mesg.c revision 200420
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 39#ifndef lint 40static const char copyright[] = 41"@(#) Copyright (c) 1987, 1993\n\ 42 The Regents of the University of California. All rights reserved.\n"; 43#endif /* not lint */ 44 45#ifndef lint 46#if 0 47static char sccsid[] = "@(#)mesg.c 8.2 (Berkeley) 1/21/94"; 48#endif 49#endif /* not lint */ 50#include <sys/cdefs.h> 51__FBSDID("$FreeBSD: head/usr.bin/mesg/mesg.c 200420 2009-12-11 23:35:38Z delphij $"); 52 53#include <sys/types.h> 54#include <sys/stat.h> 55 56#include <err.h> 57#include <stdio.h> 58#include <stdlib.h> 59#include <unistd.h> 60 61static void usage(void); 62 63int 64main(int argc, char *argv[]) 65{ 66 struct stat sb; 67 char *tty; 68 int ch; 69 70 while ((ch = getopt(argc, argv, "")) != -1) 71 switch (ch) { 72 case '?': 73 default: 74 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) < 0) 84 err(2, "%s", tty); 85 86 if (*argv == NULL) { 87 if (sb.st_mode & S_IWGRP) { 88 (void)puts("is y"); 89 exit(0); 90 } 91 (void)puts("is n"); 92 exit(1); 93 } 94 95 switch (*argv[0]) { 96 case 'y': 97 if (chmod(tty, sb.st_mode | S_IWGRP) < 0) 98 err(2, "%s", tty); 99 exit(0); 100 case 'n': 101 if (chmod(tty, sb.st_mode & ~S_IWGRP) < 0) 102 err(2, "%s", tty); 103 exit(1); 104 } 105 106 usage(); 107 return(0); 108} 109 110static void 111usage(void) 112{ 113 (void)fprintf(stderr, "usage: mesg [n | y]\n"); 114 exit(2); 115} 116