MDEV-9401: wsrep_forced_binlog_format with binlog causes crash

Some statements are always replicated in STATEMENT binlog format.
So upon their execution, the current binlog format is temporarily
switched to STATEMENT even though the session's format is different.
This state, stored in THD's current_stmt_binlog_format, was getting
incorrectly masked by wsrep_forced_binlog_format, causing assertions
and unintended generation of row events.

Backported galera.galera_forced_binlog_format and added a test
specific to this case.

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

@@ -0,0 +1,40 @@
+RESET MASTER;
+SET SESSION binlog_format = 'STATEMENT';
+Warnings:
+Warning	1105	MariaDB Galera does not support binlog format: STATEMENT
+CREATE TABLE t1 (f1 INTEGER PRIMARY KEY) ENGINE=InnoDB;
+INSERT INTO t1 VALUES (1);
+SET SESSION binlog_format = 'MIXED';
+Warnings:
+Warning	1105	MariaDB Galera does not support binlog format: MIXED
+INSERT INTO t1 VALUES (2);
+SHOW BINLOG EVENTS IN 'mysqld-bin.000001' FROM 245;
+Log_name	Pos	Event_type	Server_id	End_log_pos	Info
+mysqld-bin.000001	<Pos>	Query	1	<End_log_pos>	use `test`; CREATE TABLE t1 (f1 INTEGER PRIMARY KEY) ENGINE=InnoDB
+mysqld-bin.000001	<Pos>	Query	1	<End_log_pos>	BEGIN
+mysqld-bin.000001	<Pos>	Table_map	1	<End_log_pos>	table_id: ### (test.t1)
+mysqld-bin.000001	<Pos>	Write_rows	1	<End_log_pos>	table_id: ### flags: STMT_END_F
+mysqld-bin.000001	<Pos>	Xid	1	<End_log_pos>	COMMIT /* xid=### */
+mysqld-bin.000001	<Pos>	Query	1	<End_log_pos>	BEGIN
+mysqld-bin.000001	<Pos>	Table_map	1	<End_log_pos>	table_id: ### (test.t1)
+mysqld-bin.000001	<Pos>	Write_rows	1	<End_log_pos>	table_id: ### flags: STMT_END_F
+mysqld-bin.000001	<Pos>	Xid	1	<End_log_pos>	COMMIT /* xid=### */
+DROP TABLE t1;
+#
+# MDEV-9401: wsrep_forced_binlog_format with binlog causes crash
+#
+SET SESSION binlog_format = 'ROW';
+CREATE DATABASE testdb_9401;
+USE testdb_9401;
+CREATE TABLE t1 (f1 INTEGER PRIMARY KEY) ENGINE=InnoDB;
+CREATE USER dummy@localhost;
+GRANT ALL PRIVILEGES ON testdb_9401.t1 TO dummy@localhost;
+FLUSH PRIVILEGES;
+SHOW GRANTS FOR dummy@localhost;
+Grants for dummy@localhost
+GRANT USAGE ON *.* TO 'dummy'@'localhost'
+GRANT ALL PRIVILEGES ON `testdb_9401`.`t1` TO 'dummy'@'localhost'
+REVOKE ALL PRIVILEGES, GRANT OPTION FROM dummy@localhost;
+DROP USER dummy@localhost;
+DROP DATABASE testdb_9401;
+# End of tests

mysql-test/suite/galera/t/galera_forced_binlog_format-master.opt

@@ -0,0 +1 @@
+--log-bin --wsrep_forced_binlog_format=ROW

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

@@ -0,0 +1,45 @@
+#
+# Test that wsrep_forced_binlog_format=ROW indeed prevents the log to be switched to STATEMENT format on a per-connection basis
+# 
+
+--source include/have_log_bin.inc
+--source include/have_innodb.inc
+--source include/galera_cluster.inc
+
+--connection node_1
+RESET MASTER;
+
+SET SESSION binlog_format = 'STATEMENT';
+
+CREATE TABLE t1 (f1 INTEGER PRIMARY KEY) ENGINE=InnoDB;
+INSERT INTO t1 VALUES (1);
+
+SET SESSION binlog_format = 'MIXED';
+
+INSERT INTO t1 VALUES (2);
+
+--replace_regex /xid=[0-9]+/xid=###/ /table_id: [0-9]+/table_id: ###/
+--replace_column 2 <Pos> 5 <End_log_pos>
+SHOW BINLOG EVENTS IN 'mysqld-bin.000001' FROM 245;
+
+DROP TABLE t1;
+
+--echo #
+--echo # MDEV-9401: wsrep_forced_binlog_format with binlog causes crash
+--echo #
+SET SESSION binlog_format = 'ROW';
+CREATE DATABASE testdb_9401;
+USE testdb_9401;
+CREATE TABLE t1 (f1 INTEGER PRIMARY KEY) ENGINE=InnoDB;
+CREATE USER dummy@localhost;
+GRANT ALL PRIVILEGES ON testdb_9401.t1 TO dummy@localhost;
+FLUSH PRIVILEGES;
+SHOW GRANTS FOR dummy@localhost;
+# Cleanup
+REVOKE ALL PRIVILEGES, GRANT OPTION FROM dummy@localhost;
+DROP USER dummy@localhost;
+DROP DATABASE testdb_9401;
+
+--source include/galera_end.inc
+--echo # End of tests
+

sql/sql_class.h

@@ -1824,8 +1824,7 @@ class THD :public Statement,
   int is_current_stmt_binlog_format_row() const {
     DBUG_ASSERT(current_stmt_binlog_format == BINLOG_FORMAT_STMT ||
                 current_stmt_binlog_format == BINLOG_FORMAT_ROW);
-    return (WSREP_BINLOG_FORMAT((ulong)current_stmt_binlog_format) ==
-            BINLOG_FORMAT_ROW);
+    return current_stmt_binlog_format == BINLOG_FORMAT_ROW;
   }
 
 private: