sbin/mount_union/mount_union.c

   1 /*      $NetBSD: mount_union.c,v 1.20 2008/02/05 16:54:07 ad 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_union.c       8.6 (Berkeley) 4/26/95";
  44 #else
  45 __RCSID("$NetBSD: mount_union.c,v 1.20 2008/02/05 16:54:07 ad Exp $");
  46 #endif
  47 #endif /* not lint */
  48
  49 #include <sys/param.h>
  50 #include <sys/mount.h>
  51
  52 #include <miscfs/union/union.h>
  53
  54 #include <err.h>
  55 #include <stdio.h>
  56 #include <stdlib.h>
  57 #include <string.h>
  58 #include <unistd.h>
  59 #include <util.h>
  60
  61 #include <mntopts.h>
  62
  63 static const struct mntopt mopts[] = {
  64         MOPT_STDOPTS,
  65         MOPT_GETARGS,
  66         MOPT_NULL,
  67 };
  68
  69 int     mount_union(int argc, char **argv);
  70 static int      subdir(const char *, const char *);
  71 static void     usage(void);
  72
  73 #ifndef MOUNT_NOMAIN
  74 int
  75 main(int argc, char **argv)
  76 {
  77         return mount_union(argc, argv);
  78 }
  79 #endif
  80
  81 int
  82 mount_union(int argc, char *argv[])
  83 {
  84         struct union_args args;
  85         int ch, mntflags;
  86         char target[MAXPATHLEN], canon_dir[MAXPATHLEN];
  87         mntoptparse_t mp;
  88
  89
  90         mntflags = 0;
  91         args.mntflags = UNMNT_ABOVE;
  92         while ((ch = getopt(argc, argv, "bo:")) != -1)
  93                 switch (ch) {
  94                 case 'b':
  95                         args.mntflags &= ~UNMNT_OPMASK;
  96                         args.mntflags |= UNMNT_BELOW;
  97                         break;
  98                 case 'o':
  99                         mp = getmntopts(optarg, mopts, &mntflags, 0);
 100                         if (mp == NULL)
 101                                 err(1, "getmntopts");
 102                         freemntopts(mp);
 103                         break;
 104                 case '?':
 105                 default:
 106                         usage();
 107                         /* NOTREACHED */
 108                 }
 109         argc -= optind;
 110         argv += optind;
 111
 112         if (argc != 2)
 113                 usage();
 114
 115         if (realpath(argv[0], target) == NULL)       /* Check device path */
 116                 err(1, "realpath %s", argv[0]);
 117         if (strncmp(argv[0], target, MAXPATHLEN)) {
 118                 warnx("\"%s\" is a relative path.", argv[0]);
 119                 warnx("using \"%s\" instead.", target);
 120         }
 121
 122         if (realpath(argv[1], canon_dir) == NULL)    /* Check mounton path */
 123                 err(1, "realpath %s", argv[1]);
 124         if (strncmp(argv[1], canon_dir, MAXPATHLEN)) {
 125                 warnx("\"%s\" is a relative path.", argv[1]);
 126                 warnx("using \"%s\" instead.", canon_dir);
 127         }
 128
 129         if (subdir(target, canon_dir) || subdir(canon_dir, target))
 130                 errx(1, "%s (%s) and %s are not distinct paths",
 131                     argv[0], target, canon_dir);
 132
 133         args.target = target;
 134
 135         if (mount(MOUNT_UNION, canon_dir, mntflags, &args, sizeof args) == -1)
 136                 err(1, "%s on %s", target, canon_dir);
 137         if (mntflags & MNT_GETARGS) {
 138                 char buf[1024];
 139                 (void)snprintb(buf, sizeof(buf), UNMNT_BITS, args.mntflags);
 140                 printf("flags=%s\n", buf);
 141         }
 142         exit(0);
 143 }
 144
 145 static int
 146 subdir(const char *p, const char *dir)
 147 {
 148         int l;
 149
 150         l = strlen(dir);
 151         if (l <= 1)
 152                 return (1);
 153
 154         if ((strncmp(p, dir, l) == 0) && (p[l] == '/' || p[l] == '\0'))
 155                 return (1);
 156
 157         return (0);
 158 }
 159
 160 static void
 161 usage(void)
 162 {
 163         (void)fprintf(stderr,
 164                 "usage: mount_union [-br] [-o options] target_fs mount_point\n");
 165         exit(1);
 166 }