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.

1 files changed, 18 insertions, 0 deletions

diff --git a/sql/item_func.cc b/sql/item_func.cc
index ed08555133f..2f5130886e6 100644
--- a/sql/item_func.cc
+++ b/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);