1 /*
2 * Copyright (c) 1987, 1993
3 * The Regents of the University of California. All rights reserved.
4 * (c) UNIX System Laboratories, Inc.
5 * All or some portions of this file are derived from material licensed
6 * to the University of California by American Telephone and Telegraph
7 * Co. or Unix System Laboratories, Inc. and are reproduced herein with
8 * the permission of UNIX System Laboratories, Inc.
9 *
10 * %sccs.include.redist.c%
11 */
12
13 #ifndef lint
14 static char copyright[] =
15 "@(#) Copyright (c) 1987, 1993\n\
16 The Regents of the University of California. All rights reserved.\n";
17 #endif /* not lint */
18
19 #ifndef lint
20 static char sccsid[] = "@(#)mesg.c 8.2 (Berkeley) 01/21/94";
21 #endif /* not lint */
22
23 #include <sys/types.h>
24 #include <sys/stat.h>
25
26 #include <err.h>
27 #include <errno.h>
28 #include <stdio.h>
29 #include <stdlib.h>
30 #include <string.h>
31 #include <unistd.h>
32
33 int
main(argc,argv)34 main(argc, argv)
35 int argc;
36 char *argv[];
37 {
38 struct stat sb;
39 char *tty;
40 int ch;
41
42 while ((ch = getopt(argc, argv, "")) != EOF)
43 switch (ch) {
44 case '?':
45 default:
46 goto usage;
47 }
48 argc -= optind;
49 argv += optind;
50
51 if ((tty = ttyname(STDERR_FILENO)) == NULL)
52 err(1, "ttyname");
53 if (stat(tty, &sb) < 0)
54 err(1, "%s", tty);
55
56 if (*argv == NULL) {
57 if (sb.st_mode & S_IWGRP) {
58 (void)fprintf(stderr, "is y\n");
59 exit(0);
60 }
61 (void)fprintf(stderr, "is n\n");
62 exit(1);
63 }
64
65 switch (*argv[0]) {
66 case 'y':
67 if (chmod(tty, sb.st_mode | S_IWGRP) < 0)
68 err(1, "%s", tty);
69 exit(0);
70 case 'n':
71 if (chmod(tty, sb.st_mode & ~S_IWGRP) < 0)
72 err(1, "%s", tty);
73 exit(1);
74 }
75
76 usage: (void)fprintf(stderr, "usage: mesg [y | n]\n");
77 exit(2);
78 }
79