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      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 }
    109