fix for bug#16394 "Events: Crash if schedule contains SELECT"

Parsing of CREATE/ALTER EVENT statement was crashing because of early
initialization done during parsing, instead in the after parsing phase.
Moreover, we don't want SUBqueries in CREATE/ALTER EVENT therefore we
disable them, though it is possible to make them work. It can be emulated
inside SP with a cursor and SP variable (CREATE/ALTER EVENT can still
accept variables as values).


mysql-test/r/events_bugs.result:
  update result
mysql-test/t/events_bugs.test:
  tests for bug#16384
sql/sql_yacc.yy:
  disallow subqueries when SQLCOM_CREATE_EVENT | SQLCOM_ALTER_EVENT
  The fix is not big, though lex->forbid_subqueries could have been introduced.
  Easier is just to set the sql_command and check in both rules where
  subqueries enter.

mysql-test/r/events_bugs.result

@@ -190,4 +190,12 @@ events_test	mysqltest_user1	mysqltest_user1@localhost	RECURRING	ENABLED
 drop event events_test.mysqltest_user1;
 drop user mysqltest_user1@localhost;
 drop database mysqltest_db1;
+create event e_53 on schedule at (select s1 from ttx) do drop table t;
+ERROR 42000: You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near 'select s1 from ttx) do drop table t' at line 1
+create event e_53 on schedule every (select s1 from ttx) second do drop table t;
+ERROR 42000: You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near 'select s1 from ttx) second do drop table t' at line 1
+create event e_53 on schedule every 5 second starts (select s1 from ttx) do drop table t;
+ERROR 42000: You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near 'select s1 from ttx) do drop table t' at line 1
+create event e_53 on schedule every 5 second ends (select s1 from ttx) do drop table t;
+ERROR 42000: You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near 'select s1 from ttx) do drop table t' at line 1
 drop database events_test;

mysql-test/t/events_bugs.test

@@ -198,4 +198,19 @@ drop database mysqltest_db1;
 # END   - 18897: Events: unauthorized action possible with alter event rename
 #
 
+#
+# START - BUG#16394: Events: Crash if schedule contains SELECT
+#
+--error ER_PARSE_ERROR
+create event e_53 on schedule at (select s1 from ttx) do drop table t;
+--error ER_PARSE_ERROR
+create event e_53 on schedule every (select s1 from ttx) second do drop table t;
+--error ER_PARSE_ERROR
+create event e_53 on schedule every 5 second starts (select s1 from ttx) do drop table t;
+--error ER_PARSE_ERROR
+create event e_53 on schedule every 5 second ends (select s1 from ttx) do drop table t;
+#
+# END   - BUG#16394: Events: Crash if schedule contains SELECT
+#
+
 drop database events_test;

sql/sql_yacc.yy

@@ -1303,6 +1303,9 @@ event_tail:
             */
             $<ulong_num>$= YYTHD->client_capabilities & CLIENT_MULTI_QUERIES;
             YYTHD->client_capabilities &= (~CLIENT_MULTI_QUERIES);
+
+            /* We need that for disallowing subqueries */
+            Lex->sql_command= SQLCOM_CREATE_EVENT;
           }
           ON SCHEDULE_SYM ev_schedule_time
           opt_ev_on_completion
@@ -4638,6 +4641,9 @@ alter:
             */
             $<ulong_num>$= YYTHD->client_capabilities & CLIENT_MULTI_QUERIES;
             YYTHD->client_capabilities &= ~CLIENT_MULTI_QUERIES;
+
+            /* we need that for disallowing subqueries */
+            Lex->sql_command= SQLCOM_ALTER_EVENT;
           }
           ev_alter_on_schedule_completion
           opt_ev_rename_to
@@ -4653,15 +4659,15 @@ alter:
             */
             YYTHD->client_capabilities |= $<ulong_num>4;
 
-            /*
-              sql_command is set here because some rules in ev_sql_stmt
-              can overwrite it
-            */
             if (!($5 || $6 || $7 || $8 || $9))
             {
 	      yyerror(ER(ER_SYNTAX_ERROR));
               YYABORT;
             }
+            /*
+              sql_command is set here because some rules in ev_sql_stmt
+              can overwrite it
+            */
             Lex->sql_command= SQLCOM_ALTER_EVENT;
           }
         | ALTER TABLESPACE alter_tablespace_info
@@ -6959,8 +6965,10 @@ select_derived2:
         {
 	  LEX *lex= Lex;
 	  lex->derived_tables|= DERIVED_SUBQUERY;
-          if (lex->sql_command == (int)SQLCOM_HA_READ ||
-              lex->sql_command == (int)SQLCOM_KILL)
+          if (lex->sql_command == SQLCOM_HA_READ ||
+              lex->sql_command == SQLCOM_KILL ||
+              lex->sql_command == SQLCOM_CREATE_EVENT ||
+              lex->sql_command == SQLCOM_ALTER_EVENT)
 	  {
 	    yyerror(ER(ER_SYNTAX_ERROR));
 	    YYABORT;
@@ -10592,8 +10600,10 @@ subselect_start:
 	'(' SELECT_SYM
 	{
 	  LEX *lex=Lex;
-          if (lex->sql_command == (int)SQLCOM_HA_READ ||
-              lex->sql_command == (int)SQLCOM_KILL)
+          if (lex->sql_command == SQLCOM_HA_READ ||
+              lex->sql_command == SQLCOM_KILL ||
+              lex->sql_command == SQLCOM_CREATE_EVENT ||
+              lex->sql_command == SQLCOM_ALTER_EVENT)
 	  {
             yyerror(ER(ER_SYNTAX_ERROR));
 	    YYABORT;