Bug#48449: hang on show create view after upgrading when view contains function of view

SHOW CREATE TABLE on a view (v1) that contains a function whose
statement uses another view (v2), could trigger a infinite loop
if the view referenced within the function causes a warning to
be raised while opening the said view (v2).

The problem was a infinite loop over the stack of internal error
handlers. The problem would be triggered if the stack contained
two or more handlers and the first two handlers didn't handle the
raised condition. In this case, the loop variable would always
point to the second handler in the stack.

The solution is to correct the loop variable assignment so that
the loop is able to iterate over all handlers in the stack.

mysql-test/r/view.result:
  Add test case result for Bug#48449.
mysql-test/std_data/bug48449.frm:
  Add a incomplete view definition that causes a warning to be
  issued.
mysql-test/t/view.test:
  Add test case for Bug#48449
sql/sql_class.cc:
  Iterate over all handlers in the stack.

mysql-test/r/view.result

@@ -3854,6 +3854,30 @@ 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;
+#
+# Bug#48449: hang on show create view after upgrading when
+#            view contains function of view
+#
+DROP VIEW IF EXISTS v1,v2;
+DROP TABLE IF EXISTS t1,t2;
+DROP FUNCTION IF EXISTS f1;
+CREATE TABLE t1 (a INT);
+CREATE TABLE t2 (a INT);
+CREATE FUNCTION f1() RETURNS INT
+BEGIN
+SELECT a FROM v2 INTO @a;
+RETURN @a;
+END//
+# Trigger pre-locking when opening v2.
+CREATE VIEW v1 AS SELECT f1() FROM t1;
+SHOW CREATE VIEW v1;
+View	Create View	character_set_client	collation_connection
+v1	CREATE ALGORITHM=UNDEFINED DEFINER=`root`@`localhost` SQL SECURITY DEFINER VIEW `v1` AS select `f1`() AS `f1()` from `t1`	latin1	latin1_swedish_ci
+Warnings:
+Note	1599	View `test`.`v2` has no creation context
+DROP VIEW v1,v2;
+DROP TABLE t1,t2;
+DROP FUNCTION f1;
 # -----------------------------------------------------------------
 # -- End of 5.1 tests.
 # -----------------------------------------------------------------

mysql-test/t/view.test

@@ -3882,6 +3882,40 @@ CREATE DEFINER=`unknown`@`unknown` SQL SECURITY DEFINER VIEW v1 AS SELECT 1;
 LOCK TABLES v1 READ;
 DROP VIEW v1;
 
+--echo #
+--echo # Bug#48449: hang on show create view after upgrading when
+--echo #            view contains function of view
+--echo #
+
+--disable_warnings
+DROP VIEW IF EXISTS v1,v2;
+DROP TABLE IF EXISTS t1,t2;
+DROP FUNCTION IF EXISTS f1;
+--enable_warnings
+
+CREATE TABLE t1 (a INT);
+CREATE TABLE t2 (a INT);
+
+delimiter //;
+CREATE FUNCTION f1() RETURNS INT
+BEGIN
+  SELECT a FROM v2 INTO @a;
+  RETURN @a;
+END//
+delimiter ;//
+
+--echo # Trigger pre-locking when opening v2.
+CREATE VIEW v1 AS SELECT f1() FROM t1;
+
+let $MYSQLD_DATADIR= `SELECT @@datadir`;
+copy_file std_data/bug48449.frm $MYSQLD_DATADIR/test/v2.frm;
+
+SHOW CREATE VIEW v1;
+
+DROP VIEW v1,v2;
+DROP TABLE t1,t2;
+DROP FUNCTION f1;
+
 --echo # -----------------------------------------------------------------
 --echo # -- End of 5.1 tests.
 --echo # -----------------------------------------------------------------

sql/sql_class.cc

@@ -725,15 +725,12 @@ void THD::push_internal_handler(Internal_error_handler *handler)
 bool THD::handle_error(uint sql_errno, const char *message,
                        MYSQL_ERROR::enum_warning_level level)
 {
-  if (!m_internal_handler)
-    return FALSE;
-
   for (Internal_error_handler *error_handler= m_internal_handler;
        error_handler;
-       error_handler= m_internal_handler->m_prev_internal_handler)
+       error_handler= error_handler->m_prev_internal_handler)
   {
     if (error_handler->handle_error(sql_errno, message, level, this))
-    return TRUE;
+      return TRUE;
   }
 
   return FALSE;