tdb2: import TDB1 code.

We import the entire codebase, putting a "tdb1_" prefix on the files
and changing the "tdb_" prefix to "tdb1_" everywhere.

The next patches will gradually merge it with the TDB2 code where
necessary.

Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
(Imported from CCAN commit 19e6c1a250ade1e7204ada17163294855585e825)

1 files changed, 847 insertions, 0 deletions

diff --git a/lib/tdb2/tdb1_lock.c b/lib/tdb2/tdb1_lock.c
new file mode 100644
index 0000000000..bed70ba2ec
--- /dev/null
+++ b/lib/tdb2/tdb1_lock.c
@@ -0,0 +1,847 @@
+ /*
+   Unix SMB/CIFS implementation.
+
+   trivial database library
+
+   Copyright (C) Andrew Tridgell              1999-2005
+   Copyright (C) Paul `Rusty' Russell		   2000
+   Copyright (C) Jeremy Allison			   2000-2003
+
+     ** 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 "tdb1_private.h"
+
+_PUBLIC_ void tdb1_setalarm_sigptr(struct tdb1_context *tdb, volatile sig_atomic_t *ptr)
+{
+	tdb->interrupt_sig_ptr = ptr;
+}
+
+static int fcntl_lock(struct tdb1_context *tdb,
+		      int rw, off_t off, off_t len, bool waitflag)
+{
+	struct flock fl;
+
+	fl.l_type = rw;
+	fl.l_whence = SEEK_SET;
+	fl.l_start = off;
+	fl.l_len = len;
+	fl.l_pid = 0;
+
+	if (waitflag)
+		return fcntl(tdb->fd, F_SETLKW, &fl);
+	else
+		return fcntl(tdb->fd, F_SETLK, &fl);
+}
+
+static int fcntl_unlock(struct tdb1_context *tdb, int rw, off_t off, off_t len)
+{
+	struct flock fl;
+#if 0 /* Check they matched up locks and unlocks correctly. */
+	char line[80];
+	FILE *locks;
+	bool found = false;
+
+	locks = fopen("/proc/locks", "r");
+
+	while (fgets(line, 80, locks)) {
+		char *p;
+		int type, start, l;
+
+		/* eg. 1: FLOCK  ADVISORY  WRITE 2440 08:01:2180826 0 EOF */
+		p = strchr(line, ':') + 1;
+		if (strncmp(p, " POSIX  ADVISORY  ", strlen(" POSIX  ADVISORY  ")))
+			continue;
+		p += strlen(" FLOCK  ADVISORY  ");
+		if (strncmp(p, "READ  ", strlen("READ  ")) == 0)
+			type = F_RDLCK;
+		else if (strncmp(p, "WRITE ", strlen("WRITE ")) == 0)
+			type = F_WRLCK;
+		else
+			abort();
+		p += 6;
+		if (atoi(p) != getpid())
+			continue;
+		p = strchr(strchr(p, ' ') + 1, ' ') + 1;
+		start = atoi(p);
+		p = strchr(p, ' ') + 1;
+		if (strncmp(p, "EOF", 3) == 0)
+			l = 0;
+		else
+			l = atoi(p) - start + 1;
+
+		if (off == start) {
+			if (len != l) {
+				fprintf(stderr, "Len %u should be %u: %s",
+					(int)len, l, line);
+				abort();
+			}
+			if (type != rw) {
+				fprintf(stderr, "Type %s wrong: %s",
+					rw == F_RDLCK ? "READ" : "WRITE", line);
+				abort();
+			}
+			found = true;
+			break;
+		}
+	}
+
+	if (!found) {
+		fprintf(stderr, "Unlock on %u@%u not found!\n",
+			(int)off, (int)len);
+		abort();
+	}
+
+	fclose(locks);
+#endif
+
+	fl.l_type = F_UNLCK;
+	fl.l_whence = SEEK_SET;
+	fl.l_start = off;
+	fl.l_len = len;
+	fl.l_pid = 0;
+
+	return fcntl(tdb->fd, F_SETLKW, &fl);
+}
+
+/* list -1 is the alloc list, otherwise a hash chain. */
+static tdb1_off_t lock_offset(int list)
+{
+	return TDB1_FREELIST_TOP + 4*list;
+}
+
+/* a byte range locking function - return 0 on success
+   this functions locks/unlocks 1 byte at the specified offset.
+
+   On error, errno is also set so that errors are passed back properly
+   through tdb1_open().
+
+   note that a len of zero means lock to end of file
+*/
+int tdb1_brlock(struct tdb1_context *tdb,
+	       int rw_type, tdb1_off_t offset, size_t len,
+	       enum tdb1_lock_flags flags)
+{
+	int ret;
+
+	if (tdb->flags & TDB1_NOLOCK) {
+		return 0;
+	}
+
+	if (flags & TDB1_LOCK_MARK_ONLY) {
+		return 0;
+	}
+
+	if ((rw_type == F_WRLCK) && (tdb->read_only || tdb->traverse_read)) {
+		tdb->ecode = TDB1_ERR_RDONLY;
+		return -1;
+	}
+
+	do {
+		ret = fcntl_lock(tdb, rw_type, offset, len,
+				 flags & TDB1_LOCK_WAIT);
+		/* Check for a sigalarm break. */
+		if (ret == -1 && errno == EINTR &&
+				tdb->interrupt_sig_ptr &&
+				*tdb->interrupt_sig_ptr) {
+			break;
+		}
+	} while (ret == -1 && errno == EINTR);
+
+	if (ret == -1) {
+		tdb->ecode = TDB1_ERR_LOCK;
+		/* Generic lock error. errno set by fcntl.
+		 * EAGAIN is an expected return from non-blocking
+		 * locks. */
+		if (!(flags & TDB1_LOCK_PROBE) && errno != EAGAIN) {
+			TDB1_LOG((tdb, TDB1_DEBUG_TRACE,"tdb1_brlock failed (fd=%d) at offset %d rw_type=%d flags=%d len=%d\n",
+				 tdb->fd, offset, rw_type, flags, (int)len));
+		}
+		return -1;
+	}
+	return 0;
+}
+
+int tdb1_brunlock(struct tdb1_context *tdb,
+		 int rw_type, tdb1_off_t offset, size_t len)
+{
+	int ret;
+
+	if (tdb->flags & TDB1_NOLOCK) {
+		return 0;
+	}
+
+	do {
+		ret = fcntl_unlock(tdb, rw_type, offset, len);
+	} while (ret == -1 && errno == EINTR);
+
+	if (ret == -1) {
+		TDB1_LOG((tdb, TDB1_DEBUG_TRACE,"tdb1_brunlock failed (fd=%d) at offset %d rw_type=%d len=%d\n",
+			 tdb->fd, offset, rw_type, (int)len));
+	}
+	return ret;
+}
+
+/*
+  upgrade a read lock to a write lock. This needs to be handled in a
+  special way as some OSes (such as solaris) have too conservative
+  deadlock detection and claim a deadlock when progress can be
+  made. For those OSes we may loop for a while.
+*/
+int tdb1_allrecord_upgrade(struct tdb1_context *tdb)
+{
+	int count = 1000;
+
+	if (tdb->allrecord_lock.count != 1) {
+		TDB1_LOG((tdb, TDB1_DEBUG_ERROR,
+			 "tdb1_allrecord_upgrade failed: count %u too high\n",
+			 tdb->allrecord_lock.count));
+		return -1;
+	}
+
+	if (tdb->allrecord_lock.off != 1) {
+		TDB1_LOG((tdb, TDB1_DEBUG_ERROR,
+			 "tdb1_allrecord_upgrade failed: already upgraded?\n"));
+		return -1;
+	}
+
+	while (count--) {
+		struct timeval tv;
+		if (tdb1_brlock(tdb, F_WRLCK, TDB1_FREELIST_TOP, 0,
+			       TDB1_LOCK_WAIT|TDB1_LOCK_PROBE) == 0) {
+			tdb->allrecord_lock.ltype = F_WRLCK;
+			tdb->allrecord_lock.off = 0;
+			return 0;
+		}
+		if (errno != EDEADLK) {
+			break;
+		}
+		/* sleep for as short a time as we can - more portable than usleep() */
+		tv.tv_sec = 0;
+		tv.tv_usec = 1;
+		select(0, NULL, NULL, NULL, &tv);
+	}
+	TDB1_LOG((tdb, TDB1_DEBUG_TRACE,"tdb1_allrecord_upgrade failed\n"));
+	return -1;
+}
+
+static struct tdb1_lock_type *tdb1_find_nestlock(struct tdb1_context *tdb,
+						 tdb1_off_t offset)
+{
+	unsigned int i;
+
+	for (i=0; i<tdb->num_lockrecs; i++) {
+		if (tdb->lockrecs[i].off == offset) {
+			return &tdb->lockrecs[i];
+		}
+	}
+	return NULL;
+}
+
+/* lock an offset in the database. */
+int tdb1_nest_lock(struct tdb1_context *tdb, uint32_t offset, int ltype,
+		  enum tdb1_lock_flags flags)
+{
+	struct tdb1_lock_type *new_lck;
+
+	if (offset >= lock_offset(tdb->header.hash_size)) {
+		tdb->ecode = TDB1_ERR_LOCK;
+		TDB1_LOG((tdb, TDB1_DEBUG_ERROR,"tdb1_lock: invalid offset %u for ltype=%d\n",
+			 offset, ltype));
+		return -1;
+	}
+	if (tdb->flags & TDB1_NOLOCK)
+		return 0;
+
+	new_lck = tdb1_find_nestlock(tdb, offset);
+	if (new_lck) {
+		/*
+		 * Just increment the in-memory struct, posix locks
+		 * don't stack.
+		 */
+		new_lck->count++;
+		return 0;
+	}
+
+	new_lck = (struct tdb1_lock_type *)realloc(
+		tdb->lockrecs,
+		sizeof(*tdb->lockrecs) * (tdb->num_lockrecs+1));
+	if (new_lck == NULL) {
+		errno = ENOMEM;
+		return -1;
+	}
+	tdb->lockrecs = new_lck;
+
+	/* Since fcntl locks don't nest, we do a lock for the first one,
+	   and simply bump the count for future ones */
+	if (tdb1_brlock(tdb, ltype, offset, 1, flags)) {
+		return -1;
+	}
+
+	tdb->lockrecs[tdb->num_lockrecs].off = offset;
+	tdb->lockrecs[tdb->num_lockrecs].count = 1;
+	tdb->lockrecs[tdb->num_lockrecs].ltype = ltype;
+	tdb->num_lockrecs++;
+
+	return 0;
+}
+
+static int tdb1_lock_and_recover(struct tdb1_context *tdb)
+{
+	int ret;
+
+	/* We need to match locking order in transaction commit. */
+	if (tdb1_brlock(tdb, F_WRLCK, TDB1_FREELIST_TOP, 0, TDB1_LOCK_WAIT)) {
+		return -1;
+	}
+
+	if (tdb1_brlock(tdb, F_WRLCK, TDB1_OPEN_LOCK, 1, TDB1_LOCK_WAIT)) {
+		tdb1_brunlock(tdb, F_WRLCK, TDB1_FREELIST_TOP, 0);
+		return -1;
+	}
+
+	ret = tdb1_transaction_recover(tdb);
+
+	tdb1_brunlock(tdb, F_WRLCK, TDB1_OPEN_LOCK, 1);
+	tdb1_brunlock(tdb, F_WRLCK, TDB1_FREELIST_TOP, 0);
+
+	return ret;
+}
+
+static bool have_data_locks(const struct tdb1_context *tdb)
+{
+	unsigned int i;
+
+	for (i = 0; i < tdb->num_lockrecs; i++) {
+		if (tdb->lockrecs[i].off >= lock_offset(-1))
+			return true;
+	}
+	return false;
+}
+
+static int tdb1_lock_list(struct tdb1_context *tdb, int list, int ltype,
+			 enum tdb1_lock_flags waitflag)
+{
+	int ret;
+	bool check = false;
+
+	/* a allrecord lock allows us to avoid per chain locks */
+	if (tdb->allrecord_lock.count &&
+	    (ltype == tdb->allrecord_lock.ltype || ltype == F_RDLCK)) {
+		return 0;
+	}
+
+	if (tdb->allrecord_lock.count) {
+		tdb->ecode = TDB1_ERR_LOCK;
+		ret = -1;
+	} else {
+		/* Only check when we grab first data lock. */
+		check = !have_data_locks(tdb);
+		ret = tdb1_nest_lock(tdb, lock_offset(list), ltype, waitflag);
+
+		if (ret == 0 && check && tdb1_needs_recovery(tdb)) {
+			tdb1_nest_unlock(tdb, lock_offset(list), ltype, false);
+
+			if (tdb1_lock_and_recover(tdb) == -1) {
+				return -1;
+			}
+			return tdb1_lock_list(tdb, list, ltype, waitflag);
+		}
+	}
+	return ret;
+}
+
+/* lock a list in the database. list -1 is the alloc list */
+int tdb1_lock(struct tdb1_context *tdb, int list, int ltype)
+{
+	int ret;
+
+	ret = tdb1_lock_list(tdb, list, ltype, TDB1_LOCK_WAIT);
+	if (ret) {
+		TDB1_LOG((tdb, TDB1_DEBUG_ERROR, "tdb1_lock failed on list %d "
+			 "ltype=%d (%s)\n",  list, ltype, strerror(errno)));
+	}
+	return ret;
+}
+
+/* lock a list in the database. list -1 is the alloc list. non-blocking lock */
+int tdb1_lock_nonblock(struct tdb1_context *tdb, int list, int ltype)
+{
+	return tdb1_lock_list(tdb, list, ltype, TDB1_LOCK_NOWAIT);
+}
+
+
+int tdb1_nest_unlock(struct tdb1_context *tdb, uint32_t offset, int ltype,
+		    bool mark_lock)
+{
+	int ret = -1;
+	struct tdb1_lock_type *lck;
+
+	if (tdb->flags & TDB1_NOLOCK)
+		return 0;
+
+	/* Sanity checks */
+	if (offset >= lock_offset(tdb->header.hash_size)) {
+		TDB1_LOG((tdb, TDB1_DEBUG_ERROR, "tdb1_unlock: offset %u invalid (%d)\n", offset, tdb->header.hash_size));
+		return ret;
+	}
+
+	lck = tdb1_find_nestlock(tdb, offset);
+	if ((lck == NULL) || (lck->count == 0)) {
+		TDB1_LOG((tdb, TDB1_DEBUG_ERROR, "tdb1_unlock: count is 0\n"));
+		return -1;
+	}
+
+	if (lck->count > 1) {
+		lck->count--;
+		return 0;
+	}
+
+	/*
+	 * This lock has count==1 left, so we need to unlock it in the
+	 * kernel. We don't bother with decrementing the in-memory array
+	 * element, we're about to overwrite it with the last array element
+	 * anyway.
+	 */
+
+	if (mark_lock) {
+		ret = 0;
+	} else {
+		ret = tdb1_brunlock(tdb, ltype, offset, 1);
+	}
+
+	/*
+	 * Shrink the array by overwriting the element just unlocked with the
+	 * last array element.
+	 */
+	*lck = tdb->lockrecs[--tdb->num_lockrecs];
+
+	/*
+	 * We don't bother with realloc when the array shrinks, but if we have
+	 * a completely idle tdb we should get rid of the locked array.
+	 */
+
+	if (tdb->num_lockrecs == 0) {
+		SAFE_FREE(tdb->lockrecs);
+	}
+
+	if (ret)
+		TDB1_LOG((tdb, TDB1_DEBUG_ERROR, "tdb1_unlock: An error occurred unlocking!\n"));
+	return ret;
+}
+
+int tdb1_unlock(struct tdb1_context *tdb, int list, int ltype)
+{
+	/* a global lock allows us to avoid per chain locks */
+	if (tdb->allrecord_lock.count &&
+	    (ltype == tdb->allrecord_lock.ltype || ltype == F_RDLCK)) {
+		return 0;
+	}
+
+	if (tdb->allrecord_lock.count) {
+		tdb->ecode = TDB1_ERR_LOCK;
+		return -1;
+	}
+
+	return tdb1_nest_unlock(tdb, lock_offset(list), ltype, false);
+}
+
+/*
+  get the transaction lock
+ */
+int tdb1_transaction_lock(struct tdb1_context *tdb, int ltype,
+			 enum tdb1_lock_flags lockflags)
+{
+	return tdb1_nest_lock(tdb, TDB1_TRANSACTION_LOCK, ltype, lockflags);
+}
+
+/*
+  release the transaction lock
+ */
+int tdb1_transaction_unlock(struct tdb1_context *tdb, int ltype)
+{
+	return tdb1_nest_unlock(tdb, TDB1_TRANSACTION_LOCK, ltype, false);
+}
+
+/* Returns 0 if all done, -1 if error, 1 if ok. */
+static int tdb1_allrecord_check(struct tdb1_context *tdb, int ltype,
+			       enum tdb1_lock_flags flags, bool upgradable)
+{
+	/* There are no locks on read-only dbs */
+	if (tdb->read_only || tdb->traverse_read) {
+		tdb->ecode = TDB1_ERR_LOCK;
+		return -1;
+	}
+
+	if (tdb->allrecord_lock.count && tdb->allrecord_lock.ltype == ltype) {
+		tdb->allrecord_lock.count++;
+		return 0;
+	}
+
+	if (tdb->allrecord_lock.count) {
+		/* a global lock of a different type exists */
+		tdb->ecode = TDB1_ERR_LOCK;
+		return -1;
+	}
+
+	if (tdb1_have_extra_locks(tdb)) {
+		/* can't combine global and chain locks */
+		tdb->ecode = TDB1_ERR_LOCK;
+		return -1;
+	}
+
+	if (upgradable && ltype != F_RDLCK) {
+		/* tdb error: you can't upgrade a write lock! */
+		tdb->ecode = TDB1_ERR_LOCK;
+		return -1;
+	}
+	return 1;
+}
+
+/* We only need to lock individual bytes, but Linux merges consecutive locks
+ * so we lock in contiguous ranges. */
+static int tdb1_chainlock_gradual(struct tdb1_context *tdb,
+				 int ltype, enum tdb1_lock_flags flags,
+				 size_t off, size_t len)
+{
+	int ret;
+	enum tdb1_lock_flags nb_flags = (flags & ~TDB1_LOCK_WAIT);
+
+	if (len <= 4) {
+		/* Single record.  Just do blocking lock. */
+		return tdb1_brlock(tdb, ltype, off, len, flags);
+	}
+
+	/* First we try non-blocking. */
+	ret = tdb1_brlock(tdb, ltype, off, len, nb_flags);
+	if (ret == 0) {
+		return 0;
+	}
+
+	/* Try locking first half, then second. */
+	ret = tdb1_chainlock_gradual(tdb, ltype, flags, off, len / 2);
+	if (ret == -1)
+		return -1;
+
+	ret = tdb1_chainlock_gradual(tdb, ltype, flags,
+				    off + len / 2, len - len / 2);
+	if (ret == -1) {
+		tdb1_brunlock(tdb, ltype, off, len / 2);
+		return -1;
+	}
+	return 0;
+}
+
+/* lock/unlock entire database.  It can only be upgradable if you have some
+ * other way of guaranteeing exclusivity (ie. transaction write lock).
+ * We do the locking gradually to avoid being starved by smaller locks. */
+int tdb1_allrecord_lock(struct tdb1_context *tdb, int ltype,
+		       enum tdb1_lock_flags flags, bool upgradable)
+{
+	switch (tdb1_allrecord_check(tdb, ltype, flags, upgradable)) {
+	case -1:
+		return -1;
+	case 0:
+		return 0;
+	}
+
+	/* We cover two kinds of locks:
+	 * 1) Normal chain locks.  Taken for almost all operations.
+	 * 3) Individual records locks.  Taken after normal or free
+	 *    chain locks.
+	 *
+	 * It is (1) which cause the starvation problem, so we're only
+	 * gradual for that. */
+	if (tdb1_chainlock_gradual(tdb, ltype, flags, TDB1_FREELIST_TOP,
+				  tdb->header.hash_size * 4) == -1) {
+		return -1;
+	}
+
+	/* Grab individual record locks. */
+	if (tdb1_brlock(tdb, ltype, lock_offset(tdb->header.hash_size), 0,
+		       flags) == -1) {
+		tdb1_brunlock(tdb, ltype, TDB1_FREELIST_TOP,
+			     tdb->header.hash_size * 4);
+		return -1;
+	}
+
+	tdb->allrecord_lock.count = 1;
+	/* If it's upgradable, it's actually exclusive so we can treat
+	 * it as a write lock. */
+	tdb->allrecord_lock.ltype = upgradable ? F_WRLCK : ltype;
+	tdb->allrecord_lock.off = upgradable;
+
+	if (tdb1_needs_recovery(tdb)) {
+		bool mark = flags & TDB1_LOCK_MARK_ONLY;
+		tdb1_allrecord_unlock(tdb, ltype, mark);
+		if (mark) {
+			tdb->ecode = TDB1_ERR_LOCK;
+			TDB1_LOG((tdb, TDB1_DEBUG_ERROR,
+				 "tdb1_lockall_mark cannot do recovery\n"));
+			return -1;
+		}
+		if (tdb1_lock_and_recover(tdb) == -1) {
+			return -1;
+		}
+		return tdb1_allrecord_lock(tdb, ltype, flags, upgradable);
+	}
+
+	return 0;
+}
+
+
+
+/* unlock entire db */
+int tdb1_allrecord_unlock(struct tdb1_context *tdb, int ltype, bool mark_lock)
+{
+	/* There are no locks on read-only dbs */
+	if (tdb->read_only || tdb->traverse_read) {
+		tdb->ecode = TDB1_ERR_LOCK;
+		return -1;
+	}
+
+	if (tdb->allrecord_lock.count == 0) {
+		tdb->ecode = TDB1_ERR_LOCK;
+		return -1;
+	}
+
+	/* Upgradable locks are marked as write locks. */
+	if (tdb->allrecord_lock.ltype != ltype
+	    && (!tdb->allrecord_lock.off || ltype != F_RDLCK)) {
+		tdb->ecode = TDB1_ERR_LOCK;
+		return -1;
+	}
+
+	if (tdb->allrecord_lock.count > 1) {
+		tdb->allrecord_lock.count--;
+		return 0;
+	}
+
+	if (!mark_lock && tdb1_brunlock(tdb, ltype, TDB1_FREELIST_TOP, 0)) {
+		TDB1_LOG((tdb, TDB1_DEBUG_ERROR, "tdb1_unlockall failed (%s)\n", strerror(errno)));
+		return -1;
+	}
+
+	tdb->allrecord_lock.count = 0;
+	tdb->allrecord_lock.ltype = 0;
+
+	return 0;
+}
+
+/* lock entire database with write lock */
+_PUBLIC_ int tdb1_lockall(struct tdb1_context *tdb)
+{
+	return tdb1_allrecord_lock(tdb, F_WRLCK, TDB1_LOCK_WAIT, false);
+}
+
+/* lock entire database with write lock - mark only */
+_PUBLIC_ int tdb1_lockall_mark(struct tdb1_context *tdb)
+{
+	return tdb1_allrecord_lock(tdb, F_WRLCK, TDB1_LOCK_MARK_ONLY, false);
+}
+
+/* unlock entire database with write lock - unmark only */
+_PUBLIC_ int tdb1_lockall_unmark(struct tdb1_context *tdb)
+{
+	return tdb1_allrecord_unlock(tdb, F_WRLCK, true);
+}
+
+/* lock entire database with write lock - nonblocking varient */
+_PUBLIC_ int tdb1_lockall_nonblock(struct tdb1_context *tdb)
+{
+	int ret = tdb1_allrecord_lock(tdb, F_WRLCK, TDB1_LOCK_NOWAIT, false);
+	return ret;
+}
+
+/* unlock entire database with write lock */
+_PUBLIC_ int tdb1_unlockall(struct tdb1_context *tdb)
+{
+	return tdb1_allrecord_unlock(tdb, F_WRLCK, false);
+}
+
+/* lock entire database with read lock */
+_PUBLIC_ int tdb1_lockall_read(struct tdb1_context *tdb)
+{
+	return tdb1_allrecord_lock(tdb, F_RDLCK, TDB1_LOCK_WAIT, false);
+}
+
+/* lock entire database with read lock - nonblock varient */
+_PUBLIC_ int tdb1_lockall_read_nonblock(struct tdb1_context *tdb)
+{
+	int ret = tdb1_allrecord_lock(tdb, F_RDLCK, TDB1_LOCK_NOWAIT, false);
+	return ret;
+}
+
+/* unlock entire database with read lock */
+_PUBLIC_ int tdb1_unlockall_read(struct tdb1_context *tdb)
+{
+	return tdb1_allrecord_unlock(tdb, F_RDLCK, false);
+}
+
+/* lock/unlock one hash chain. This is meant to be used to reduce
+   contention - it cannot guarantee how many records will be locked */
+_PUBLIC_ int tdb1_chainlock(struct tdb1_context *tdb, TDB1_DATA key)
+{
+	int ret = tdb1_lock(tdb, TDB1_BUCKET(tdb->hash_fn(&key)), F_WRLCK);
+	return ret;
+}
+
+/* lock/unlock one hash chain, non-blocking. This is meant to be used
+   to reduce contention - it cannot guarantee how many records will be
+   locked */
+_PUBLIC_ int tdb1_chainlock_nonblock(struct tdb1_context *tdb, TDB1_DATA key)
+{
+	int ret = tdb1_lock_nonblock(tdb, TDB1_BUCKET(tdb->hash_fn(&key)), F_WRLCK);
+	return ret;
+}
+
+/* mark a chain as locked without actually locking it. Warning! use with great caution! */
+_PUBLIC_ int tdb1_chainlock_mark(struct tdb1_context *tdb, TDB1_DATA key)
+{
+	int ret = tdb1_nest_lock(tdb, lock_offset(TDB1_BUCKET(tdb->hash_fn(&key))),
+				F_WRLCK, TDB1_LOCK_MARK_ONLY);
+	return ret;
+}
+
+/* unmark a chain as locked without actually locking it. Warning! use with great caution! */
+_PUBLIC_ int tdb1_chainlock_unmark(struct tdb1_context *tdb, TDB1_DATA key)
+{
+	return tdb1_nest_unlock(tdb, lock_offset(TDB1_BUCKET(tdb->hash_fn(&key))),
+			       F_WRLCK, true);
+}
+
+_PUBLIC_ int tdb1_chainunlock(struct tdb1_context *tdb, TDB1_DATA key)
+{
+	return tdb1_unlock(tdb, TDB1_BUCKET(tdb->hash_fn(&key)), F_WRLCK);
+}
+
+_PUBLIC_ int tdb1_chainlock_read(struct tdb1_context *tdb, TDB1_DATA key)
+{
+	int ret;
+	ret = tdb1_lock(tdb, TDB1_BUCKET(tdb->hash_fn(&key)), F_RDLCK);
+	return ret;
+}
+
+_PUBLIC_ int tdb1_chainunlock_read(struct tdb1_context *tdb, TDB1_DATA key)
+{
+	return tdb1_unlock(tdb, TDB1_BUCKET(tdb->hash_fn(&key)), F_RDLCK);
+}
+
+/* record lock stops delete underneath */
+int tdb1_lock_record(struct tdb1_context *tdb, tdb1_off_t off)
+{
+	if (tdb->allrecord_lock.count) {
+		return 0;
+	}
+	return off ? tdb1_brlock(tdb, F_RDLCK, off, 1, TDB1_LOCK_WAIT) : 0;
+}
+
+/*
+  Write locks override our own fcntl readlocks, so check it here.
+  Note this is meant to be F_SETLK, *not* F_SETLKW, as it's not
+  an error to fail to get the lock here.
+*/
+int tdb1_write_lock_record(struct tdb1_context *tdb, tdb1_off_t off)
+{
+	struct tdb1_traverse_lock *i;
+	for (i = &tdb->travlocks; i; i = i->next)
+		if (i->off == off)
+			return -1;
+	if (tdb->allrecord_lock.count) {
+		if (tdb->allrecord_lock.ltype == F_WRLCK) {
+			return 0;
+		}
+		return -1;
+	}
+	return tdb1_brlock(tdb, F_WRLCK, off, 1, TDB1_LOCK_NOWAIT|TDB1_LOCK_PROBE);
+}
+
+int tdb1_write_unlock_record(struct tdb1_context *tdb, tdb1_off_t off)
+{
+	if (tdb->allrecord_lock.count) {
+		return 0;
+	}
+	return tdb1_brunlock(tdb, F_WRLCK, off, 1);
+}
+
+/* fcntl locks don't stack: avoid unlocking someone else's */
+int tdb1_unlock_record(struct tdb1_context *tdb, tdb1_off_t off)
+{
+	struct tdb1_traverse_lock *i;
+	uint32_t count = 0;
+
+	if (tdb->allrecord_lock.count) {
+		return 0;
+	}
+
+	if (off == 0)
+		return 0;
+	for (i = &tdb->travlocks; i; i = i->next)
+		if (i->off == off)
+			count++;
+	return (count == 1 ? tdb1_brunlock(tdb, F_RDLCK, off, 1) : 0);
+}
+
+bool tdb1_have_extra_locks(struct tdb1_context *tdb)
+{
+	unsigned int extra = tdb->num_lockrecs;
+
+	/* A transaction holds the lock for all records. */
+	if (!tdb->transaction && tdb->allrecord_lock.count) {
+		return true;
+	}
+
+	/* We always hold the active lock if CLEAR_IF_FIRST. */
+	if (tdb1_find_nestlock(tdb, TDB1_ACTIVE_LOCK)) {
+		extra--;
+	}
+
+	/* In a transaction, we expect to hold the transaction lock */
+	if (tdb->transaction
+	    && tdb1_find_nestlock(tdb, TDB1_TRANSACTION_LOCK)) {
+		extra--;
+	}
+
+	return extra;
+}
+
+/* The transaction code uses this to remove all locks. */
+void tdb1_release_transaction_locks(struct tdb1_context *tdb)
+{
+	unsigned int i, active = 0;
+
+	if (tdb->allrecord_lock.count != 0) {
+		tdb1_brunlock(tdb, tdb->allrecord_lock.ltype, TDB1_FREELIST_TOP, 0);
+		tdb->allrecord_lock.count = 0;
+	}
+
+	for (i=0;i<tdb->num_lockrecs;i++) {
+		struct tdb1_lock_type *lck = &tdb->lockrecs[i];
+
+		/* Don't release the active lock!  Copy it to first entry. */
+		if (lck->off == TDB1_ACTIVE_LOCK) {
+			tdb->lockrecs[active++] = *lck;
+		} else {
+			tdb1_brunlock(tdb, lck->ltype, lck->off, 1);
+		}
+	}
+	tdb->num_lockrecs = active;
+	if (tdb->num_lockrecs == 0) {
+		SAFE_FREE(tdb->lockrecs);
+	}
+}