sbin/mount_null/mount_null.c

   1 /*      $NetBSD: mount_null.c,v 1.17 2007/07/16 17:06:54 pooka Exp $    */
   2
   3 /*
   4  * Copyright (c) 1992, 1993, 1994
   5  *      The Regents of the University of California.  All rights reserved.
   6  *
   7  * This code is derived from software donated to Berkeley by
   8  * Jan-Simon Pendry.
   9  *
  10  * Redistribution and use in source and binary forms, with or without
  11  * modification, are permitted provided that the following conditions
  12  * are met:
  13  * 1. Redistributions of source code must retain the above copyright
  14  *    notice, this list of conditions and the following disclaimer.
  15  * 2. Redistributions in binary form must reproduce the above copyright
  16  *    notice, this list of conditions and the following disclaimer in the
  17  *    documentation and/or other materials provided with the distribution.
  18  * 3. Neither the name of the University nor the names of its contributors
  19  *    may be used to endorse or promote products derived from this software
  20  *    without specific prior written permission.
  21  *
  22  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
  23  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  24  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  25  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
  26  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  27  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  28  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  29  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  30  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  31  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  32  * SUCH DAMAGE.
  33  */
  34
  35 #include <sys/cdefs.h>
  36 #ifndef lint
  37 __COPYRIGHT("@(#) Copyright (c) 1992, 1993, 1994\
  38  The Regents of the University of California.  All rights reserved.");
  39 #endif /* not lint */
  40
  41 #ifndef lint
  42 #if 0
  43 static char sccsid[] = "@(#)mount_null.c        8.6 (Berkeley) 4/26/95";
  44 #else
  45 __RCSID("$NetBSD: mount_null.c,v 1.17 2007/07/16 17:06:54 pooka Exp $");
  46 #endif
  47 #endif /* not lint */
  48
  49 #include <sys/param.h>
  50 #include <sys/mount.h>
  51 #include <miscfs/nullfs/null.h>
  52
  53 #include <err.h>
  54 #include <stdio.h>
  55 #include <unistd.h>
  56 #include <stdlib.h>
  57 #include <string.h>
  58
  59 #include <mntopts.h>
  60
  61 static const struct mntopt mopts[] = {
  62         MOPT_STDOPTS,
  63         MOPT_GETARGS,
  64         MOPT_NULL,
  65 };
  66
  67 int     mount_null(int argc, char **argv);
  68 static int      subdir(const char *, const char *);
  69 static void     usage(void);
  70
  71 #ifndef MOUNT_NOMAIN
  72 int
  73 main(int argc, char **argv)
  74 {
  75         return mount_null(argc, argv);
  76 }
  77 #endif
  78
  79 int
  80 mount_null(int argc, char *argv[])
  81 {
  82         struct null_args args;
  83         int ch, mntflags;
  84         char target[MAXPATHLEN], canon_dir[MAXPATHLEN];
  85         mntoptparse_t mp;
  86
  87         mntflags = 0;
  88         while ((ch = getopt(argc, argv, "o:")) != -1)
  89                 switch(ch) {
  90                 case 'o':
  91                         mp = getmntopts(optarg, mopts, &mntflags, 0);
  92                         if (mp == NULL)
  93                                 err(1, "getmntopts");
  94                         freemntopts(mp);
  95                         break;
  96                 case '?':
  97                 default:
  98                         usage();
  99                 }
 100         argc -= optind;
 101         argv += optind;
 102
 103         if (argc != 2)
 104                 usage();
 105
 106         if (realpath(argv[0], target) == NULL)        /* Check device path */
 107                 err(1, "realpath %s", argv[0]);
 108         if (strncmp(argv[0], target, MAXPATHLEN)) {
 109                 warnx("\"%s\" is a relative path.", argv[0]);
 110                 warnx("using \"%s\" instead.", target);
 111         }
 112
 113         if (realpath(argv[1], canon_dir) == NULL)    /* Check mounton path */
 114                 err(1, "realpath %s", argv[1]);
 115         if (strncmp(argv[1], canon_dir, MAXPATHLEN)) {
 116                 warnx("\"%s\" is a relative path.", argv[1]);
 117                 warnx("using \"%s\" instead.", canon_dir);
 118         }
 119
 120         if (subdir(target, canon_dir) || subdir(canon_dir, target))
 121                 errx(1, "%s (%s) and %s (%s) are not distinct paths",
 122                     argv[0], target, argv[1], canon_dir);
 123
 124         args.la.target = target;
 125
 126         if (mount(MOUNT_NULL, canon_dir, mntflags, &args, sizeof args) == -1)
 127                 err(1, "%s on %s", target, canon_dir);
 128         exit(0);
 129 }
 130
 131 static int
 132 subdir(const char *p, const char *dir)
 133 {
 134         int l;
 135
 136         l = strlen(dir);
 137         if (l <= 1)
 138                 return (1);
 139
 140         if ((strncmp(p, dir, l) == 0) && (p[l] == '/' || p[l] == '\0'))
 141                 return (1);
 142
 143         return (0);
 144 }
 145
 146 static void
 147 usage(void)
 148 {
 149         (void)fprintf(stderr,
 150                 "usage: mount_null [-o options] target_fs mount_point\n");
 151         exit(1);
 152 }