BSD 4_4_Lite2 release

[unix-history] / usr / src / sbin / mount_null / mount_null.c

/*
* 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. All advertising materials mentioning features or use of this software
*    must display the following acknowledgement:
*      This product includes software developed by the University of
*      California, Berkeley and its contributors.
* 4. 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
static char sccsid[] = "@(#)mount_null.c        8.6 (Berkeley) 4/26/95";
#endif /* not lint */

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

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

#include "mntopts.h"

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

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

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

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

       if (argc != 2)
               usage();

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

       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("loopback", argv[1], mntflags, &args))
               err(1, NULL);
       exit(0);
}

int
subdir(p, dir)
       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)fprintf(stderr,
               "usage: mount_null [-o options] target_fs mount_point\n");
       exit(1);
}