xref: /illumos-gate/usr/src/cmd/mesg/mesg.c (revision 7c478bd9)
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 
54 static void error(const char *s);
55 static void newmode(mode_t m);
56 static void usage(void);
57 
58 static char *tty;
59 
60 int
main(int argc,char * argv[])61 main(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 
147 void
error(const char * s)148 error(const char *s)
149 {
150 	(void) fprintf(stderr, "mesg: ");
151 	(void) fprintf(stderr, "%s\n", s);
152 	exit(2);
153 }
154 
155 void
newmode(mode_t m)156 newmode(mode_t m)
157 {
158 	if (chmod(tty, m) < 0)
159 		error("cannot change mode");
160 }
161 
162 void
usage(void)163 usage(void)
164 {
165 	(void) fprintf(stderr, gettext("usage: mesg [-y | -n | y | n]\n"));
166 	exit(2);
167 }
168