sbin/mount_union/mount_union.c

   1 /*
   2  * Copyright (c) 1992, 1993, 1994
   3  *      The Regents of the University of California.  All rights reserved.
   4  *
   5  * This code is derived from software donated to Berkeley by
   6  * Jan-Simon Pendry.
   7  *
   8  * Redistribution and use in source and binary forms, with or without
   9  * modification, are permitted provided that the following conditions
  10  * are met:
  11  * 1. Redistributions of source code must retain the above copyright
  12  *    notice, this list of conditions and the following disclaimer.
  13  * 2. Redistributions in binary form must reproduce the above copyright
  14  *    notice, this list of conditions and the following disclaimer in the
  15  *    documentation and/or other materials provided with the distribution.
  16  * 3. All advertising materials mentioning features or use of this software
  17  *    must display the following acknowledgement:
  18  *      This product includes software developed by the University of
  19  *      California, Berkeley and its contributors.
  20  * 4. Neither the name of the University nor the names of its contributors
  21  *    may be used to endorse or promote products derived from this software
  22  *    without specific prior written permission.
  23  *
  24  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
  25  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  26  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  27  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
  28  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  29  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  30  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  31  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  32  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  33  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  34  * SUCH DAMAGE.
  35  *
  36  * @(#) Copyright (c) 1992, 1993, 1994 The Regents of the University of California.  All rights reserved.
  37  * @(#)mount_union.c    8.5 (Berkeley) 3/27/94
  38  * $FreeBSD: src/sbin/mount_union/mount_union.c,v 1.12 1999/10/09 11:54:14 phk Exp $
  39  * $DragonFly: src/sbin/mount_union/mount_union.c,v 1.7 2005/04/02 21:42:09 dillon Exp $
  40  */
  41
  42 #include <sys/param.h>
  43 #include <sys/mount.h>
  44
  45 #include <vfs/union/union.h>
  46
  47 #include <err.h>
  48 #include <stdio.h>
  49 #include <stdlib.h>
  50 #include <string.h>
  51 #include <sysexits.h>
  52 #include <unistd.h>
  53
  54 #include "mntopts.h"
  55
  56 static struct mntopt mopts[] = {
  57         MOPT_STDOPTS,
  58         MOPT_NULL
  59 };
  60
  61 static int      subdir(const char *, const char *);
  62 static void     usage(void) __dead2;
  63
  64 int
  65 main(int argc, char **argv)
  66 {
  67         struct union_args args;
  68         int ch, mntflags;
  69         char source[MAXPATHLEN];
  70         char target[MAXPATHLEN];
  71         struct vfsconf vfc;
  72         int error;
  73
  74         mntflags = 0;
  75         args.mntflags = UNMNT_ABOVE;
  76         while ((ch = getopt(argc, argv, "bo:r")) != -1)
  77                 switch (ch) {
  78                 case 'b':
  79                         args.mntflags &= ~UNMNT_OPMASK;
  80                         args.mntflags |= UNMNT_BELOW;
  81                         break;
  82                 case 'o':
  83                         getmntopts(optarg, mopts, &mntflags, 0);
  84                         break;
  85                 case 'r':
  86                         args.mntflags &= ~UNMNT_OPMASK;
  87                         args.mntflags |= UNMNT_REPLACE;
  88                         break;
  89                 case '?':
  90                 default:
  91                         usage();
  92                         /* NOTREACHED */
  93                 }
  94         argc -= optind;
  95         argv += optind;
  96
  97         if (argc != 2)
  98                 usage();
  99
 100         /* resolve both target and source with realpath(3) */
 101         checkpath(argv[0], target);
 102         checkpath(argv[1], source);
 103
 104         if (subdir(target, source) || subdir(source, target))
 105                 errx(EX_USAGE, "%s (%s) and %s (%s) are not distinct paths",
 106                     argv[0], target, argv[1], source);
 107
 108         args.target = target;
 109
 110         error = getvfsbyname("union", &vfc);
 111         if (error && vfsisloadable("union")) {
 112                 if (vfsload("union"))
 113                         err(EX_OSERR, "vfsload(union)");
 114                 endvfsent();    /* flush cache */
 115                 error = getvfsbyname("union", &vfc);
 116         }
 117         if (error)
 118                 errx(EX_OSERR, "union filesystem is not available");
 119
 120         if (mount(vfc.vfc_name, source, mntflags, &args))
 121                 err(EX_OSERR, "%s", target);
 122         exit(0);
 123 }
 124
 125 static int
 126 subdir(const char *p, const char *dir)
 127 {
 128         int l;
 129
 130         l = strlen(dir);
 131         if (l <= 1)
 132                 return (1);
 133
 134         if ((strncmp(p, dir, l) == 0) && (p[l] == '/' || p[l] == '\0'))
 135                 return (1);
 136
 137         return (0);
 138 }
 139
 140 static void
 141 usage(void)
 142 {
 143         fprintf(stderr,
 144             "usage: mount_union [-br] [-o options] target_fs mount_point\n");
 145         exit(EX_USAGE);
 146 }