ldb_tdb: Ensure we can not commit an index that is corrupt due to partial re-index

The re-index traverse can abort part-way though and we need to ensure
that the transaction is never committed as that will leave an un-useable db.

BUG: https://bugzilla.samba.org/show_bug.cgi?id=13335

Signed-off-by: Andrew Bartlett <abartlet@samba.org>
Reviewed-by: Gary Lockyer <gary@catalyst.net.nz>
(cherry picked from commit e481e4f30f4dc540f6f129b4f2faea48ee195673)

2 files changed, 32 insertions, 0 deletions

diff --git a/lib/ldb/ldb_tdb/ldb_tdb.c b/lib/ldb/ldb_tdb/ldb_tdb.c
index 16e4b8ea26e..a530a454b29 100644
--- a/lib/ldb/ldb_tdb/ldb_tdb.c
+++ b/lib/ldb/ldb_tdb/ldb_tdb.c
@@ -410,6 +410,10 @@ static int ltdb_modified(struct ldb_module *module, struct ldb_dn *dn)
 		ret = ltdb_cache_reload(module);
 	}
 
+	if (ret != LDB_SUCCESS) {
+		ltdb->reindex_failed = true;
+	}
+
 	return ret;
 }
 
@@ -1404,9 +1408,17 @@ static int ltdb_start_trans(struct ldb_module *module)
 
 	ltdb_index_transaction_start(module);
 
+	ltdb->reindex_failed = false;
+
 	return LDB_SUCCESS;
 }
 
+/*
+ * Forward declaration to allow prepare_commit to in fact abort the
+ * transaction
+ */
+static int ltdb_del_trans(struct ldb_module *module);
+
 static int ltdb_prepare_commit(struct ldb_module *module)
 {
 	int ret;
@@ -1417,6 +1429,24 @@ static int ltdb_prepare_commit(struct ldb_module *module)
 		return LDB_SUCCESS;
 	}
 
+	/*
+	 * Check if the last re-index failed.
+	 *
+	 * This can happen if for example a duplicate value was marked
+	 * unique.  We must not write a partial re-index into the DB.
+	 */
+	if (ltdb->reindex_failed) {
+		/*
+		 * We must instead abort the transaction so we get the
+		 * old values and old index back
+		 */
+		ltdb_del_trans(module);
+		ldb_set_errstring(ldb_module_get_ctx(module),
+				  "Failure during re-index, so "
+				  "transaction must be aborted.");
+		return LDB_ERR_OPERATIONS_ERROR;
+	}
+
 	ret = ltdb_index_transaction_commit(module);
 	if (ret != LDB_SUCCESS) {
 		tdb_transaction_cancel(ltdb->tdb);
diff --git a/lib/ldb/ldb_tdb/ldb_tdb.h b/lib/ldb/ldb_tdb/ldb_tdb.h
index 7e182495928..9591ee59bf1 100644
--- a/lib/ldb/ldb_tdb/ldb_tdb.h
+++ b/lib/ldb/ldb_tdb/ldb_tdb.h
@@ -37,6 +37,8 @@ struct ltdb_private {
 
 	bool read_only;
 
+	bool reindex_failed;
+
 	const struct ldb_schema_syntax *GUID_index_syntax;
 };