Bug #14875: Bad view DEFINER makes SHOW CREATE VIEW fail

When reading a view definition from a .frm file it was
throwing a SQL error if the DEFINER user is not defined.
Changed it to a warning to match the (documented) case
when a view with undefined DEFINER user is created.

mysql-test/r/view_grant.result

@@ -533,3 +533,18 @@ View	Create View
 v2	CREATE ALGORITHM=UNDEFINED DEFINER=`some_user`@`localhost` SQL SECURITY INVOKER VIEW `v2` AS select 1 AS `1`
 drop view v1;
 drop view v2;
+CREATE TABLE t1 (a INT PRIMARY KEY);
+INSERT INTO t1 VALUES (1), (2), (3);
+CREATE DEFINER = 'no-such-user'@localhost VIEW v AS SELECT a from t1;
+Warnings:
+Note	1449	There is no 'no-such-user'@'localhost' registered
+SHOW CREATE VIEW v;
+View	Create View
+v	CREATE ALGORITHM=UNDEFINED DEFINER=`no-such-user`@`localhost` SQL SECURITY DEFINER VIEW `v` AS select `t1`.`a` AS `a` from `t1`
+Warnings:
+Note	1449	There is no 'no-such-user'@'localhost' registered
+SELECT * FROM v;
+ERROR HY000: There is no 'no-such-user'@'localhost' registered
+DROP VIEW v;
+DROP TABLE t1;
+USE test;

mysql-test/t/view_grant.test

@@ -712,3 +712,17 @@ show create view v1;
 show create view v2;
 drop view v1;
 drop view v2;
+
+#
+# BUG#14875: Bad view DEFINER makes SHOW CREATE VIEW fail
+#
+CREATE TABLE t1 (a INT PRIMARY KEY);
+INSERT INTO t1 VALUES (1), (2), (3);
+CREATE DEFINER = 'no-such-user'@localhost VIEW v AS SELECT a from t1;
+--warning 1448
+SHOW CREATE VIEW v;
+--error 1449
+SELECT * FROM v;
+DROP VIEW v;
+DROP TABLE t1;
+USE test;

sql/sql_acl.cc

@@ -959,6 +959,8 @@ bool acl_getroot_no_password(Security_context *sctx, char *user, char *host,
 
   sctx->master_access= 0;
   sctx->db_access= 0;
+  sctx->priv_user= (char *) "";
+  *sctx->priv_host= 0;
 
   /*
      Find acl entry in user database.

sql/table.cc

@@ -2428,8 +2428,18 @@ bool st_table_list::prepare_view_securety_context(THD *thd)
                                 definer.host.str,
                                 thd->db))
     {
-      my_error(ER_NO_SUCH_USER, MYF(0), definer.user.str, definer.host.str);
-      DBUG_RETURN(TRUE);
+      if (thd->lex->sql_command == SQLCOM_SHOW_CREATE)
+      {
+        push_warning_printf(thd, MYSQL_ERROR::WARN_LEVEL_NOTE, 
+                            ER_NO_SUCH_USER, 
+                            ER(ER_NO_SUCH_USER),
+                            definer.user.str, definer.host.str);
+      }
+      else
+      {
+        my_error(ER_NO_SUCH_USER, MYF(0), definer.user.str, definer.host.str);
+        DBUG_RETURN(TRUE);
+      }
     }
   }
   DBUG_RETURN(FALSE);