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// Copyright (c) 2008 David Caldwell, All Rights Reserved.
#include <string.h>
#include <stdlib.h>
#include <err.h>
#include "lengthof.h"
#include "mbr.h"
struct mbr init_mbr(struct device *dev)
{
return (struct mbr) {
.mbr_signature = MBR_SIGNATURE,
};
}
#define le2(a, o) ((a)[o] << 0 | (a)[(o)+1] << 8)
#define le4(a, o) (le2(a,o) | (a)[(o)+2] << 16 | (a)[(o)+3] << 24)
struct mbr mbr_from_sector(void *sector)
{
struct mbr mbr;
unsigned char *mbr_buf = sector;
memcpy(mbr.code, mbr_buf, sizeof(mbr.code));
mbr.disk_signature = le4(mbr_buf, 440);
mbr.unused = le2(mbr_buf, 444);
for (int i=0; i<lengthof(mbr.partition); i++) {
int po = 446 + i*16;
struct mbr_partition *p = &mbr.partition[i];
p->status = mbr_buf[po + 0];
p->first_sector.head = mbr_buf[po + 1];
p->first_sector.sector = mbr_buf[po + 2] & 0x3f;
p->first_sector.cylinder = (mbr_buf[po + 2] & 0xc0) << 2 | mbr_buf[po + 3];
p->partition_type = mbr_buf[po + 4];
p->last_sector.head = mbr_buf[po + 5];
p->last_sector.sector = mbr_buf[po + 6] & 0x3f;
p->last_sector.cylinder = (mbr_buf[po + 6] & 0xc0) << 2 | mbr_buf[po + 7];
p->first_sector_lba = le4(mbr_buf, po + 8);
p->sectors = le4(mbr_buf, po + 12);
}
mbr.mbr_signature = le2(mbr_buf, 510);
return mbr;
}
void *sector_from_mbr(struct device *dev, struct mbr mbr)
{
unsigned char *mbr_buf = alloc_sectors(dev, 1);
memcpy(mbr_buf, mbr.code, sizeof(mbr.code));
mbr_buf[440] = mbr.disk_signature >> 0 & 0xff;
mbr_buf[441] = mbr.disk_signature >> 8 & 0xff;
mbr_buf[442] = mbr.disk_signature >> 16 & 0xff;
mbr_buf[443] = mbr.disk_signature >> 24 & 0xff;
mbr_buf[444] = mbr.unused >> 0 & 0xff;
mbr_buf[445] = mbr.unused >> 8 & 0xff;
for (int i=0; i<lengthof(mbr.partition); i++) {
int po = 446 + i*16;
struct mbr_partition *p = &mbr.partition[i];
mbr_buf[po + 0] = p->status;
mbr_buf[po + 1] = p->first_sector.head;
mbr_buf[po + 2] = p->first_sector.sector & 0x3f |
p->first_sector.cylinder >> 2 & 0xc0;
mbr_buf[po + 3] = p->first_sector.cylinder & 0xff;
mbr_buf[po + 4] = p->partition_type;
mbr_buf[po + 5] = p->last_sector.head;
mbr_buf[po + 6] = p->last_sector.sector & 0x3f |
p->last_sector.cylinder >> 2 & 0xc0;
mbr_buf[po + 7] = p->last_sector.cylinder & 0xff;
mbr_buf[po + 8] = p->first_sector_lba >> 0 & 0xff;
mbr_buf[po + 9] = p->first_sector_lba >> 8 & 0xff;
mbr_buf[po + 10] = p->first_sector_lba >> 16 & 0xff;
mbr_buf[po + 11] = p->first_sector_lba >> 24 & 0xff;
mbr_buf[po + 12] = p->sectors >> 0 & 0xff;
mbr_buf[po + 13] = p->sectors >> 8 & 0xff;
mbr_buf[po + 14] = p->sectors >> 16 & 0xff;
mbr_buf[po + 15] = p->sectors >> 24 & 0xff;
}
mbr_buf[510] = mbr.mbr_signature >> 0 & 0xff;
mbr_buf[511] = mbr.mbr_signature >> 8 & 0xff;
return mbr_buf;
}
struct mbr read_mbr(struct device *dev)
{
void *sector = get_sectors(dev, 0, 1);
struct mbr mbr = mbr_from_sector(sector);
free(sector);
return mbr;
}
bool write_mbr(struct device *dev, struct mbr mbr)
{
void *sector = sector_from_mbr(dev, mbr);
bool status = device_write(dev, sector, 0, 1);
free(sector);
return status;
}
#include <stdio.h>
void dump_mbr(struct mbr mbr)
{
//char code[440];
printf("disk_signature = %08x\n", mbr.disk_signature);
printf("unused = %02x\n", mbr.unused);
for (int i=0; i<4; i++) {
printf("[%d] status = %02x\n", i, mbr.partition[i].status);
printf("[%d] first_sector.cylinder = %d\n", i, mbr.partition[i].first_sector.cylinder);
printf("[%d] first_sector.head = %d\n", i, mbr.partition[i].first_sector.head);
printf("[%d] first_sector.sector = %d\n", i, mbr.partition[i].first_sector.sector);
printf("[%d] partition_type = %02x\n", i, mbr.partition[i].partition_type);
printf("[%d] last_sector.cylinder = %d\n", i, mbr.partition[i].last_sector.cylinder);
printf("[%d] last_sector.head = %d\n", i, mbr.partition[i].last_sector.head);
printf("[%d] last_sector.sector = %d\n", i, mbr.partition[i].last_sector.sector);
printf("[%d] first_sector_lba = %u\n", i, mbr.partition[i].first_sector_lba);
printf("[%d] sectors = %u\n", i, mbr.partition[i].sectors);
}
printf("signature = %02x\n",mbr.mbr_signature);
}
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