1 /*-
2 * SPDX-License-Identifier: BSD-3-Clause
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 #ifndef lint
36 static const char copyright[] =
37 "@(#) Copyright (c) 1992, 1993, 1994\n\
38 The Regents of the University of California. All rights reserved.\n";
39 #endif /* not lint */
40
41 #ifndef lint
42 #if 0
43 static char sccsid[] = "@(#)mount_null.c 8.6 (Berkeley) 4/26/95";
44 #endif
45 static const char rcsid[] =
46 "$FreeBSD$";
47 #endif /* not lint */
48
49 #include <sys/param.h>
50 #include <sys/mount.h>
51 #include <sys/uio.h>
52
53 #include <err.h>
54 #include <stdio.h>
55 #include <stdlib.h>
56 #include <string.h>
57 #include <sysexits.h>
58 #include <unistd.h>
59
60 #include "mntopts.h"
61
62 int subdir(const char *, const char *);
63 static void usage(void) __dead2;
64
65 int
main(int argc,char * argv[])66 main(int argc, char *argv[])
67 {
68 struct iovec *iov;
69 char *p, *val;
70 char source[MAXPATHLEN];
71 char target[MAXPATHLEN];
72 char errmsg[255];
73 int ch, iovlen;
74 char nullfs[] = "nullfs";
75
76 iov = NULL;
77 iovlen = 0;
78 errmsg[0] = '\0';
79 while ((ch = getopt(argc, argv, "o:")) != -1)
80 switch(ch) {
81 case 'o':
82 val = strdup("");
83 p = strchr(optarg, '=');
84 if (p != NULL) {
85 free(val);
86 *p = '\0';
87 val = p + 1;
88 }
89 build_iovec(&iov, &iovlen, optarg, val, (size_t)-1);
90 break;
91 case '?':
92 default:
93 usage();
94 }
95 argc -= optind;
96 argv += optind;
97
98 if (argc != 2)
99 usage();
100
101 /* resolve target and source with realpath(3) */
102 if (checkpath(argv[0], target) != 0)
103 err(EX_USAGE, "%s", target);
104 if (checkpath(argv[1], source) != 0)
105 err(EX_USAGE, "%s", source);
106
107 if (subdir(target, source) || subdir(source, target))
108 errx(EX_USAGE, "%s (%s) and %s are not distinct paths",
109 argv[0], target, argv[1]);
110
111 build_iovec(&iov, &iovlen, "fstype", nullfs, (size_t)-1);
112 build_iovec(&iov, &iovlen, "fspath", source, (size_t)-1);
113 build_iovec(&iov, &iovlen, "target", target, (size_t)-1);
114 build_iovec(&iov, &iovlen, "errmsg", errmsg, sizeof(errmsg));
115 if (nmount(iov, iovlen, 0) < 0) {
116 if (errmsg[0] != 0)
117 err(1, "%s: %s", source, errmsg);
118 else
119 err(1, "%s", source);
120 }
121 exit(0);
122 }
123
124 int
subdir(const char * p,const char * dir)125 subdir(const char *p, const char *dir)
126 {
127 int l;
128
129 l = strlen(dir);
130 if (l <= 1)
131 return (1);
132
133 if ((strncmp(p, dir, l) == 0) && (p[l] == '/' || p[l] == '\0'))
134 return (1);
135
136 return (0);
137 }
138
139 static void
usage(void)140 usage(void)
141 {
142 (void)fprintf(stderr,
143 "usage: mount_nullfs [-o options] target mount-point\n");
144 exit(1);
145 }
146