added support for a prepare_commit() op in ldb modules

This op will be used by the partition module to give us good
transaction semantics across the 4 partitions that sam.ldb uses.

2 files changed, 32 insertions, 2 deletions

diff --git a/source4/lib/ldb/ldb_tdb/ldb_tdb.c b/source4/lib/ldb/ldb_tdb/ldb_tdb.c
index 9df62be936..0f84b67afa 100644
--- a/source4/lib/ldb/ldb_tdb/ldb_tdb.c
+++ b/source4/lib/ldb/ldb_tdb/ldb_tdb.c
@@ -857,18 +857,46 @@ static int ltdb_start_trans(struct ldb_module *module)
 	return LDB_SUCCESS;
 }
 
-static int ltdb_end_trans(struct ldb_module *module)
+static int ltdb_prepare_commit(struct ldb_module *module)
 {
 	void *data = ldb_module_get_private(module);
 	struct ltdb_private *ltdb = talloc_get_type(data, struct ltdb_private);
 
-	ltdb->in_transaction--;
+	if (ltdb->in_transaction != 1) {
+		return LDB_SUCCESS;
+	}
 
 	if (ltdb_index_transaction_commit(module) != 0) {
 		tdb_transaction_cancel(ltdb->tdb);
+		ltdb->in_transaction--;
+		return ltdb_err_map(tdb_error(ltdb->tdb));
+	}
+
+	if (tdb_transaction_prepare_commit(ltdb->tdb) != 0) {
+		ltdb->in_transaction--;
 		return ltdb_err_map(tdb_error(ltdb->tdb));
 	}
 
+	ltdb->prepared_commit = true;
+
+	return LDB_SUCCESS;
+}
+
+static int ltdb_end_trans(struct ldb_module *module)
+{
+	void *data = ldb_module_get_private(module);
+	struct ltdb_private *ltdb = talloc_get_type(data, struct ltdb_private);
+
+	if (!ltdb->prepared_commit) {
+		int ret = ltdb_prepare_commit(module);
+		if (ret != LDB_SUCCESS) {
+			return ret;
+		}
+	}
+
+	ltdb->in_transaction--;
+	ltdb->prepared_commit = false;
+
 	if (tdb_transaction_commit(ltdb->tdb) != 0) {
 		return ltdb_err_map(tdb_error(ltdb->tdb));
 	}
@@ -1209,6 +1237,7 @@ static const struct ldb_module_ops ltdb_ops = {
 	.extended          = ltdb_handle_request,
 	.start_transaction = ltdb_start_trans,
 	.end_transaction   = ltdb_end_trans,
+	.prepare_commit    = ltdb_prepare_commit,
 	.del_transaction   = ltdb_del_trans,
 };
 
diff --git a/source4/lib/ldb/ldb_tdb/ldb_tdb.h b/source4/lib/ldb/ldb_tdb/ldb_tdb.h
index 5a1c8fee2d..370cd0729b 100644
--- a/source4/lib/ldb/ldb_tdb/ldb_tdb.h
+++ b/source4/lib/ldb/ldb_tdb/ldb_tdb.h
@@ -30,6 +30,7 @@ struct ltdb_private {
 
 	bool check_base;
 	struct ltdb_idxptr *idxptr;
+	bool prepared_commit;
 };
 
 /*