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/*
* 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. All advertising materials mentioning features or use of this software
* must display the following acknowledgement:
* This product includes software developed by the University of
* California, Berkeley and its contributors.
* 4. 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.
*/
#ifndef lint
static char sccsid[] = "@(#)uucplock.c 8.1 (Berkeley) 6/6/93";
#endif /* not lint */
#include <sys/types.h>
#include <sys/file.h>
#include <sys/dir.h>
#include <errno.h>
#include <syslog.h>
#include <unistd.h>
#include <signal.h>
#include <stdio.h>
#include <stdlib.h>
#include <paths.h>
#define LOCKFMT "LCK..%s"
/* Forward declarations */
static int put_pid (int fd, pid_t pid);
static pid_t get_pid (int fd);
/*
* uucp style locking routines
* return: 0 - success
* -1 - failure
*/
int uu_lock (char *ttyname)
{
int fd;
pid_t pid;
char tbuf[MAXNAMLEN];
(void)sprintf(tbuf, _PATH_UUCPLOCK LOCKFMT, 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) {
syslog(LOG_ERR, "lock open: %m");
return(-1);
}
if ((pid = get_pid (fd)) == -1) {
syslog(LOG_ERR, "lock read: %m");
(void)close(fd);
return(-1);
}
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
*/
if (lseek(fd, 0L, L_SET) < 0) {
syslog(LOG_ERR, "lock lseek: %m");
(void)close(fd);
return(-1);
}
/* fall out and finish the locking process */
}
pid = getpid();
if (!put_pid (fd, pid)) {
syslog(LOG_ERR, "lock write: %m");
(void)close(fd);
(void)unlink(tbuf);
return(-1);
}
(void)close(fd);
return(0);
}
int uu_unlock (char *ttyname)
{
char tbuf[MAXNAMLEN];
(void)sprintf(tbuf, _PATH_UUCPLOCK LOCKFMT, ttyname);
return(unlink(tbuf));
}
static int put_pid (int fd, pid_t pid)
{
char buf [32];
int len;
len = sprintf (buf, "%10ld\n", pid);
return write (fd, buf, len) == len;
}
static pid_t get_pid (int fd)
{
int bytes_read;
char buf [32];
pid_t pid;
bytes_read = read (fd, buf, sizeof (buf) - 1);
if (bytes_read > 0) {
buf [bytes_read] = '\0';
pid = strtol (buf, (char **) NULL, 10);
}
else
pid = -1;
return pid;
}
/* end of uucplock.c */
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