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mount_union.c revision 1.16 
      1 /*	$NetBSD: mount_union.c,v 1.16 2006/03/21 21:11:42 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. 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\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_union.c	8.6 (Berkeley) 4/26/95";
     44 #else
     45 __RCSID("$NetBSD: mount_union.c,v 1.16 2006/03/21 21:11:42 christos 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 static const struct mntopt mopts[] = {
     64 	MOPT_STDOPTS,
     65 	MOPT_GETARGS,
     66 	{ NULL }
     67 };
     68 
     69 int	mount_union(int argc, char **argv);
     70 static int	subdir(const char *, const char *);
     71 static void	usage(void);
     72 
     73 #ifndef MOUNT_NOMAIN
     74 int
     75 main(int argc, char **argv)
     76 {
     77 	return mount_union(argc, argv);
     78 }
     79 #endif
     80 
     81 int
     82 mount_union(int argc, char *argv[])
     83 {
     84 	struct union_args args;
     85 	int ch, mntflags;
     86 	char target[MAXPATHLEN], canon_dir[MAXPATHLEN];
     87 	mntoptparse_t mp;
     88 
     89 
     90 	mntflags = 0;
     91 	args.mntflags = UNMNT_ABOVE;
     92 	while ((ch = getopt(argc, argv, "bo:r")) != -1)
     93 		switch (ch) {
     94 		case 'b':
     95 			args.mntflags &= ~UNMNT_OPMASK;
     96 			args.mntflags |= UNMNT_BELOW;
     97 			break;
     98 		case 'o':
     99 			mp = getmntopts(optarg, mopts, &mntflags, 0);
    100 			if (mp == NULL)
    101 				err(1, "getmntopts");
    102 			freemntopts(mp);
    103 			break;
    104 		case 'r':
    105 			args.mntflags &= ~UNMNT_OPMASK;
    106 			args.mntflags |= UNMNT_REPLACE;
    107 			break;
    108 		case '?':
    109 		default:
    110 			usage();
    111 			/* NOTREACHED */
    112 		}
    113 	argc -= optind;
    114 	argv += optind;
    115 
    116 	if (argc != 2)
    117 		usage();
    118 
    119 	if (realpath(argv[0], target) == NULL)       /* Check device path */
    120 		err(1, "realpath %s", argv[0]);
    121 	if (strncmp(argv[0], target, MAXPATHLEN)) {
    122 		warnx("\"%s\" is a relative path.", argv[0]);
    123 		warnx("using \"%s\" instead.", target);
    124 	}
    125 
    126 	if (realpath(argv[1], canon_dir) == NULL)    /* Check mounton path */
    127 		err(1, "realpath %s", argv[1]);
    128 	if (strncmp(argv[1], canon_dir, MAXPATHLEN)) {
    129 		warnx("\"%s\" is a relative path.", argv[1]);
    130 		warnx("using \"%s\" instead.", canon_dir);
    131 	}
    132 
    133 	if (subdir(target, canon_dir) || subdir(canon_dir, target))
    134 		errx(1, "%s (%s) and %s are not distinct paths",
    135 		    argv[0], target, canon_dir);
    136 
    137 	args.target = target;
    138 
    139 	if (mount(MOUNT_UNION, canon_dir, mntflags, &args))
    140 		err(1, "%s on %s", target, canon_dir);
    141 	if (mntflags & MNT_GETARGS) {
    142 		char buf[1024];
    143 		(void)snprintb(buf, sizeof(buf), UNMNT_BITS, args.mntflags);
    144 		printf("flags=%s\n", buf);
    145 	}
    146 	exit(0);
    147 }
    148 
    149 static int
    150 subdir(const char *p, const char *dir)
    151 {
    152 	int l;
    153 
    154 	l = strlen(dir);
    155 	if (l <= 1)
    156 		return (1);
    157 
    158 	if ((strncmp(p, dir, l) == 0) && (p[l] == '/' || p[l] == '\0'))
    159 		return (1);
    160 
    161 	return (0);
    162 }
    163 
    164 static void
    165 usage(void)
    166 {
    167 	(void)fprintf(stderr,
    168 		"usage: mount_union [-br] [-o options] target_fs mount_point\n");
    169 	exit(1);
    170 }
    171