fix for bug #12533 (crash on DESCRIBE <view> after renaming base table column)

mysql-test/r/view.result:
  result of test for bug #12533
mysql-test/t/view.test:
  test for bug #12533 (crash on DESCRIBE <view> after renaming base table column)
sql/sql_show.cc:
  close thread tables even if process_table bails out

mysql-test/r/view.result

@@ -2115,3 +2115,15 @@ CREATE VIEW v1 AS SELECT f1();
 ERROR HY000: View's SELECT refers to a temporary table 't1'
 DROP FUNCTION f1;
 DROP TABLE t1;
+DROP TABLE IF EXISTS t1;
+DROP VIEW  IF EXISTS v1;
+CREATE TABLE t1 (f4 CHAR(5));
+CREATE VIEW v1 AS SELECT * FROM t1;
+DESCRIBE v1;
+Field	Type	Null	Key	Default	Extra
+f4	char(5)	YES		NULL	
+ALTER TABLE t1 CHANGE COLUMN f4 f4x CHAR(5);
+DESCRIBE v1;
+ERROR HY000: View 'test.v1' references invalid table(s) or column(s) or function(s)
+DROP TABLE t1;
+DROP VIEW v1;

mysql-test/t/view.test

@@ -1966,3 +1966,20 @@ CREATE VIEW v1 AS SELECT f1();
 DROP FUNCTION f1;
 DROP TABLE t1;
 
+#
+# BUG #12533 (crash on DESCRIBE <view> after renaming base table column)
+#
+--disable_warnings
+DROP TABLE IF EXISTS t1;
+DROP VIEW  IF EXISTS v1;
+--enable_warnings
+
+CREATE TABLE t1 (f4 CHAR(5));
+CREATE VIEW v1 AS SELECT * FROM t1;
+DESCRIBE v1;
+
+ALTER TABLE t1 CHANGE COLUMN f4 f4x CHAR(5);
+--error 1356
+DESCRIBE v1;
+DROP TABLE t1;
+DROP VIEW v1;

sql/sql_show.cc

@@ -1985,13 +1985,15 @@ int get_all_tables(THD *thd, TABLE_LIST *tables, COND *cond)
     lex->all_selects_list= lsel;
     res= open_normal_and_derived_tables(thd, show_table_list,
                                         MYSQL_LOCK_IGNORE_FLUSH);
-    if (schema_table->process_table(thd, show_table_list,
+    /*
+      get_all_tables() returns 1 on failure and 0 on success thus
+      return only these and not the result code of ::process_table()
+    */
+    error= test(schema_table->process_table(thd, show_table_list,
                                     table, res, show_table_list->db,
-                                    show_table_list->alias))
-      goto err;
+                                    show_table_list->alias));
     close_thread_tables(thd);
     show_table_list->table= 0;
-    error= 0;
     goto err;
   }
 
@@ -2090,11 +2092,12 @@ int get_all_tables(THD *thd, TABLE_LIST *tables, COND *cond)
             lex->derived_tables= 0;
             res= open_normal_and_derived_tables(thd, show_table_list,
                                                 MYSQL_LOCK_IGNORE_FLUSH);
-            if (schema_table->process_table(thd, show_table_list, table,
+            res= schema_table->process_table(thd, show_table_list, table,
                                             res, base_name,
-                                            show_table_list->alias))
-              goto err;
+                                            show_table_list->alias);
             close_thread_tables(thd);
+            if (res)
+              goto err;
           }
         }
       }