usr/src/cmd/mesg/mesg.c

   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
  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
 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
 156 newmode(mode_t m)
 157 {
 158         if (chmod(tty, m) < 0)
 159                 error("cannot change mode");
 160 }
 161
 162 void
 163 usage(void)
 164 {
 165         (void) fprintf(stderr, gettext("usage: mesg [-y | -n | y | n]\n"));
 166         exit(2);
 167 }