1/*	$NetBSD: mount_union.c,v 1.21 2008/07/20 01:20:23 lukem Exp $	*/
2
3/*
4 * Copyright (c) 1992, 1993, 1994
5 *	The Regents of the University of California.  All rights reserved.
6 *
7 * This code is derived from software donated to Berkeley by
8 * Jan-Simon Pendry.
9 *
10 * Redistribution and use in source and binary forms, with or without
11 * modification, are permitted provided that the following conditions
12 * are met:
13 * 1. Redistributions of source code must retain the above copyright
14 *    notice, this list of conditions and the following disclaimer.
15 * 2. Redistributions in binary form must reproduce the above copyright
16 *    notice, this list of conditions and the following disclaimer in the
17 *    documentation and/or other materials provided with the distribution.
18 * 3. Neither the name of the University nor the names of its contributors
19 *    may be used to endorse or promote products derived from this software
20 *    without specific prior written permission.
21 *
22 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
23 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
24 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
25 * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
26 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
27 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
28 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
29 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
30 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
31 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
32 * SUCH DAMAGE.
33 */
34
35#include <sys/cdefs.h>
36#ifndef lint
37__COPYRIGHT("@(#) Copyright (c) 1992, 1993, 1994\
38 The Regents of the University of California.  All rights reserved.");
39#endif /* not lint */
40
41#ifndef lint
42#if 0
43static char sccsid[] = "@(#)mount_union.c	8.6 (Berkeley) 4/26/95";
44#else
45__RCSID("$NetBSD: mount_union.c,v 1.21 2008/07/20 01:20:23 lukem Exp $");
46#endif
47#endif /* not lint */
48
49#include <sys/param.h>
50#include <sys/mount.h>
51
52#include <miscfs/union/union.h>
53
54#include <err.h>
55#include <stdio.h>
56#include <stdlib.h>
57#include <string.h>
58#include <unistd.h>
59#include <util.h>
60
61#include <mntopts.h>
62
63static const struct mntopt mopts[] = {
64	MOPT_STDOPTS,
65	MOPT_GETARGS,
66	MOPT_NULL,
67};
68
69int	mount_union(int argc, char **argv);
70static int	subdir(const char *, const char *);
71__dead static void	usage(void);
72
73#ifndef MOUNT_NOMAIN
74int
75main(int argc, char **argv)
76{
77	return mount_union(argc, argv);
78}
79#endif
80
81int
82mount_union(int argc, char *argv[])
83{
84	struct union_args args;
85	int ch, mntflags;
86	char target[MAXPATHLEN], canon_dir[MAXPATHLEN];
87	mntoptparse_t mp;
88
89
90	mntflags = 0;
91	args.mntflags = UNMNT_ABOVE;
92	while ((ch = getopt(argc, argv, "bo:")) != -1)
93		switch (ch) {
94		case 'b':
95			args.mntflags &= ~UNMNT_OPMASK;
96			args.mntflags |= UNMNT_BELOW;
97			break;
98		case 'o':
99			mp = getmntopts(optarg, mopts, &mntflags, 0);
100			if (mp == NULL)
101				err(1, "getmntopts");
102			freemntopts(mp);
103			break;
104		case '?':
105		default:
106			usage();
107			/* NOTREACHED */
108		}
109	argc -= optind;
110	argv += optind;
111
112	if (argc != 2)
113		usage();
114
115	if (realpath(argv[0], target) == NULL)       /* Check device path */
116		err(1, "realpath %s", argv[0]);
117	if (strncmp(argv[0], target, MAXPATHLEN)) {
118		warnx("\"%s\" is a relative path.", argv[0]);
119		warnx("using \"%s\" instead.", target);
120	}
121
122	if (realpath(argv[1], canon_dir) == NULL)    /* Check mounton path */
123		err(1, "realpath %s", argv[1]);
124	if (strncmp(argv[1], canon_dir, MAXPATHLEN)) {
125		warnx("\"%s\" is a relative path.", argv[1]);
126		warnx("using \"%s\" instead.", canon_dir);
127	}
128
129	if (subdir(target, canon_dir) || subdir(canon_dir, target))
130		errx(1, "%s (%s) and %s are not distinct paths",
131		    argv[0], target, canon_dir);
132
133	args.target = target;
134
135	if (mount(MOUNT_UNION, canon_dir, mntflags, &args, sizeof args) == -1)
136		err(1, "%s on %s", target, canon_dir);
137	if (mntflags & MNT_GETARGS) {
138		char buf[1024];
139		(void)snprintb(buf, sizeof(buf), UNMNT_BITS, args.mntflags);
140		printf("flags=%s\n", buf);
141	}
142	exit(0);
143}
144
145static int
146subdir(const char *p, const char *dir)
147{
148	int l;
149
150	l = strlen(dir);
151	if (l <= 1)
152		return (1);
153
154	if ((strncmp(p, dir, l) == 0) && (p[l] == '/' || p[l] == '\0'))
155		return (1);
156
157	return (0);
158}
159
160static void
161usage(void)
162{
163	(void)fprintf(stderr,
164		"usage: mount_union [-br] [-o options] target_fs mount_point\n");
165	exit(1);
166}
167