ladybird/Kernel/Devices/GPTPartitionTable.cpp

/*
 * Copyright (c) 2018-2020, Andreas Kling <kling@serenityos.org>
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions are met:
 *
 * 1. Redistributions of source code must retain the above copyright notice, this
 *    list of conditions and the following disclaimer.
 *
 * 2. 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.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "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 COPYRIGHT HOLDER OR CONTRIBUTORS 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.
 */

#include <AK/ByteBuffer.h>
#include <Kernel/Devices/GPTPartitionTable.h>

#ifndef GPT_DEBUG
#    define GPT_DEBUG
#endif

namespace Kernel {

GPTPartitionTable::GPTPartitionTable(BlockDevice& device)
    : m_device(move(device))
{
}

GPTPartitionTable::~GPTPartitionTable()
{
}

const GPTPartitionHeader& GPTPartitionTable::header() const
{
    return *reinterpret_cast<const GPTPartitionHeader*>(m_cached_header);
}

bool GPTPartitionTable::initialize()
{
    auto header_buffer = UserOrKernelBuffer::for_kernel_buffer(m_cached_header);
    if (!m_device->read_block(1, header_buffer)) {
        return false;
    }

    auto& header = this->header();

#ifdef GPT_DEBUG
    klog() << "GPTPartitionTable::initialize: gpt_signature=0x" << String::format("%x", header.sig[1]) << String::format("%x", header.sig[0]);
#endif

    if (header.sig[0] != GPT_SIGNATURE && header.sig[1] != GPT_SIGNATURE2) {
        klog() << "GPTPartitionTable::initialize: bad GPT signature 0x" << String::format("%x", header.sig[1]) << String::format("%x", header.sig[0]);
        return false;
    }

    return true;
}

RefPtr<DiskPartition> GPTPartitionTable::partition(unsigned index)
{
    ASSERT(index >= 1 && index <= 4294967294);

    auto& header = this->header();
    unsigned lba = header.partition_array_start_lba + (((index - 1) * header.partition_entry_size) / BytesPerSector);

    if (header.sig[0] != GPT_SIGNATURE) {
        klog() << "GPTPartitionTable::initialize: bad gpt signature - not initialized? 0x" << String::format("%x", header.sig);
        return nullptr;
    }

    u8 entries_per_sector = BytesPerSector / header.partition_entry_size;

    GPTPartitionEntry entries[entries_per_sector];
    auto entries_buffer = UserOrKernelBuffer::for_kernel_buffer((u8*)&entries);
    this->m_device->read_blocks(lba, 1, entries_buffer);
    GPTPartitionEntry& entry = entries[((index - 1) % entries_per_sector)];

#ifdef GPT_DEBUG
    klog() << "GPTPartitionTable::partition " << index;
    klog() << "GPTPartitionTable - offset = " << entry.first_lba[1] << entry.first_lba[0];
#endif

    if (entry.first_lba[0] == 0x00) {
#ifdef GPT_DEBUG
        klog() << "GPTPartitionTable::partition: missing partition requested index=" << index;
#endif

        return nullptr;
    }

#ifdef GPT_DEBUG
    klog() << "GPTPartitionTable::partition: found partition index=" << index << " type=" << String::format("%x", entry.partition_guid[3]) << "-" << String::format("%x", entry.partition_guid[2]) << "-" << String::format("%x", entry.partition_guid[1]) << "-" << String::format("%x", entry.partition_guid[0]);
#endif
    return DiskPartition::create(m_device, entry.first_lba[0], entry.last_lba[0]);
}

}