MDEV-24833 : Signal 11 on wsrep_can_run_in_toi at wsrep_mysqld.cc:1994

Problem was that when engine substitution is allowd (e.g. sql_mode='')
we must also check db_type. Additionally, we did not resolve
default storage engine on that case and used that to check is
TOI possible or not.

mysql-test/suite/galera/r/galera_can_run_toi.result

+connection node_2;
+connection node_1;
+SET sql_mode='';
+CREATE TABLE t3 (c1 VARCHAR(10));
+ALTER TABLE t3 ENGINE=NonExistentEngine;
+Warnings:
+Warning	1286	Unknown storage engine 'NonExistentEngine'
+SHOW CREATE TABLE t3;
+Table	Create Table
+t3	CREATE TABLE `t3` (
+  `c1` varchar(10) DEFAULT NULL
+) ENGINE=InnoDB DEFAULT CHARSET=latin1
+INSERT INTO t3 values (1);
+SET sql_mode=default;
+ALTER TABLE t3 engine=innodbCLUSTER;
+ERROR 42000: Unknown storage engine 'innodbCLUSTER'
+SHOW CREATE TABLE t3;
+Table	Create Table
+t3	CREATE TABLE `t3` (
+  `c1` varchar(10) DEFAULT NULL
+) ENGINE=InnoDB DEFAULT CHARSET=latin1
+DROP TABLE t3;
+SET sql_mode='';
+SET SESSION default_storage_engine=MyISAM;
+SELECT @@default_storage_engine;
+@@default_storage_engine
+MyISAM
+SET GLOBAL wsrep_replicate_myisam=OFF;
+SET GLOBAL wsrep_strict_ddl=ON;
+CREATE TABLE t3 (c1 VARCHAR(10)) ENGINE=InnoDB;
+ALTER TABLE t3 ENGINE=NonExistentEngine;
+ERROR HY000: DDL-statement is forbidden as table storage engine does not support Galera replication
+SHOW CREATE TABLE t3;
+Table	Create Table
+t3	CREATE TABLE `t3` (
+  `c1` varchar(10) DEFAULT NULL
+) ENGINE=InnoDB DEFAULT CHARSET=latin1
+DROP TABLE t3;

mysql-test/suite/galera/t/galera_can_run_toi.test

+--source include/galera_cluster.inc
+#
+# MDEV-24833 : Signal 11 on wsrep_can_run_in_toi at wsrep_mysqld.cc:1994
+#
+SET sql_mode='';
+CREATE TABLE t3 (c1 VARCHAR(10));
+ALTER TABLE t3 ENGINE=NonExistentEngine;
+SHOW CREATE TABLE t3;
+INSERT INTO t3 values (1);
+SET sql_mode=default;
+--error ER_UNKNOWN_STORAGE_ENGINE
+ALTER TABLE t3 engine=innodbCLUSTER;
+SHOW CREATE TABLE t3;
+DROP TABLE t3;
+#
+# Test default_storage_engine to engine that is not supported by Galera
+#
+SET sql_mode='';
+SET SESSION default_storage_engine=MyISAM;
+SELECT @@default_storage_engine;
+SET GLOBAL wsrep_replicate_myisam=OFF;
+SET GLOBAL wsrep_strict_ddl=ON;
+CREATE TABLE t3 (c1 VARCHAR(10)) ENGINE=InnoDB;
+--error ER_GALERA_REPLICATION_NOT_SUPPORTED
+ALTER TABLE t3 ENGINE=NonExistentEngine;
+SHOW CREATE TABLE t3;
+DROP TABLE t3;
+
+--disable_query_log
+SET GLOBAL sql_mode=default;
+SET GLOBAL default_storage_engine=default;
+SET GLOBAL wsrep_replicate_myisam=default;
+SET GLOBAL wsrep_strict_ddl=default;
+--enable_query_log

sql/wsrep_mysqld.cc

@@ -32,6 +32,7 @@
 #include "sp_head.h"
 #include "sql_show.h"
 #include "sp.h"
+#include "handler.h"
 #include "wsrep_priv.h"
 #include "wsrep_thd.h"
 #include "wsrep_sst.h"
@@ -1991,10 +1992,23 @@ bool wsrep_can_run_in_toi(THD *thd, const char *db, const char *table,
     return true;
     break;
   case SQLCOM_ALTER_TABLE:
-    if (create_info &&
-        !wsrep_should_replicate_ddl(thd, create_info->db_type->db_type))
-      return false;
-    /* fallthrough */
+  {
+    if (create_info)
+    {
+      enum legacy_db_type db_type;
+
+      if (create_info->db_type)
+        db_type= create_info->db_type->db_type;
+      else
+      {
+	const handlerton *hton= ha_default_handlerton(thd);
+	db_type= hton->db_type;
+      }
+      if (!wsrep_should_replicate_ddl(thd, db_type))
+        return false;
+    }
+  }
+  /* fallthrough */
   default:
     if (table && !thd->find_temporary_table(db, table))
     {