Bug#47734: Assertion failed: ! is_set() when locking a view with non-existing definer

The problem was that a failure to open a view wasn't being
properly handled. When opening a view with unknown definer,
the open procedure would be treated as successful and would
later crash when attempting to lock the view (which wasn't
opened to begin with).

The solution is to skip further processing when opening a
table if it fails with a fatal error.

mysql-test/r/view.result:
  Add test case result for Bug#47734.
mysql-test/t/view.test:
  Add test case for Bug#47734.
sql/sql_base.cc:
  Skip further processing if opening a table failed due to
  a fatal error (for the statement).

mysql-test/r/view.result

@@ -3844,6 +3844,16 @@ CREATE VIEW v1 AS SELECT a FROM t1;
 ALTER TABLE v1;
 DROP VIEW v1;
 DROP TABLE t1;
+#
+# Bug#47734: Assertion failed: ! is_set() when locking a view with non-existing definer
+#
+DROP VIEW IF EXISTS v1;
+CREATE DEFINER=`unknown`@`unknown` SQL SECURITY DEFINER VIEW v1 AS SELECT 1;
+Warnings:
+Note	1449	The user specified as a definer ('unknown'@'unknown') does not exist
+LOCK TABLES v1 READ;
+ERROR HY000: The user specified as a definer ('unknown'@'unknown') does not exist
+DROP VIEW v1;
 # -----------------------------------------------------------------
 # -- End of 5.1 tests.
 # -----------------------------------------------------------------

mysql-test/t/view.test

@@ -3869,6 +3869,18 @@ ALTER TABLE v1;
 DROP VIEW v1;
 DROP TABLE t1;
 
+--echo #
+--echo # Bug#47734: Assertion failed: ! is_set() when locking a view with non-existing definer
+--echo #
+
+--disable_warnings
+DROP VIEW IF EXISTS v1;
+--enable_warnings
+
+CREATE DEFINER=`unknown`@`unknown` SQL SECURITY DEFINER VIEW v1 AS SELECT 1;
+--error ER_NO_SUCH_USER
+LOCK TABLES v1 READ;
+DROP VIEW v1;
 
 --echo # -----------------------------------------------------------------
 --echo # -- End of 5.1 tests.

sql/sql_base.cc

@@ -4591,7 +4591,20 @@ int open_tables(THD *thd, TABLE_LIST **start, uint *counter, uint flags)
         safe_to_ignore_table= prelock_handler.safely_trapped_errors();
       }
       else
+      {
         tables->table= open_table(thd, tables, &new_frm_mem, &refresh, flags);
+
+        /*
+          Skip further processing if there has been a fatal error while
+          trying to open a table. For example, this might happen due to
+          stack shortage, unknown definer in views, etc.
+        */
+        if (!tables->table && thd->is_error())
+        {
+          result= -1;
+          goto err;
+        }
+      }
     }
     else
       DBUG_PRINT("tcache", ("referenced table: '%s'.'%s' 0x%lx",