xref: /freebsd/sbin/mount_unionfs/mount_unionfs.c (revision 8e537d168674d6b65869f73c20813001af875738)
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
38 char 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
44 static 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 
61 static struct mntopt mopts[] = {
62 	MOPT_STDOPTS,
63 	{ NULL }
64 };
65 
66 static int	subdir __P((const char *, const char *));
67 static void	usage __P((void)) __dead2;
68 
69 int
70 main(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 
79 	mntflags = 0;
80 	args.mntflags = UNMNT_ABOVE;
81 	while ((ch = getopt(argc, argv, "bo:r")) != EOF)
82 		switch (ch) {
83 		case 'b':
84 			args.mntflags &= ~UNMNT_OPMASK;
85 			args.mntflags |= UNMNT_BELOW;
86 			break;
87 		case 'o':
88 			getmntopts(optarg, mopts, &mntflags, 0);
89 			break;
90 		case 'r':
91 			args.mntflags &= ~UNMNT_OPMASK;
92 			args.mntflags |= UNMNT_REPLACE;
93 			break;
94 		case '?':
95 		default:
96 			usage();
97 			/* NOTREACHED */
98 		}
99 	argc -= optind;
100 	argv += optind;
101 
102 	if (argc != 2)
103 		usage();
104 
105 	if (realpath(argv[0], target) == 0)
106 		err(EX_OSERR, "%s", target);
107 
108 	if (subdir(target, argv[1]) || subdir(argv[1], target))
109 		errx(EX_USAGE, "%s (%s) and %s are not distinct paths",
110 		    argv[0], target, argv[1]);
111 
112 	args.target = target;
113 
114 	vfc = getvfsbyname("union");
115 	if(!vfc && vfsisloadable("union")) {
116 		if(vfsload("union"))
117 			err(1, "vfsload(union)");
118 		endvfsent();	/* flush cache */
119 		vfc = getvfsbyname("union");
120 	}
121 	if (!vfc)
122 		errx(EX_OSERR, "union filesystem is not available");
123 
124 	if (mount(vfc->vfc_index, argv[1], mntflags, &args))
125 		err(EX_OSERR, target);
126 	exit(0);
127 }
128 
129 int
130 subdir(p, dir)
131 	const char *p;
132 	const char *dir;
133 {
134 	int l;
135 
136 	l = strlen(dir);
137 	if (l <= 1)
138 		return (1);
139 
140 	if ((strncmp(p, dir, l) == 0) && (p[l] == '/' || p[l] == '\0'))
141 		return (1);
142 
143 	return (0);
144 }
145 
146 void
147 usage()
148 {
149 	(void)fprintf(stderr,
150 		"usage: mount_union [-br] [-o options] target_fs mount_point\n");
151 	exit(EX_USAGE);
152 }
153