Fix for bug #46456 [Ver->Prg]: HANDLER OPEN + TRUNCATE + DROP

(temporary) TABLE, crash

Problem: if one has an open "HANDLER t1", further "TRUNCATE t1" 
doesn't close the handler and leaves handler table hash in an 
inconsistent state, that may lead to a server crash.

Fix: TRUNCATE should implicitly close all open handlers.

Doc. request: the fact should be described in the manual accordingly.

mysql-test/r/handler_myisam.result

@@ -741,3 +741,19 @@ USE information_schema;
 HANDLER COLUMNS OPEN;
 ERROR HY000: Incorrect usage of HANDLER OPEN and information_schema
 USE test;
+#
+# BUG #46456: HANDLER OPEN + TRUNCATE + DROP (temporary) TABLE, crash 
+#
+CREATE TABLE t1 AS SELECT 1 AS f1;
+HANDLER t1 OPEN;
+TRUNCATE t1;
+HANDLER t1 READ FIRST;
+ERROR 42S02: Unknown table 't1' in HANDLER
+DROP TABLE t1;
+CREATE TEMPORARY TABLE t1 AS SELECT 1 AS f1;
+HANDLER t1 OPEN;
+TRUNCATE t1;
+HANDLER t1 READ FIRST;
+ERROR 42S02: Unknown table 't1' in HANDLER
+DROP TABLE t1;
+End of 5.1 tests

mysql-test/t/handler_myisam.test

@@ -19,3 +19,22 @@ let $other_engine_type= MEMORY;
 let $other_handler_engine_type= MyISAM;
 
 --source include/handler.inc
+
+--echo #
+--echo # BUG #46456: HANDLER OPEN + TRUNCATE + DROP (temporary) TABLE, crash 
+--echo #
+CREATE TABLE t1 AS SELECT 1 AS f1; 
+HANDLER t1 OPEN;
+TRUNCATE t1;
+--error ER_UNKNOWN_TABLE
+HANDLER t1 READ FIRST;
+DROP TABLE t1;
+
+CREATE TEMPORARY TABLE t1 AS SELECT 1 AS f1; 
+HANDLER t1 OPEN;
+TRUNCATE t1;
+--error ER_UNKNOWN_TABLE
+HANDLER t1 READ FIRST;
+DROP TABLE t1;
+
+--echo End of 5.1 tests

sql/sql_delete.cc

@@ -1066,6 +1066,10 @@ bool mysql_truncate(THD *thd, TABLE_LIST *table_list, bool dont_send_ok)
   DBUG_ENTER("mysql_truncate");
 
   bzero((char*) &create_info,sizeof(create_info));
+
+  /* Remove tables from the HANDLER's hash. */
+  mysql_ha_rm_tables(thd, table_list, FALSE);
+
   /* If it is a temporary table, close and regenerate it */
   if (!dont_send_ok && (table= find_temporary_table(thd, table_list)))
   {