1/*
2 * CDDL HEADER START
3 *
4 * The contents of this file are subject to the terms of the
5 * Common Development and Distribution License, Version 1.0 only
6 * (the "License").  You may not use this file except in compliance
7 * with the License.
8 *
9 * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
10 * or http://www.opensolaris.org/os/licensing.
11 * See the License for the specific language governing permissions
12 * and limitations under the License.
13 *
14 * When distributing Covered Code, include this CDDL HEADER in each
15 * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
16 * If applicable, add the following below this CDDL HEADER, with the
17 * fields enclosed by brackets "[]" replaced with your own identifying
18 * information: Portions Copyright [yyyy] [name of copyright owner]
19 *
20 * CDDL HEADER END
21 */
22/*
23 * Copyright 2003 Sun Microsystems, Inc.  All rights reserved.
24 * Use is subject to license terms.
25 */
26
27#pragma ident	"%Z%%M%	%I%	%E% SMI"
28
29/*	Copyright (c) 1984, 1986, 1987, 1988, 1989 AT&T	*/
30/*	  All Rights Reserved  	*/
31
32
33/*
34 * mesg -- set current tty to accept or
35 *	forbid write permission.
36 *
37 *	mesg [-y | -n | y | n]
38 *		y allow messages
39 *		n forbid messages
40 *	return codes
41 *		0 if messages are ON or turned ON
42 *		1 if messages are OFF or turned OFF
43 *		2 if an error occurs
44 */
45
46#include <stdio.h>
47#include <stdlib.h>
48#include <unistd.h>
49#include <locale.h>
50#include <libintl.h>
51#include <sys/types.h>
52#include <sys/stat.h>
53
54static void error(const char *s);
55static void newmode(mode_t m);
56static void usage(void);
57
58static char *tty;
59
60int
61main(int argc, char *argv[])
62{
63	int i, c, r = 0;
64	int action = 0;
65	struct stat sbuf;
66
67	extern int optind;
68
69	(void) setlocale(LC_ALL, "");
70#if !defined(TEXT_DOMAIN)		/* Should be defined by cc -D */
71#define	TEXT_DOMAIN	"SYS_TEST"	/* Use this only if it weren't */
72#endif
73	(void) textdomain(TEXT_DOMAIN);
74
75	/*
76	 * Check stdin, stdout and stderr, in order, for a tty
77	 */
78	for (i = 0; i <= 2; i++) {
79		if ((tty = ttyname(i)) != NULL)
80			break;
81	}
82
83	if (stat(tty, &sbuf) < 0)
84		error("cannot stat");
85
86	if (argc < 2) {
87		if (sbuf.st_mode & (S_IWGRP | S_IWOTH)) {
88			(void) printf("is y\n");
89		} else {
90			r = 1;
91			(void) printf("is n\n");
92		}
93		exit(r);
94	}
95
96	while ((c = getopt(argc, argv, "yn")) != EOF) {
97		switch (c) {
98		case 'y':
99			if (action > 0)
100				usage();
101
102			newmode(S_IRUSR | S_IWUSR | S_IWGRP);
103			action++;
104			break;
105
106		case 'n':
107			if (action > 0)
108				usage();
109
110			newmode(S_IRUSR | S_IWUSR);
111			r = 1;
112			action++;
113			break;
114
115		case '?':
116			usage();
117			break;
118		}
119	}
120
121	/*
122	 * Required for POSIX.2
123	 */
124	if (argc > optind) {
125		if (action > 0)
126			usage();
127
128		switch (*argv[optind]) {
129		case 'y':
130			newmode(S_IRUSR | S_IWUSR | S_IWGRP);
131			break;
132
133		case 'n':
134			newmode(S_IRUSR | S_IWUSR);
135			r = 1;
136			break;
137
138		default:
139			usage();
140			break;
141		}
142	}
143
144	return (r);
145}
146
147void
148error(const char *s)
149{
150	(void) fprintf(stderr, "mesg: ");
151	(void) fprintf(stderr, "%s\n", s);
152	exit(2);
153}
154
155void
156newmode(mode_t m)
157{
158	if (chmod(tty, m) < 0)
159		error("cannot change mode");
160}
161
162void
163usage(void)
164{
165	(void) fprintf(stderr, gettext("usage: mesg [-y | -n | y | n]\n"));
166	exit(2);
167}
168