1 /* $OpenBSD: mesg.c,v 1.17 2021/07/12 15:09:20 beck Exp $ */ 2 /* $NetBSD: mesg.c,v 1.4 1994/12/23 07:16:32 jtc Exp $ */ 3 4 /* 5 * Copyright (c) 1987, 1993 6 * The Regents of the University of California. All rights reserved. 7 * (c) UNIX System Laboratories, Inc. 8 * All or some portions of this file are derived from material licensed 9 * to the University of California by American Telephone and Telegraph 10 * Co. or Unix System Laboratories, Inc. and are reproduced herein with 11 * the permission of UNIX System Laboratories, Inc. 12 * 13 * Redistribution and use in source and binary forms, with or without 14 * modification, are permitted provided that the following conditions 15 * are met: 16 * 1. Redistributions of source code must retain the above copyright 17 * notice, this list of conditions and the following disclaimer. 18 * 2. Redistributions in binary form must reproduce the above copyright 19 * notice, this list of conditions and the following disclaimer in the 20 * documentation and/or other materials provided with the distribution. 21 * 3. Neither the name of the University nor the names of its contributors 22 * may be used to endorse or promote products derived from this software 23 * without specific prior written permission. 24 * 25 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 26 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 27 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 28 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 29 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 30 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 31 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 32 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 33 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 34 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 35 * SUCH DAMAGE. 36 */ 37 38 #include <sys/types.h> 39 #include <sys/stat.h> 40 41 #include <err.h> 42 #include <errno.h> 43 #include <stdio.h> 44 #include <stdlib.h> 45 #include <string.h> 46 #include <unistd.h> 47 48 int 49 main(int argc, char *argv[]) 50 { 51 struct stat sb; 52 char *tty; 53 int ch; 54 55 while ((ch = getopt(argc, argv, "")) != -1) 56 switch (ch) { 57 case '?': 58 default: 59 goto usage; 60 } 61 argc -= optind; 62 argv += optind; 63 64 if ((tty = ttyname(STDERR_FILENO)) == NULL) 65 err(2, "ttyname"); 66 67 if (unveil(tty, "rw") == -1) 68 err(2, "unveil %s", tty); 69 if (pledge("stdio rpath fattr", NULL) == -1) 70 err(2, "pledge"); 71 72 if (stat(tty, &sb) == -1) 73 err(2, "%s", tty); 74 75 sb.st_mode &= ACCESSPERMS; 76 77 if (*argv == NULL) { 78 if (sb.st_mode & S_IWGRP) { 79 (void)fprintf(stderr, "is y\n"); 80 exit(0); 81 } 82 (void)fprintf(stderr, "is n\n"); 83 exit(1); 84 } 85 86 switch (*argv[0]) { 87 case 'y': 88 if (chmod(tty, sb.st_mode | S_IWGRP) == -1) 89 err(2, "%s", tty); 90 exit(0); 91 case 'n': 92 if (chmod(tty, sb.st_mode & ~S_IWGRP) == -1) 93 err(2, "%s", tty); 94 exit(1); 95 } 96 97 usage: (void)fprintf(stderr, "usage: mesg [n | y]\n"); 98 exit(2); 99 } 100