mount_unionfs.c revision 97196 
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
37#ifndef lint
38static const char copyright[] =
39"@(#) Copyright (c) 1992, 1993, 1994\n\
40	The Regents of the University of California.  All rights reserved.\n";
41#endif /* not lint */
42
43#ifndef lint
44#if 0
45static char sccsid[] = "@(#)mount_union.c	8.5 (Berkeley) 3/27/94";
46#else
47static const char rcsid[] =
48  "$FreeBSD: head/sbin/mount_unionfs/mount_unionfs.c 97196 2002-05-24 00:45:37Z mux $";
49#endif
50#endif /* not lint */
51
52#include <sys/param.h>
53#include <sys/mount.h>
54
55#include <fs/unionfs/union.h>
56
57#include <err.h>
58#include <stdio.h>
59#include <stdlib.h>
60#include <string.h>
61#include <sysexits.h>
62#include <unistd.h>
63
64#include "mntopts.h"
65
66static struct mntopt mopts[] = {
67	MOPT_STDOPTS,
68	{ NULL }
69};
70
71static int	subdir(const char *, const char *);
72static void	usage (void) __dead2;
73
74int
75main(argc, argv)
76	int argc;
77	char *argv[];
78{
79	struct iovec iov[8];
80	int ch, mntflags, unionflags;
81	char source[MAXPATHLEN];
82	char target[MAXPATHLEN];
83	struct vfsconf vfc;
84	int error;
85
86	mntflags = 0;
87	unionflags = UNMNT_ABOVE;
88	while ((ch = getopt(argc, argv, "bo:r")) != -1)
89		switch (ch) {
90		case 'b':
91			unionflags &= ~UNMNT_OPMASK;
92			unionflags |= UNMNT_BELOW;
93			break;
94		case 'o':
95			getmntopts(optarg, mopts, &mntflags, 0);
96			break;
97		case 'r':
98			unionflags &= ~UNMNT_OPMASK;
99			unionflags |= UNMNT_REPLACE;
100			break;
101		case '?':
102		default:
103			usage();
104			/* NOTREACHED */
105		}
106	argc -= optind;
107	argv += optind;
108
109	if (argc != 2)
110		usage();
111
112	/* resolve both target and source with realpath(3) */
113	(void)checkpath(argv[0], target);
114	(void)checkpath(argv[1], source);
115
116	if (subdir(target, source) || subdir(source, target))
117		errx(EX_USAGE, "%s (%s) and %s (%s) are not distinct paths",
118		    argv[0], target, argv[1], source);
119
120	error = getvfsbyname("unionfs", &vfc);
121	if (error && vfsisloadable("unionfs")) {
122		if (vfsload("unionfs"))
123			err(EX_OSERR, "vfsload(unionfs)");
124		endvfsent();	/* flush cache */
125		error = getvfsbyname("unionfs", &vfc);
126	}
127	if (error)
128		errx(EX_OSERR, "union filesystem is not available");
129
130	iov[0].iov_base = "fstype";
131	iov[0].iov_len = sizeof("fstype");
132	iov[1].iov_base = vfc.vfc_name;
133	iov[1].iov_len = strlen(vfc.vfc_name) + 1;
134	iov[2].iov_base = "fspath";
135	iov[2].iov_len = sizeof("fspath");
136	iov[3].iov_base = source;
137	iov[3].iov_len = strlen(source) + 1;
138	iov[4].iov_base = "target";
139	iov[4].iov_len = sizeof("target");
140	iov[5].iov_base = target;
141	iov[5].iov_len = strlen(target) + 1;
142	iov[6].iov_base = "unionflags";
143	iov[6].iov_len = sizeof("unionflags");
144	iov[7].iov_base = (char *)&unionflags;
145	iov[7].iov_len = sizeof(unionflags);
146	if (nmount(iov, 8, mntflags))
147		err(EX_OSERR, "%s", target);
148	exit(0);
149}
150
151int
152subdir(p, dir)
153	const char *p;
154	const char *dir;
155{
156	int l;
157
158	l = strlen(dir);
159	if (l <= 1)
160		return (1);
161
162	if ((strncmp(p, dir, l) == 0) && (p[l] == '/' || p[l] == '\0'))
163		return (1);
164
165	return (0);
166}
167
168void
169usage()
170{
171	(void)fprintf(stderr,
172		"usage: mount_unionfs [-br] [-o options] target_fs mount_point\n");
173	exit(EX_USAGE);
174}
175