term-utils/mesg.c

   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
  63 /* exit codes */
  64
  65 #define IS_ALLOWED        0  /* Receiving messages is allowed.  */
  66 #define IS_NOT_ALLOWED    1  /* Receiving messages is not allowed.  */
  67 #define MESG_EXIT_FAILURE 2  /* An error occurred.  */
  68
  69 static void __attribute__((__noreturn__)) usage(void)
  70 {
  71         FILE *out = stdout;
  72         fputs(USAGE_HEADER, out);
  73         /* TRANSLATORS: this program uses for y and n rpmatch(3),
  74          * which means they can be translated.  */
  75         fprintf(out,
  76               _(" %s [options] [y | n]\n"), program_invocation_short_name);
  77
  78         fputs(USAGE_SEPARATOR, out);
  79         fputs(_("Control write access of other users to your terminal.\n"), out);
  80
  81         fputs(USAGE_OPTIONS, out);
  82         fputs(_(" -v, --verbose  explain what is being done\n"), out);
  83         printf(USAGE_HELP_OPTIONS(16));
  84         printf(USAGE_MAN_TAIL("mesg(1)"));
  85
  86         exit(EXIT_SUCCESS);
  87 }
  88
  89 int main(int argc, char *argv[])
  90 {
  91         struct stat sb;
  92         char *tty;
  93         int ch, fd, verbose = FALSE, ret;
  94
  95         static const struct option longopts[] = {
  96                 { "verbose",    no_argument,       NULL, 'v' },
  97                 { "version",    no_argument,       NULL, 'V' },
  98                 { "help",       no_argument,       NULL, 'h' },
  99                 { NULL,         0, NULL, 0 }
 100         };
 101
 102         setlocale(LC_ALL, "");
 103         bindtextdomain(PACKAGE, LOCALEDIR);
 104         textdomain(PACKAGE);
 105         close_stdout_atexit();
 106
 107         while ((ch = getopt_long(argc, argv, "vVh", longopts, NULL)) != -1)
 108                 switch (ch) {
 109                 case 'v':
 110                         verbose = TRUE;
 111                         break;
 112
 113                 case 'V':
 114                         print_version(EXIT_SUCCESS);
 115                 case 'h':
 116                         usage();
 117                 default:
 118                         errtryhelp(EXIT_FAILURE);
 119                 }
 120
 121         argc -= optind;
 122         argv += optind;
 123
 124         if (!isatty(STDERR_FILENO)) {
 125                 if (verbose)
 126                         warnx(_("no tty"));
 127                 exit(MESG_EXIT_FAILURE);
 128         }
 129         if ((tty = ttyname(STDERR_FILENO)) == NULL)
 130                 err(MESG_EXIT_FAILURE, _("ttyname failed"));
 131         if ((fd = open(tty, O_RDONLY)) < 0)
 132                 err(MESG_EXIT_FAILURE, _("cannot open %s"), tty);
 133         if (fstat(fd, &sb))
 134                 err(MESG_EXIT_FAILURE, _("stat of %s failed"), tty);
 135
 136         if (!*argv) {
 137                 close(fd);
 138                 if (sb.st_mode & (S_IWGRP | S_IWOTH)) {
 139                         puts(_("is y"));
 140                         return IS_ALLOWED;
 141                 }
 142                 puts(_("is n"));
 143                 return IS_NOT_ALLOWED;
 144         }
 145
 146         switch (rpmatch(argv[0])) {
 147         case RPMATCH_YES:
 148 #ifdef USE_TTY_GROUP
 149                 if (fchmod(fd, sb.st_mode | S_IWGRP) < 0)
 150 #else
 151                 if (fchmod(fd, sb.st_mode | S_IWGRP | S_IWOTH) < 0)
 152 #endif
 153                         err(MESG_EXIT_FAILURE, _("change %s mode failed"), tty);
 154                 if (verbose)
 155                         puts(_("write access to your terminal is allowed"));
 156                 ret = IS_ALLOWED;
 157                 break;
 158         case RPMATCH_NO:
 159                 if (fchmod(fd, sb.st_mode & ~(S_IWGRP|S_IWOTH)) < 0)
 160                          err(MESG_EXIT_FAILURE, _("change %s mode failed"), tty);
 161                 if (verbose)
 162                         puts(_("write access to your terminal is denied"));
 163                 ret = IS_NOT_ALLOWED;
 164                 break;
 165         case RPMATCH_INVALID:
 166                 warnx(_("invalid argument: %s"), argv[0]);
 167                 errtryhelp(EXIT_FAILURE);
 168         default:
 169                 abort();
 170         }
 171         close(fd);
 172         return ret;
 173 }