7zin.cpp

来自「由7-zip提供的压缩、解压缩程序」· C++ 代码 · 共 1,295 行 · 第 1/3 页

// 7zIn.cpp

#include "StdAfx.h"

#include "7zIn.h"
#include "7zMethods.h"
#include "7zDecode.h"
#include "../../Common/StreamObjects.h"
#include "../../Common/StreamUtils.h"
#include "../../../Common/CRC.h"

namespace NArchive {
namespace N7z {

class CStreamSwitch
{
  CInArchive *_archive;
  bool _needRemove;
public:
  CStreamSwitch(): _needRemove(false) {}
  ~CStreamSwitch() { Remove(); }
  void Remove();
  void Set(CInArchive *archive, const Byte *data, size_t size);
  void Set(CInArchive *archive, const CByteBuffer &byteBuffer);
  HRESULT Set(CInArchive *archive, const CObjectVector<CByteBuffer> *dataVector);
};

void CStreamSwitch::Remove()
{
  if (_needRemove)
  {
    _archive->DeleteByteStream();
    _needRemove = false;
  }
}

void CStreamSwitch::Set(CInArchive *archive, const Byte *data, size_t size)
{
  Remove();
  _archive = archive;
  _archive->AddByteStream(data, size);
  _needRemove = true;
}

void CStreamSwitch::Set(CInArchive *archive, const CByteBuffer &byteBuffer)
{
  Set(archive, byteBuffer, byteBuffer.GetCapacity());
}

HRESULT CStreamSwitch::Set(CInArchive *archive, const CObjectVector<CByteBuffer> *dataVector)
{
  Remove();
  Byte external;
  RINOK(archive->ReadByte(external));
  if (external != 0)
  {
    CNum dataIndex;
    RINOK(archive->ReadNum(dataIndex));
    Set(archive, (*dataVector)[dataIndex]);
  }
  return S_OK;
}

  
CInArchiveException::CInArchiveException(CCauseType cause):
  Cause(cause)
{}

HRESULT CInArchive::ReadDirect(IInStream *stream, void *data, UInt32 size, 
    UInt32 *processedSize)
{
  UInt32 realProcessedSize;
  HRESULT result = ReadStream(stream, data, size, &realProcessedSize);
  if(processedSize != NULL)
    *processedSize = realProcessedSize;
  _position += realProcessedSize;
  return result;
}

HRESULT CInArchive::ReadDirect(void *data, UInt32 size, UInt32 *processedSize)
{
  return ReadDirect(_stream, data, size, processedSize);
}

HRESULT CInArchive::SafeReadDirect(void *data, UInt32 size)
{
  UInt32 realProcessedSize;
  RINOK(ReadDirect(data, size, &realProcessedSize));
  if (realProcessedSize != size)
    throw CInArchiveException(CInArchiveException::kUnexpectedEndOfArchive);
  return S_OK;
}

HRESULT CInArchive::SafeReadDirectByte(Byte &b)
{
  return SafeReadDirect(&b, 1);
}

HRESULT CInArchive::SafeReadDirectUInt32(UInt32 &value)
{
  value = 0;
  for (int i = 0; i < 4; i++)
  {
    Byte b;
    RINOK(SafeReadDirectByte(b));
    value |= (UInt32(b) << (8 * i));
  }
  return S_OK;
}

HRESULT CInArchive::SafeReadDirectUInt64(UInt64 &value)
{
  value = 0;
  for (int i = 0; i < 8; i++)
  {
    Byte b;
    RINOK(SafeReadDirectByte(b));
    value |= (UInt64(b) << (8 * i));
  }
  return S_OK;
}

HRESULT CInArchive::ReadNumber(UInt64 &value)
{
  Byte firstByte;
  RINOK(ReadByte(firstByte));
  Byte mask = 0x80;
  value = 0;
  for (int i = 0; i < 8; i++)
  {
    if ((firstByte & mask) == 0)
    {
      UInt64 highPart = firstByte & (mask - 1);
      value += (highPart << (i * 8));
      return S_OK;
    }
    Byte b;
    RINOK(ReadByte(b));
    value |= (UInt64(b) << (8 * i));
    mask >>= 1;
  }
  return S_OK;
}

HRESULT CInArchive::ReadNum(CNum &value)
{ 
  UInt64 value64;
  RINOK(ReadNumber(value64)); 
  if (value64 > kNumMax)
    return E_FAIL;
  value = (CNum)value64;
  return S_OK;
}

HRESULT CInArchive::ReadUInt32(UInt32 &value)
{
  value = 0;
  for (int i = 0; i < 4; i++)
  {
    Byte b;
    RINOK(ReadByte(b));
    value |= (UInt32(b) << (8 * i));
  }
  return S_OK;
}

HRESULT CInArchive::ReadUInt64(UInt64 &value)
{
  value = 0;
  for (int i = 0; i < 8; i++)
  {
    Byte b;
    RINOK(ReadByte(b));
    value |= (UInt64(b) << (8 * i));
  }
  return S_OK;
}

static inline bool TestSignatureCandidate(const void *testBytes)
{
  for (int i = 0; i < kSignatureSize; i++)
    if (((const Byte *)testBytes)[i] != kSignature[i])
      return false;
  return true;
}

#ifdef _7Z_VOL
static inline bool TestFinishSignatureCandidate(const void *testBytes)
{
  for (int i = 0; i < kSignatureSize; i++)
    if (((const Byte *)testBytes)[i] != kFinishSignature[i])
      return false;
  return true;
}
#endif

HRESULT CInArchive::FindAndReadSignature(IInStream *stream, const UInt64 *searchHeaderSizeLimit)
{
  _position = _arhiveBeginStreamPosition;
  RINOK(stream->Seek(_arhiveBeginStreamPosition, STREAM_SEEK_SET, NULL));

  Byte signature[kSignatureSize];
  UInt32 processedSize; 
  RINOK(ReadDirect(stream, signature, kSignatureSize, &processedSize));
  if(processedSize != kSignatureSize)
    return S_FALSE;
  if (TestSignatureCandidate(signature))
    return S_OK;

  CByteBuffer byteBuffer;
  const UInt32 kBufferSize = (1 << 16);
  byteBuffer.SetCapacity(kBufferSize);
  Byte *buffer = byteBuffer;
  UInt32 numPrevBytes = kSignatureSize - 1;
  memmove(buffer, signature + 1, numPrevBytes);
  UInt64 curTestPos = _arhiveBeginStreamPosition + 1;
  while(true)
  {
    if (searchHeaderSizeLimit != NULL)
      if (curTestPos - _arhiveBeginStreamPosition > *searchHeaderSizeLimit)
        return S_FALSE;
    UInt32 numReadBytes = kBufferSize - numPrevBytes;
    RINOK(ReadDirect(stream, buffer + numPrevBytes, numReadBytes, &processedSize));
    UInt32 numBytesInBuffer = numPrevBytes + processedSize;
    if (numBytesInBuffer < kSignatureSize)
      return S_FALSE;
    UInt32 numTests = numBytesInBuffer - kSignatureSize + 1;
    for(UInt32 pos = 0; pos < numTests; pos++, curTestPos++)
    { 
      if (TestSignatureCandidate(buffer + pos))
      {
        _arhiveBeginStreamPosition = curTestPos;
        _position = curTestPos + kSignatureSize;
        return stream->Seek(_position, STREAM_SEEK_SET, NULL);
      }
    }
    numPrevBytes = numBytesInBuffer - numTests;
    memmove(buffer, buffer + numTests, numPrevBytes);
  }
}

// Out: _position must point to end of signature

#ifdef _7Z_VOL
HRESULT CInArchive::FindFinishSignature(IInStream *stream, const UInt64 *searchHeaderSizeLimit)
{
  RINOK(stream->Seek(0, STREAM_SEEK_END, &_position));
  if (_position < kSignatureSize)
    return S_FALSE;

  CByteBuffer byteBuffer;
  const UInt32 kBufferSize = (1 << 18);
  byteBuffer.SetCapacity(kBufferSize);
  Byte *buffer = byteBuffer;
  UInt32 numPrevBytes = 0;
  UInt64 limitPos = 0;
  if (searchHeaderSizeLimit != NULL)
    if (*searchHeaderSizeLimit < _position)
      limitPos = _position - *searchHeaderSizeLimit;

  while(_position >= limitPos)
  {
    UInt32 numReadBytes = kBufferSize - numPrevBytes;
    if (numReadBytes > _position)
      numReadBytes = (UInt32)_position;
    UInt32 numBytesInBuffer = numPrevBytes + numReadBytes;
    if (numBytesInBuffer < kSignatureSize)
      return S_FALSE;
    _position -= numReadBytes;
    RINOK(stream->Seek(_position, STREAM_SEEK_SET, &_position));
    UInt32 startPos = kBufferSize - numBytesInBuffer;
    UInt32 processedSize;
    RINOK(ReadDirect(stream, buffer + startPos, numReadBytes, &processedSize));
    if (processedSize != numReadBytes)
      return S_FALSE;
    _position -= processedSize;
    for(UInt32 pos = kBufferSize; pos >= startPos + kSignatureSize; pos--)
    { 
      if (TestFinishSignatureCandidate(buffer + pos - kSignatureSize))
      {
        _position += pos - startPos;
        return stream->Seek(_position, STREAM_SEEK_SET, NULL);
      }
    }
    numPrevBytes = kSignatureSize - 1;
    memmove(buffer + kBufferSize - numPrevBytes, buffer + startPos + 1, numPrevBytes);
  }
  return S_FALSE;
}
#endif

// S_FALSE means that file is not archive
HRESULT CInArchive::Open(IInStream *stream, const UInt64 *searchHeaderSizeLimit)
{
  Close();
  RINOK(stream->Seek(0, STREAM_SEEK_CUR, &_arhiveBeginStreamPosition))
  _position = _arhiveBeginStreamPosition;
  #ifdef _7Z_VOL
  HRESULT result = FindFinishSignature(stream, searchHeaderSizeLimit);
  if (result == S_OK)
    _finishSignature = true;
  else
  {
    if (result != S_FALSE)
      return result;
    _finishSignature = false;
    RINOK(FindAndReadSignature(stream, searchHeaderSizeLimit));
  }
  #else
  RINOK(FindAndReadSignature(stream, searchHeaderSizeLimit));
  #endif
  _stream = stream;
  return S_OK;
}
  
void CInArchive::Close()
{
  _stream.Release();
}

HRESULT CInArchive::SkeepData(UInt64 size)
{
  for (UInt64 i = 0; i < size; i++)
  {
    Byte temp;
    RINOK(ReadByte(temp));
  }
  return S_OK;
}

HRESULT CInArchive::SkeepData()
{
  UInt64 size;
  RINOK(ReadNumber(size));
  return SkeepData(size);
}

HRESULT CInArchive::ReadArchiveProperties(CInArchiveInfo &archiveInfo)
{
  while(true)
  {
    UInt64 type;
    RINOK(ReadID(type));
    if (type == NID::kEnd)
      break;
    SkeepData();
  }
  return S_OK;
}

HRESULT CInArchive::GetNextFolderItem(CFolder &folder)
{
  CNum numCoders;
  RINOK(ReadNum(numCoders));

  folder.Coders.Clear();
  folder.Coders.Reserve((int)numCoders);
  CNum numInStreams = 0;
  CNum numOutStreams = 0;
  CNum i;
  for (i = 0; i < numCoders; i++)
  {
    folder.Coders.Add(CCoderInfo());
    CCoderInfo &coder = folder.Coders.Back();

    while (true)
    {
      coder.AltCoders.Add(CAltCoderInfo());
      CAltCoderInfo &altCoder = coder.AltCoders.Back();
      Byte mainByte;
      RINOK(ReadByte(mainByte));
      altCoder.MethodID.IDSize = mainByte & 0xF;
      RINOK(ReadBytes(altCoder.MethodID.ID, altCoder.MethodID.IDSize));
      if ((mainByte & 0x10) != 0)
      {
        RINOK(ReadNum(coder.NumInStreams));
        RINOK(ReadNum(coder.NumOutStreams));
      }
      else
      {
        coder.NumInStreams = 1;
        coder.NumOutStreams = 1;
      }
      if ((mainByte & 0x20) != 0)
      {
        CNum propertiesSize = 0;
        RINOK(ReadNum(propertiesSize));
        altCoder.Properties.SetCapacity((size_t)propertiesSize);
        RINOK(ReadBytes((Byte *)altCoder.Properties, (size_t)propertiesSize));
      }
      if ((mainByte & 0x80) == 0)
        break;
    }
    numInStreams += coder.NumInStreams;
    numOutStreams += coder.NumOutStreams;
  }

  CNum numBindPairs;
  // RINOK(ReadNumber(numBindPairs));
  numBindPairs = numOutStreams - 1;
  folder.BindPairs.Clear();
  folder.BindPairs.Reserve(numBindPairs);
  for (i = 0; i < numBindPairs; i++)
  {
    CBindPair bindPair;
    RINOK(ReadNum(bindPair.InIndex));
    RINOK(ReadNum(bindPair.OutIndex)); 
    folder.BindPairs.Add(bindPair);
  }

  CNum numPackedStreams = numInStreams - numBindPairs;
  folder.PackStreams.Reserve(numPackedStreams);
  if (numPackedStreams == 1)
  {
    for (CNum j = 0; j < numInStreams; j++)
      if (folder.FindBindPairForInStream(j) < 0)
      {
        folder.PackStreams.Add(j);
        break;
      }
  }
  else
    for(i = 0; i < numPackedStreams; i++)
    {
      CNum packStreamInfo;
      RINOK(ReadNum(packStreamInfo));
      folder.PackStreams.Add(packStreamInfo);
    }

  return S_OK;
}