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  "$FreeBSD$";
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
60int	subdir(const char *, const char *);
61static void	usage(void) __dead2;
62
63int
64main(int argc, char *argv[])
65{
66	struct iovec *iov;
67	char *p, *val;
68	char source[MAXPATHLEN];
69	char target[MAXPATHLEN];
70	char errmsg[255];
71	int ch, mntflags, iovlen;
72	char nullfs[] = "nullfs";
73
74	iov = NULL;
75	iovlen = 0;
76	mntflags = 0;
77	errmsg[0] = '\0';
78	while ((ch = getopt(argc, argv, "o:")) != -1)
79		switch(ch) {
80		case 'o':
81			val = strdup("");
82			p = strchr(optarg, '=');
83			if (p != NULL) {
84				free(val);
85				*p = '\0';
86				val = p + 1;
87			}
88			build_iovec(&iov, &iovlen, optarg, val, (size_t)-1);
89			break;
90		case '?':
91		default:
92			usage();
93		}
94	argc -= optind;
95	argv += optind;
96
97	if (argc != 2)
98		usage();
99
100	/* resolve target and source with realpath(3) */
101	(void)checkpath(argv[0], target);
102	(void)checkpath(argv[1], source);
103
104	if (subdir(target, source) || subdir(source, target))
105		errx(EX_USAGE, "%s (%s) and %s are not distinct paths",
106		    argv[0], target, argv[1]);
107
108	build_iovec(&iov, &iovlen, "fstype", nullfs, (size_t)-1);
109	build_iovec(&iov, &iovlen, "fspath", source, (size_t)-1);
110	build_iovec(&iov, &iovlen, "target", target, (size_t)-1);
111	build_iovec(&iov, &iovlen, "errmsg", errmsg, sizeof(errmsg));
112	if (nmount(iov, iovlen, mntflags) < 0) {
113		if (errmsg[0] != 0)
114			err(1, "%s: %s", source, errmsg);
115		else
116			err(1, "%s", source);
117	}
118	exit(0);
119}
120
121int
122subdir(const char *p, const char *dir)
123{
124	int l;
125
126	l = strlen(dir);
127	if (l <= 1)
128		return (1);
129
130	if ((strncmp(p, dir, l) == 0) && (p[l] == '/' || p[l] == '\0'))
131		return (1);
132
133	return (0);
134}
135
136static void
137usage(void)
138{
139	(void)fprintf(stderr,
140		"usage: mount_nullfs [-o options] target mount-point\n");
141	exit(1);
142}
143