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mbr.c revision 1.4 
      1 /*	$NetBSD: mbr.c,v 1.4 2012/02/02 21:54:34 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 static int find_mbr_part(struct of_dev *, uint32_t, char *,
     43     struct disklabel *, uint32_t, uint8_t, int);
     44 static void make_dos_label(struct disklabel *, uint32_t);
     45 
     46 /*
     47  * Find a valid MBR disklabel.
     48  */
     49 int
     50 search_mbr_label(struct of_dev *devp, u_long off, char *buf,
     51     struct disklabel *lp, u_long off0)
     52 {
     53 	static uint8_t fat_types[] = {
     54 		MBR_PTYPE_FAT12, MBR_PTYPE_FAT16S, MBR_PTYPE_FAT16B,
     55 		MBR_PTYPE_FAT32, MBR_PTYPE_FAT32L, MBR_PTYPE_FAT16L
     56 	};
     57 	size_t read;
     58 	uint32_t poff;
     59 	int i;
     60 
     61 	/* Find a disklabel in a NetBSD or 386BSD partition. */
     62 	poff = find_mbr_part(devp, off, buf, lp, 0, MBR_PTYPE_NETBSD, 0);
     63 #ifdef COMPAT_386BSD_MBRPART
     64 	if (poff == 0) {
     65 		poff = find_mbr_part(devp, off, buf, lp, 0,
     66 		    MBR_PTYPE_386BSD, 0);
     67 		if (poff != 0)
     68 			printf("WARNING: old BSD partition ID!\n");
     69 	}
     70 #endif
     71 	if (poff != 0) {
     72 		if (strategy(devp, F_READ, poff + LABELSECTOR, DEV_BSIZE,
     73 		    buf, &read) == 0 && read == DEV_BSIZE)
     74 			if (getdisklabel(buf, lp) == NULL)
     75 				return 0;
     76 	}
     77 
     78 	/*
     79 	 * No BSD partition with a valid disklabel found, so try to
     80 	 * construct a label from a DOS partition.
     81 	 */
     82 	for (i = 0; i < sizeof(fat_types); i++) {
     83 		poff = find_mbr_part(devp, off, buf, lp, 0, fat_types[i], 0);
     84 		if (poff != 0) {
     85 			make_dos_label(lp, poff);
     86 			return 0;
     87 		}
     88 	}
     89 
     90 	return ERDLAB;
     91 }
     92 
     93 static int
     94 find_mbr_part(struct of_dev *devp, uint32_t off, char *buf,
     95     struct disklabel *lp, uint32_t off0, uint8_t ptype, int recursion)
     96 {
     97 	size_t read;
     98 	struct mbr_partition *p;
     99 	int i;
    100 	uint32_t poff;
    101 
    102 	if (strategy(devp, F_READ, off, DEV_BSIZE, buf, &read)
    103 	    || read != DEV_BSIZE)
    104 		return 0;
    105 
    106 	if (*(uint16_t *)&buf[MBR_MAGIC_OFFSET] != sa_htole16(MBR_MAGIC))
    107 		return 0;
    108 
    109 	if (recursion++ <= 1)
    110 		off0 += off;
    111 
    112 	for (p = (struct mbr_partition *)(buf + MBR_PART_OFFSET), i = 0;
    113 	     i < MBR_PART_COUNT; i++, p++) {
    114 		if (p->mbrp_type == ptype) {
    115 			recursion--;
    116 			return sa_le32toh(p->mbrp_start) + off0;
    117 		}
    118 		else if (p->mbrp_type == MBR_PTYPE_EXT) {
    119 			poff = find_mbr_part(devp, sa_le32toh(p->mbrp_start),
    120 			    buf, lp, off0, ptype, recursion);
    121 			if (poff != 0) {
    122 				recursion--;
    123 				return poff;
    124 			}
    125 			if (strategy(devp, F_READ, off, DEV_BSIZE, buf, &read)
    126 			    || read != DEV_BSIZE) {
    127 				recursion--;
    128 				return 0;
    129 			}
    130 		}
    131 	}
    132 
    133 	recursion--;
    134 	return 0;
    135 }
    136 
    137 static void
    138 make_dos_label(struct disklabel *lp, uint32_t poff)
    139 {
    140 	int i;
    141 
    142 	/* clear all partitions */
    143 	lp->d_npartitions = RAW_PART + 1;
    144 	for (i = 0; i < MAXPARTITIONS; i++) {
    145 		lp->d_partitions[i].p_size = 0;
    146 		lp->d_partitions[i].p_offset = 0;
    147 		lp->d_partitions[i].p_fstype = 0;
    148 	}
    149 
    150 	/* set DOS partition as root partition */
    151 	lp->d_partitions[0].p_offset = poff;
    152 	lp->d_partitions[0].p_fstype = FS_MSDOS;
    153 
    154 	/* disklabel is valid */
    155 	lp->d_magic = lp->d_magic2 = DISKMAGIC;
    156 	lp->d_checksum = 0;
    157 	lp->d_checksum = dkcksum(lp);
    158 }
    159