r6560: added a tdb_chainlock_read() call in ldb_search(). This guarantees

that ldb_search() sees a single consistent view of the database (by
blocking writes during a ldb_search)
(This used to be commit 917f2a8a073fd501f0626bea4f9deb91b95fdc90)

3 files changed, 43 insertions, 0 deletions

diff --git a/source4/lib/ldb/ldb_tdb/ldb_search.c b/source4/lib/ldb/ldb_tdb/ldb_search.c
index 4f45fdf376..7883ee6e7b 100644
--- a/source4/lib/ldb/ldb_tdb/ldb_search.c
+++ b/source4/lib/ldb/ldb_tdb/ldb_search.c
@@ -472,9 +472,14 @@ int ltdb_search(struct ldb_module *module, const char *base,
 	struct ldb_parse_tree *tree;
 	int ret;
 
+	if (ltdb_lock_read(module) != 0) {
+		return -1;
+	}
+
 	ltdb->last_err_string = NULL;
 
 	if (ltdb_cache_load(module) != 0) {
+		ltdb_unlock_read(module);
 		return -1;
 	}
 
@@ -484,6 +489,7 @@ int ltdb_search(struct ldb_module *module, const char *base,
 	tree = ldb_parse_tree(ldb, expression);
 	if (!tree) {
 		ltdb->last_err_string = "expression parse failed";
+		ltdb_unlock_read(module);
 		return -1;
 	}
 
@@ -501,6 +507,7 @@ int ltdb_search(struct ldb_module *module, const char *base,
 	}
 
 	ldb_parse_tree_free(ldb, tree);
+	ltdb_unlock_read(module);
 
 	return ret;
 }
diff --git a/source4/lib/ldb/ldb_tdb/ldb_tdb.c b/source4/lib/ldb/ldb_tdb/ldb_tdb.c
index 87582cf4eb..b47d79de52 100644
--- a/source4/lib/ldb/ldb_tdb/ldb_tdb.c
+++ b/source4/lib/ldb/ldb_tdb/ldb_tdb.c
@@ -249,6 +249,40 @@ static int ltdb_unlock(struct ldb_module *module, const char *lockname)
 
 
 /*
+  lock the database for read - use by ltdb_search
+*/
+int ltdb_lock_read(struct ldb_module *module)
+{
+	struct ltdb_private *ltdb = module->private_data;
+	TDB_DATA key;
+	int ret;
+	key = ltdb_key(module, LDBLOCK);
+	if (!key.dptr) {
+		return -1;
+	}
+	ret = tdb_chainlock_read(ltdb->tdb, key);
+	talloc_free(key.dptr);
+	return ret;
+}
+
+/*
+  unlock the database after a ltdb_lock_read()
+*/
+int ltdb_unlock_read(struct ldb_module *module)
+{
+	struct ltdb_private *ltdb = module->private_data;
+	TDB_DATA key;
+	key = ltdb_key(module, LDBLOCK);
+	if (!key.dptr) {
+		return -1;
+	}
+	tdb_chainunlock_read(ltdb->tdb, key);
+	talloc_free(key.dptr);
+	return 0;
+}
+
+
+/*
   we've made a modification to a dn - possibly reindex and 
   update sequence number
 */
diff --git a/source4/lib/ldb/ldb_tdb/ldb_tdb.h b/source4/lib/ldb/ldb_tdb/ldb_tdb.h
index 9fb60b6359..dfb985319e 100644
--- a/source4/lib/ldb/ldb_tdb/ldb_tdb.h
+++ b/source4/lib/ldb/ldb_tdb/ldb_tdb.h
@@ -104,6 +104,8 @@ struct TDB_DATA ltdb_key(struct ldb_module *module, const char *dn);
 int ltdb_store(struct ldb_module *module, const struct ldb_message *msg, int flgs);
 int ltdb_delete_noindex(struct ldb_module *module, const char *dn);
 int ltdb_modify_internal(struct ldb_module *module, const struct ldb_message *msg);
+int ltdb_lock_read(struct ldb_module *module);
+int ltdb_unlock_read(struct ldb_module *module);
 
 /* The following definitions come from lib/ldb/ldb_tdb/ldb_match.c  */
 int ltdb_val_equal(struct ldb_module *module,