1 /*-
2 * SPDX-License-Identifier: BSD-3-Clause
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 #ifndef lint
38 static const char copyright[] =
39 "@(#) Copyright (c) 1987, 1993\n\
40 The Regents of the University of California. All rights reserved.\n";
41 #endif /* not lint */
42
43 #ifndef lint
44 #if 0
45 static char sccsid[] = "@(#)mesg.c 8.2 (Berkeley) 1/21/94";
46 #endif
47 #endif /* not lint */
48 #include <sys/cdefs.h>
49 __FBSDID("$FreeBSD$");
50
51 #include <sys/types.h>
52 #include <sys/stat.h>
53
54 #include <err.h>
55 #include <stdio.h>
56 #include <stdlib.h>
57 #include <string.h>
58 #include <unistd.h>
59
60 static void usage(void);
61
62 int
main(int argc,char * argv[])63 main(int argc, char *argv[])
64 {
65 struct stat sb;
66 char *tty;
67 int ch;
68
69 while ((ch = getopt(argc, argv, "")) != -1)
70 switch (ch) {
71 case '?':
72 default:
73 usage();
74 }
75 argc -= optind;
76 argv += optind;
77
78 if ((tty = ttyname(STDIN_FILENO)) == NULL &&
79 (tty = ttyname(STDOUT_FILENO)) == NULL &&
80 (tty = ttyname(STDERR_FILENO)) == NULL)
81 err(2, "ttyname");
82 if (stat(tty, &sb) < 0)
83 err(2, "%s", tty);
84
85 if (*argv == NULL) {
86 if (sb.st_mode & S_IWGRP) {
87 (void)puts("is y");
88 exit(0);
89 }
90 (void)puts("is n");
91 exit(1);
92 }
93
94 switch (*argv[0]) {
95 case 'y':
96 if (chmod(tty, sb.st_mode | S_IWGRP) < 0)
97 err(2, "%s", tty);
98 exit(0);
99 case 'n':
100 if (chmod(tty, sb.st_mode & ~S_IWGRP) < 0)
101 err(2, "%s", tty);
102 exit(1);
103 }
104
105 usage();
106 return(0);
107 }
108
109 static void
usage(void)110 usage(void)
111 {
112 (void)fprintf(stderr, "usage: mesg [n | y]\n");
113 exit(2);
114 }
115