtime changes when a transaction completes */
-#if HAVE_UTIME
- utime(tdb->name, NULL);
-#endif
-
- need_repack = tdb->transaction->need_repack;
-
- /* use a transaction cancel to free memory and remove the
- transaction locks */
- _tdb_transaction_cancel(tdb);
-
- if (need_repack) {
- return tdb_repack(tdb);
- }
-
- return 0;
-}
-
-
-/*
- recover from an aborted transaction. Must be called with exclusive
- database write access already established (including the open
- lock to prevent new processes attaching)
-*/
-int tdb_transaction_recover(struct tdb_context *tdb)
-{
- tdb_off_t recovery_head, recovery_eof;
- unsigned char *data, *p;
- uint32_t zero = 0;
- struct tdb_record rec;
-
- /* find the recovery area */
- if (tdb_ofs_read(tdb, TDB_RECOVERY_HEAD, &recovery_head) == -1) {
- TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_transaction_recover: failed to read recovery head\n"));
- tdb->ecode = TDB_ERR_IO;
- return -1;
- }
-
- if (recovery_head == 0) {
- /* we have never allocated a recovery record */
- return 0;
- }
-
- /* read the recovery record */
- if (tdb->methods->tdb_read(tdb, recovery_head, &rec,
- sizeof(rec), DOCONV()) == -1) {
- TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_transaction_recover: failed to read recovery record\n"));
- tdb->ecode = TDB_ERR_IO;
- return -1;
- }
-
- if (rec.magic != TDB_RECOVERY_MAGIC) {
- /* there is no valid recovery data */
- return 0;
- }
-
- if (tdb->read_only) {
- TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_transaction_recover: attempt to recover read only database\n"));
- tdb->ecode = TDB_ERR_CORRUPT;
- return -1;
- }
-
- recovery_eof = rec.key_len;
-
- data = (unsigned char *)malloc(rec.data_len);
- if (data == NULL) {
- TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_transaction_recover: failed to allocate recovery data\n"));
- tdb->ecode = TDB_ERR_OOM;
- return -1;
- }
-
- /* read the full recovery data */
- if (tdb->methods->tdb_read(tdb, recovery_head + sizeof(rec), data,
- rec.data_len, 0) == -1) {
- TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_transaction_recover: failed to read recovery data\n"));
- tdb->ecode = TDB_ERR_IO;
- return -1;
- }
-
- /* recover the file data */
- p = data;
- while (p+8 < data + rec.data_len) {
- uint32_t ofs, len;
- if (DOCONV()) {
- tdb_convert(p, 8);
- }
- memcpy(&ofs, p, 4);
- memcpy(&len, p+4, 4);
-
- if (tdb->methods->tdb_write(tdb, ofs, p+8, len) == -1) {
- free(data);
- TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_transaction_recover: failed to recover %d bytes at offset %d\n", len, ofs));
- tdb->ecode = TDB_ERR_IO;
- return -1;
- }
- p += 8 + len;
- }
-
- free(data);
-
- if (transaction_sync(tdb, 0, tdb->map_size) == -1) {
- TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_transaction_recover: failed to sync recovery\n"));
- tdb->ecode = TDB_ERR_IO;
- return -1;
- }
-
- /* if the recovery area is after the recovered eof then remove it */
- if (recovery_eof <= recovery_head) {
- if (tdb_ofs_write(tdb, TDB_RECOVERY_HEAD, &zero) == -1) {
- TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_transaction_recover: failed to remove recovery head\n"));
- tdb->ecode = TDB_ERR_IO;
- return -1;
- }
- }
-
- /* remove the recovery magic */
- if (tdb_ofs_write(tdb, recovery_head + offsetof(struct tdb_record, magic),
- &zero) == -1) {
- TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_transaction_recover: failed to remove recovery magic\n"));
- tdb->ecode = TDB_ERR_IO;
- return -1;
- }
-
- if (transaction_sync(tdb, 0, recovery_eof) == -1) {
- TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_transaction_recover: failed to sync2 recovery\n"));
- tdb->ecode = TDB_ERR_IO;
- return -1;
- }
-
- TDB_LOG((tdb, TDB_DEBUG_TRACE, "tdb_transaction_recover: recovered %d byte database\n",
- recovery_eof));
-
- /* all done */
- return 0;
-}
-
-/* Any I/O failures we say "needs recovery". */
-bool tdb_needs_recovery(struct tdb_context *tdb)
-{
- tdb_off_t recovery_head;
- struct tdb_record rec;
-
- /* find the recovery area */
- if (tdb_ofs_read(tdb, TDB_RECOVERY_HEAD, &recovery_head) == -1) {
- return true;
- }
-
- if (recovery_head == 0) {
- /* we have never allocated a recovery record */
- return false;
- }
-
- /* read the recovery record */
- if (tdb->methods->tdb_read(tdb, recovery_head, &rec,
- sizeof(rec), DOCONV()) == -1) {
- return true;
- }
-
- return (rec.magic == TDB_RECOVERY_MAGIC);
-}
projects / ccan / blobdiff