MDEV-4017 - GET_LOCK() with negative timeouts has strange behavior

GET_LOCK() silently accepted negative values and NULL for timeout.
Fixed GET_LOCK() to issue a warning and return NULL in such cases.

mysql-test/extra/binlog_tests/mix_innodb_myisam_binlog.test

@@ -228,7 +228,7 @@ rollback;
 create table t0 (n int);
 insert t0 select * from t1;
 set autocommit=1;
-insert into t0 select GET_LOCK("lock1",null);
+insert into t0 select GET_LOCK("lock1",0);
 set autocommit=0;
 create table t2 (n int) engine=innodb;
 insert into t2 values (3); 

mysql-test/r/func_misc.result

@@ -361,5 +361,18 @@ set optimizer_switch=@optimizer_switch_save;
 drop view  v_merge, vm;
 drop table t1,tv;
 #
+# MDEV-4017 - GET_LOCK() with negative timeouts has strange behavior
+#
+SELECT GET_LOCK('ul1', NULL);
+GET_LOCK('ul1', NULL)
+NULL
+Warnings:
+Warning	1411	Incorrect timeout value: 'NULL' for function get_lock
+SELECT GET_LOCK('ul1', -1);
+GET_LOCK('ul1', -1)
+NULL
+Warnings:
+Warning	1411	Incorrect timeout value: '-1' for function get_lock
+#
 # End of 5.5 tests
 #

mysql-test/suite/binlog/r/binlog_row_mix_innodb_myisam.result

@@ -258,7 +258,7 @@ Warning	1196	Some non-transactional changed tables couldn't be rolled back
 create table t0 (n int);
 insert t0 select * from t1;
 set autocommit=1;
-insert into t0 select GET_LOCK("lock1",null);
+insert into t0 select GET_LOCK("lock1",0);
 set autocommit=0;
 create table t2 (n int) engine=innodb;
 insert into t2 values (3);

mysql-test/suite/binlog/r/binlog_stm_mix_innodb_myisam.result

@@ -242,7 +242,7 @@ Warning	1196	Some non-transactional changed tables couldn't be rolled back
 create table t0 (n int);
 insert t0 select * from t1;
 set autocommit=1;
-insert into t0 select GET_LOCK("lock1",null);
+insert into t0 select GET_LOCK("lock1",0);
 Warnings:
 Note	1592	Unsafe statement written to the binary log using statement format since BINLOG_FORMAT = STATEMENT. Statement is unsafe because it uses a system function that may return a different value on the slave.
 set autocommit=0;
@@ -288,7 +288,7 @@ master-bin.000001	#	Query	#	#	BEGIN
 master-bin.000001	#	Query	#	#	use `test`; insert t0 select * from t1
 master-bin.000001	#	Query	#	#	COMMIT
 master-bin.000001	#	Query	#	#	BEGIN
-master-bin.000001	#	Query	#	#	use `test`; insert into t0 select GET_LOCK("lock1",null)
+master-bin.000001	#	Query	#	#	use `test`; insert into t0 select GET_LOCK("lock1",0)
 master-bin.000001	#	Query	#	#	COMMIT
 master-bin.000001	#	Query	#	#	use `test`; create table t2 (n int) engine=innodb
 master-bin.000001	#	Query	#	#	use `test`; DROP /*!40005 TEMPORARY */ TABLE IF EXISTS `t1`,`ti`

mysql-test/t/func_misc.test

@@ -391,6 +391,11 @@ set optimizer_switch=@optimizer_switch_save;
 drop view  v_merge, vm;
 drop table t1,tv;
 
+--echo #
+--echo # MDEV-4017 - GET_LOCK() with negative timeouts has strange behavior
+--echo #
+SELECT GET_LOCK('ul1', NULL);
+SELECT GET_LOCK('ul1', -1);
 
 --echo #
 --echo # End of 5.5 tests

sql/item_func.cc

@@ -4184,7 +4184,25 @@ longlong Item_func_get_lock::val_int()
     it's not guaranteed to be same as on master.
   */
   if (thd->slave_thread)
+  {
+    null_value= 0;
     DBUG_RETURN(1);
+  }
+
+  if (args[1]->null_value ||
+      (!args[1]->unsigned_flag && ((longlong) timeout < 0)))
+  {
+    char buf[22];
+    if (args[1]->null_value)
+      strmov(buf, "NULL");
+    else
+      llstr(((longlong) timeout), buf);
+    push_warning_printf(thd, MYSQL_ERROR::WARN_LEVEL_WARN,
+                        ER_WRONG_VALUE_FOR_TYPE, ER(ER_WRONG_VALUE_FOR_TYPE),
+                        "timeout", buf, "get_lock");
+    null_value= 1;
+    DBUG_RETURN(0);
+  }
 
   mysql_mutex_lock(&LOCK_user_locks);