mount_unionfs.c revision 101829 
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 101829 2002-08-13 16:07:39Z mux $";
49#endif
50#endif /* not lint */
51
52#include <sys/param.h>
53#include <sys/mount.h>
54#include <sys/uio.h>
55
56#include <err.h>
57#include <stdio.h>
58#include <stdlib.h>
59#include <string.h>
60#include <sysexits.h>
61#include <unistd.h>
62
63#include "mntopts.h"
64
65static struct mntopt mopts[] = {
66	MOPT_STDOPTS,
67	{ NULL }
68};
69
70static int	subdir(const char *, const char *);
71static void	usage (void) __dead2;
72
73int
74main(argc, argv)
75	int argc;
76	char *argv[];
77{
78	struct iovec iov[8];
79	int ch, mntflags;
80	char source[MAXPATHLEN];
81	char target[MAXPATHLEN];
82	int iovcnt;
83
84	iovcnt = 6;
85	mntflags = 0;
86	while ((ch = getopt(argc, argv, "bo:r")) != -1)
87		switch (ch) {
88		case 'b':
89			iov[6].iov_base = "below";
90			iov[6].iov_len = strlen(iov[6].iov_base) + 1;
91			iov[7].iov_base = NULL;
92			iov[7].iov_len = 0;
93			iovcnt = 8;
94			break;
95		case 'o':
96			getmntopts(optarg, mopts, &mntflags, 0);
97			break;
98		case 'r':
99			iov[6].iov_base = "replace";
100			iov[6].iov_len = strlen(iov[6].iov_base) + 1;
101			iov[7].iov_base = NULL;
102			iov[7].iov_len = 0;
103			iovcnt = 8;
104			break;
105		case '?':
106		default:
107			usage();
108			/* NOTREACHED */
109		}
110	argc -= optind;
111	argv += optind;
112
113	if (argc != 2)
114		usage();
115
116	/* resolve both target and source with realpath(3) */
117	(void)checkpath(argv[0], target);
118	(void)checkpath(argv[1], source);
119
120	if (subdir(target, source) || subdir(source, target))
121		errx(EX_USAGE, "%s (%s) and %s (%s) are not distinct paths",
122		    argv[0], target, argv[1], source);
123
124	iov[0].iov_base = "fstype";
125	iov[0].iov_len = strlen(iov[0].iov_base) + 1;
126	iov[1].iov_base = "unionfs";
127	iov[1].iov_len = strlen(iov[1].iov_base) + 1;
128	iov[2].iov_base = "fspath";
129	iov[2].iov_len = strlen(iov[2].iov_base) + 1;
130	iov[3].iov_base = source;
131	iov[3].iov_len = strlen(source) + 1;
132	iov[4].iov_base = "target";
133	iov[4].iov_len = strlen(iov[4].iov_base) + 1;
134	iov[5].iov_base = target;
135	iov[5].iov_len = strlen(target) + 1;
136	if (nmount(iov, iovcnt, mntflags))
137		err(EX_OSERR, "%s", target);
138	exit(0);
139}
140
141int
142subdir(p, dir)
143	const char *p;
144	const char *dir;
145{
146	int l;
147
148	l = strlen(dir);
149	if (l <= 1)
150		return (1);
151
152	if ((strncmp(p, dir, l) == 0) && (p[l] == '/' || p[l] == '\0'))
153		return (1);
154
155	return (0);
156}
157
158void
159usage()
160{
161	(void)fprintf(stderr,
162		"usage: mount_unionfs [-br] [-o options] target_fs mount_point\n");
163	exit(EX_USAGE);
164}
165