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 #include <sys/types.h>
38 #include <sys/stat.h>
39
40 #include <err.h>
41 #include <stdio.h>
42 #include <stdlib.h>
43 #include <string.h>
44 #include <unistd.h>
45
46 static void usage(void) __dead2;
47
48 int
main(int argc,char * argv[])49 main(int argc, char *argv[])
50 {
51 struct stat sb;
52 char *tty;
53 int ch;
54
55 while ((ch = getopt(argc, argv, "")) != -1)
56 switch (ch) {
57 case '?':
58 default:
59 usage();
60 }
61 argc -= optind;
62 argv += optind;
63
64 if ((tty = ttyname(STDIN_FILENO)) == NULL &&
65 (tty = ttyname(STDOUT_FILENO)) == NULL &&
66 (tty = ttyname(STDERR_FILENO)) == NULL)
67 err(2, "ttyname");
68 if (stat(tty, &sb) < 0)
69 err(2, "%s", tty);
70
71 if (*argv == NULL) {
72 if (sb.st_mode & S_IWGRP) {
73 (void)puts("is y");
74 exit(0);
75 }
76 (void)puts("is n");
77 exit(1);
78 }
79
80 switch (*argv[0]) {
81 case 'y':
82 if (chmod(tty, sb.st_mode | S_IWGRP) < 0)
83 err(2, "%s", tty);
84 exit(0);
85 case 'n':
86 if (chmod(tty, sb.st_mode & ~S_IWGRP) < 0)
87 err(2, "%s", tty);
88 exit(1);
89 }
90
91 usage();
92 return(0);
93 }
94
95 static void
usage(void)96 usage(void)
97 {
98 (void)fprintf(stderr, "usage: mesg [n | y]\n");
99 exit(2);
100 }
101