7zin.cpp

一个7ZIP的解压源码。比较详细。里面含有四种语言的实现代码。

  
  if (type == NID::kAdditionalStreamsInfo)
  {
    HRESULT result = ReadAndDecodePackedStreams(
        EXTERNAL_CODECS_LOC_VARS
        database.ArchiveInfo.StartPositionAfterHeader, 
        database.ArchiveInfo.DataStartPosition2,
        dataVector
        #ifndef _NO_CRYPTO
        , getTextPassword
        #endif
        );
    RINOK(result);
    database.ArchiveInfo.DataStartPosition2 += database.ArchiveInfo.StartPositionAfterHeader;
    type = ReadID();
  }

  CRecordVector<UInt64> unPackSizes;
  CRecordVector<bool> digestsDefined;
  CRecordVector<UInt32> digests;
  
  if (type == NID::kMainStreamsInfo)
  {
    ReadStreamsInfo(&dataVector,
        database.ArchiveInfo.DataStartPosition,
        database.PackSizes, 
        database.PackCRCsDefined, 
        database.PackCRCs, 
        database.Folders,
        database.NumUnPackStreamsVector,
        unPackSizes,
        digestsDefined,
        digests);
    database.ArchiveInfo.DataStartPosition += database.ArchiveInfo.StartPositionAfterHeader;
    type = ReadID();
  }
  else
  {
    for(int i = 0; i < database.Folders.Size(); i++)
    {
      database.NumUnPackStreamsVector.Add(1);
      CFolder &folder = database.Folders[i];
      unPackSizes.Add(folder.GetUnPackSize());
      digestsDefined.Add(folder.UnPackCRCDefined);
      digests.Add(folder.UnPackCRC);
    }
  }

  database.Files.Clear();

  if (type == NID::kEnd)
    return S_OK;
  if (type != NID::kFilesInfo)
    ThrowIncorrect();
  
  CNum numFiles = ReadNum();
  database.Files.Reserve(numFiles);
  CNum i;
  for(i = 0; i < numFiles; i++)
    database.Files.Add(CFileItem());

  database.ArchiveInfo.FileInfoPopIDs.Add(NID::kSize);
  if (!database.PackSizes.IsEmpty())
    database.ArchiveInfo.FileInfoPopIDs.Add(NID::kPackInfo);
  if (numFiles > 0  && !digests.IsEmpty())
    database.ArchiveInfo.FileInfoPopIDs.Add(NID::kCRC);

  CBoolVector emptyStreamVector;
  emptyStreamVector.Reserve((int)numFiles);
  for(i = 0; i < numFiles; i++)
    emptyStreamVector.Add(false);
  CBoolVector emptyFileVector;
  CBoolVector antiFileVector;
  CNum numEmptyStreams = 0;

  for (;;)
  {
    UInt64 type = ReadID();
    if (type == NID::kEnd)
      break;
    UInt64 size = ReadNumber();
    bool isKnownType = true;
    if (type > ((UInt32)1 << 30))
      isKnownType = false;
    else switch((UInt32)type)
    {
      case NID::kName:
      {
        CStreamSwitch streamSwitch;
        streamSwitch.Set(this, &dataVector);
        for(int i = 0; i < database.Files.Size(); i++)
          _inByteBack->ReadString(database.Files[i].Name);
        break;
      }
      case NID::kWinAttributes:
      {
        CBoolVector boolVector;
        ReadBoolVector2(database.Files.Size(), boolVector);
        CStreamSwitch streamSwitch;
        streamSwitch.Set(this, &dataVector);
        for(i = 0; i < numFiles; i++)
        {
          CFileItem &file = database.Files[i];
          file.AreAttributesDefined = boolVector[i];
          if (file.AreAttributesDefined)
            file.Attributes = ReadUInt32();
        }
        break;
      }
      case NID::kStartPos:
      {
        CBoolVector boolVector;
        ReadBoolVector2(database.Files.Size(), boolVector);
        CStreamSwitch streamSwitch;
        streamSwitch.Set(this, &dataVector);
        for(i = 0; i < numFiles; i++)
        {
          CFileItem &file = database.Files[i];
          file.IsStartPosDefined = boolVector[i];
          if (file.IsStartPosDefined)
            file.StartPos = ReadUInt64();
        }
        break;
      }
      case NID::kEmptyStream:
      {
        ReadBoolVector(numFiles, emptyStreamVector);
        for (i = 0; i < (CNum)emptyStreamVector.Size(); i++)
          if (emptyStreamVector[i])
            numEmptyStreams++;
        emptyFileVector.Reserve(numEmptyStreams);
        antiFileVector.Reserve(numEmptyStreams);
        for (i = 0; i < numEmptyStreams; i++)
        {
          emptyFileVector.Add(false);
          antiFileVector.Add(false);
        }
        break;
      }
      case NID::kEmptyFile:
      {
        ReadBoolVector(numEmptyStreams, emptyFileVector);
        break;
      }
      case NID::kAnti:
      {
        ReadBoolVector(numEmptyStreams, antiFileVector);
        break;
      }
      case NID::kCreationTime:
      case NID::kLastWriteTime:
      case NID::kLastAccessTime:
      {
        ReadTime(dataVector, database.Files, (UInt32)type);
        break;
      }
      default:
        isKnownType = false;
    }
    if (isKnownType)
      database.ArchiveInfo.FileInfoPopIDs.Add(type);
    else
      SkeepData(size);
  }

  CNum emptyFileIndex = 0;
  CNum sizeIndex = 0;
  for(i = 0; i < numFiles; i++)
  {
    CFileItem &file = database.Files[i];
    file.HasStream = !emptyStreamVector[i];
    if(file.HasStream)
    {
      file.IsDirectory = false;
      file.IsAnti = false;
      file.UnPackSize = unPackSizes[sizeIndex];
      file.FileCRC = digests[sizeIndex];
      file.IsFileCRCDefined = digestsDefined[sizeIndex];
      sizeIndex++;
    }
    else
    {
      file.IsDirectory = !emptyFileVector[emptyFileIndex];
      file.IsAnti = antiFileVector[emptyFileIndex];
      emptyFileIndex++;
      file.UnPackSize = 0;
      file.IsFileCRCDefined = false;
    }
  }
  return S_OK;
}


void CArchiveDatabaseEx::FillFolderStartPackStream()
{
  FolderStartPackStreamIndex.Clear();
  FolderStartPackStreamIndex.Reserve(Folders.Size());
  CNum startPos = 0;
  for(int i = 0; i < Folders.Size(); i++)
  {
    FolderStartPackStreamIndex.Add(startPos);
    startPos += (CNum)Folders[i].PackStreams.Size();
  }
}

void CArchiveDatabaseEx::FillStartPos()
{
  PackStreamStartPositions.Clear();
  PackStreamStartPositions.Reserve(PackSizes.Size());
  UInt64 startPos = 0;
  for(int i = 0; i < PackSizes.Size(); i++)
  {
    PackStreamStartPositions.Add(startPos);
    startPos += PackSizes[i];
  }
}

void CArchiveDatabaseEx::FillFolderStartFileIndex()
{
  FolderStartFileIndex.Clear();
  FolderStartFileIndex.Reserve(Folders.Size());
  FileIndexToFolderIndexMap.Clear();
  FileIndexToFolderIndexMap.Reserve(Files.Size());
  
  int folderIndex = 0;
  CNum indexInFolder = 0;
  for (int i = 0; i < Files.Size(); i++)
  {
    const CFileItem &file = Files[i];
    bool emptyStream = !file.HasStream;
    if (emptyStream && indexInFolder == 0)
    {
      FileIndexToFolderIndexMap.Add(kNumNoIndex);
      continue;
    }
    if (indexInFolder == 0)
    {
      // v3.13 incorrectly worked with empty folders
      // v4.07: Loop for skipping empty folders
      for (;;)
      {
        if (folderIndex >= Folders.Size())
          ThrowIncorrect();
        FolderStartFileIndex.Add(i); // check it
        if (NumUnPackStreamsVector[folderIndex] != 0)
          break;
        folderIndex++;
      }
    }
    FileIndexToFolderIndexMap.Add(folderIndex);
    if (emptyStream)
      continue;
    indexInFolder++;
    if (indexInFolder >= NumUnPackStreamsVector[folderIndex])
    {
      folderIndex++;
      indexInFolder = 0;
    }
  }
}

HRESULT CInArchive::ReadDatabase2(
    DECL_EXTERNAL_CODECS_LOC_VARS
    CArchiveDatabaseEx &database
    #ifndef _NO_CRYPTO
    , ICryptoGetTextPassword *getTextPassword
    #endif
    )
{
  database.Clear();
  database.ArchiveInfo.StartPosition = _arhiveBeginStreamPosition;

  database.ArchiveInfo.Version.Major = _header[6];
  database.ArchiveInfo.Version.Minor = _header[7];

  if (database.ArchiveInfo.Version.Major != kMajorVersion)
    ThrowUnsupportedVersion();

  UInt32 crcFromArchive = GetUInt32FromMem(_header + 8);
  UInt64 nextHeaderOffset = GetUInt64FromMem(_header + 0xC);
  UInt64 nextHeaderSize = GetUInt64FromMem(_header + 0x14);
  UInt32 nextHeaderCRC =  GetUInt32FromMem(_header + 0x1C);
  UInt32 crc = CrcCalc(_header + 0xC, 20);

  #ifdef FORMAT_7Z_RECOVERY
  if (crcFromArchive == 0 && nextHeaderOffset == 0 && nextHeaderSize == 0 && nextHeaderCRC == 0)
  {
    UInt64 cur, cur2;
    RINOK(_stream->Seek(0, STREAM_SEEK_CUR, &cur));
    const int kCheckSize = 500;
    Byte buf[kCheckSize];
    RINOK(_stream->Seek(0, STREAM_SEEK_END, &cur2));
    int checkSize = kCheckSize;
    if (cur2 - cur < kCheckSize)
      checkSize = (int)(cur2 - cur);
    RINOK(_stream->Seek(-checkSize, STREAM_SEEK_END, &cur2));
    
    UInt32 realProcessedSize;
    RINOK(_stream->Read(buf, (UInt32)kCheckSize, &realProcessedSize));

    int i;
    for (i = (int)realProcessedSize - 2; i >= 0; i--)
      if (buf[i] == 0x17 && buf[i + 1] == 0x6 || buf[i] == 0x01 && buf[i + 1] == 0x04)
        break;
    if (i < 0)
      return S_FALSE;
    nextHeaderSize = realProcessedSize - i;
    nextHeaderOffset = cur2 - cur + i;
    nextHeaderCRC = CrcCalc(buf + i, (size_t)nextHeaderSize);
    RINOK(_stream->Seek(cur, STREAM_SEEK_SET, NULL));
  }
  #endif

  #ifdef FORMAT_7Z_RECOVERY
  crcFromArchive = crc;
  #endif

  database.ArchiveInfo.StartPositionAfterHeader = _arhiveBeginStreamPosition + kHeaderSize;

  if (crc != crcFromArchive)
    ThrowIncorrect();

  if (nextHeaderSize == 0)
    return S_OK;

  if (nextHeaderSize > (UInt64)0xFFFFFFFF)
    return S_FALSE;

  RINOK(_stream->Seek(nextHeaderOffset, STREAM_SEEK_CUR, NULL));

  CByteBuffer buffer2;
  buffer2.SetCapacity((size_t)nextHeaderSize);

  UInt32 realProcessedSize;
  RINOK(_stream->Read(buffer2, (UInt32)nextHeaderSize, &realProcessedSize));
  if (realProcessedSize != (UInt32)nextHeaderSize)
    return S_FALSE;
  if (CrcCalc(buffer2, (UInt32)nextHeaderSize) != nextHeaderCRC)
    ThrowIncorrect();
  
  CStreamSwitch streamSwitch;
  streamSwitch.Set(this, buffer2);
  
  CObjectVector<CByteBuffer> dataVector;
  
  for (;;)
  {
    UInt64 type = ReadID();
    if (type == NID::kHeader)
      break;
    if (type != NID::kEncodedHeader)
      ThrowIncorrect();
    HRESULT result = ReadAndDecodePackedStreams(
        EXTERNAL_CODECS_LOC_VARS
        database.ArchiveInfo.StartPositionAfterHeader, 
        database.ArchiveInfo.DataStartPosition2,
        dataVector
        #ifndef _NO_CRYPTO
        , getTextPassword
        #endif
        );
    RINOK(result);
    if (dataVector.Size() == 0)
      return S_OK;
    if (dataVector.Size() > 1)
      ThrowIncorrect();
    streamSwitch.Remove();
    streamSwitch.Set(this, dataVector.Front());
  }

  return ReadHeader(
    EXTERNAL_CODECS_LOC_VARS
    database
    #ifndef _NO_CRYPTO
    , getTextPassword
    #endif
    );
}

HRESULT CInArchive::ReadDatabase(
    DECL_EXTERNAL_CODECS_LOC_VARS
    CArchiveDatabaseEx &database
    #ifndef _NO_CRYPTO
    , ICryptoGetTextPassword *getTextPassword
    #endif
    )
{
  try
  {
    return ReadDatabase2(
      EXTERNAL_CODECS_LOC_VARS database
      #ifndef _NO_CRYPTO
      , getTextPassword
      #endif
      );
  }
  catch(CInArchiveException &) { return S_FALSE; }
}

}}