/*

 * 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);

}