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/* $OpenBSD: uucplock.c,v 1.12 2009/10/27 23:59:45 deraadt Exp $ */
/* $NetBSD: uucplock.c,v 1.7 1997/02/11 09:24:08 mrg Exp $ */
/*
* Copyright (c) 1988, 1993
* The Regents of the University of California. All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
* 3. Neither the name of the University nor the names of its contributors
* may be used to endorse or promote products derived from this software
* without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
* ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
* SUCH DAMAGE.
*/
#include <sys/types.h>
#include <sys/file.h>
#include <sys/dir.h>
#include <stdio.h>
#include <string.h>
#include <signal.h>
#include <unistd.h>
#include <stdlib.h>
#include <errno.h>
#include "pathnames.h"
/*
* uucp style locking routines
* return: 0 - success
* -1 - failure
*/
int
uu_lock(char *ttyname)
{
int fd, len;
char tbuf[sizeof(_PATH_LOCKDIRNAME) + MAXNAMLEN];
char text_pid[81];
pid_t pid;
(void)snprintf(tbuf, sizeof tbuf, _PATH_LOCKDIRNAME, ttyname);
fd = open(tbuf, O_RDWR|O_CREAT|O_EXCL, 0660);
if (fd < 0) {
/*
* file is already locked
* check to see if the process holding the lock still exists
*/
fd = open(tbuf, O_RDWR, 0);
if (fd < 0) {
perror(tbuf);
fprintf(stderr, "Can't open lock file.\n");
return(-1);
}
len = read(fd, text_pid, sizeof(text_pid)-1);
if (len<=0) {
perror(tbuf);
(void)close(fd);
fprintf(stderr, "Can't read lock file.\n");
return(-1);
}
text_pid[len] = 0;
pid = atol(text_pid);
if (kill(pid, 0) == 0 || errno != ESRCH) {
(void)close(fd); /* process is still running */
return(-1);
}
/*
* The process that locked the file isn't running, so
* we'll lock it ourselves
*/
fprintf(stderr, "Stale lock on %s PID=%ld... overriding.\n",
ttyname, (long)pid);
if (lseek(fd, (off_t)0, SEEK_SET) < 0) {
perror(tbuf);
(void)close(fd);
fprintf(stderr, "Can't seek lock file.\n");
return(-1);
}
/* fall out and finish the locking process */
}
pid = getpid();
(void)snprintf(text_pid, sizeof text_pid, "%10ld\n", (long)pid);
len = strlen(text_pid);
if (write(fd, text_pid, len) != len) {
(void)close(fd);
(void)unlink(tbuf);
perror("lock write");
return(-1);
}
(void)close(fd);
return(0);
}
int
uu_unlock(char *ttyname)
{
char tbuf[sizeof(_PATH_LOCKDIRNAME) + MAXNAMLEN];
(void)snprintf(tbuf, sizeof tbuf, _PATH_LOCKDIRNAME, ttyname);
return(unlink(tbuf));
}
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