Merge bk-internal:/home/bk/mysql-5.0-runtime

into  mysql.com:/home/jimw/my/mysql-5.0-18005

mysql-test/r/trigger.result

@@ -1078,3 +1078,15 @@ i1
 43
 51
 DROP TABLE t1;
+create trigger wont_work after update on mysql.user for each row
+begin
+set @a:= 1;
+end|
+ERROR HY000: Triggers can not be created on system tables
+use mysql|
+create trigger wont_work after update on event for each row
+begin
+set @a:= 1;
+end|
+ERROR HY000: Triggers can not be created on system tables
+End of 5.0 tests

mysql-test/t/trigger.test

@@ -1281,4 +1281,26 @@ SELECT * FROM t1;
 
 DROP TABLE t1;
 
-# End of 5.0 tests
+#
+# Bug #18005: Creating a trigger on mysql.event leads to server crash on
+# scheduler startup
+#
+# Bug #18361: Triggers on mysql.user table cause server crash
+#
+# We don't allow triggers on the mysql schema
+delimiter |;
+--error ER_NO_TRIGGERS_ON_SYSTEM_SCHEMA
+create trigger wont_work after update on mysql.user for each row
+begin
+ set @a:= 1;
+end|
+# Try when we're already using the mysql schema
+use mysql|
+--error ER_NO_TRIGGERS_ON_SYSTEM_SCHEMA
+create trigger wont_work after update on event for each row
+begin
+ set @a:= 1;
+end|
+delimiter ;|
+
+--echo End of 5.0 tests

sql/share/errmsg.txt

@@ -5619,3 +5619,5 @@ ER_NON_GROUPING_FIELD_USED 42000
 	eng "non-grouping field '%-.64s' is used in %-.64s clause"
 ER_TABLE_CANT_HANDLE_SPKEYS
         eng "The used table type doesn't support SPATIAL indexes"
+ER_NO_TRIGGERS_ON_SYSTEM_SCHEMA
+	eng "Triggers can not be created on system tables"

sql/sql_trigger.cc

@@ -183,6 +183,15 @@ bool mysql_create_or_drop_trigger(THD *thd, TABLE_LIST *tables, bool create)
       !(tables= add_table_for_trigger(thd, thd->lex->spname)))
     DBUG_RETURN(TRUE);
 
+  /*
+    We don't allow creating triggers on tables in the 'mysql' schema
+  */
+  if (create && !my_strcasecmp(system_charset_info, "mysql", tables->db))
+  {
+    my_error(ER_NO_TRIGGERS_ON_SYSTEM_SCHEMA, MYF(0));
+    DBUG_RETURN(TRUE);
+  }
+
   /* We should have only one table in table list. */
   DBUG_ASSERT(tables->next_global == 0);