lckpwdf.c revision 7c478bd95313f5f23a4c958a745db2134aa03244
/*
* CDDL HEADER START
*
* The contents of this file are subject to the terms of the
* Common Development and Distribution License, Version 1.0 only
* (the "License"). You may not use this file except in compliance
* with the License.
*
* You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
* or http://www.opensolaris.org/os/licensing.
* See the License for the specific language governing permissions
* and limitations under the License.
*
* When distributing Covered Code, include this CDDL HEADER in each
* file and include the License file at usr/src/OPENSOLARIS.LICENSE.
* If applicable, add the following below this CDDL HEADER, with the
* fields enclosed by brackets "[]" replaced with your own identifying
* information: Portions Copyright [yyyy] [name of copyright owner]
*
* CDDL HEADER END
*/
/*
* Copyright 2004 Sun Microsystems, Inc. All rights reserved.
* Use is subject to license terms.
*/
#pragma ident "%Z%%M% %I% %E% SMI"
/* Copyright (c) 1988 AT&T */
/* All Rights Reserved */
#pragma weak lckpwdf = _lckpwdf
#pragma weak ulckpwdf = _ulckpwdf
#include "synonyms.h"
#include <sys/types.h>
#include <stdio.h>
#include <signal.h>
#include <fcntl.h>
#include <unistd.h>
#include <shadow.h>
#include <errno.h>
#include <thread.h>
#include "mtlib.h"
#define LOCKFILE "/etc/.pwd.lock"
#define S_WAITTIME 15
static struct flock flock = {
0, /* l_type */
0, /* l_whence */
0, /* l_start */
0, /* l_len */
0, /* l_sysid */
0 /* l_pid */
};
/*
* lckpwdf() returns a 0 for a successful lock within W_WAITTIME
* seconds and -1 otherwise. We stand on our head to make it MT-safe.
*/
static pid_t lck_pid = 0; /* process's pid at last lock */
static thread_t lck_tid = 0; /* thread that holds the lock */
static int fildes = -1;
static mutex_t lck_lock = DEFAULTMUTEX;
int
lckpwdf(void)
{
int seconds = 0;
lmutex_lock(&lck_lock);
for (;;) {
if (lck_pid != 0 && lck_pid != getpid()) {
/* somebody forked */
lck_pid = 0;
lck_tid = 0;
}
if (lck_tid == 0) {
if ((fildes = creat(LOCKFILE, 0600)) == -1)
break;
flock.l_type = F_WRLCK;
if (fcntl(fildes, F_SETLK, &flock) != -1) {
lck_pid = getpid();
lck_tid = thr_self();
lmutex_unlock(&lck_lock);
return (0);
}
(void) close(fildes);
fildes = -1;
}
if (seconds++ >= S_WAITTIME) {
/*
* For compatibility with the past, pretend
* that we were interrupted by SIGALRM.
*/
errno = EINTR;
break;
}
lmutex_unlock(&lck_lock);
(void) sleep(1);
lmutex_lock(&lck_lock);
}
lmutex_unlock(&lck_lock);
return (-1);
}
/*
* ulckpwdf() returns 0 for a successful unlock and -1 otherwise
*/
int
ulckpwdf(void)
{
lmutex_lock(&lck_lock);
if (lck_tid == thr_self() && fildes >= 0) {
flock.l_type = F_UNLCK;
(void) fcntl(fildes, F_SETLK, &flock);
(void) close(fildes);
fildes = -1;
lck_pid = 0;
lck_tid = 0;
lmutex_unlock(&lck_lock);
return (0);
}
lmutex_unlock(&lck_lock);
return (-1);
}