Bug#27302459: EMPTY VALUE IN MYSQL.PLUGIN TABLE CAUSES SERVER TO EXIT ON STARTUP

Description:- During server startup, the server exits if
the 'mysql.plugin' system table has any rows with empty
value for the field 'name' (plugin name).

mysql-test/r/plugin.result

@@ -277,3 +277,5 @@ UNUSABLE
 uninstall soname 'ha_example';
 select plugin_name from information_schema.plugins where plugin_library like 'ha_example%';
 plugin_name
+insert mysql.plugin values ();
+delete from mysql.plugin where name = '';

mysql-test/t/plugin.test

@@ -224,3 +224,9 @@ select plugin_name from information_schema.plugins where plugin_library like 'ha
 uninstall soname 'ha_example';
 select plugin_name from information_schema.plugins where plugin_library like 'ha_example%';
 
+#
+# Bug#27302459: EMPTY VALUE IN MYSQL.PLUGIN TABLE CAUSES SERVER TO EXIT ON STARTUP
+#
+insert mysql.plugin values ();
+source include/restart_mysqld.inc;
+delete from mysql.plugin where name = '';

sql/sql_plugin.cc

@@ -1781,6 +1781,9 @@ static void plugin_load(MEM_ROOT *tmp_root)
     LEX_STRING name= {(char *)str_name.ptr(), str_name.length()};
     LEX_STRING dl= {(char *)str_dl.ptr(), str_dl.length()};
 
+    if (!name.length || !dl.length)
+      continue;
+
     /*
       there're no other threads running yet, so we don't need a mutex.
       but plugin_add() before is designed to work in multi-threaded