dolphin-emulator/Source/Core/DiscIO/FileSystemGCWii.cpp

// Copyright 2008 Dolphin Emulator Project
// Licensed under GPLv2+
// Refer to the license.txt file included.

#include <algorithm>
#include <cinttypes>
#include <cstddef>
#include <cstring>
#include <optional>
#include <string>
#include <vector>

#include "Common/CommonFuncs.h"
#include "Common/CommonTypes.h"
#include "Common/FileUtil.h"
#include "Common/Logging/Log.h"
#include "Common/MsgHandler.h"
#include "Common/StringUtil.h"
#include "DiscIO/FileSystemGCWii.h"
#include "DiscIO/Filesystem.h"
#include "DiscIO/Volume.h"

namespace DiscIO
{
FileInfoGCWii::FileInfoGCWii(u64 name_offset, u64 offset, u64 file_size, std::string name)
    : m_NameOffset(name_offset), m_Offset(offset), m_FileSize(file_size), m_Name(name)
{
}

FileInfoGCWii::~FileInfoGCWii()
{
}

FileSystemGCWii::FileSystemGCWii(const Volume* _rVolume, const Partition& partition)
  : FileSystem(_rVolume, partition), m_Initialized(false), m_Valid(false), m_offset_shift(0)
{
  m_Valid = DetectFileSystem();
}

FileSystemGCWii::~FileSystemGCWii()
{
  m_FileInfoVector.clear();
}

const std::vector<FileInfoGCWii>& FileSystemGCWii::GetFileList()
{
  if (!m_Initialized)
    InitFileSystem();

  return m_FileInfoVector;
}

const FileInfo* FileSystemGCWii::FindFileInfo(const std::string& path)
{
  if (!m_Initialized)
    InitFileSystem();

  return FindFileInfo(path, 0);
}

const FileInfo* FileSystemGCWii::FindFileInfo(const std::string& path,
                                              size_t search_start_offset) const
{
  // Given a path like "directory1/directory2/fileA.bin", this function will
  // find directory1 and then call itself to search for "directory2/fileA.bin".

  if (path.empty() || path == "/")
    return &m_FileInfoVector[search_start_offset];

  // It's only possible to search in directories. Searching in a file is an error
  if (!m_FileInfoVector[search_start_offset].IsDirectory())
    return nullptr;

  size_t first_dir_separator = path.find('/');
  const std::string searching_for = path.substr(0, first_dir_separator);
  const std::string rest_of_path =
      (first_dir_separator != std::string::npos) ? path.substr(first_dir_separator + 1) : "";

  size_t search_end_offset = m_FileInfoVector[search_start_offset].GetSize();
  search_start_offset++;
  while (search_start_offset < search_end_offset)
  {
    const FileInfoGCWii& file_info = m_FileInfoVector[search_start_offset];

    if (file_info.GetName() == searching_for)
    {
      // A match is found. The rest of the path is passed on to finish the search.
      const FileInfo* result = FindFileInfo(rest_of_path, search_start_offset);

      // If the search wasn't successful, the loop continues, just in case there's a second
      // file info that matches searching_for (which probably won't happen in practice)
      if (result)
        return result;
    }

    if (file_info.IsDirectory())
    {
      // Skip a directory and everything that it contains

      if (file_info.GetSize() <= search_start_offset)
      {
        // The next offset (obtained by GetSize) is supposed to be larger than
        // the current offset. If an FST is malformed and breaks that rule,
        // there's a risk that next offset pointers form a loop.
        // To avoid infinite loops, this method returns.
        ERROR_LOG(DISCIO, "Invalid next offset in file system");
        return nullptr;
      }

      search_start_offset = file_info.GetSize();
    }
    else
    {
      // Skip a single file
      search_start_offset++;
    }
  }

  return nullptr;
}

const FileInfo* FileSystemGCWii::FindFileInfo(u64 disc_offset)
{
  if (!m_Initialized)
    InitFileSystem();

  for (auto& file_info : m_FileInfoVector)
  {
    if ((file_info.GetOffset() <= disc_offset) &&
        ((file_info.GetOffset() + file_info.GetSize()) > disc_offset))
    {
      return &file_info;
    }
  }

  return nullptr;
}

std::string FileSystemGCWii::GetPath(u64 _Address)
{
  if (!m_Initialized)
    InitFileSystem();

  for (size_t i = 0; i < m_FileInfoVector.size(); ++i)
  {
    const FileInfoGCWii& file_info = m_FileInfoVector[i];
    if ((file_info.GetOffset() <= _Address) &&
        ((file_info.GetOffset() + file_info.GetSize()) > _Address))
    {
      return GetPathFromFSTOffset(i);
    }
  }

  return "";
}

std::string FileSystemGCWii::GetPathFromFSTOffset(size_t file_info_offset)
{
  if (!m_Initialized)
    InitFileSystem();

  // Root entry doesn't have a name
  if (file_info_offset == 0)
    return "";

  const FileInfoGCWii& file_info = m_FileInfoVector[file_info_offset];
  if (file_info.IsDirectory())
  {
    // The offset of the parent directory is stored in the current directory.

    if (file_info.GetOffset() >= file_info_offset)
    {
      // The offset of the parent directory is supposed to be smaller than
      // the current offset. If an FST is malformed and breaks that rule,
      // there's a risk that parent directory pointers form a loop.
      // To avoid stack overflows, this method returns.
      ERROR_LOG(DISCIO, "Invalid parent offset in file system");
      return "";
    }
    return GetPathFromFSTOffset(file_info.GetOffset()) + file_info.GetName() + "/";
  }
  else
  {
    // The parent directory can be found by searching backwards
    // for a directory that contains this file.

    size_t parent_offset = file_info_offset - 1;
    while (!(m_FileInfoVector[parent_offset].IsDirectory() &&
             m_FileInfoVector[parent_offset].GetSize() > file_info_offset))
    {
      parent_offset--;
    }
    return GetPathFromFSTOffset(parent_offset) + file_info.GetName();
  }
}

u64 FileSystemGCWii::ReadFile(const FileInfo* file_info, u8* _pBuffer, u64 _MaxBufferSize,
                              u64 _OffsetInFile)
{
  if (!m_Initialized)
    InitFileSystem();

  if (!file_info || file_info->IsDirectory())
    return 0;

  if (_OffsetInFile >= file_info->GetSize())
    return 0;

  u64 read_length = std::min(_MaxBufferSize, file_info->GetSize() - _OffsetInFile);

  DEBUG_LOG(DISCIO, "Reading %" PRIx64 " bytes at %" PRIx64 " from file %s. Offset: %" PRIx64
                    " Size: %" PRIx64,
            read_length, _OffsetInFile, GetPath(file_info->GetOffset()).c_str(),
            file_info->GetOffset(), file_info->GetSize());

  m_rVolume->Read(file_info->GetOffset() + _OffsetInFile, read_length, _pBuffer, m_partition);
  return read_length;
}

bool FileSystemGCWii::ExportFile(const FileInfo* file_info, const std::string& _rExportFilename)
{
  if (!m_Initialized)
    InitFileSystem();

  if (!file_info || file_info->IsDirectory())
    return false;

  u64 remainingSize = file_info->GetSize();
  u64 fileOffset = file_info->GetOffset();

  File::IOFile f(_rExportFilename, "wb");
  if (!f)
    return false;

  bool result = true;

  while (remainingSize)
  {
    // Limit read size to 128 MB
    size_t readSize = (size_t)std::min(remainingSize, (u64)0x08000000);

    std::vector<u8> buffer(readSize);

    result = m_rVolume->Read(fileOffset, readSize, &buffer[0], m_partition);

    if (!result)
      break;

    f.WriteBytes(&buffer[0], readSize);

    remainingSize -= readSize;
    fileOffset += readSize;
  }

  return result;
}

bool FileSystemGCWii::ExportApploader(const std::string& _rExportFolder) const
{
  std::optional<u32> apploader_size = m_rVolume->ReadSwapped<u32>(0x2440 + 0x14, m_partition);
  const std::optional<u32> trailer_size = m_rVolume->ReadSwapped<u32>(0x2440 + 0x18, m_partition);
  constexpr u32 header_size = 0x20;
  if (!apploader_size || !trailer_size)
    return false;
  *apploader_size += *trailer_size + header_size;
  DEBUG_LOG(DISCIO, "Apploader size -> %x", *apploader_size);

  std::vector<u8> buffer(*apploader_size);
  if (m_rVolume->Read(0x2440, *apploader_size, buffer.data(), m_partition))
  {
    std::string exportName(_rExportFolder + "/apploader.img");

    File::IOFile AppFile(exportName, "wb");
    if (AppFile)
    {
      AppFile.WriteBytes(buffer.data(), *apploader_size);
      return true;
    }
  }

  return false;
}

std::optional<u64> FileSystemGCWii::GetBootDOLOffset() const
{
  std::optional<u32> offset = m_rVolume->ReadSwapped<u32>(0x420, m_partition);
  return offset ? static_cast<u64>(*offset) << m_offset_shift : std::optional<u64>();
}

std::optional<u32> FileSystemGCWii::GetBootDOLSize(u64 dol_offset) const
{
  u32 dol_size = 0;

  // Iterate through the 7 code segments
  for (u8 i = 0; i < 7; i++)
  {
    const std::optional<u32> offset =
        m_rVolume->ReadSwapped<u32>(dol_offset + 0x00 + i * 4, m_partition);
    const std::optional<u32> size =
        m_rVolume->ReadSwapped<u32>(dol_offset + 0x90 + i * 4, m_partition);
    if (!offset || !size)
      return {};
    dol_size = std::max(*offset + *size, dol_size);
  }

  // Iterate through the 11 data segments
  for (u8 i = 0; i < 11; i++)
  {
    const std::optional<u32> offset =
        m_rVolume->ReadSwapped<u32>(dol_offset + 0x1c + i * 4, m_partition);
    const std::optional<u32> size =
        m_rVolume->ReadSwapped<u32>(dol_offset + 0xac + i * 4, m_partition);
    if (!offset || !size)
      return {};
    dol_size = std::max(*offset + *size, dol_size);
  }

  return dol_size;
}

bool FileSystemGCWii::ExportDOL(const std::string& _rExportFolder) const
{
  std::optional<u64> dol_offset = GetBootDOLOffset();
  if (!dol_offset)
    return false;
  std::optional<u32> dol_size = GetBootDOLSize(*dol_offset);
  if (!dol_size)
    return false;

  std::vector<u8> buffer(*dol_size);
  if (m_rVolume->Read(*dol_offset, *dol_size, &buffer[0], m_partition))
  {
    std::string exportName(_rExportFolder + "/boot.dol");

    File::IOFile DolFile(exportName, "wb");
    if (DolFile)
    {
      DolFile.WriteBytes(&buffer[0], *dol_size);
      return true;
    }
  }

  return false;
}

std::string FileSystemGCWii::GetStringFromOffset(u64 _Offset) const
{
  std::string data(255, 0x00);
  m_rVolume->Read(_Offset, data.size(), (u8*)&data[0], m_partition);
  data.erase(std::find(data.begin(), data.end(), 0x00), data.end());

  // TODO: Should we really always use SHIFT-JIS?
  // It makes some filenames in Pikmin (NTSC-U) sane, but is it correct?
  return SHIFTJISToUTF8(data);
}

bool FileSystemGCWii::DetectFileSystem()
{
  if (m_rVolume->ReadSwapped<u32>(0x18, m_partition) == u32(0x5D1C9EA3))
  {
    m_offset_shift = 2;  // Wii file system
    return true;
  }
  else if (m_rVolume->ReadSwapped<u32>(0x1c, m_partition) == u32(0xC2339F3D))
  {
    m_offset_shift = 0;  // GameCube file system
    return true;
  }

  return false;
}

void FileSystemGCWii::InitFileSystem()
{
  m_Initialized = true;

  // read the whole FST
  const std::optional<u32> fst_offset_unshifted = m_rVolume->ReadSwapped<u32>(0x424, m_partition);
  if (!fst_offset_unshifted)
    return;
  const u64 FSTOffset = static_cast<u64>(*fst_offset_unshifted) << m_offset_shift;

  // read all fileinfos
  const std::optional<u32> root_name_offset = m_rVolume->ReadSwapped<u32>(FSTOffset, m_partition);
  const std::optional<u32> root_offset = m_rVolume->ReadSwapped<u32>(FSTOffset + 0x4, m_partition);
  const std::optional<u32> root_size = m_rVolume->ReadSwapped<u32>(FSTOffset + 0x8, m_partition);
  if (!root_name_offset || !root_offset || !root_size)
    return;
  FileInfoGCWii root(*root_name_offset, static_cast<u64>(*root_offset) << m_offset_shift,
                     *root_size, "");

  if (!root.IsDirectory())
    return;

  // 12 bytes (the size of a file entry) times 10 * 1024 * 1024 is 120 MiB,
  // more than total RAM in a Wii. No file system should use anywhere near that much.
  static const u32 ARBITRARY_FILE_SYSTEM_SIZE_LIMIT = 10 * 1024 * 1024;
  if (root.GetSize() > ARBITRARY_FILE_SYSTEM_SIZE_LIMIT)
  {
    // Without this check, Dolphin can crash by trying to allocate too much
    // memory when loading the file systems of certain malformed disc images.

    ERROR_LOG(DISCIO, "File system is abnormally large! Aborting loading");
    return;
  }

  if (m_FileInfoVector.size())
    PanicAlert("Wtf?");
  u64 NameTableOffset = FSTOffset + (root.GetSize() * 0xC);

  m_FileInfoVector.reserve((size_t)root.GetSize());
  for (u32 i = 0; i < root.GetSize(); i++)
  {
    const u64 read_offset = FSTOffset + (i * 0xC);
    const u32 name_offset = m_rVolume->ReadSwapped<u32>(read_offset, m_partition).value_or(0);
    const u32 offset = m_rVolume->ReadSwapped<u32>(read_offset + 0x4, m_partition).value_or(0);
    const u32 size = m_rVolume->ReadSwapped<u32>(read_offset + 0x8, m_partition).value_or(0);
    const std::string name = GetStringFromOffset(NameTableOffset + (name_offset & 0xFFFFFF));
    m_FileInfoVector.emplace_back(
        name_offset, static_cast<u64>(offset) << (m_offset_shift * !(name_offset & 0xFF000000)),
        size, name);
  }
}

}  // namespace