dolphin/Source/Core/DiscIO/DiscScrubber.cpp

// Copyright 2009 Dolphin Emulator Project
// Licensed under GPLv2+
// Refer to the license.txt file included.

#include <algorithm>
#include <cinttypes>
#include <cstddef>
#include <cstdio>
#include <memory>
#include <string>
#include <vector>

#include "Common/CommonTypes.h"
#include "Common/FileUtil.h"
#include "Common/Logging/Log.h"
#include "DiscIO/DiscScrubber.h"
#include "DiscIO/Filesystem.h"
#include "DiscIO/Volume.h"
#include "DiscIO/VolumeCreator.h"

namespace DiscIO
{
#define CLUSTER_SIZE 0x8000

DiscScrubber::DiscScrubber() = default;
DiscScrubber::~DiscScrubber() = default;

bool DiscScrubber::SetupScrub(const std::string& filename, int block_size)
{
  bool success = true;
  m_Filename = filename;
  m_BlockSize = block_size;

  if (CLUSTER_SIZE % m_BlockSize != 0)
  {
    ERROR_LOG(DISCIO, "Block size %i is not a factor of 0x8000, scrubbing not possible",
              m_BlockSize);
    return false;
  }

  m_disc = CreateVolumeFromFilename(filename);
  if (!m_disc)
    return false;

  m_FileSize = m_disc->GetSize();

  u32 numClusters = (u32)(m_FileSize / CLUSTER_SIZE);

  // Warn if not DVD5 or DVD9 size
  if (numClusters != 0x23048 && numClusters != 0x46090)
  {
    WARN_LOG(DISCIO, "%s is not a standard sized Wii disc! (%x blocks)", filename.c_str(),
             numClusters);
  }

  // Table of free blocks
  m_FreeTable.resize(numClusters, 1);

  // Fill out table of free blocks
  success = ParseDisc();

  // Done with it; need it closed for the next part
  m_disc.reset();
  m_BlockCount = 0;

  m_isScrubbing = success;
  return success;
}

size_t DiscScrubber::GetNextBlock(File::IOFile& in, u8* buffer)
{
  u64 CurrentOffset = m_BlockCount * m_BlockSize;
  u64 i = CurrentOffset / CLUSTER_SIZE;

  size_t ReadBytes = 0;
  if (m_isScrubbing && m_FreeTable[i])
  {
    DEBUG_LOG(DISCIO, "Freeing 0x%016" PRIx64, CurrentOffset);
    std::fill(buffer, buffer + m_BlockSize, 0x00);
    in.Seek(m_BlockSize, SEEK_CUR);
    ReadBytes = m_BlockSize;
  }
  else
  {
    DEBUG_LOG(DISCIO, "Used    0x%016" PRIx64, CurrentOffset);
    in.ReadArray(buffer, m_BlockSize, &ReadBytes);
  }

  m_BlockCount++;
  return ReadBytes;
}

void DiscScrubber::MarkAsUsed(u64 _Offset, u64 _Size)
{
  u64 CurrentOffset = _Offset;
  u64 EndOffset = CurrentOffset + _Size;

  DEBUG_LOG(DISCIO, "Marking 0x%016" PRIx64 " - 0x%016" PRIx64 " as used", _Offset, EndOffset);

  while ((CurrentOffset < EndOffset) && (CurrentOffset < m_FileSize))
  {
    m_FreeTable[CurrentOffset / CLUSTER_SIZE] = 0;
    CurrentOffset += CLUSTER_SIZE;
  }
}

// Compensate for 0x400 (SHA-1) per 0x8000 (cluster), and round to whole clusters
void DiscScrubber::MarkAsUsedE(u64 partition_data_offset, u64 offset, u64 size)
{
  u64 first_cluster_start = offset / 0x7c00 * CLUSTER_SIZE + partition_data_offset;

  u64 last_cluster_end;
  if (size == 0)
  {
    // Without this special case, a size of 0 can be rounded to 1 cluster instead of 0
    last_cluster_end = first_cluster_start;
  }
  else
  {
    last_cluster_end = ((offset + size - 1) / 0x7c00 + 1) * CLUSTER_SIZE + partition_data_offset;
  }

  MarkAsUsed(first_cluster_start, last_cluster_end - first_cluster_start);
}

// Helper functions for reading the BE volume
bool DiscScrubber::ReadFromVolume(u64 _Offset, u32& _Buffer, bool _Decrypt)
{
  return m_disc->ReadSwapped(_Offset, &_Buffer, _Decrypt);
}

bool DiscScrubber::ReadFromVolume(u64 _Offset, u64& _Buffer, bool _Decrypt)
{
  u32 temp_buffer;
  if (!m_disc->ReadSwapped(_Offset, &temp_buffer, _Decrypt))
    return false;
  _Buffer = static_cast<u64>(temp_buffer) << 2;
  return true;
}

bool DiscScrubber::ParseDisc()
{
  // Mark the header as used - it's mostly 0s anyways
  MarkAsUsed(0, 0x50000);

  for (int x = 0; x < 4; x++)
  {
    if (!ReadFromVolume(0x40000 + (x * 8) + 0, PartitionGroup[x].numPartitions, false) ||
        !ReadFromVolume(0x40000 + (x * 8) + 4, PartitionGroup[x].PartitionsOffset, false))
      return false;

    // Read all partitions
    for (u32 i = 0; i < PartitionGroup[x].numPartitions; i++)
    {
      SPartition Partition;

      Partition.GroupNumber = x;
      Partition.Number = i;

      if (!ReadFromVolume(PartitionGroup[x].PartitionsOffset + (i * 8) + 0, Partition.Offset,
                          false) ||
          !ReadFromVolume(PartitionGroup[x].PartitionsOffset + (i * 8) + 4, Partition.Type,
                          false) ||
          !ReadFromVolume(Partition.Offset + 0x2a4, Partition.Header.TMDSize, false) ||
          !ReadFromVolume(Partition.Offset + 0x2a8, Partition.Header.TMDOffset, false) ||
          !ReadFromVolume(Partition.Offset + 0x2ac, Partition.Header.CertChainSize, false) ||
          !ReadFromVolume(Partition.Offset + 0x2b0, Partition.Header.CertChainOffset, false) ||
          !ReadFromVolume(Partition.Offset + 0x2b4, Partition.Header.H3Offset, false) ||
          !ReadFromVolume(Partition.Offset + 0x2b8, Partition.Header.DataOffset, false) ||
          !ReadFromVolume(Partition.Offset + 0x2bc, Partition.Header.DataSize, false))
        return false;

      PartitionGroup[x].PartitionsVec.push_back(Partition);
    }

    for (auto& rPartition : PartitionGroup[x].PartitionsVec)
    {
      const SPartitionHeader& rHeader = rPartition.Header;

      MarkAsUsed(rPartition.Offset, 0x2c0);

      MarkAsUsed(rPartition.Offset + rHeader.TMDOffset, rHeader.TMDSize);
      MarkAsUsed(rPartition.Offset + rHeader.CertChainOffset, rHeader.CertChainSize);
      MarkAsUsed(rPartition.Offset + rHeader.H3Offset, 0x18000);
      // This would mark the whole (encrypted) data area
      // we need to parse FST and other crap to find what's free within it!
      // MarkAsUsed(rPartition.Offset + rHeader.DataOffset, rHeader.DataSize);

      // Parse Data! This is where the big gain is
      if (!ParsePartitionData(rPartition))
        return false;
    }
  }

  return true;
}

// Operations dealing with encrypted space are done here - the volume is swapped to allow this
bool DiscScrubber::ParsePartitionData(SPartition& partition)
{
  bool parsed_ok = true;

  // Switch out the main volume temporarily
  std::unique_ptr<IVolume> old_volume;
  m_disc.swap(old_volume);

  // Ready some stuff
  m_disc = CreateVolumeFromFilename(m_Filename, partition.GroupNumber, partition.Number);
  if (m_disc == nullptr)
  {
    ERROR_LOG(DISCIO, "Failed to create volume from file %s", m_Filename.c_str());
    m_disc.swap(old_volume);
    return false;
  }

  std::unique_ptr<IFileSystem> filesystem(CreateFileSystem(m_disc.get()));
  if (!filesystem)
  {
    ERROR_LOG(DISCIO, "Failed to create filesystem for group %d partition %u",
              partition.GroupNumber, partition.Number);
    parsed_ok = false;
  }
  else
  {
    // Mark things as used which are not in the filesystem
    // Header, Header Information, Apploader
    parsed_ok = parsed_ok && ReadFromVolume(0x2440 + 0x14, partition.Header.ApploaderSize, true);
    parsed_ok =
        parsed_ok && ReadFromVolume(0x2440 + 0x18, partition.Header.ApploaderTrailerSize, true);
    MarkAsUsedE(partition.Offset + partition.Header.DataOffset, 0,
                0x2440 + partition.Header.ApploaderSize + partition.Header.ApploaderTrailerSize);

    // DOL
    partition.Header.DOLOffset = filesystem->GetBootDOLOffset();
    partition.Header.DOLSize = filesystem->GetBootDOLSize(partition.Header.DOLOffset);
    parsed_ok = parsed_ok && partition.Header.DOLOffset && partition.Header.DOLSize;
    MarkAsUsedE(partition.Offset + partition.Header.DataOffset, partition.Header.DOLOffset,
                partition.Header.DOLSize);

    // FST
    parsed_ok = parsed_ok && ReadFromVolume(0x424, partition.Header.FSTOffset, true);
    parsed_ok = parsed_ok && ReadFromVolume(0x428, partition.Header.FSTSize, true);
    MarkAsUsedE(partition.Offset + partition.Header.DataOffset, partition.Header.FSTOffset,
                partition.Header.FSTSize);

    // Go through the filesystem and mark entries as used
    for (SFileInfo file : filesystem->GetFileList())
    {
      DEBUG_LOG(DISCIO, "%s", file.m_FullPath.empty() ? "/" : file.m_FullPath.c_str());
      if ((file.m_NameOffset & 0x1000000) == 0)
        MarkAsUsedE(partition.Offset + partition.Header.DataOffset, file.m_Offset, file.m_FileSize);
    }
  }

  // Swap back
  m_disc.swap(old_volume);

  return parsed_ok;
}

}  // namespace DiscIO