Allow null mounts to accept -o update
[dragonfly.git] / sbin / mount_null / mount_null.c
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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. All advertising materials mentioning features or use of this software
17 * must display the following acknowledgement:
18 * This product includes software developed by the University of
19 * California, Berkeley and its contributors.
20 * 4. Neither the name of the University nor the names of its contributors
21 * may be used to endorse or promote products derived from this software
22 * without specific prior written permission.
23 *
24 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
25 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
26 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
27 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
28 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
29 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
30 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
31 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
32 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
33 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
34 * SUCH DAMAGE.
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35 *
36 * @(#) Copyright (c) 1992, 1993, 1994 The Regents of the University of California. All rights reserved.
37 * @(#)mount_null.c 8.6 (Berkeley) 4/26/95
38 * $FreeBSD: src/sbin/mount_null/mount_null.c,v 1.13 1999/10/09 11:54:11 phk Exp $
91117902 39 * $DragonFly: src/sbin/mount_null/mount_null.c,v 1.11 2008/09/18 16:08:31 dillon Exp $
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40 */
41
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42#include <sys/param.h>
43#include <sys/mount.h>
38a690d7 44#include <vfs/nullfs/null.h>
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45
46#include <err.h>
47#include <stdio.h>
48#include <stdlib.h>
49#include <string.h>
50#include <sysexits.h>
51#include <unistd.h>
52
53#include "mntopts.h"
54
55struct mntopt mopts[] = {
56 MOPT_STDOPTS,
8b02b69a 57 MOPT_UPDATE,
c19a7073 58 MOPT_NULL
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59};
60
9a76cd75 61static void usage(void) __dead2;
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62
63int
b5744197 64main(int argc, char **argv)
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65{
66 struct null_args args;
67 int ch, mntflags;
68 char source[MAXPATHLEN];
69 char target[MAXPATHLEN];
70 struct vfsconf vfc;
71 int error;
72
8b02b69a 73 bzero(&args, sizeof(args));
984263bc 74 mntflags = 0;
8b02b69a 75 while ((ch = getopt(argc, argv, "o:u")) != -1)
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76 switch(ch) {
77 case 'o':
78 getmntopts(optarg, mopts, &mntflags, 0);
79 break;
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80 case 'u':
81 mntflags |= MNT_UPDATE;
82 break;
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83 case '?':
84 default:
85 usage();
86 }
87 argc -= optind;
88 argv += optind;
89
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90 /*
91 * Resolve target and source with realpath(3). Only the mount point
92 * needs be specified in update mode, but mount(8) passes us two
93 * arguments, the second of which is the source directory.
94 */
95 if ((mntflags & MNT_UPDATE) && argc == 1) {
96 args.target = NULL;
97 checkpath(argv[0], source);
98 } else if (argc == 2) {
99 args.target = target;
100 checkpath(argv[0], target);
101 checkpath(argv[1], source);
102 } else
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103 usage();
104
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105 /*
106 * Mount points that did not use distinct paths (e.g. / on /mnt)
107 * used to be disallowed because mount linkages were stored in
108 * vnodes and would lead to endlessly recursive trees. DragonFly
109 * stores mount linkages in the namecache topology and does not
110 * have this problem, so paths no longer need to be distinct.
111 */
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112
113 error = getvfsbyname("null", &vfc);
114 if (error && vfsisloadable("null")) {
115 if(vfsload("null"))
116 err(EX_OSERR, "vfsload(null)");
117 endvfsent();
118 error = getvfsbyname("null", &vfc);
119 }
120 if (error)
121 errx(EX_OSERR, "null/loopback filesystem is not available");
122
123 if (mount(vfc.vfc_name, source, mntflags, &args))
124 err(1, NULL);
125 exit(0);
126}
127
984263bc 128static void
b5744197 129usage(void)
984263bc 130{
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131 fprintf(stderr,
132 "usage: mount_null [-o options] target_fs mount_point\n");
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133 fprintf(stderr,
134 " mount_null -u [-o options] mount_point\n");
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135 exit(1);
136}