1 /* $OpenBSD: uucplock.c,v 1.11 2006/03/16 19:32:46 deraadt Exp $ */ 2 /* $NetBSD: uucplock.c,v 1.7 1997/02/11 09:24:08 mrg Exp $ */ 3 4 /*- 5 * SPDX-License-Identifier: BSD-3-Clause 6 * 7 * Copyright (c) 1988, 1993 8 * The Regents of the University of California. All rights reserved. 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. Neither the name of the University nor the names of its contributors 19 * may be used to endorse or promote products derived from this software 20 * without specific prior written permission. 21 * 22 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 23 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 24 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 25 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 26 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 27 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 28 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 29 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 30 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 31 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 32 * SUCH DAMAGE. 33 */ 34 35 #include <sys/types.h> 36 #include <sys/file.h> 37 #include <sys/dirent.h> 38 #include <stdio.h> 39 #include <string.h> 40 #include <signal.h> 41 #include <unistd.h> 42 #include <stdlib.h> 43 #include <errno.h> 44 #include "tip.h" 45 #include "pathnames.h" 46 47 /* 48 * uucp style locking routines 49 * return: 0 - success 50 * -1 - failure 51 */ 52 53 int 54 uu_lock(char *ttyname) 55 { 56 int fd, len; 57 char tbuf[sizeof(_PATH_LOCKDIRNAME) + MAXNAMLEN]; 58 char text_pid[81]; 59 pid_t pid; 60 61 (void)snprintf(tbuf, sizeof tbuf, _PATH_LOCKDIRNAME, ttyname); 62 fd = open(tbuf, O_RDWR|O_CREAT|O_EXCL, 0660); 63 if (fd < 0) { 64 /* 65 * file is already locked 66 * check to see if the process holding the lock still exists 67 */ 68 fd = open(tbuf, O_RDWR, 0); 69 if (fd < 0) { 70 perror(tbuf); 71 fprintf(stderr, "Can't open lock file.\n"); 72 return(-1); 73 } 74 len = read(fd, text_pid, sizeof(text_pid)-1); 75 if (len<=0) { 76 perror(tbuf); 77 (void)close(fd); 78 fprintf(stderr, "Can't read lock file.\n"); 79 return(-1); 80 } 81 text_pid[len] = 0; 82 pid = atol(text_pid); 83 84 if (kill(pid, 0) == 0 || errno != ESRCH) { 85 (void)close(fd); /* process is still running */ 86 return(-1); 87 } 88 /* 89 * The process that locked the file isn't running, so 90 * we'll lock it ourselves 91 */ 92 fprintf(stderr, "Stale lock on %s PID=%ld... overriding.\n", 93 ttyname, (long)pid); 94 if (lseek(fd, (off_t)0, SEEK_SET) < 0) { 95 perror(tbuf); 96 (void)close(fd); 97 fprintf(stderr, "Can't seek lock file.\n"); 98 return(-1); 99 } 100 /* fall out and finish the locking process */ 101 } 102 pid = getpid(); 103 (void)snprintf(text_pid, sizeof text_pid, "%10ld\n", (long)pid); 104 len = strlen(text_pid); 105 if (write(fd, text_pid, len) != len) { 106 (void)close(fd); 107 (void)unlink(tbuf); 108 perror("lock write"); 109 return(-1); 110 } 111 (void)close(fd); 112 return(0); 113 } 114 115 int 116 uu_unlock(char *ttyname) 117 { 118 char tbuf[sizeof(_PATH_LOCKDIRNAME) + MAXNAMLEN]; 119 120 (void)snprintf(tbuf, sizeof tbuf, _PATH_LOCKDIRNAME, ttyname); 121 unexcl(); 122 return(unlink(tbuf)); 123 } 124