/*-
 * Copyright (c) 1999 Ian Freislich
 * 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.
 *
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR 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 AUTHOR 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.
 *
 *	$Id: lockfile.c,v 1.3 2002/06/19 09:21:44 ianf Exp $
 */

#include <fcntl.h>
#include <stdarg.h>
#include <unistd.h>

int
openlock(const char *path, int flags, ...)
{
	mode_t		mode;
	va_list		ap;
	int		fd, result;
#ifndef HAS_FLOCK
	struct flock	fl;
#endif

	if (flags & O_CREAT) {
		va_start(ap, flags);
		mode = (mode_t)va_arg(ap, int);
		va_end(ap);
		fd = open(path, flags & ~O_NONBLOCK, mode);
	} else
		fd = open(path, flags & ~O_NONBLOCK);
	if (fd < 0)
		return(fd);

#ifdef HAS_FLOCK
	result = flock(fd, LOCK_EX|(flags & O_NONBLOCK ? LOCK_NB : NULL));
#else
	fl.l_start = 0;
	fl.l_len = 0;
	fl.l_type = (flags & O_ACCMODE) == O_RDONLY ? F_RDLCK : fl.l_type;
	fl.l_type = (flags & O_ACCMODE) == O_WRONLY ? F_WRLCK : fl.l_type;
	fl.l_type = (flags & O_ACCMODE) == O_RDWR ? F_WRLCK : fl.l_type;
	fl.l_whence = SEEK_SET;
	result = fcntl(fd, (flags & O_NONBLOCK) ? F_SETLK : F_SETLKW, &fl);
#endif

	if (result < 0) {
		close(fd);
		return(-1);
	}
	return(fd);
}