+void add_notifier __P((struct notifier **, notify_func, void *));
+void remove_notifier __P((struct notifier **, notify_func, void *));
+void notify __P((struct notifier *, int));
+
+/* Procedures exported from tty.c. */
+void tty_init __P((void));
+void tty_device_check __P((void));
+void tty_check_options __P((void));
+int connect_tty __P((void));
+void disconnect_tty __P((void));
+void tty_close_fds __P((void));
+void cleanup_tty __P((void));