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. 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 * @(#) Copyright (c) 1992, 1993, 1994 The Regents of the University of California. All rights reserved.
33 * @(#)mount_null.c 8.6 (Berkeley) 4/26/95
34 * $FreeBSD: src/sbin/mount_null/mount_null.c,v 1.13 1999/10/09 11:54:11 phk Exp $
35 */
36
37 #include <sys/param.h>
38 #include <sys/mount.h>
39 #include <vfs/nullfs/null.h>
40
41 #include <err.h>
42 #include <mntopts.h>
43 #include <stdio.h>
44 #include <stdlib.h>
45 #include <string.h>
46 #include <sysexits.h>
47 #include <unistd.h>
48
49 struct mntopt mopts[] = {
50 MOPT_STDOPTS,
51 MOPT_UPDATE,
52 MOPT_NULL
53 };
54
55 static void usage(void) __dead2;
56
57 int
main(int argc,char ** argv)58 main(int argc, char **argv)
59 {
60 struct null_args args;
61 int ch, mntflags;
62 char source[MAXPATHLEN];
63 char target[MAXPATHLEN];
64 struct vfsconf vfc;
65 int error;
66
67 bzero(&args, sizeof(args));
68 mntflags = 0;
69 while ((ch = getopt(argc, argv, "o:u")) != -1)
70 switch(ch) {
71 case 'o':
72 getmntopts(optarg, mopts, &mntflags, 0);
73 break;
74 case 'u':
75 mntflags |= MNT_UPDATE;
76 break;
77 case '?':
78 default:
79 usage();
80 }
81 argc -= optind;
82 argv += optind;
83
84 /*
85 * Resolve target and source with realpath(3). Only the mount point
86 * needs be specified in update mode, but mount(8) passes us two
87 * arguments, the second of which is the source directory.
88 */
89 if ((mntflags & MNT_UPDATE) && argc == 1) {
90 args.target = NULL;
91 checkpath(argv[0], source);
92 } else if (argc == 2) {
93 args.target = target;
94 checkpath(argv[0], target);
95 checkpath(argv[1], source);
96 } else
97 usage();
98
99 /*
100 * Mount points that did not use distinct paths (e.g. / on /mnt)
101 * used to be disallowed because mount linkages were stored in
102 * vnodes and would lead to endlessly recursive trees. DragonFly
103 * stores mount linkages in the namecache topology and does not
104 * have this problem, so paths no longer need to be distinct.
105 */
106
107 error = getvfsbyname("null", &vfc);
108 if (error && vfsisloadable("null")) {
109 if(vfsload("null"))
110 err(EX_OSERR, "vfsload(null)");
111 endvfsent();
112 error = getvfsbyname("null", &vfc);
113 }
114 if (error)
115 errx(EX_OSERR, "null/loopback filesystem is not available");
116
117 if (mount(vfc.vfc_name, source, mntflags, &args))
118 err(1, NULL);
119 exit(0);
120 }
121
122 static void
usage(void)123 usage(void)
124 {
125 fprintf(stderr,
126 "usage: mount_null [-o options] target_fs mount_point\n");
127 fprintf(stderr,
128 " mount_null -u [-o options] mount_point\n");
129 exit(1);
130 }
131