/*	$OpenBSD: tty.c,v 1.12 2021/07/12 15:09:20 beck Exp $	*/
/*	$NetBSD: tty.c,v 1.4 1994/12/07 00:46:57 jtc Exp $	*/

/*
 * Copyright (c) 1988, 1993
 *	The Regents of the University of California.  All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 * 3. Neither the name of the University nor the names of its contributors
 *    may be used to endorse or promote products derived from this software
 *    without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 */

#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <paths.h>
#include <err.h>

static void usage(void);

int
main(int argc, char *argv[])
{
	int ch, sflag;
	char *t;

	sflag = 0;
	while ((ch = getopt(argc, argv, "s")) != -1) {
		switch(ch) {
		case 's':
			sflag = 1;
			break;
		case '?':
		default:
			usage();
			/* NOTREACHED */
		}
	}

	if (unveil(_PATH_DEVDB, "r") == -1)
		err(1, "unveil %s", _PATH_DEVDB);
	if (pledge("stdio rpath", NULL) == -1)
		err(1, "pledge");

	t = ttyname(STDIN_FILENO);
	if (!sflag)
		puts(t ? t : "not a tty");
	exit(t ? 0 : 1);
}

static void
usage(void)
{
	fprintf(stderr, "usage: tty [-s]\n");
	exit(2);
}