123 lines
2.5 KiB
C
123 lines
2.5 KiB
C
/*
|
|
* lock.c - lock/unlock the serial device.
|
|
*
|
|
* This code is derived from chat.c.
|
|
*/
|
|
|
|
static char rcsid[] = "$Id: lock.c,v 1.2 1994/09/25 02:32:04 wollman Exp $";
|
|
|
|
#include <stdio.h>
|
|
#include <string.h>
|
|
#include <stdlib.h>
|
|
#include <fcntl.h>
|
|
#include <errno.h>
|
|
#include <sys/types.h>
|
|
#include <sys/stat.h>
|
|
#include <syslog.h>
|
|
|
|
#ifdef sun
|
|
# if defined(SUNOS) && SUNOS >= 41
|
|
# ifndef HDB
|
|
# define HDB
|
|
# endif
|
|
# endif
|
|
#endif
|
|
|
|
#ifndef LOCK_DIR
|
|
# if defined(__NetBSD__) || defined(__FreeBSD__)
|
|
# define PIDSTRING
|
|
# define LOCK_PREFIX "/var/spool/lock/LCK.."
|
|
# else
|
|
# ifdef HDB
|
|
# define PIDSTRING
|
|
# define LOCK_PREFIX "/usr/spool/locks/LCK.."
|
|
# else /* HDB */
|
|
# define LOCK_PREFIX "/usr/spool/uucp/LCK.."
|
|
# endif /* HDB */
|
|
# endif
|
|
#endif /* LOCK_DIR */
|
|
|
|
static char *lock_file;
|
|
|
|
/*
|
|
* Create a lock file for the named lock device
|
|
*/
|
|
int
|
|
lock(dev)
|
|
char *dev;
|
|
{
|
|
char hdb_lock_buffer[12];
|
|
int fd, pid, n;
|
|
char *p;
|
|
|
|
if ((p = strrchr(dev, '/')) != NULL)
|
|
dev = p + 1;
|
|
lock_file = malloc(strlen(LOCK_PREFIX) + strlen(dev) + 1);
|
|
if (lock_file == NULL)
|
|
novm("lock file name");
|
|
strcat(strcpy(lock_file, LOCK_PREFIX), dev);
|
|
|
|
while ((fd = open(lock_file, O_EXCL | O_CREAT | O_RDWR, 0644)) < 0) {
|
|
if (errno == EEXIST
|
|
&& (fd = open(lock_file, O_RDONLY, 0)) >= 0) {
|
|
/* Read the lock file to find out who has the device locked */
|
|
#ifdef PIDSTRING
|
|
n = read(fd, hdb_lock_buffer, 11);
|
|
if (n > 0) {
|
|
hdb_lock_buffer[n] = 0;
|
|
pid = atoi(hdb_lock_buffer);
|
|
}
|
|
#else
|
|
n = read(fd, &pid, sizeof(pid));
|
|
#endif
|
|
if (n <= 0) {
|
|
syslog(LOG_ERR, "Can't read pid from lock file %s", lock_file);
|
|
close(fd);
|
|
} else {
|
|
if (kill(pid, 0) == -1 && errno == ESRCH) {
|
|
/* pid no longer exists - remove the lock file */
|
|
if (unlink(lock_file) == 0) {
|
|
close(fd);
|
|
syslog(LOG_NOTICE, "Removed stale lock on %s (pid %d)",
|
|
dev, pid);
|
|
continue;
|
|
} else
|
|
syslog(LOG_WARNING, "Couldn't remove stale lock on %s",
|
|
dev);
|
|
} else
|
|
syslog(LOG_NOTICE, "Device %s is locked by pid %d",
|
|
dev, pid);
|
|
}
|
|
close(fd);
|
|
} else
|
|
syslog(LOG_ERR, "Can't create lock file %s: %m", lock_file);
|
|
free(lock_file);
|
|
lock_file = NULL;
|
|
return -1;
|
|
}
|
|
|
|
# ifdef PIDSTRING
|
|
sprintf(hdb_lock_buffer, "%10d\n", getpid());
|
|
write(fd, hdb_lock_buffer, 11);
|
|
# else
|
|
pid = getpid();
|
|
write(fd, &pid, sizeof pid);
|
|
# endif
|
|
|
|
close(fd);
|
|
return 0;
|
|
}
|
|
|
|
/*
|
|
* Remove our lockfile
|
|
*/
|
|
unlock()
|
|
{
|
|
if (lock_file) {
|
|
unlink(lock_file);
|
|
free(lock_file);
|
|
lock_file = NULL;
|
|
}
|
|
}
|
|
|