/*
 * 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.
 *
 * @(#) Copyright (c) 1992, 1993, 1994 The Regents of the University of California.  All rights reserved.
 * @(#)mount_null.c     8.6 (Berkeley) 4/26/95
 * $FreeBSD: src/sbin/mount_null/mount_null.c,v 1.13 1999/10/09 11:54:11 phk Exp $
 */

#include <sys/param.h>
#include <sys/mount.h>
#include <vfs/nullfs/null.h>

#include <err.h>
#include <mntopts.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <sysexits.h>
#include <unistd.h>

struct mntopt mopts[] = {
        MOPT_STDOPTS,
        MOPT_UPDATE,
        MOPT_NULL
};

static void     usage(void) __dead2;

int
main(int argc, char **argv)
{
        struct null_args args;
        int ch, mntflags;
        char source[MAXPATHLEN];
        char target[MAXPATHLEN];
        struct vfsconf vfc;
        int error;

        bzero(&args, sizeof(args));
        mntflags = 0;
        while ((ch = getopt(argc, argv, "o:u")) != -1)
                switch(ch) {
                case 'o':
                        getmntopts(optarg, mopts, &mntflags, 0);
                        break;
                case 'u':
                        mntflags |= MNT_UPDATE;
                        break;
                case '?':
                default:
                        usage();
                }
        argc -= optind;
        argv += optind;

        /*
         * Resolve target and source with realpath(3).  Only the mount point
         * needs be specified in update mode, but mount(8) passes us two
         * arguments, the second of which is the source directory.
         */
        if ((mntflags & MNT_UPDATE) && argc == 1) {
                args.target = NULL;
                checkpath(argv[0], source);
        } else if (argc == 2) {
                args.target = target;
                checkpath(argv[0], target);
                checkpath(argv[1], source);
        } else
                usage();

        /*
         * Mount points that did not use distinct paths (e.g. / on /mnt)
         * used to be disallowed because mount linkages were stored in
         * vnodes and would lead to endlessly recursive trees.  DragonFly
         * stores mount linkages in the namecache topology and does not
         * have this problem, so paths no longer need to be distinct.
         */

        error = getvfsbyname("null", &vfc);
        if (error && vfsisloadable("null")) {
                if(vfsload("null"))
                        err(EX_OSERR, "vfsload(null)");
                endvfsent();
                error = getvfsbyname("null", &vfc);
        }
        if (error)
                errx(EX_OSERR, "null/loopback filesystem is not available");

        if (mount(vfc.vfc_name, source, mntflags, &args))
                err(1, NULL);
        exit(0);
}

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