ref: 803375001a1985ae323c86fa3f6f2c4eff14e1e9
dir: lwext4/src/ext4_mbr.c
/*
* Copyright (c) 2015 Grzegorz Kostka (kostka.grzegorz@gmail.com)
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
*
* - Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* - Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
* - The name of the author may not be used to endorse or promote products
* derived from this software without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
* IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
* OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
* IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
* NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
* DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
* THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
* THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*/
/** @addtogroup lwext4
* @{
*/
/**
* @file ext4_mbr.c
* @brief Master boot record parser
*/
#include "ext4_config.h"
#include "ext4_types.h"
#include "ext4_misc.h"
#include "ext4_errno.h"
#include "ext4_debug.h"
#include "ext4_mbr.h"
#include <inttypes.h>
#include <string.h>
#define MBR_SIGNATURE 0xAA55
#pragma pack(push, 1)
struct ext4_part_entry {
uint8_t status;
uint8_t chs1[3];
uint8_t type;
uint8_t chs2[3];
uint32_t first_lba;
uint32_t sectors;
};
struct ext4_mbr {
uint8_t bootstrap[446];
struct ext4_part_entry part_entry[4];
uint16_t signature;
};
#pragma pack(pop)
int ext4_mbr_scan(struct ext4_blockdev *parent, struct ext4_mbr_bdevs *bdevs)
{
int r;
size_t i;
ext4_dbg(DEBUG_MBR, DBG_INFO "ext4_mbr_scan\n");
memset(bdevs, 0, sizeof(struct ext4_mbr_bdevs));
r = ext4_block_init(parent);
if (r != EOK)
return r;
r = ext4_block_readbytes(parent, 0, parent->bdif->ph_bbuf, 512);
if (r != EOK) {
goto blockdev_fini;
}
const struct ext4_mbr *mbr = (void *)parent->bdif->ph_bbuf;
if (to_le16(mbr->signature) != MBR_SIGNATURE) {
ext4_dbg(DEBUG_MBR, DBG_ERROR "ext4_mbr_scan: unknown "
"signature: 0x%x\n", to_le16(mbr->signature));
r = ENOENT;
goto blockdev_fini;
}
/*Show bootstrap code*/
ext4_dbg(DEBUG_MBR, "mbr_part: bootstrap:");
for (i = 0; i < sizeof(mbr->bootstrap); ++i) {
if (!(i & 0xF))
ext4_dbg(DEBUG_MBR | DEBUG_NOPREFIX, "\n");
ext4_dbg(DEBUG_MBR | DEBUG_NOPREFIX, "%02x, ", mbr->bootstrap[i]);
}
ext4_dbg(DEBUG_MBR | DEBUG_NOPREFIX, "\n\n");
for (i = 0; i < 4; ++i) {
const struct ext4_part_entry *pe = &mbr->part_entry[i];
ext4_dbg(DEBUG_MBR, "mbr_part: %d\n", (int)i);
ext4_dbg(DEBUG_MBR, "\tstatus: 0x%x\n", pe->status);
ext4_dbg(DEBUG_MBR, "\ttype 0x%x:\n", pe->type);
ext4_dbg(DEBUG_MBR, "\tfirst_lba: 0x%"PRIx32"\n", pe->first_lba);
ext4_dbg(DEBUG_MBR, "\tsectors: 0x%"PRIx32"\n", pe->sectors);
if (!pe->sectors)
continue; /*Empty entry*/
if (pe->type != 0x83)
continue; /*Unsupported entry. 0x83 - linux native*/
bdevs->partitions[i].bdif = parent->bdif;
bdevs->partitions[i].part_offset =
(uint64_t)pe->first_lba * parent->bdif->ph_bsize;
bdevs->partitions[i].part_size =
(uint64_t)pe->sectors * parent->bdif->ph_bsize;
}
blockdev_fini:
ext4_block_fini(parent);
return r;
}
int ext4_mbr_write(struct ext4_blockdev *parent, struct ext4_mbr_parts *parts)
{
int r;
uint64_t disk_size = parent->part_size;
uint32_t division_sum = parts->division[0] + parts->division[1] +
parts->division[2] + parts->division[3];
if (division_sum > 100)
return EINVAL;
ext4_dbg(DEBUG_MBR, DBG_INFO "ext4_mbr_write\n");
r = ext4_block_init(parent);
if (r != EOK)
return r;
/*Calculate CHS*/
uint32_t k = 16;
while ((k < 256) && ((disk_size / k / 63) > 1024))
k *= 2;
if (k == 256)
--k;
const uint32_t cyl_size = 63 * k;
const uint32_t cyl_count = disk_size / cyl_size;
struct ext4_mbr *mbr = (void *)parent->bdif->ph_bbuf;
memset(mbr, 0, sizeof(struct ext4_mbr));
uint32_t cyl_it = 0;
for (int i = 0; i < 4; ++i) {
uint32_t cyl_part = cyl_count * parts->division[i] / 100;
if (!cyl_part)
continue;
uint32_t part_start = cyl_it * cyl_size;
uint32_t part_size = cyl_part * cyl_size;
if (i == 0) {
part_start += 63;
part_size -= 63;
}
uint32_t cyl_end = cyl_part + cyl_it - 1;
mbr->part_entry[i].status = 0;
mbr->part_entry[i].chs1[0] = i ? 0 : 1;;
mbr->part_entry[i].chs1[1] = (cyl_it >> 2) + 1;
mbr->part_entry[i].chs1[2] = cyl_it;
mbr->part_entry[i].type = 0x83;
mbr->part_entry[i].chs2[0] = k - 1;
mbr->part_entry[i].chs2[1] = (cyl_end >> 2) + 63;
mbr->part_entry[i].chs2[2] = cyl_end;
mbr->part_entry[i].first_lba = part_start;
mbr->part_entry[i].sectors = part_size;
cyl_it += cyl_part;
}
mbr->signature = MBR_SIGNATURE;
r = ext4_block_writebytes(parent, 0, parent->bdif->ph_bbuf, 512);
if (r != EOK)
goto blockdev_fini;
blockdev_fini:
ext4_block_fini(parent);
return r;
}
/**
* @}
*/