1/*	$NetBSD: mesg.c,v 1.7 2005/07/30 16:14:39 christos Exp $	*/
2
3/*
4 * Copyright (c) 1987, 1993
5 *	The Regents of the University of California.  All rights reserved.
6 * (c) UNIX System Laboratories, Inc.
7 * All or some portions of this file are derived from material licensed
8 * to the University of California by American Telephone and Telegraph
9 * Co. or Unix System Laboratories, Inc. and are reproduced herein with
10 * the permission of UNIX System Laboratories, Inc.
11 *
12 * Redistribution and use in source and binary forms, with or without
13 * modification, are permitted provided that the following conditions
14 * are met:
15 * 1. Redistributions of source code must retain the above copyright
16 *    notice, this list of conditions and the following disclaimer.
17 * 2. Redistributions in binary form must reproduce the above copyright
18 *    notice, this list of conditions and the following disclaimer in the
19 *    documentation and/or other materials provided with the distribution.
20 * 3. Neither the name of the University nor the names of its contributors
21 *    may be used to endorse or promote products derived from this software
22 *    without specific prior written permission.
23 *
24 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
25 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
26 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
27 * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
28 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
29 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
30 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
31 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
32 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
33 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
34 * SUCH DAMAGE.
35 */
36
37#include <sys/cdefs.h>
38
39#ifndef lint
40__COPYRIGHT("@(#) Copyright (c) 1987, 1993\
41 The Regents of the University of California.  All rights reserved.");
42#endif /* not lint */
43
44#ifndef lint
45#if 0
46static char sccsid[] = "@(#)mesg.c	8.2 (Berkeley) 1/21/94";
47#endif
48__RCSID("$NetBSD: mesg.c,v 1.7 2005/07/30 16:14:39 christos Exp $");
49#endif /* not lint */
50
51#include <sys/types.h>
52#include <sys/stat.h>
53
54#include <err.h>
55#include <errno.h>
56#include <stdio.h>
57#include <stdlib.h>
58#include <string.h>
59#include <unistd.h>
60
61int
62main(int argc, char *argv[])
63{
64	struct stat sb;
65	char *tty;
66	int ch;
67
68	setprogname(*argv);
69
70	while ((ch = getopt(argc, argv, "")) != -1)
71		switch (ch) {
72		case '?':
73		default:
74			goto usage;
75		}
76	argc -= optind;
77	argv += optind;
78
79	if ((tty = ttyname(STDIN_FILENO)) == NULL &&
80	    (tty = ttyname(STDOUT_FILENO)) == NULL &&
81	    (tty = ttyname(STDERR_FILENO)) == NULL)
82		err(2, "ttyname");
83	if (stat(tty, &sb) == -1)
84		err(2, "%s", tty);
85
86	if (*argv == NULL) {
87		if (sb.st_mode & S_IWGRP) {
88			(void)fprintf(stderr, "is y\n");
89			return 0;
90		}
91		(void)fprintf(stderr, "is n\n");
92		return 1;
93	}
94
95	switch (*argv[0]) {
96	case 'y':
97		if (chmod(tty, sb.st_mode | S_IWGRP) == -1)
98			err(2, "%s", tty);
99		return 0;
100	case 'n':
101		if (chmod(tty, sb.st_mode & ~S_IWGRP) == -1)
102			err(2, "%s", tty);
103		return 1;
104	}
105
106usage:	(void)fprintf(stderr, "Usage: %s [y | n]\n", getprogname());
107	return 2;
108}
109