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mount_union.c revision 1.1 
      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  * Redistribution and use in source and binary forms, with or without
      9  * modification, are permitted provided that the following conditions
     10  * are met:
     11  * 1. Redistributions of source code must retain the above copyright
     12  *    notice, this list of conditions and the following disclaimer.
     13  * 2. Redistributions in binary form must reproduce the above copyright
     14  *    notice, this list of conditions and the following disclaimer in the
     15  *    documentation and/or other materials provided with the distribution.
     16  * 3. All advertising materials mentioning features or use of this software
     17  *    must display the following acknowledgement:
     18  *	This product includes software developed by the University of
     19  *	California, Berkeley and its contributors.
     20  * 4. Neither the name of the University nor the names of its contributors
     21  *    may be used to endorse or promote products derived from this software
     22  *    without specific prior written permission.
     23  *
     24  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
     25  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
     26  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
     27  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
     28  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
     29  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
     30  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
     31  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
     32  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
     33  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
     34  * SUCH DAMAGE.
     35  */
     36 
     37 #ifndef lint
     38 char copyright[] =
     39 "@(#) Copyright (c) 1992, 1993, 1994\n\
     40 	The Regents of the University of California.  All rights reserved.\n";
     41 #endif /* not lint */
     42 
     43 #ifndef lint
     44 /*static char sccsid[] = "from: @(#)mount_union.c	8.5 (Berkeley) 3/27/94";*/
     45 static char *rcsid = "$Id: mount_union.c,v 1.1 1994/06/08 19:29:13 mycroft Exp $";
     46 #endif /* not lint */
     47 
     48 #include <sys/param.h>
     49 #include <sys/mount.h>
     50 
     51 #include <miscfs/union/union.h>
     52 
     53 #include <err.h>
     54 #include <stdio.h>
     55 #include <stdlib.h>
     56 #include <string.h>
     57 #include <unistd.h>
     58 
     59 #include "mntopts.h"
     60 
     61 struct mntopt mopts[] = {
     62 	MOPT_STDOPTS,
     63 	{ NULL }
     64 };
     65 
     66 int	subdir __P((const char *, const char *));
     67 void	usage __P((void));
     68 
     69 int
     70 main(argc, argv)
     71 	int argc;
     72 	char *argv[];
     73 {
     74 	struct union_args args;
     75 	int ch, mntflags;
     76 	char target[MAXPATHLEN];
     77 
     78 	mntflags = 0;
     79 	args.mntflags = UNMNT_ABOVE;
     80 	while ((ch = getopt(argc, argv, "bo:r")) != EOF)
     81 		switch (ch) {
     82 		case 'b':
     83 			args.mntflags &= ~UNMNT_OPMASK;
     84 			args.mntflags |= UNMNT_BELOW;
     85 			break;
     86 		case 'o':
     87 			getmntopts(optarg, mopts, &mntflags);
     88 			break;
     89 		case 'r':
     90 			args.mntflags &= ~UNMNT_OPMASK;
     91 			args.mntflags |= UNMNT_REPLACE;
     92 			break;
     93 		case '?':
     94 		default:
     95 			usage();
     96 			/* NOTREACHED */
     97 		}
     98 	argc -= optind;
     99 	argv += optind;
    100 
    101 	if (argc != 2)
    102 		usage();
    103 
    104 	if (realpath(argv[0], target) == 0)
    105 		err(1, "%s", target);
    106 
    107 	if (subdir(target, argv[1]) || subdir(argv[1], target))
    108 		errx(1, "%s (%s) and %s are not distinct paths",
    109 		    argv[0], target, argv[1]);
    110 
    111 	args.target = target;
    112 
    113 	if (mount(MOUNT_UNION, argv[1], mntflags, &args))
    114 		err(1, NULL);
    115 	exit(0);
    116 }
    117 
    118 int
    119 subdir(p, dir)
    120 	const char *p;
    121 	const char *dir;
    122 {
    123 	int l;
    124 
    125 	l = strlen(dir);
    126 	if (l <= 1)
    127 		return (1);
    128 
    129 	if ((strncmp(p, dir, l) == 0) && (p[l] == '/' || p[l] == '\0'))
    130 		return (1);
    131 
    132 	return (0);
    133 }
    134 
    135 void
    136 usage()
    137 {
    138 	(void)fprintf(stderr,
    139 		"usage: mount_union [-br] [-o options] target_fs mount_point\n");
    140 	exit(1);
    141 }
    142