Thank you Nicola,
When I use g_object_unref() instead of g_free(file_info); I've got this error :And you're also g_freeing a GFileInfo, which is a GObject. Try to use g_object_unref() instead. Ciao
(process:30949): GLib-GObject-CRITICAL **: g_object_unref: assertion `G_IS_OBJECT (object)' failed