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/*
* Copyright (c) 2020, Liav A. <liavalb@hotmail.co.il>
*
* SPDX-License-Identifier: BSD-2-Clause
*/
#include <AK/ByteBuffer.h>
#include <Kernel/Debug.h>
#include <Kernel/Storage/Partition/MBRPartitionTable.h>
namespace Kernel {
#define MBR_SIGNATURE 0xaa55
#define MBR_PROTECTIVE 0xEE
#define EBR_CHS_CONTAINER 0x05
#define EBR_LBA_CONTAINER 0x0F
Result<NonnullOwnPtr<MBRPartitionTable>, PartitionTable::Error> MBRPartitionTable::try_to_initialize(const StorageDevice& device)
{
auto table = make<MBRPartitionTable>(device);
if (table->contains_ebr())
return { PartitionTable::Error::ConatinsEBR };
if (table->is_protective_mbr())
return { PartitionTable::Error::MBRProtective };
if (!table->is_valid())
return { PartitionTable::Error::Invalid };
return table;
}
OwnPtr<MBRPartitionTable> MBRPartitionTable::try_to_initialize(const StorageDevice& device, u32 start_lba)
{
auto table = make<MBRPartitionTable>(device, start_lba);
if (!table->is_valid())
return {};
return table;
}
bool MBRPartitionTable::read_boot_record()
{
auto buffer = UserOrKernelBuffer::for_kernel_buffer(m_cached_header.data());
if (!m_device->read_block(m_start_lba, buffer))
return false;
m_header_valid = true;
return m_header_valid;
}
MBRPartitionTable::MBRPartitionTable(const StorageDevice& device, u32 start_lba)
: PartitionTable(device)
, m_start_lba(start_lba)
, m_cached_header(ByteBuffer::create_zeroed(m_device->block_size()).release_value()) // FIXME: Do something sensible if this fails because of OOM.
{
if (!read_boot_record() || !initialize())
return;
m_header_valid = true;
auto& header = this->header();
for (size_t index = 0; index < 4; index++) {
auto& entry = header.entry[index];
if (entry.offset == 0x00) {
continue;
}
m_partitions.empend(entry.offset, (entry.offset + entry.length), entry.type);
}
m_valid = true;
}
MBRPartitionTable::MBRPartitionTable(const StorageDevice& device)
: PartitionTable(device)
, m_start_lba(0)
, m_cached_header(ByteBuffer::create_zeroed(m_device->block_size()).release_value()) // FIXME: Do something sensible if this fails because of OOM.
{
if (!read_boot_record() || contains_ebr() || is_protective_mbr() || !initialize())
return;
auto& header = this->header();
for (size_t index = 0; index < 4; index++) {
auto& entry = header.entry[index];
if (entry.offset == 0x00) {
continue;
}
m_partitions.empend(entry.offset, (entry.offset + entry.length), entry.type);
}
m_valid = true;
}
MBRPartitionTable::~MBRPartitionTable()
{
}
const MBRPartitionTable::Header& MBRPartitionTable::header() const
{
return *(const MBRPartitionTable::Header*)m_cached_header.data();
}
bool MBRPartitionTable::initialize()
{
auto& header = this->header();
dbgln_if(MBR_DEBUG, "Master Boot Record: mbr_signature={:#08x}", header.mbr_signature);
if (header.mbr_signature != MBR_SIGNATURE) {
dbgln("Master Boot Record: invalid signature");
return false;
}
return true;
}
bool MBRPartitionTable::contains_ebr() const
{
for (int i = 0; i < 4; i++) {
if (header().entry[i].type == EBR_CHS_CONTAINER || header().entry[i].type == EBR_LBA_CONTAINER)
return true;
}
return false;
}
bool MBRPartitionTable::is_protective_mbr() const
{
return header().entry[0].type == MBR_PROTECTIVE;
}
}
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