Merge branch 'singletdb' into single

1 files changed, 0 insertions, 1119 deletions

diff --git a/source3/lib/tdb/common/transaction.c b/source3/lib/tdb/common/transaction.c
deleted file mode 100644
index 7acda640c8..0000000000
--- a/source3/lib/tdb/common/transaction.c
+++ /dev/null
@@ -1,1119 +0,0 @@
- /* 
-   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
-    global 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.
-
-*/
-
-
-/*
-  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;
-
-	/* old file size before transaction */
-	tdb_len_t old_map_size;
-};
-
-
-/*
-  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;
-
-	/* 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;
-	}
-	return TDB_ERRCODE(TDB_ERR_IO, -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;
-	}
-
-	return 0;
-}
-
-/*
-  brlock during a transaction - ignore them
-*/
-static int transaction_brlock(struct tdb_context *tdb, tdb_off_t offset, 
-			      int rw_type, int lck_type, int probe, size_t len)
-{
-	return 0;
-}
-
-static const struct tdb_methods transaction_methods = {
-	transaction_read,
-	transaction_write,
-	transaction_next_hash_chain,
-	transaction_oob,
-	transaction_expand_file,
-	transaction_brlock
-};
-
-
-/*
-  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) {
-		tdb->transaction->nesting++;
-		TDB_LOG((tdb, TDB_DEBUG_TRACE, "tdb_transaction_start: nesting %d\n", 
-			 tdb->transaction->nesting));
-		return 0;
-	}
-
-	if (tdb->num_locks != 0 || tdb->global_lock.count) {
-		/* 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_brlock(tdb, FREELIST_TOP, F_RDLCK, F_SETLKW, 0, 0) == -1) {
-		TDB_LOG((tdb, TDB_DEBUG_ERROR, "tdb_transaction_start: failed to get hash locks\n"));
-		tdb->ecode = TDB_ERR_LOCK;
-		goto fail;
-	}
-
-	/* 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;
-
-	return 0;
-	
-fail:
-	tdb_brlock(tdb, FREELIST_TOP, F_UNLCK, F_SETLKW, 0, 0);
-	tdb_transaction_unlock(tdb);
-	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)
-{	
-	int i;
-
-	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);
-
-	/* remove any global lock created during the transaction */
-	if (tdb->global_lock.count != 0) {
-		tdb_brlock(tdb, FREELIST_TOP, F_UNLCK, F_SETLKW, 0, 4*tdb->header.hash_size);
-		tdb->global_lock.count = 0;
-	}
-
-	/* remove any locks created during the transaction */
-	if (tdb->num_locks != 0) {
-		for (i=0;i<tdb->num_lockrecs;i++) {
-			tdb_brlock(tdb,FREELIST_TOP+4*tdb->lockrecs[i].list,
-				   F_UNLCK,F_SETLKW, 0, 1);
-		}
-		tdb->num_locks = 0;
-		tdb->num_lockrecs = 0;
-		SAFE_FREE(tdb->lockrecs);
-	}
-
-	/* restore the normal io methods */
-	tdb->methods = tdb->transaction->io_methods;
-
-	tdb_brlock(tdb, FREELIST_TOP, F_UNLCK, F_SETLKW, 0, 0);
-	tdb_transaction_unlock(tdb);
-	SAFE_FREE(tdb->transaction->hash_heads);
-	SAFE_FREE(tdb->transaction);
-	
-	return 0;
-}
-
-/*
-  sync to disk
-*/
-static int transaction_sync(struct tdb_context *tdb, tdb_off_t offset, tdb_len_t length)
-{	
-	if (fsync(tdb->fd) != 0) {
-		tdb->ecode = TDB_ERR_IO;
-		TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_transaction: fsync failed\n"));
-		return -1;
-	}
-#ifdef HAVE_MMAP
-	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;
-}
-
-
-/*
-  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 list_struct rec;
-	const struct tdb_methods *methods = tdb->transaction->io_methods;
-	tdb_off_t recovery_head;
-
-	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 && 
-	    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;
-	}
-
-	*recovery_size = tdb_recovery_size(tdb);
-
-	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;
-	}
-
-	/* 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 != 0) {
-		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);
-
-	/* round up to a multiple of page size */
-	*recovery_max_size = TDB_ALIGN(sizeof(rec) + *recovery_size, tdb->page_size) - sizeof(rec);
-	*recovery_offset = tdb->map_size;
-	recovery_head = *recovery_offset;
-
-	if (methods->tdb_expand_file(tdb, tdb->transaction->old_map_size, 
-				     (tdb->map_size - tdb->transaction->old_map_size) +
-				     sizeof(rec) + *recovery_max_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 list_struct *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 list_struct *)data;
-	memset(rec, 0, sizeof(*rec));
-
-	rec->magic    = 0;
-	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 list_struct, 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;
-}
-
-/*
-  commit the current transaction
-*/
-int tdb_transaction_commit(struct tdb_context *tdb)
-{	
-	const struct tdb_methods *methods;
-	tdb_off_t magic_offset = 0;
-	uint32_t zero = 0;
-	int i;
-
-	if (tdb->transaction == NULL) {
-		TDB_LOG((tdb, TDB_DEBUG_ERROR, "tdb_transaction_commit: no transaction\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_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;
-	}
-
-	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->num_locks || tdb->global_lock.count) {
-		tdb->ecode = TDB_ERR_LOCK;
-		TDB_LOG((tdb, TDB_DEBUG_ERROR, "tdb_transaction_commit: locks pending on commit\n"));
-		tdb_transaction_cancel(tdb);
-		return -1;
-	}
-
-	/* upgrade the main transaction lock region to a write lock */
-	if (tdb_brlock_upgrade(tdb, FREELIST_TOP, 0) == -1) {
-		TDB_LOG((tdb, TDB_DEBUG_ERROR, "tdb_transaction_start: failed to upgrade hash locks\n"));
-		tdb->ecode = TDB_ERR_LOCK;
-		tdb_transaction_cancel(tdb);
-		return -1;
-	}
-
-	/* get the global lock - this prevents new users attaching to the database
-	   during the commit */
-	if (tdb_brlock(tdb, GLOBAL_LOCK, F_WRLCK, F_SETLKW, 0, 1) == -1) {
-		TDB_LOG((tdb, TDB_DEBUG_ERROR, "tdb_transaction_commit: failed to get global lock\n"));
-		tdb->ecode = TDB_ERR_LOCK;
-		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, &magic_offset) == -1) {
-			TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_transaction_commit: failed to setup recovery data\n"));
-			tdb_brlock(tdb, GLOBAL_LOCK, F_UNLCK, F_SETLKW, 0, 1);
-			tdb_transaction_cancel(tdb);
-			return -1;
-		}
-	}
-
-	/* 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_commit: expansion failed\n"));
-			tdb_brlock(tdb, GLOBAL_LOCK, F_UNLCK, F_SETLKW, 0, 1);
-			tdb_transaction_cancel(tdb);
-			return -1;
-		}
-		tdb->map_size = tdb->transaction->old_map_size;
-		methods->tdb_oob(tdb, tdb->map_size + 1, 1);
-	}
-
-	/* 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_brlock(tdb, GLOBAL_LOCK, F_UNLCK, F_SETLKW, 0, 1);
-
-			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;
-
-	if (!(tdb->flags & TDB_NOSYNC)) {
-		/* ensure the new data is on disk */
-		if (transaction_sync(tdb, 0, tdb->map_size) == -1) {
-			return -1;
-		}
-
-		/* remove the recovery marker */
-		if (methods->tdb_write(tdb, magic_offset, &zero, 4) == -1) {
-			TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_transaction_commit: failed to remove recovery magic\n"));
-			return -1;
-		}
-
-		/* ensure the recovery marker has been removed on disk */
-		if (transaction_sync(tdb, magic_offset, 4) == -1) {
-			return -1;
-		}
-	}
-
-	tdb_brlock(tdb, GLOBAL_LOCK, F_UNLCK, F_SETLKW, 0, 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 */
-#ifdef HAVE_UTIME
-	utime(tdb->name, NULL);
-#endif
-
-	/* use a transaction cancel to free memory and remove the
-	   transaction locks */
-	tdb_transaction_cancel(tdb);
-
-	return 0;
-}
-
-
-/*
-  recover from an aborted transaction. Must be called with exclusive
-  database write access already established (including the global
-  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 list_struct 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 list_struct, 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;			
-	}
-	
-	/* reduce the file size to the old size */
-	tdb_munmap(tdb);
-	if (ftruncate(tdb->fd, recovery_eof) != 0) {
-		TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_transaction_recover: failed to reduce to recovery size\n"));
-		tdb->ecode = TDB_ERR_IO;
-		return -1;			
-	}
-	tdb->map_size = recovery_eof;
-	tdb_mmap(tdb);
-
-	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;
-}