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mount_null.c revision 1.13 
      1 /*	$NetBSD: mount_null.c,v 1.13 2005/02/05 15:14:25 xtraeme 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_null.c	8.6 (Berkeley) 4/26/95";
     44 #else
     45 __RCSID("$NetBSD: mount_null.c,v 1.13 2005/02/05 15:14:25 xtraeme Exp $");
     46 #endif
     47 #endif /* not lint */
     48 
     49 #include <sys/param.h>
     50 #include <sys/mount.h>
     51 #include <miscfs/nullfs/null.h>
     52 
     53 #include <err.h>
     54 #include <stdio.h>
     55 #include <unistd.h>
     56 #include <stdlib.h>
     57 #include <string.h>
     58 
     59 #include <mntopts.h>
     60 
     61 static const struct mntopt mopts[] = {
     62 	MOPT_STDOPTS,
     63 	MOPT_GETARGS,
     64 	{ NULL }
     65 };
     66 
     67 int	mount_null(int argc, char **argv);
     68 static int	subdir(const char *, const char *);
     69 static void	usage(void);
     70 
     71 #ifndef MOUNT_NOMAIN
     72 int
     73 main(int argc, char **argv)
     74 {
     75 	return mount_null(argc, argv);
     76 }
     77 #endif
     78 
     79 int
     80 mount_null(int argc, char *argv[])
     81 {
     82 	struct null_args args;
     83 	int ch, mntflags;
     84 	char target[MAXPATHLEN], canon_dir[MAXPATHLEN];
     85 
     86 	mntflags = 0;
     87 	while ((ch = getopt(argc, argv, "o:")) != -1)
     88 		switch(ch) {
     89 		case 'o':
     90 			getmntopts(optarg, mopts, &mntflags, 0);
     91 			break;
     92 		case '?':
     93 		default:
     94 			usage();
     95 		}
     96 	argc -= optind;
     97 	argv += optind;
     98 
     99 	if (argc != 2)
    100 		usage();
    101 
    102 	if (realpath(argv[0], target) == NULL)        /* Check device path */
    103 		err(1, "realpath %s", argv[0]);
    104 	if (strncmp(argv[0], target, MAXPATHLEN)) {
    105 		warnx("\"%s\" is a relative path.", argv[0]);
    106 		warnx("using \"%s\" instead.", target);
    107 	}
    108 
    109 	if (realpath(argv[1], canon_dir) == NULL)    /* Check mounton path */
    110 		err(1, "realpath %s", argv[1]);
    111 	if (strncmp(argv[1], canon_dir, MAXPATHLEN)) {
    112 		warnx("\"%s\" is a relative path.", argv[1]);
    113 		warnx("using \"%s\" instead.", canon_dir);
    114 	}
    115 
    116 	if (subdir(target, canon_dir) || subdir(canon_dir, target))
    117 		errx(1, "%s (%s) and %s (%s) are not distinct paths",
    118 		    argv[0], target, argv[1], canon_dir);
    119 
    120 	args.la.target = target;
    121 
    122 	if (mount(MOUNT_NULL, canon_dir, mntflags, &args))
    123 		err(1, "%s on %s", target, canon_dir);
    124 	exit(0);
    125 }
    126 
    127 static int
    128 subdir(const char *p, const char *dir)
    129 {
    130 	int l;
    131 
    132 	l = strlen(dir);
    133 	if (l <= 1)
    134 		return (1);
    135 
    136 	if ((strncmp(p, dir, l) == 0) && (p[l] == '/' || p[l] == '\0'))
    137 		return (1);
    138 
    139 	return (0);
    140 }
    141 
    142 static void
    143 usage(void)
    144 {
    145 	(void)fprintf(stderr,
    146 		"usage: mount_null [-o options] target_fs mount_point\n");
    147 	exit(1);
    148 }
    149