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  * %sccs.include.redist.c%
9  */
10 
11 #ifndef lint
12 char copyright[] =
13 "@(#) Copyright (c) 1992, 1993, 1994\n\
14 	The Regents of the University of California.  All rights reserved.\n";
15 #endif /* not lint */
16 
17 #ifndef lint
18 static char sccsid[] = "@(#)mount_union.c	8.5 (Berkeley) 03/27/94";
19 #endif /* not lint */
20 
21 #include <sys/param.h>
22 #include <sys/mount.h>
23 
24 #include <miscfs/union/union.h>
25 
26 #include <err.h>
27 #include <stdio.h>
28 #include <stdlib.h>
29 #include <string.h>
30 #include <unistd.h>
31 
32 #include "mntopts.h"
33 
34 struct mntopt mopts[] = {
35 	MOPT_STDOPTS,
36 	{ NULL }
37 };
38 
39 int	subdir __P((const char *, const char *));
40 void	usage __P((void));
41 
42 int
43 main(argc, argv)
44 	int argc;
45 	char *argv[];
46 {
47 	struct union_args args;
48 	int ch, mntflags;
49 	char target[MAXPATHLEN];
50 
51 	mntflags = 0;
52 	args.mntflags = UNMNT_ABOVE;
53 	while ((ch = getopt(argc, argv, "bo:r")) != EOF)
54 		switch (ch) {
55 		case 'b':
56 			args.mntflags &= ~UNMNT_OPMASK;
57 			args.mntflags |= UNMNT_BELOW;
58 			break;
59 		case 'o':
60 			getmntopts(optarg, mopts, &mntflags);
61 			break;
62 		case 'r':
63 			args.mntflags &= ~UNMNT_OPMASK;
64 			args.mntflags |= UNMNT_REPLACE;
65 			break;
66 		case '?':
67 		default:
68 			usage();
69 			/* NOTREACHED */
70 		}
71 	argc -= optind;
72 	argv += optind;
73 
74 	if (argc != 2)
75 		usage();
76 
77 	if (realpath(argv[0], target) == 0)
78 		err(1, "%s", target);
79 
80 	if (subdir(target, argv[1]) || subdir(argv[1], target))
81 		errx(1, "%s (%s) and %s are not distinct paths",
82 		    argv[0], target, argv[1]);
83 
84 	args.target = target;
85 
86 	if (mount(MOUNT_UNION, argv[1], mntflags, &args))
87 		err(1, NULL);
88 	exit(0);
89 }
90 
91 int
92 subdir(p, dir)
93 	const char *p;
94 	const char *dir;
95 {
96 	int l;
97 
98 	l = strlen(dir);
99 	if (l <= 1)
100 		return (1);
101 
102 	if ((strncmp(p, dir, l) == 0) && (p[l] == '/' || p[l] == '\0'))
103 		return (1);
104 
105 	return (0);
106 }
107 
108 void
109 usage()
110 {
111 	(void)fprintf(stderr,
112 		"usage: mount_union [-br] [-o options] target_fs mount_point\n");
113 	exit(1);
114 }
115