MDEV-7996 : CURRENT_USER definer does not replicate for triggers

THD's lex->definer initially holds "*current_user" for CURRENT_USER().
As a result when wsrep tries to create the trigger query, it incorrectly
uses "*current_user". Fixed by calling get_current_user() to get the
real current user.

Merged galera_create_trigger.test from github.com/codership/mysql-wsrep.

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

+CREATE TABLE definer_root (f1 INTEGER, trigger_user VARCHAR(100)) ENGINE=InnoDB;
+CREATE TABLE definer_user (f1 INTEGER, trigger_user VARCHAR(100)) ENGINE=InnoDB;
+CREATE TABLE definer_current_user (f1 INTEGER, trigger_user VARCHAR(100)) ENGINE=InnoDB;
+CREATE TABLE definer_default (f1 INTEGER, trigger_user VARCHAR(100)) ENGINE=InnoDB;
+CREATE USER 'user1';
+CREATE DEFINER=root@localhost TRIGGER definer_root BEFORE INSERT ON definer_root FOR EACH ROW SET NEW.trigger_user = CURRENT_USER();
+CREATE DEFINER=user1 TRIGGER definer_user BEFORE INSERT ON definer_user FOR EACH ROW SET NEW.trigger_user = CURRENT_USER();
+CREATE DEFINER=current_user TRIGGER definer_current_user BEFORE INSERT ON definer_current_user FOR EACH ROW SET NEW.trigger_user = CURRENT_USER();
+CREATE TRIGGER definer_default BEFORE INSERT ON definer_default FOR EACH ROW SET NEW.trigger_user = CURRENT_USER();
+INSERT INTO definer_root (f1) VALUES (1);
+SELECT DEFINER = 'root@localhost' FROM INFORMATION_SCHEMA.TRIGGERS WHERE TRIGGER_NAME = 'definer_root';
+DEFINER = 'root@localhost'
+1
+SELECT trigger_user = 'root@localhost' FROM definer_root;
+trigger_user = 'root@localhost'
+1
+INSERT INTO definer_user (f1) VALUES (1);
+SELECT DEFINER = 'user1@%' FROM INFORMATION_SCHEMA.TRIGGERS WHERE TRIGGER_NAME = 'definer_user';
+DEFINER = 'user1@%'
+1
+SELECT trigger_user = 'user1@%' FROM definer_user;
+trigger_user = 'user1@%'
+1
+INSERT INTO definer_current_user (f1) VALUES (1);
+SELECT DEFINER = 'root@localhost' FROM INFORMATION_SCHEMA.TRIGGERS WHERE TRIGGER_NAME = 'definer_current_user';
+DEFINER = 'root@localhost'
+1
+SELECT trigger_user = 'root@localhost' FROM definer_current_user;
+trigger_user = 'root@localhost'
+1
+INSERT INTO definer_default (f1) VALUES (1);
+SELECT DEFINER = 'root@localhost' FROM INFORMATION_SCHEMA.TRIGGERS WHERE TRIGGER_NAME = 'definer_default';
+DEFINER = 'root@localhost'
+1
+SELECT trigger_user = 'root@localhost' FROM definer_default;
+trigger_user = 'root@localhost'
+1
+DROP TABLE definer_current_user;
+DROP TABLE definer_user;
+DROP TABLE definer_root;
+DROP TABLE definer_default;
+DROP USER 'user1';

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

+--source include/galera_cluster.inc
+--source include/have_innodb.inc
+
+#
+# Test CREATE TRIGGER, especially with different DEFINER
+#
+
+CREATE TABLE definer_root (f1 INTEGER, trigger_user VARCHAR(100)) ENGINE=InnoDB;
+CREATE TABLE definer_user (f1 INTEGER, trigger_user VARCHAR(100)) ENGINE=InnoDB;
+CREATE TABLE definer_current_user (f1 INTEGER, trigger_user VARCHAR(100)) ENGINE=InnoDB;
+CREATE TABLE definer_default (f1 INTEGER, trigger_user VARCHAR(100)) ENGINE=InnoDB;
+
+CREATE USER 'user1';
+CREATE DEFINER=root@localhost TRIGGER definer_root BEFORE INSERT ON definer_root FOR EACH ROW SET NEW.trigger_user = CURRENT_USER();
+CREATE DEFINER=user1 TRIGGER definer_user BEFORE INSERT ON definer_user FOR EACH ROW SET NEW.trigger_user = CURRENT_USER();
+CREATE DEFINER=current_user TRIGGER definer_current_user BEFORE INSERT ON definer_current_user FOR EACH ROW SET NEW.trigger_user = CURRENT_USER();
+CREATE TRIGGER definer_default BEFORE INSERT ON definer_default FOR EACH ROW SET NEW.trigger_user = CURRENT_USER();
+
+--connection node_2
+INSERT INTO definer_root (f1) VALUES (1);
+SELECT DEFINER = 'root@localhost' FROM INFORMATION_SCHEMA.TRIGGERS WHERE TRIGGER_NAME = 'definer_root';
+SELECT trigger_user = 'root@localhost' FROM definer_root;
+
+INSERT INTO definer_user (f1) VALUES (1);
+SELECT DEFINER = 'user1@%' FROM INFORMATION_SCHEMA.TRIGGERS WHERE TRIGGER_NAME = 'definer_user';
+SELECT trigger_user = 'user1@%' FROM definer_user;
+
+INSERT INTO definer_current_user (f1) VALUES (1);
+SELECT DEFINER = 'root@localhost' FROM INFORMATION_SCHEMA.TRIGGERS WHERE TRIGGER_NAME = 'definer_current_user';
+SELECT trigger_user = 'root@localhost' FROM definer_current_user;
+
+INSERT INTO definer_default (f1) VALUES (1);
+SELECT DEFINER = 'root@localhost' FROM INFORMATION_SCHEMA.TRIGGERS WHERE TRIGGER_NAME = 'definer_default';
+SELECT trigger_user = 'root@localhost' FROM definer_default;
+
+--connection node_1
+DROP TABLE definer_current_user;
+DROP TABLE definer_user;
+DROP TABLE definer_root;
+DROP TABLE definer_default;
+
+DROP USER 'user1';
+

sql/sql_trigger.cc

@@ -2464,9 +2464,13 @@ int wsrep_create_trigger_query(THD *thd, uchar** buf, size_t* buf_len)
   if (lex->definer)
   {
     /* SUID trigger. */
+    LEX_USER *d= get_current_user(thd, lex->definer);
 
-    definer_user= lex->definer->user;
-    definer_host= lex->definer->host;
+    if (!d)
+      return 1;
+
+    definer_user= d->user;
+    definer_host= d->host;
   }
   else
   {