usr.bin/mesg/mesg.c

   1 /*      $NetBSD: mesg.c,v 1.8 2008/07/21 14:19:24 lukem Exp $   */
   2
   3 /*
   4  * Copyright (c) 1987, 1993
   5  *      The Regents of the University of California.  All rights reserved.
   6  * (c) UNIX System Laboratories, Inc.
   7  * All or some portions of this file are derived from material licensed
   8  * to the University of California by American Telephone and Telegraph
   9  * Co. or Unix System Laboratories, Inc. and are reproduced herein with
  10  * the permission of UNIX System Laboratories, Inc.
  11  *
  12  * Redistribution and use in source and binary forms, with or without
  13  * modification, are permitted provided that the following conditions
  14  * are met:
  15  * 1. Redistributions of source code must retain the above copyright
  16  *    notice, this list of conditions and the following disclaimer.
  17  * 2. Redistributions in binary form must reproduce the above copyright
  18  *    notice, this list of conditions and the following disclaimer in the
  19  *    documentation and/or other materials provided with the distribution.
  20  * 3. Neither the name of the University nor the names of its contributors
  21  *    may be used to endorse or promote products derived from this software
  22  *    without specific prior written permission.
  23  *
  24  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
  25  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  26  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  27  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
  28  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  29  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  30  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  31  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  32  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  33  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  34  * SUCH DAMAGE.
  35  */
  36
  37 #include <sys/cdefs.h>
  38
  39 #ifndef lint
  40 __COPYRIGHT("@(#) Copyright (c) 1987, 1993\
  41  The Regents of the University of California.  All rights reserved.");
  42 #endif /* not lint */
  43
  44 #ifndef lint
  45 #if 0
  46 static char sccsid[] = "@(#)mesg.c      8.2 (Berkeley) 1/21/94";
  47 #endif
  48 __RCSID("$NetBSD: mesg.c,v 1.8 2008/07/21 14:19:24 lukem Exp $");
  49 #endif /* not lint */
  50
  51 #include <sys/types.h>
  52 #include <sys/stat.h>
  53
  54 #include <err.h>
  55 #include <errno.h>
  56 #include <stdio.h>
  57 #include <stdlib.h>
  58 #include <string.h>
  59 #include <unistd.h>
  60
  61 int
  62 main(int argc, char *argv[])
  63 {
  64         struct stat sb;
  65         char *tty;
  66         int ch;
  67
  68         setprogname(*argv);
  69
  70         while ((ch = getopt(argc, argv, "")) != -1)
  71                 switch (ch) {
  72                 case '?':
  73                 default:
  74                         goto usage;
  75                 }
  76         argc -= optind;
  77         argv += optind;
  78
  79         if ((tty = ttyname(STDIN_FILENO)) == NULL &&
  80             (tty = ttyname(STDOUT_FILENO)) == NULL &&
  81             (tty = ttyname(STDERR_FILENO)) == NULL)
  82                 err(2, "ttyname");
  83         if (stat(tty, &sb) == -1)
  84                 err(2, "%s", tty);
  85
  86         if (*argv == NULL) {
  87                 if (sb.st_mode & S_IWGRP) {
  88                         (void)fprintf(stderr, "is y\n");
  89                         return 0;
  90                 }
  91                 (void)fprintf(stderr, "is n\n");
  92                 return 1;
  93         }
  94
  95         switch (*argv[0]) {
  96         case 'y':
  97                 if (chmod(tty, sb.st_mode | S_IWGRP) == -1)
  98                         err(2, "%s", tty);
  99                 return 0;
 100         case 'n':
 101                 if (chmod(tty, sb.st_mode & ~S_IWGRP) == -1)
 102                         err(2, "%s", tty);
 103                 return 1;
 104         }
 105
 106 usage:  (void)fprintf(stderr, "Usage: %s [y | n]\n", getprogname());
 107         return 2;
 108 }