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mbr.c revision 1.1 
      1 /*	$NetBSD: mbr.c,v 1.1 2009/09/11 12:00:12 phx Exp $	*/
      2 
      3 /*
      4  * Copyright (C) 1995, 1996 Wolfgang Solfrank.
      5  * Copyright (C) 1995, 1996 TooLs GmbH.
      6  * All rights reserved.
      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 TooLs GmbH.
     19  * 4. The name of TooLs GmbH may not be used to endorse or promote products
     20  *    derived from this software without specific prior written permission.
     21  *
     22  * THIS SOFTWARE IS PROVIDED BY TOOLS GMBH ``AS IS'' AND ANY EXPRESS OR
     23  * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
     24  * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
     25  * IN NO EVENT SHALL TOOLS GMBH BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
     26  * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
     27  * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS;
     28  * OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY,
     29  * WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR
     30  * OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF
     31  * ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
     32  */
     33 
     34 #include <sys/param.h>
     35 #include <sys/bootblock.h>
     36 
     37 #include <lib/libsa/byteorder.h>
     38 #include <lib/libsa/stand.h>
     39 
     40 #include "mbr.h"
     41 
     42 
     43 static u_long
     44 get_long(const void *p)
     45 {
     46 	const unsigned char *cp = p;
     47 
     48 	return cp[0] | (cp[1] << 8) | (cp[2] << 16) | (cp[3] << 24);
     49 }
     50 
     51 
     52 /*
     53  * Find a valid MBR disklabel.
     54  */
     55 int
     56 search_mbr_label(struct of_dev *devp, u_long off, char *buf,
     57     struct disklabel *lp, u_long off0)
     58 {
     59 	size_t read;
     60 	struct mbr_partition *p;
     61 	int i;
     62 	u_long poff;
     63 	static int recursion;
     64 
     65 	if (strategy(devp, F_READ, off, DEV_BSIZE, buf, &read)
     66 	    || read != DEV_BSIZE)
     67 		return ERDLAB;
     68 
     69 	if (*(u_int16_t *)&buf[MBR_MAGIC_OFFSET] != sa_htole16(MBR_MAGIC))
     70 		return ERDLAB;
     71 
     72 	if (recursion++ <= 1)
     73 		off0 += off;
     74 	for (p = (struct mbr_partition *)(buf + MBR_PART_OFFSET), i = 0;
     75 	     i < MBR_PART_COUNT; i++, p++) {
     76 		if (p->mbrp_type == MBR_PTYPE_NETBSD
     77 #ifdef COMPAT_386BSD_MBRPART
     78 		    || (p->mbrp_type == MBR_PTYPE_386BSD &&
     79 			(printf("WARNING: old BSD partition ID!\n"), 1)
     80 			/* XXX XXX - libsa printf() is void */ )
     81 #endif
     82 		    ) {
     83 			poff = get_long(&p->mbrp_start) + off0;
     84 			if (strategy(devp, F_READ, poff + LABELSECTOR,
     85 				     DEV_BSIZE, buf, &read) == 0
     86 			    && read == DEV_BSIZE) {
     87 				if (!getdisklabel(buf, lp)) {
     88 					recursion--;
     89 					return 0;
     90 				}
     91 			}
     92 			if (strategy(devp, F_READ, off, DEV_BSIZE, buf, &read)
     93 			    || read != DEV_BSIZE) {
     94 				recursion--;
     95 				return ERDLAB;
     96 			}
     97 		} else if (p->mbrp_type == MBR_PTYPE_EXT) {
     98 			poff = get_long(&p->mbrp_start);
     99 			if (!search_mbr_label(devp, poff, buf, lp, off0)) {
    100 				recursion--;
    101 				return 0;
    102 			}
    103 			if (strategy(devp, F_READ, off, DEV_BSIZE, buf, &read)
    104 			    || read != DEV_BSIZE) {
    105 				recursion--;
    106 				return ERDLAB;
    107 			}
    108 		}
    109 	}
    110 
    111 	recursion--;
    112 	return ERDLAB;
    113 }
    114