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      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
     77 main(int argc, char **argv)
     78 {
     79 	return mount_union(argc, argv);
     80 }
     81 #endif
     82 
     83 int
     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
    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
    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