1 /*- 2 * SPDX-License-Identifier: BSD-3-Clause 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 #ifndef lint 38 static const char copyright[] = 39 "@(#) Copyright (c) 1987, 1993\n\ 40 The Regents of the University of California. All rights reserved.\n"; 41 #endif /* not lint */ 42 43 #ifndef lint 44 #endif /* not lint */ 45 #include <sys/cdefs.h> 46 #include <sys/types.h> 47 #include <sys/stat.h> 48 49 #include <err.h> 50 #include <stdio.h> 51 #include <stdlib.h> 52 #include <string.h> 53 #include <unistd.h> 54 55 static void usage(void) __dead2; 56 57 int 58 main(int argc, char *argv[]) 59 { 60 struct stat sb; 61 char *tty; 62 int ch; 63 64 while ((ch = getopt(argc, argv, "")) != -1) 65 switch (ch) { 66 case '?': 67 default: 68 usage(); 69 } 70 argc -= optind; 71 argv += optind; 72 73 if ((tty = ttyname(STDIN_FILENO)) == NULL && 74 (tty = ttyname(STDOUT_FILENO)) == NULL && 75 (tty = ttyname(STDERR_FILENO)) == NULL) 76 err(2, "ttyname"); 77 if (stat(tty, &sb) < 0) 78 err(2, "%s", tty); 79 80 if (*argv == NULL) { 81 if (sb.st_mode & S_IWGRP) { 82 (void)puts("is y"); 83 exit(0); 84 } 85 (void)puts("is n"); 86 exit(1); 87 } 88 89 switch (*argv[0]) { 90 case 'y': 91 if (chmod(tty, sb.st_mode | S_IWGRP) < 0) 92 err(2, "%s", tty); 93 exit(0); 94 case 'n': 95 if (chmod(tty, sb.st_mode & ~S_IWGRP) < 0) 96 err(2, "%s", tty); 97 exit(1); 98 } 99 100 usage(); 101 return(0); 102 } 103 104 static void 105 usage(void) 106 { 107 (void)fprintf(stderr, "usage: mesg [n | y]\n"); 108 exit(2); 109 } 110