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mount_union.c revision 1.1.1.1 
      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[] = "@(#)mount_union.c	8.5 (Berkeley) 3/27/94";
     45 #endif /* not lint */
     46 
     47 #include <sys/param.h>
     48 #include <sys/mount.h>
     49 
     50 #include <miscfs/union/union.h>
     51 
     52 #include <err.h>
     53 #include <stdio.h>
     54 #include <stdlib.h>
     55 #include <string.h>
     56 #include <unistd.h>
     57 
     58 #include "mntopts.h"
     59 
     60 struct mntopt mopts[] = {
     61 	MOPT_STDOPTS,
     62 	{ NULL }
     63 };
     64 
     65 int	subdir __P((const char *, const char *));
     66 void	usage __P((void));
     67 
     68 int
     69 main(argc, argv)
     70 	int argc;
     71 	char *argv[];
     72 {
     73 	struct union_args args;
     74 	int ch, mntflags;
     75 	char target[MAXPATHLEN];
     76 
     77 	mntflags = 0;
     78 	args.mntflags = UNMNT_ABOVE;
     79 	while ((ch = getopt(argc, argv, "bo:r")) != EOF)
     80 		switch (ch) {
     81 		case 'b':
     82 			args.mntflags &= ~UNMNT_OPMASK;
     83 			args.mntflags |= UNMNT_BELOW;
     84 			break;
     85 		case 'o':
     86 			getmntopts(optarg, mopts, &mntflags);
     87 			break;
     88 		case 'r':
     89 			args.mntflags &= ~UNMNT_OPMASK;
     90 			args.mntflags |= UNMNT_REPLACE;
     91 			break;
     92 		case '?':
     93 		default:
     94 			usage();
     95 			/* NOTREACHED */
     96 		}
     97 	argc -= optind;
     98 	argv += optind;
     99 
    100 	if (argc != 2)
    101 		usage();
    102 
    103 	if (realpath(argv[0], target) == 0)
    104 		err(1, "%s", target);
    105 
    106 	if (subdir(target, argv[1]) || subdir(argv[1], target))
    107 		errx(1, "%s (%s) and %s are not distinct paths",
    108 		    argv[0], target, argv[1]);
    109 
    110 	args.target = target;
    111 
    112 	if (mount(MOUNT_UNION, argv[1], mntflags, &args))
    113 		err(1, NULL);
    114 	exit(0);
    115 }
    116 
    117 int
    118 subdir(p, dir)
    119 	const char *p;
    120 	const char *dir;
    121 {
    122 	int l;
    123 
    124 	l = strlen(dir);
    125 	if (l <= 1)
    126 		return (1);
    127 
    128 	if ((strncmp(p, dir, l) == 0) && (p[l] == '/' || p[l] == '\0'))
    129 		return (1);
    130 
    131 	return (0);
    132 }
    133 
    134 void
    135 usage()
    136 {
    137 	(void)fprintf(stderr,
    138 		"usage: mount_union [-br] [-o options] target_fs mount_point\n");
    139 	exit(1);
    140 }
    141