1/*	$NetBSD: mount_null.c,v 1.18 2008/07/20 01:20:22 lukem 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
43static char sccsid[] = "@(#)mount_null.c	8.6 (Berkeley) 4/26/95";
44#else
45__RCSID("$NetBSD: mount_null.c,v 1.18 2008/07/20 01:20:22 lukem Exp $");
46#endif
47#endif /* not lint */
48
49#include <sys/param.h>
50#include <sys/mount.h>
51#include <miscfs/nullfs/null.h>
52
53#include <err.h>
54#include <stdio.h>
55#include <unistd.h>
56#include <stdlib.h>
57#include <string.h>
58
59#include <mntopts.h>
60
61static const struct mntopt mopts[] = {
62	MOPT_STDOPTS,
63	MOPT_GETARGS,
64	MOPT_NULL,
65};
66
67int	mount_null(int argc, char **argv);
68static int	subdir(const char *, const char *);
69__dead static void	usage(void);
70
71#ifndef MOUNT_NOMAIN
72int
73main(int argc, char **argv)
74{
75	return mount_null(argc, argv);
76}
77#endif
78
79int
80mount_null(int argc, char *argv[])
81{
82	struct null_args args;
83	int ch, mntflags;
84	char target[MAXPATHLEN], canon_dir[MAXPATHLEN];
85	mntoptparse_t mp;
86
87	mntflags = 0;
88	while ((ch = getopt(argc, argv, "o:")) != -1)
89		switch(ch) {
90		case 'o':
91			mp = getmntopts(optarg, mopts, &mntflags, 0);
92			if (mp == NULL)
93				err(1, "getmntopts");
94			freemntopts(mp);
95			break;
96		case '?':
97		default:
98			usage();
99		}
100	argc -= optind;
101	argv += optind;
102
103	if (argc != 2)
104		usage();
105
106	if (realpath(argv[0], target) == NULL)        /* Check device path */
107		err(1, "realpath %s", argv[0]);
108	if (strncmp(argv[0], target, MAXPATHLEN)) {
109		warnx("\"%s\" is a relative path.", argv[0]);
110		warnx("using \"%s\" instead.", target);
111	}
112
113	if (realpath(argv[1], canon_dir) == NULL)    /* Check mounton path */
114		err(1, "realpath %s", argv[1]);
115	if (strncmp(argv[1], canon_dir, MAXPATHLEN)) {
116		warnx("\"%s\" is a relative path.", argv[1]);
117		warnx("using \"%s\" instead.", canon_dir);
118	}
119
120	if (subdir(target, canon_dir) || subdir(canon_dir, target))
121		errx(1, "%s (%s) and %s (%s) are not distinct paths",
122		    argv[0], target, argv[1], canon_dir);
123
124	args.la.target = target;
125
126	if (mount(MOUNT_NULL, canon_dir, mntflags, &args, sizeof args) == -1)
127		err(1, "%s on %s", target, canon_dir);
128	exit(0);
129}
130
131static int
132subdir(const char *p, const char *dir)
133{
134	int l;
135
136	l = strlen(dir);
137	if (l <= 1)
138		return (1);
139
140	if ((strncmp(p, dir, l) == 0) && (p[l] == '/' || p[l] == '\0'))
141		return (1);
142
143	return (0);
144}
145
146static void
147usage(void)
148{
149	(void)fprintf(stderr,
150		"usage: mount_null [-o options] target_fs mount_point\n");
151	exit(1);
152}
153