/usr.bin/tip/tip/uucplock.c

  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 * Copyright (c) 1988, 1993
  6 *	The Regents of the University of California.  All rights reserved.
  7 *
  8 * Redistribution and use in source and binary forms, with or without
  9 * modification, are permitted provided that the following conditions
 10 * are met:
 11 * 1. Redistributions of source code must retain the above copyright
 12 *    notice, this list of conditions and the following disclaimer.
 13 * 2. Redistributions in binary form must reproduce the above copyright
 14 *    notice, this list of conditions and the following disclaimer in the
 15 *    documentation and/or other materials provided with the distribution.
 16 * 3. Neither the name of the University nor the names of its contributors
 17 *    may be used to endorse or promote products derived from this software
 18 *    without specific prior written permission.
 19 *
 20 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
 21 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 22 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 23 * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
 24 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 25 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 26 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 27 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 28 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 29 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 30 * SUCH DAMAGE.
 31 */
 32
 33#include <sys/cdefs.h>
 34__FBSDID("$FreeBSD$");
 35
 36#ifndef lint
 37#if 0
 38static char sccsid[] = "@(#)uucplock.c	8.1 (Berkeley) 6/6/93";
 39static const char rcsid[] = "$OpenBSD: uucplock.c,v 1.11 2006/03/16 19:32:46 deraadt Exp $";
 40#endif
 41#endif /* not lint */
 42
 43#include <sys/types.h>
 44#include <sys/file.h>
 45#include <sys/dirent.h>
 46#include <stdio.h>
 47#include <string.h>
 48#include <signal.h>
 49#include <unistd.h>
 50#include <stdlib.h>
 51#include <errno.h>
 52#include "tip.h"
 53#include "pathnames.h"
 54
 55/*
 56 * uucp style locking routines
 57 * return: 0 - success
 58 *	  -1 - failure
 59 */
 60
 61int
 62uu_lock(char *ttyname)
 63{
 64	int fd, len;
 65	char tbuf[sizeof(_PATH_LOCKDIRNAME) + MAXNAMLEN];
 66	char text_pid[81];
 67	pid_t pid;
 68
 69	(void)snprintf(tbuf, sizeof tbuf, _PATH_LOCKDIRNAME, ttyname);
 70	fd = open(tbuf, O_RDWR|O_CREAT|O_EXCL, 0660);
 71	if (fd < 0) {
 72		/*
 73		 * file is already locked
 74		 * check to see if the process holding the lock still exists
 75		 */
 76		fd = open(tbuf, O_RDWR, 0);
 77		if (fd < 0) {
 78			perror(tbuf);
 79			fprintf(stderr, "Can't open lock file.\n");
 80			return(-1);
 81		}
 82		len = read(fd, text_pid, sizeof(text_pid)-1);
 83		if (len<=0) {
 84			perror(tbuf);
 85			(void)close(fd);
 86			fprintf(stderr, "Can't read lock file.\n");
 87			return(-1);
 88		}
 89		text_pid[len] = 0;
 90		pid = atol(text_pid);
 91
 92		if (kill(pid, 0) == 0 || errno != ESRCH) {
 93			(void)close(fd);	/* process is still running */
 94			return(-1);
 95		}
 96		/*
 97		 * The process that locked the file isn't running, so
 98		 * we'll lock it ourselves
 99		 */
100		fprintf(stderr, "Stale lock on %s PID=%ld... overriding.\n",
101			ttyname, (long)pid);
102		if (lseek(fd, (off_t)0, SEEK_SET) < 0) {
103			perror(tbuf);
104			(void)close(fd);
105			fprintf(stderr, "Can't seek lock file.\n");
106			return(-1);
107		}
108		/* fall out and finish the locking process */
109	}
110	pid = getpid();
111	(void)snprintf(text_pid, sizeof text_pid, "%10ld\n", (long)pid);
112	len = strlen(text_pid);
113	if (write(fd, text_pid, len) != len) {
114		(void)close(fd);
115		(void)unlink(tbuf);
116		perror("lock write");
117		return(-1);
118	}
119	(void)close(fd);
120	return(0);
121}
122
123int
124uu_unlock(char *ttyname)
125{
126	char tbuf[sizeof(_PATH_LOCKDIRNAME) + MAXNAMLEN];
127
128	(void)snprintf(tbuf, sizeof tbuf, _PATH_LOCKDIRNAME, ttyname);
129	unexcl();
130	return(unlink(tbuf));
131}