1 /* $OpenBSD: mesg.c,v 1.18 2022/12/04 23:50:48 cheloha Exp $ */
2 /* $NetBSD: mesg.c,v 1.4 1994/12/23 07:16:32 jtc Exp $ */
3
4 /*
5 * Copyright (c) 1987, 1993
6 * The Regents of the University of California. All rights reserved.
7 * (c) UNIX System Laboratories, Inc.
8 * All or some portions of this file are derived from material licensed
9 * to the University of California by American Telephone and Telegraph
10 * Co. or Unix System Laboratories, Inc. and are reproduced herein with
11 * the permission of UNIX System Laboratories, Inc.
12 *
13 * Redistribution and use in source and binary forms, with or without
14 * modification, are permitted provided that the following conditions
15 * are met:
16 * 1. Redistributions of source code must retain the above copyright
17 * notice, this list of conditions and the following disclaimer.
18 * 2. Redistributions in binary form must reproduce the above copyright
19 * notice, this list of conditions and the following disclaimer in the
20 * documentation and/or other materials provided with the distribution.
21 * 3. Neither the name of the University nor the names of its contributors
22 * may be used to endorse or promote products derived from this software
23 * without specific prior written permission.
24 *
25 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
26 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
27 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
28 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
29 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
30 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
31 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
32 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
33 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
34 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
35 * SUCH DAMAGE.
36 */
37
38 #include <sys/types.h>
39 #include <sys/stat.h>
40
41 #include <err.h>
42 #include <errno.h>
43 #include <stdio.h>
44 #include <stdlib.h>
45 #include <string.h>
46 #include <unistd.h>
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 default:
58 goto usage;
59 }
60 argc -= optind;
61 argv += optind;
62
63 if ((tty = ttyname(STDERR_FILENO)) == NULL)
64 err(2, "ttyname");
65
66 if (unveil(tty, "rw") == -1)
67 err(2, "unveil %s", tty);
68 if (pledge("stdio rpath fattr", NULL) == -1)
69 err(2, "pledge");
70
71 if (stat(tty, &sb) == -1)
72 err(2, "%s", tty);
73
74 sb.st_mode &= ACCESSPERMS;
75
76 if (*argv == NULL) {
77 if (sb.st_mode & S_IWGRP) {
78 (void)fprintf(stderr, "is y\n");
79 exit(0);
80 }
81 (void)fprintf(stderr, "is n\n");
82 exit(1);
83 }
84
85 switch (*argv[0]) {
86 case 'y':
87 if (chmod(tty, sb.st_mode | S_IWGRP) == -1)
88 err(2, "%s", tty);
89 exit(0);
90 case 'n':
91 if (chmod(tty, sb.st_mode & ~S_IWGRP) == -1)
92 err(2, "%s", tty);
93 exit(1);
94 }
95
96 usage: (void)fprintf(stderr, "usage: mesg [n | y]\n");
97 exit(2);
98 }
99