if( g_slist_length(glk_data->image_cache) >= IMAGE_CACHE_MAX_NUM ) {
struct image_info *head = (struct image_info*) glk_data->image_cache->data;
if( g_slist_length(glk_data->image_cache) >= IMAGE_CACHE_MAX_NUM ) {
struct image_info *head = (struct image_info*) glk_data->image_cache->data;