mount_nullfs.c revision 146853 
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 * 4. Neither the name of the University nor the names of its contributors
17 *    may be used to endorse or promote products derived from this software
18 *    without specific prior written permission.
19 *
20 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
21 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
22 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
23 * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
24 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
25 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
26 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
27 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
28 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
29 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
30 * SUCH DAMAGE.
31 */
32
33#ifndef lint
34static const char copyright[] =
35"@(#) Copyright (c) 1992, 1993, 1994\n\
36	The Regents of the University of California.  All rights reserved.\n";
37#endif /* not lint */
38
39#ifndef lint
40#if 0
41static char sccsid[] = "@(#)mount_null.c	8.6 (Berkeley) 4/26/95";
42#endif
43static const char rcsid[] =
44  "$FreeBSD: head/sbin/mount_nullfs/mount_nullfs.c 146853 2005-06-01 09:39:36Z delphij $";
45#endif /* not lint */
46
47#include <sys/param.h>
48#include <sys/mount.h>
49#include <sys/uio.h>
50
51#include <err.h>
52#include <stdio.h>
53#include <stdlib.h>
54#include <string.h>
55#include <sysexits.h>
56#include <unistd.h>
57
58#include "mntopts.h"
59
60struct mntopt mopts[] = {
61	MOPT_STDOPTS,
62	MOPT_NULL
63};
64
65int	subdir(const char *, const char *);
66static void	usage(void) __dead2;
67
68int
69main(argc, argv)
70	int argc;
71	char *argv[];
72{
73	struct iovec iov[6];
74	int ch, mntflags;
75	char source[MAXPATHLEN];
76	char target[MAXPATHLEN];
77
78	mntflags = 0;
79	while ((ch = getopt(argc, argv, "o:")) != -1)
80		switch(ch) {
81		case 'o':
82			getmntopts(optarg, mopts, &mntflags, 0);
83			break;
84		case '?':
85		default:
86			usage();
87		}
88	argc -= optind;
89	argv += optind;
90
91	if (argc != 2)
92		usage();
93
94	/* resolve target and source with realpath(3) */
95	(void)checkpath(argv[0], target);
96	(void)checkpath(argv[1], source);
97
98	if (subdir(target, source) || subdir(source, target))
99		errx(EX_USAGE, "%s (%s) and %s are not distinct paths",
100		    argv[0], target, argv[1]);
101
102	iov[0].iov_base = "fstype";
103	iov[0].iov_len = sizeof("fstype");
104	iov[1].iov_base = "nullfs";
105	iov[1].iov_len = strlen(iov[1].iov_base) + 1;
106	iov[2].iov_base = "fspath";
107	iov[2].iov_len = sizeof("fspath");
108	iov[3].iov_base = source;
109	iov[3].iov_len = strlen(source) + 1;
110	iov[4].iov_base = "target";
111	iov[4].iov_len = sizeof("target");
112	iov[5].iov_base = target;
113	iov[5].iov_len = strlen(target) + 1;
114
115	if (nmount(iov, 6, mntflags))
116		err(1, NULL);
117	exit(0);
118}
119
120int
121subdir(p, dir)
122	const char *p;
123	const char *dir;
124{
125	int l;
126
127	l = strlen(dir);
128	if (l <= 1)
129		return (1);
130
131	if ((strncmp(p, dir, l) == 0) && (p[l] == '/' || p[l] == '\0'))
132		return (1);
133
134	return (0);
135}
136
137static void
138usage()
139{
140	(void)fprintf(stderr,
141		"usage: mount_nullfs [-o options] target mount-point\n");
142	exit(1);
143}
144