1 /* $NetBSD: mount_union.c,v 1.23 2020/07/26 08:20:23 mlelstv 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
43 static char sccsid[] = "@(#)mount_union.c 8.6 (Berkeley) 4/26/95";
44 #else
45 __RCSID("$NetBSD: mount_union.c,v 1.23 2020/07/26 08:20:23 mlelstv 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
63 #include "mountprog.h"
64
65 static const struct mntopt mopts[] = {
66 MOPT_STDOPTS,
67 MOPT_GETARGS,
68 MOPT_NULL,
69 };
70
71 int mount_union(int argc, char **argv);
72 static int subdir(const char *, const char *);
73 __dead static void usage(void);
74
75 #ifndef MOUNT_NOMAIN
76 int
main(int argc,char ** argv)77 main(int argc, char **argv)
78 {
79 return mount_union(argc, argv);
80 }
81 #endif
82
83 int
mount_union(int argc,char * argv[])84 mount_union(int argc, char *argv[])
85 {
86 struct union_args args;
87 int ch, mntflags;
88 char target[MAXPATHLEN], canon_dir[MAXPATHLEN];
89 mntoptparse_t mp;
90
91
92 mntflags = 0;
93 args.mntflags = UNMNT_ABOVE;
94 while ((ch = getopt(argc, argv, "bo:")) != -1)
95 switch (ch) {
96 case 'b':
97 args.mntflags &= ~UNMNT_OPMASK;
98 args.mntflags |= UNMNT_BELOW;
99 break;
100 case 'o':
101 mp = getmntopts(optarg, mopts, &mntflags, 0);
102 if (mp == NULL)
103 err(1, "getmntopts");
104 freemntopts(mp);
105 break;
106 case '?':
107 default:
108 usage();
109 /* NOTREACHED */
110 }
111 argc -= optind;
112 argv += optind;
113
114 if (argc != 2)
115 usage();
116
117 pathadj(argv[0], target);
118 pathadj(argv[1], canon_dir);
119
120 if (subdir(target, canon_dir) || subdir(canon_dir, target))
121 errx(1, "%s (%s) and %s are not distinct paths",
122 argv[0], target, canon_dir);
123
124 args.target = target;
125
126 if (mount(MOUNT_UNION, canon_dir, mntflags, &args, sizeof args) == -1)
127 err(1, "%s on %s", target, canon_dir);
128 if (mntflags & MNT_GETARGS) {
129 char buf[1024];
130 (void)snprintb(buf, sizeof(buf), UNMNT_BITS, args.mntflags);
131 printf("flags=%s\n", buf);
132 }
133 exit(0);
134 }
135
136 static int
subdir(const char * p,const char * dir)137 subdir(const char *p, const char *dir)
138 {
139 int l;
140
141 l = strlen(dir);
142 if (l <= 1)
143 return (1);
144
145 if ((strncmp(p, dir, l) == 0) && (p[l] == '/' || p[l] == '\0'))
146 return (1);
147
148 return (0);
149 }
150
151 static void
usage(void)152 usage(void)
153 {
154 (void)fprintf(stderr,
155 "usage: mount_union [-br] [-o options] target_fs mount_point\n");
156 exit(1);
157 }
158