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mount_union.c revision 1.10 
      1 /*	$NetBSD: mount_union.c,v 1.10 2003/03/19 18:35:08 christos 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. All advertising materials mentioning features or use of this software
     19  *    must display the following acknowledgement:
     20  *	This product includes software developed by the University of
     21  *	California, Berkeley and its contributors.
     22  * 4. Neither the name of the University nor the names of its contributors
     23  *    may be used to endorse or promote products derived from this software
     24  *    without specific prior written permission.
     25  *
     26  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
     27  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
     28  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
     29  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
     30  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
     31  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
     32  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
     33  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
     34  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
     35  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
     36  * SUCH DAMAGE.
     37  */
     38 
     39 #include <sys/cdefs.h>
     40 #ifndef lint
     41 __COPYRIGHT("@(#) Copyright (c) 1992, 1993, 1994\n\
     42 	The Regents of the University of California.  All rights reserved.\n");
     43 #endif /* not lint */
     44 
     45 #ifndef lint
     46 #if 0
     47 static char sccsid[] = "@(#)mount_union.c	8.6 (Berkeley) 4/26/95";
     48 #else
     49 __RCSID("$NetBSD: mount_union.c,v 1.10 2003/03/19 18:35:08 christos Exp $");
     50 #endif
     51 #endif /* not lint */
     52 
     53 #include <sys/param.h>
     54 #include <sys/mount.h>
     55 
     56 #include <miscfs/union/union.h>
     57 
     58 #include <err.h>
     59 #include <stdio.h>
     60 #include <stdlib.h>
     61 #include <string.h>
     62 #include <unistd.h>
     63 #include <util.h>
     64 
     65 #include "mntopts.h"
     66 
     67 static const struct mntopt mopts[] = {
     68 	MOPT_STDOPTS,
     69 	MOPT_GETARGS,
     70 	{ NULL }
     71 };
     72 
     73 int	main __P((int, char *[]));
     74 int	mount_union __P((int argc, char **argv));
     75 static int	subdir __P((const char *, const char *));
     76 static void	usage __P((void));
     77 
     78 #ifndef MOUNT_NOMAIN
     79 int
     80 main(argc, argv)
     81 	int argc;
     82 	char **argv;
     83 {
     84 	return mount_union(argc, argv);
     85 }
     86 #endif
     87 
     88 int
     89 mount_union(argc, argv)
     90 	int argc;
     91 	char *argv[];
     92 {
     93 	struct union_args args;
     94 	int ch, mntflags;
     95 	char target[MAXPATHLEN];
     96 
     97 	mntflags = 0;
     98 	args.mntflags = UNMNT_ABOVE;
     99 	while ((ch = getopt(argc, argv, "bo:r")) != -1)
    100 		switch (ch) {
    101 		case 'b':
    102 			args.mntflags &= ~UNMNT_OPMASK;
    103 			args.mntflags |= UNMNT_BELOW;
    104 			break;
    105 		case 'o':
    106 			getmntopts(optarg, mopts, &mntflags, 0);
    107 			break;
    108 		case 'r':
    109 			args.mntflags &= ~UNMNT_OPMASK;
    110 			args.mntflags |= UNMNT_REPLACE;
    111 			break;
    112 		case '?':
    113 		default:
    114 			usage();
    115 			/* NOTREACHED */
    116 		}
    117 	argc -= optind;
    118 	argv += optind;
    119 
    120 	if (argc != 2)
    121 		usage();
    122 
    123 	if (realpath(argv[0], target) == 0)
    124 		err(1, "%s", target);
    125 
    126 	if (subdir(target, argv[1]) || subdir(argv[1], target))
    127 		errx(1, "%s (%s) and %s are not distinct paths",
    128 		    argv[0], target, argv[1]);
    129 
    130 	args.target = target;
    131 
    132 	if (mount(MOUNT_UNION, argv[1], mntflags, &args))
    133 		err(1, "%s on %s", target, argv[1]);
    134 	if (mntflags & MNT_GETARGS) {
    135 		char buf[1024];
    136 		(void)snprintb(buf, sizeof(buf), UNMNT_BITS, args.mntflags);
    137 		printf("flags=%s\n", buf);
    138 	}
    139 	exit(0);
    140 }
    141 
    142 static int
    143 subdir(p, dir)
    144 	const char *p;
    145 	const char *dir;
    146 {
    147 	int l;
    148 
    149 	l = strlen(dir);
    150 	if (l <= 1)
    151 		return (1);
    152 
    153 	if ((strncmp(p, dir, l) == 0) && (p[l] == '/' || p[l] == '\0'))
    154 		return (1);
    155 
    156 	return (0);
    157 }
    158 
    159 static void
    160 usage()
    161 {
    162 	(void)fprintf(stderr,
    163 		"usage: mount_union [-br] [-o options] target_fs mount_point\n");
    164 	exit(1);
    165 }
    166