1 /* 2 * Copyright (c) 1987 Regents of the University of California. 3 * 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 40 char copyright[] = 41 "@(#) Copyright (c) 1987 Regents of the University of California.\n\ 42 All rights reserved.\n"; 43 #endif /* not lint */ 44 45 #ifndef lint 46 /*static char sccsid[] = "from: @(#)mesg.c 4.7 (Berkeley) 3/1/91";*/ 47 static char rcsid[] = "$Id: mesg.c,v 1.3 1994/05/17 04:15:59 cgd Exp $"; 48 #endif /* not lint */ 49 50 /* 51 * mesg -- set current tty to accept or 52 * forbid write permission. 53 * 54 * mesg [y] [n] 55 * y allow messages 56 * n forbid messages 57 */ 58 59 #include <sys/types.h> 60 #include <sys/stat.h> 61 #include <stdio.h> 62 63 static char *tty; 64 65 main(argc, argv) 66 int argc; 67 char **argv; 68 { 69 struct stat sbuf; 70 char *ttyname(); 71 72 if (!(tty = ttyname(2))) { 73 fputs("mesg: not a device in /dev.\n", stderr); 74 exit(-1); 75 } 76 if (stat(tty, &sbuf) < 0) { 77 perror("mesg"); 78 exit(-1); 79 } 80 if (argc < 2) { 81 if (sbuf.st_mode & 020) { 82 fputs("is y\n", stderr); 83 exit(0); 84 } 85 fputs("is n\n", stderr); 86 exit(1); 87 } 88 #define OTHER_WRITE 020 89 switch(*argv[1]) { 90 case 'y': 91 newmode(sbuf.st_mode | OTHER_WRITE); 92 exit(0); 93 case 'n': 94 newmode(sbuf.st_mode &~ OTHER_WRITE); 95 exit(1); 96 default: 97 fputs("usage: mesg [y] [n]\n", stderr); 98 exit(-1); 99 } 100 /*NOTREACHED*/ 101 } 102 103 newmode(m) 104 u_short m; 105 { 106 if (chmod(tty, m) < 0) { 107 perror("mesg"); 108 exit(-1); 109 } 110 } 111