/*	$OpenBSD: mount_union.c,v 1.11 2005/04/08 20:09:38 jaredy Exp $	*/
/*	$NetBSD: mount_union.c,v 1.3 1996/04/13 01:32:11 jtc Exp $	*/

/*
 * Copyright (c) 1992, 1993, 1994
 *	The Regents of the University of California.  All rights reserved.
 *
 * This code is derived from software donated to Berkeley by
 * Jan-Simon Pendry.
 *
 * 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. 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
char copyright[] =
"@(#) Copyright (c) 1992, 1993, 1994\n\
	The Regents of the University of California.  All rights reserved.\n";
#endif /* not lint */

#ifndef lint
#if 0
static char sccsid[] = "@(#)mount_union.c	8.5 (Berkeley) 3/27/94";
#else
static char rcsid[] = "$OpenBSD: mount_union.c,v 1.11 2005/04/08 20:09:38 jaredy Exp $";
#endif
#endif /* not lint */

#include <sys/param.h>
#include <sys/mount.h>

#include <miscfs/union/union.h>

#include <err.h>
#include <errno.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>

#include "mntopts.h"

const struct mntopt mopts[] = {
	MOPT_STDOPTS,
	{ NULL }
};

int	subdir(const char *, const char *);
void	usage(void);

int
main(int argc, char *argv[])
{
	struct union_args args;
	int ch, mntflags;
	char target[MAXPATHLEN];

	mntflags = 0;
	args.mntflags = UNMNT_ABOVE;
	while ((ch = getopt(argc, argv, "bo:r")) != -1)
		switch (ch) {
		case 'b':
			args.mntflags &= ~UNMNT_OPMASK;
			args.mntflags |= UNMNT_BELOW;
			break;
		case 'o':
			getmntopts(optarg, mopts, &mntflags);
			break;
		case 'r':
			args.mntflags &= ~UNMNT_OPMASK;
			args.mntflags |= UNMNT_REPLACE;
			break;
		case '?':
		default:
			usage();
			/* NOTREACHED */
		}
	argc -= optind;
	argv += optind;

	if (argc != 2)
		usage();

	if (realpath(argv[0], target) == 0)
		err(1, "realpath %s", argv[0]);

	if (subdir(target, argv[1]) || subdir(argv[1], target))
		errx(1, "%s (%s) and %s are not distinct paths",
		    argv[0], target, argv[1]);

	args.target = target;

	if (mount(MOUNT_UNION, argv[1], mntflags, &args)) {
		if (errno == EOPNOTSUPP)
			errx(1, "%s: Filesystem not supported by kernel",
			    argv[1]);
		else
			err(1, "%s", argv[1]);
	}
	exit(0);
}

int
subdir(const char *p, const char *dir)
{
	int l;

	l = strlen(dir);
	if (l <= 1)
		return (1);

	if ((strncmp(p, dir, l) == 0) && (p[l] == '/' || p[l] == '\0'))
		return (1);

	return (0);
}

void
usage(void)
{
	(void)fprintf(stderr,
		"usage: mount_union [-br] [-o options] target_fs mount_point\n");
	exit(1);
}