text: /*
   * Copyright (c) 2020, Liav A. <liavalb@hotmail.co.il>
   * 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/Storage/Partition/MBRPartitionTable.h>
  
  #ifndef MBR_DEBUG
  #    define MBR_DEBUG
  #endif
  
  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 nullptr;
      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()))
  {
      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;
          }
          auto partition_type = ByteBuffer::create_zeroed(sizeof(u8));
          partition_type.data()[0] = entry.type;
          m_partitions.append(DiskPartitionMetadata({ entry.offset, (entry.offset + entry.length), partition_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()))
  {
      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;
          }
          auto partition_type = ByteBuffer::create_zeroed(sizeof(u8));
          partition_type.data()[0] = entry.type;
          m_partitions.append(DiskPartitionMetadata({ entry.offset, (entry.offset + entry.length), partition_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();
  #ifdef MBR_DEBUG
  
      klog() << "Master Boot Record: mbr_signature=0x" << String::format("%x", header.mbr_signature);
  
  #endif
      if (header.mbr_signature != MBR_SIGNATURE) {
          klog() << "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;
  }
  
  }
  