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/cdefs.h> 36 __FBSDID("$FreeBSD$"); 37 38 #ifndef lint 39 #if 0 40 static char sccsid[] = "@(#)uucplock.c 8.1 (Berkeley) 6/6/93"; 41 static const char rcsid[] = "$OpenBSD: uucplock.c,v 1.11 2006/03/16 19:32:46 deraadt Exp $"; 42 #endif 43 #endif /* not lint */ 44 45 #include <sys/types.h> 46 #include <sys/file.h> 47 #include <sys/dirent.h> 48 #include <stdio.h> 49 #include <string.h> 50 #include <signal.h> 51 #include <unistd.h> 52 #include <stdlib.h> 53 #include <errno.h> 54 #include "tip.h" 55 #include "pathnames.h" 56 57 /* 58 * uucp style locking routines 59 * return: 0 - success 60 * -1 - failure 61 */ 62 63 int 64 uu_lock(char *ttyname) 65 { 66 int fd, len; 67 char tbuf[sizeof(_PATH_LOCKDIRNAME) + MAXNAMLEN]; 68 char text_pid[81]; 69 pid_t pid; 70 71 (void)snprintf(tbuf, sizeof tbuf, _PATH_LOCKDIRNAME, ttyname); 72 fd = open(tbuf, O_RDWR|O_CREAT|O_EXCL, 0660); 73 if (fd < 0) { 74 /* 75 * file is already locked 76 * check to see if the process holding the lock still exists 77 */ 78 fd = open(tbuf, O_RDWR, 0); 79 if (fd < 0) { 80 perror(tbuf); 81 fprintf(stderr, "Can't open lock file.\n"); 82 return(-1); 83 } 84 len = read(fd, text_pid, sizeof(text_pid)-1); 85 if (len<=0) { 86 perror(tbuf); 87 (void)close(fd); 88 fprintf(stderr, "Can't read lock file.\n"); 89 return(-1); 90 } 91 text_pid[len] = 0; 92 pid = atol(text_pid); 93 94 if (kill(pid, 0) == 0 || errno != ESRCH) { 95 (void)close(fd); /* process is still running */ 96 return(-1); 97 } 98 /* 99 * The process that locked the file isn't running, so 100 * we'll lock it ourselves 101 */ 102 fprintf(stderr, "Stale lock on %s PID=%ld... overriding.\n", 103 ttyname, (long)pid); 104 if (lseek(fd, (off_t)0, SEEK_SET) < 0) { 105 perror(tbuf); 106 (void)close(fd); 107 fprintf(stderr, "Can't seek lock file.\n"); 108 return(-1); 109 } 110 /* fall out and finish the locking process */ 111 } 112 pid = getpid(); 113 (void)snprintf(text_pid, sizeof text_pid, "%10ld\n", (long)pid); 114 len = strlen(text_pid); 115 if (write(fd, text_pid, len) != len) { 116 (void)close(fd); 117 (void)unlink(tbuf); 118 perror("lock write"); 119 return(-1); 120 } 121 (void)close(fd); 122 return(0); 123 } 124 125 int 126 uu_unlock(char *ttyname) 127 { 128 char tbuf[sizeof(_PATH_LOCKDIRNAME) + MAXNAMLEN]; 129 130 (void)snprintf(tbuf, sizeof tbuf, _PATH_LOCKDIRNAME, ttyname); 131 unexcl(); 132 return(unlink(tbuf)); 133 } 134