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。

  packSizes.Clear();
  packSizes.Reserve(numPackStreams);
  for (CNum i = 0; i < numPackStreams; i++)
    packSizes.Add(ReadNumber());

  UInt64 type;
  for (;;)
  {
    type = ReadID();
    if (type == NID::kEnd)
      break;
    if (type == NID::kCRC)
    {
      ReadHashDigests(numPackStreams, packCRCsDefined, packCRCs); 
      continue;
    }
    SkeepData();
  }
  if (packCRCsDefined.IsEmpty())
  {
    packCRCsDefined.Reserve(numPackStreams);
    packCRCsDefined.Clear();
    packCRCs.Reserve(numPackStreams);
    packCRCs.Clear();
    for(CNum i = 0; i < numPackStreams; i++)
    {
      packCRCsDefined.Add(false);
      packCRCs.Add(0);
    }
  }
}

void CInArchive::ReadUnPackInfo(
    const CObjectVector<CByteBuffer> *dataVector,
    CObjectVector<CFolder> &folders)
{
  WaitAttribute(NID::kFolder);
  CNum numFolders = ReadNum();

  {
    CStreamSwitch streamSwitch;
    streamSwitch.Set(this, dataVector);
    folders.Clear();
    folders.Reserve(numFolders);
    for(CNum i = 0; i < numFolders; i++)
    {
      folders.Add(CFolder());
      GetNextFolderItem(folders.Back());
    }
  }

  WaitAttribute(NID::kCodersUnPackSize);

  CNum i;
  for (i = 0; i < numFolders; i++)
  {
    CFolder &folder = folders[i];
    CNum numOutStreams = folder.GetNumOutStreams();
    folder.UnPackSizes.Reserve(numOutStreams);
    for (CNum j = 0; j < numOutStreams; j++)
      folder.UnPackSizes.Add(ReadNumber());
  }

  for (;;)
  {
    UInt64 type = ReadID();
    if (type == NID::kEnd)
      return;
    if (type == NID::kCRC)
    {
      CRecordVector<bool> crcsDefined;
      CRecordVector<UInt32> crcs;
      ReadHashDigests(numFolders, crcsDefined, crcs); 
      for(i = 0; i < numFolders; i++)
      {
        CFolder &folder = folders[i];
        folder.UnPackCRCDefined = crcsDefined[i];
        folder.UnPackCRC = crcs[i];
      }
      continue;
    }
    SkeepData();
  }
}

void CInArchive::ReadSubStreamsInfo(
    const CObjectVector<CFolder> &folders,
    CRecordVector<CNum> &numUnPackStreamsInFolders,
    CRecordVector<UInt64> &unPackSizes,
    CRecordVector<bool> &digestsDefined, 
    CRecordVector<UInt32> &digests)
{
  numUnPackStreamsInFolders.Clear();
  numUnPackStreamsInFolders.Reserve(folders.Size());
  UInt64 type;
  for (;;)
  {
    type = ReadID();
    if (type == NID::kNumUnPackStream)
    {
      for(int i = 0; i < folders.Size(); i++)
        numUnPackStreamsInFolders.Add(ReadNum());
      continue;
    }
    if (type == NID::kCRC || type == NID::kSize)
      break;
    if (type == NID::kEnd)
      break;
    SkeepData();
  }

  if (numUnPackStreamsInFolders.IsEmpty())
    for(int i = 0; i < folders.Size(); i++)
      numUnPackStreamsInFolders.Add(1);

  int i;
  for(i = 0; i < numUnPackStreamsInFolders.Size(); i++)
  {
    // v3.13 incorrectly worked with empty folders
    // v4.07: we check that folder is empty
    CNum numSubstreams = numUnPackStreamsInFolders[i];
    if (numSubstreams == 0)
      continue;
    UInt64 sum = 0;
    for (CNum j = 1; j < numSubstreams; j++)
      if (type == NID::kSize)
      {
        UInt64 size = ReadNumber();
        unPackSizes.Add(size);
        sum += size;
      }
    unPackSizes.Add(folders[i].GetUnPackSize() - sum);
  }
  if (type == NID::kSize)
    type = ReadID();

  int numDigests = 0;
  int numDigestsTotal = 0;
  for(i = 0; i < folders.Size(); i++)
  {
    CNum numSubstreams = numUnPackStreamsInFolders[i];
    if (numSubstreams != 1 || !folders[i].UnPackCRCDefined)
      numDigests += numSubstreams;
    numDigestsTotal += numSubstreams;
  }

  for (;;)
  {
    if (type == NID::kCRC)
    {
      CRecordVector<bool> digestsDefined2; 
      CRecordVector<UInt32> digests2;
      ReadHashDigests(numDigests, digestsDefined2, digests2);
      int digestIndex = 0;
      for (i = 0; i < folders.Size(); i++)
      {
        CNum numSubstreams = numUnPackStreamsInFolders[i];
        const CFolder &folder = folders[i];
        if (numSubstreams == 1 && folder.UnPackCRCDefined)
        {
          digestsDefined.Add(true);
          digests.Add(folder.UnPackCRC);
        }
        else
          for (CNum j = 0; j < numSubstreams; j++, digestIndex++)
          {
            digestsDefined.Add(digestsDefined2[digestIndex]);
            digests.Add(digests2[digestIndex]);
          }
      }
    }
    else if (type == NID::kEnd)
    {
      if (digestsDefined.IsEmpty())
      {
        digestsDefined.Clear();
        digests.Clear();
        for (int i = 0; i < numDigestsTotal; i++)
        {
          digestsDefined.Add(false);
          digests.Add(0);
        }
      }
      return;
    }
    else
      SkeepData();
    type = ReadID();
  }
}

void CInArchive::ReadStreamsInfo(
    const CObjectVector<CByteBuffer> *dataVector,
    UInt64 &dataOffset,
    CRecordVector<UInt64> &packSizes,
    CRecordVector<bool> &packCRCsDefined,
    CRecordVector<UInt32> &packCRCs,
    CObjectVector<CFolder> &folders,
    CRecordVector<CNum> &numUnPackStreamsInFolders,
    CRecordVector<UInt64> &unPackSizes,
    CRecordVector<bool> &digestsDefined, 
    CRecordVector<UInt32> &digests)
{
  for (;;)
  {
    UInt64 type = ReadID();
    if (type > ((UInt32)1 << 30))
      ThrowIncorrect();
    switch((UInt32)type)
    {
      case NID::kEnd:
        return;
      case NID::kPackInfo:
      {
        ReadPackInfo(dataOffset, packSizes, packCRCsDefined, packCRCs);
        break;
      }
      case NID::kUnPackInfo:
      {
        ReadUnPackInfo(dataVector, folders);
        break;
      }
      case NID::kSubStreamsInfo:
      {
        ReadSubStreamsInfo(folders, numUnPackStreamsInFolders,
            unPackSizes, digestsDefined, digests);
        break;
      }
      default:
        ThrowIncorrect();
    }
  }
}

void CInArchive::ReadBoolVector(int numItems, CBoolVector &v)
{
  v.Clear();
  v.Reserve(numItems);
  Byte b = 0;
  Byte mask = 0;
  for(int i = 0; i < numItems; i++)
  {
    if (mask == 0)
    {
      b = ReadByte();
      mask = 0x80;
    }
    v.Add((b & mask) != 0);
    mask >>= 1;
  }
}

void CInArchive::ReadBoolVector2(int numItems, CBoolVector &v)
{
  Byte allAreDefined = ReadByte();
  if (allAreDefined == 0)
  {
    ReadBoolVector(numItems, v);
    return;
  }
  v.Clear();
  v.Reserve(numItems);
  for (int i = 0; i < numItems; i++)
    v.Add(true);
}

void CInArchive::ReadTime(const CObjectVector<CByteBuffer> &dataVector,
    CObjectVector<CFileItem> &files, UInt32 type)
{
  CBoolVector boolVector;
  ReadBoolVector2(files.Size(), boolVector);

  CStreamSwitch streamSwitch;
  streamSwitch.Set(this, &dataVector);

  for(int i = 0; i < files.Size(); i++)
  {
    CFileItem &file = files[i];
    CArchiveFileTime fileTime;
    fileTime.dwLowDateTime = 0;
    fileTime.dwHighDateTime = 0;
    bool defined = boolVector[i];
    if (defined)
    {
      fileTime.dwLowDateTime = ReadUInt32();
      fileTime.dwHighDateTime = ReadUInt32();
    }
    switch(type)
    {
      case NID::kCreationTime:
        file.IsCreationTimeDefined = defined;
        if (defined)
          file.CreationTime = fileTime;
        break;
      case NID::kLastWriteTime:
        file.IsLastWriteTimeDefined = defined;
        if (defined)
          file.LastWriteTime = fileTime;
        break;
      case NID::kLastAccessTime:
        file.IsLastAccessTimeDefined = defined;
        if (defined)
          file.LastAccessTime = fileTime;
        break;
    }
  }
}

HRESULT CInArchive::ReadAndDecodePackedStreams(
    DECL_EXTERNAL_CODECS_LOC_VARS
    UInt64 baseOffset, 
    UInt64 &dataOffset, CObjectVector<CByteBuffer> &dataVector
    #ifndef _NO_CRYPTO
    , ICryptoGetTextPassword *getTextPassword
    #endif
    )
{
  CRecordVector<UInt64> packSizes;
  CRecordVector<bool> packCRCsDefined;
  CRecordVector<UInt32> packCRCs;
  CObjectVector<CFolder> folders;
  
  CRecordVector<CNum> numUnPackStreamsInFolders;
  CRecordVector<UInt64> unPackSizes;
  CRecordVector<bool> digestsDefined;
  CRecordVector<UInt32> digests;
  
  ReadStreamsInfo(NULL, 
    dataOffset,
    packSizes, 
    packCRCsDefined, 
    packCRCs, 
    folders,
    numUnPackStreamsInFolders,
    unPackSizes,
    digestsDefined, 
    digests);
  
  // database.ArchiveInfo.DataStartPosition2 += database.ArchiveInfo.StartPositionAfterHeader;
  
  CNum packIndex = 0;
  CDecoder decoder(
    #ifdef _ST_MODE
    false
    #else
    true
    #endif
    );
  UInt64 dataStartPos = baseOffset + dataOffset;
  for(int i = 0; i < folders.Size(); i++)
  {
    const CFolder &folder = folders[i];
    dataVector.Add(CByteBuffer());
    CByteBuffer &data = dataVector.Back();
    UInt64 unPackSize64 = folder.GetUnPackSize();
    size_t unPackSize = (size_t)unPackSize64;
    if (unPackSize != unPackSize64)
      ThrowUnsupported();
    data.SetCapacity(unPackSize);
    
    CSequentialOutStreamImp2 *outStreamSpec = new CSequentialOutStreamImp2;
    CMyComPtr<ISequentialOutStream> outStream = outStreamSpec;
    outStreamSpec->Init(data, unPackSize);
    
    HRESULT result = decoder.Decode(
      EXTERNAL_CODECS_LOC_VARS
      _stream, dataStartPos, 
      &packSizes[packIndex], folder, outStream, NULL
      #ifndef _NO_CRYPTO
      , getTextPassword
      #endif
      #ifdef COMPRESS_MT
      , false, 1
      #endif
      );
    RINOK(result);
    
    if (folder.UnPackCRCDefined)
      if (CrcCalc(data, unPackSize) != folder.UnPackCRC)
        ThrowIncorrect();
      for (int j = 0; j < folder.PackStreams.Size(); j++)
        dataStartPos += packSizes[packIndex++];
  }
  return S_OK;
}

HRESULT CInArchive::ReadHeader(
    DECL_EXTERNAL_CODECS_LOC_VARS
    CArchiveDatabaseEx &database
    #ifndef _NO_CRYPTO
    , ICryptoGetTextPassword *getTextPassword
    #endif
    )
{
  UInt64 type = ReadID();

  if (type == NID::kArchiveProperties)
  {
    ReadArchiveProperties(database.ArchiveInfo);
    type = ReadID();
  }
 
  CObjectVector<CByteBuffer> dataVector;