mount_unionfs.c revision 23680 
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.
35 */
36
37#ifndef lint
38char copyright[] =
39"@(#) Copyright (c) 1992, 1993, 1994\n\
40	The Regents of the University of California.  All rights reserved.\n";
41#endif /* not lint */
42
43#ifndef lint
44static char sccsid[] = "@(#)mount_union.c	8.5 (Berkeley) 3/27/94";
45#endif /* not lint */
46
47#include <sys/param.h>
48#include <sys/mount.h>
49
50#include <miscfs/union/union.h>
51
52#include <err.h>
53#include <stdio.h>
54#include <stdlib.h>
55#include <string.h>
56#include <sysexits.h>
57#include <unistd.h>
58
59#include "mntopts.h"
60
61static struct mntopt mopts[] = {
62	MOPT_STDOPTS,
63	{ NULL }
64};
65
66static int	subdir __P((const char *, const char *));
67static void	usage __P((void)) __dead2;
68
69int
70main(argc, argv)
71	int argc;
72	char *argv[];
73{
74	struct union_args args;
75	int ch, mntflags;
76	char target[MAXPATHLEN];
77	struct vfsconf vfc;
78	int error;
79
80	mntflags = 0;
81	args.mntflags = UNMNT_ABOVE;
82	while ((ch = getopt(argc, argv, "bo:r")) != EOF)
83		switch (ch) {
84		case 'b':
85			args.mntflags &= ~UNMNT_OPMASK;
86			args.mntflags |= UNMNT_BELOW;
87			break;
88		case 'o':
89			getmntopts(optarg, mopts, &mntflags, 0);
90			break;
91		case 'r':
92			args.mntflags &= ~UNMNT_OPMASK;
93			args.mntflags |= UNMNT_REPLACE;
94			break;
95		case '?':
96		default:
97			usage();
98			/* NOTREACHED */
99		}
100	argc -= optind;
101	argv += optind;
102
103	if (argc != 2)
104		usage();
105
106	if (realpath(argv[0], target) == 0)
107		err(EX_OSERR, "%s", target);
108
109	if (subdir(target, argv[1]) || subdir(argv[1], target))
110		errx(EX_USAGE, "%s (%s) and %s are not distinct paths",
111		    argv[0], target, argv[1]);
112
113	args.target = target;
114
115	error = getvfsbyname("union", &vfc);
116	if (error && vfsisloadable("union")) {
117		if (vfsload("union"))
118			err(EX_OSERR, "vfsload(union)");
119		endvfsent();	/* flush cache */
120		error = getvfsbyname("union", &vfc);
121	}
122	if (error)
123		errx(EX_OSERR, "union filesystem is not available");
124
125	if (mount(vfc.vfc_name, argv[1], mntflags, &args))
126		err(EX_OSERR, target);
127	exit(0);
128}
129
130int
131subdir(p, dir)
132	const char *p;
133	const char *dir;
134{
135	int l;
136
137	l = strlen(dir);
138	if (l <= 1)
139		return (1);
140
141	if ((strncmp(p, dir, l) == 0) && (p[l] == '/' || p[l] == '\0'))
142		return (1);
143
144	return (0);
145}
146
147void
148usage()
149{
150	(void)fprintf(stderr,
151		"usage: mount_union [-br] [-o options] target_fs mount_point\n");
152	exit(EX_USAGE);
153}
154