xref: /freebsd/sbin/mount_nullfs/mount_nullfs.c (revision 6472ac3d8a86336899b6cfb789a4cd9897e3fab5)
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
34 static 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
41 static char sccsid[] = "@(#)mount_null.c	8.6 (Berkeley) 4/26/95";
42 #endif
43 static 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 
60 static struct mntopt mopts[] = {
61 	MOPT_STDOPTS,
62 	MOPT_END
63 };
64 
65 int	subdir(const char *, const char *);
66 static void	usage(void) __dead2;
67 
68 int
69 main(int argc, char *argv[])
70 {
71 	struct iovec iov[6];
72 	int ch, mntflags;
73 	char source[MAXPATHLEN];
74 	char target[MAXPATHLEN];
75 
76 	mntflags = 0;
77 	while ((ch = getopt(argc, argv, "o:")) != -1)
78 		switch(ch) {
79 		case 'o':
80 			getmntopts(optarg, mopts, &mntflags, 0);
81 			break;
82 		case '?':
83 		default:
84 			usage();
85 		}
86 	argc -= optind;
87 	argv += optind;
88 
89 	if (argc != 2)
90 		usage();
91 
92 	/* resolve target and source with realpath(3) */
93 	(void)checkpath(argv[0], target);
94 	(void)checkpath(argv[1], source);
95 
96 	if (subdir(target, source) || subdir(source, target))
97 		errx(EX_USAGE, "%s (%s) and %s are not distinct paths",
98 		    argv[0], target, argv[1]);
99 
100 	iov[0].iov_base = strdup("fstype");
101 	iov[0].iov_len = sizeof("fstype");
102 	iov[1].iov_base = strdup("nullfs");
103 	iov[1].iov_len = strlen(iov[1].iov_base) + 1;
104 	iov[2].iov_base = strdup("fspath");
105 	iov[2].iov_len = sizeof("fspath");
106 	iov[3].iov_base = source;
107 	iov[3].iov_len = strlen(source) + 1;
108 	iov[4].iov_base = strdup("target");
109 	iov[4].iov_len = sizeof("target");
110 	iov[5].iov_base = target;
111 	iov[5].iov_len = strlen(target) + 1;
112 
113 	if (nmount(iov, 6, mntflags))
114 		err(1, NULL);
115 	exit(0);
116 }
117 
118 int
119 subdir(const char *p, const char *dir)
120 {
121 	int l;
122 
123 	l = strlen(dir);
124 	if (l <= 1)
125 		return (1);
126 
127 	if ((strncmp(p, dir, l) == 0) && (p[l] == '/' || p[l] == '\0'))
128 		return (1);
129 
130 	return (0);
131 }
132 
133 static void
134 usage(void)
135 {
136 	(void)fprintf(stderr,
137 		"usage: mount_nullfs [-o options] target mount-point\n");
138 	exit(1);
139 }
140