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 * Redistribution and use in source and binary forms, with or without
11 * modification, are permitted provided that the following conditions
12 * are met:
13 * 1. Redistributions of source code must retain the above copyright
14 * notice, this list of conditions and the following disclaimer.
15 * 2. Redistributions in binary form must reproduce the above copyright
16 * notice, this list of conditions and the following disclaimer in the
17 * documentation and/or other materials provided with the distribution.
18 * 3. All advertising materials mentioning features or use of this software
19 * must display the following acknowledgement:
20 * This product includes software developed by the University of
21 * California, Berkeley and its contributors.
22 * 4. Neither the name of the University nor the names of its contributors
23 * may be used to endorse or promote products derived from this software
24 * without specific prior written permission.
25 *
26 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
27 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
28 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
29 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
30 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
31 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
32 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
33 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
34 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
35 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
36 * SUCH DAMAGE.
37 *
38 * Modified Fri Mar 10 20:27:19 1995, faith@cs.unc.edu, for Linux
39 * Modified Mon Jul 1 18:14:10 1996, janl@ifi.uio.no, writing to stdout
40 * as suggested by Michael Meskes <meskes@Informatik.RWTH-Aachen.DE>
41 *
42 * 1999-02-22 Arkadiusz Miśkiewicz <misiek@pld.ORG.PL>
43 * - added Native Language Support
44 *
45 * 2010-12-01 Marek Polacek <mmpolacek@gmail.com>
46 * - cleanups
47 */
48
49 #include <errno.h>
50 #include <stdio.h>
51 #include <stdlib.h>
52 #include <string.h>
53 #include <unistd.h>
54 #include <sys/types.h>
55 #include <sys/stat.h>
56 #include <getopt.h>
57
58 #include "closestream.h"
59 #include "nls.h"
60 #include "c.h"
61 #include "rpmatch.h"
62 #include "ttyutils.h"
63 #include "pathnames.h"
64
65 /* exit codes */
66
67 #define IS_ALLOWED 0 /* Receiving messages is allowed. */
68 #define IS_NOT_ALLOWED 1 /* Receiving messages is not allowed. */
69 #define MESG_EXIT_FAILURE 2 /* An error occurred. */
70
71 static void __attribute__((__noreturn__)) usage(void)
72 {
73 FILE *out = stdout;
74 fputs(USAGE_HEADER, out);
75 /* TRANSLATORS: this program uses for y and n rpmatch(3),
76 * which means they can be translated. */
77 fprintf(out,
78 _(" %s [options] [y | n]\n"), program_invocation_short_name);
79
80 fputs(USAGE_SEPARATOR, out);
81 fputs(_("Control write access of other users to your terminal.\n"), out);
82
83 fputs(USAGE_OPTIONS, out);
84 fputs(_(" -v, --verbose explain what is being done\n"), out);
85 printf(USAGE_HELP_OPTIONS(16));
86 printf(USAGE_MAN_TAIL("mesg(1)"));
87
88 exit(EXIT_SUCCESS);
89 }
90
91 int main(int argc, char *argv[])
92 {
93 struct stat sb;
94 char *tty;
95 char ttybuf[sizeof(_PATH_PROC_FDDIR) + sizeof(stringify_value(INT_MAX))];
96 int ch, fd, verbose = FALSE, ret;
97
98 static const struct option longopts[] = {
99 { "verbose", no_argument, NULL, 'v' },
100 { "version", no_argument, NULL, 'V' },
101 { "help", no_argument, NULL, 'h' },
102 { NULL, 0, NULL, 0 }
103 };
104
105 setlocale(LC_ALL, "");
106 bindtextdomain(PACKAGE, LOCALEDIR);
107 textdomain(PACKAGE);
108 close_stdout_atexit();
109
110 while ((ch = getopt_long(argc, argv, "vVh", longopts, NULL)) != -1)
111 switch (ch) {
112 case 'v':
113 verbose = TRUE;
114 break;
115
116 case 'V':
117 print_version(EXIT_SUCCESS);
118 case 'h':
119 usage();
120 default:
121 errtryhelp(EXIT_FAILURE);
122 }
123
124 argc -= optind;
125 argv += optind;
126
127 fd = get_terminal_stdfd();
128 if (fd < 0) {
129 if (verbose)
130 warnx(_("no tty"));
131 exit(MESG_EXIT_FAILURE);
132 }
133
134 tty = ttyname(fd);
135 if (!tty) {
136 snprintf(ttybuf, sizeof(ttybuf), "%s/%d", _PATH_PROC_FDDIR, fd);
137 tty = ttybuf;
138 if (verbose)
139 warnx(_("ttyname() failed, attempting to go around using: %s"), tty);
140 }
141
142 if (!*argv) {
143 if (stat(tty, &sb))
144 err(MESG_EXIT_FAILURE, _("stat of %s failed"), tty);
145 if (sb.st_mode & (S_IWGRP | S_IWOTH)) {
146 puts(_("is y"));
147 return IS_ALLOWED;
148 }
149 puts(_("is n"));
150 return IS_NOT_ALLOWED;
151 }
152
153 if ((fd = open(tty, O_RDONLY)) < 0)
154 err(MESG_EXIT_FAILURE, _("cannot open %s"), tty);
155 if (fstat(fd, &sb))
156 err(MESG_EXIT_FAILURE, _("stat of %s failed"), tty);
157
158 switch (rpmatch(argv[0])) {
159 case RPMATCH_YES:
160 #ifdef USE_TTY_GROUP
161 if (fchmod(fd, sb.st_mode | S_IWGRP) < 0)
162 #else
163 if (fchmod(fd, sb.st_mode | S_IWGRP | S_IWOTH) < 0)
164 #endif
165 err(MESG_EXIT_FAILURE, _("change %s mode failed"), tty);
166 if (verbose)
167 puts(_("write access to your terminal is allowed"));
168 ret = IS_ALLOWED;
169 break;
170 case RPMATCH_NO:
171 if (fchmod(fd, sb.st_mode & ~(S_IWGRP|S_IWOTH)) < 0)
172 err(MESG_EXIT_FAILURE, _("change %s mode failed"), tty);
173 if (verbose)
174 puts(_("write access to your terminal is denied"));
175 ret = IS_NOT_ALLOWED;
176 break;
177 case RPMATCH_INVALID:
178 warnx(_("invalid argument: %s"), argv[0]);
179 errtryhelp(EXIT_FAILURE);
180 default:
181 abort();
182 }
183 close(fd);
184 return ret;
185 }