rem: 0 from the list */
add: * 0 from the list */
context: void send_uid_list(int f){	struct idlist *list;	if (numeric_ids) return;	if (preserve_uid) {		/* we send sequences of uid/byte-length/name */		list = uidlist;		while (list) {			int len = strlen(list->name);			write_int(f, list->id);			write_byte(f, len);			write_buf(f, list->name, len);			list = list->next;		}		/* terminate the uid list with a 0 uid. We explicitly exclude		   0 from the list */		write_int(f, 0);	}	if (preserve_gid) {		list = gidlist;		while (list) {			int len = strlen(list->name);			write_int(f, list->id);			write_byte(f, len);			write_buf(f, list->name, len);			list = list->next;		}		write_int(f, 0);	}}