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。

// 7zIn.cpp

#include "StdAfx.h"

#include "7zIn.h"
#include "7zDecode.h"
#include "../../Common/StreamObjects.h"
#include "../../Common/StreamUtils.h"
extern "C" 
{ 
#include "../../../../C/7zCrc.h"
}

// define FORMAT_7Z_RECOVERY if you want to recover multivolume archives with empty StartHeader 
#ifndef _SFX
#define FORMAT_7Z_RECOVERY
#endif

namespace NArchive {
namespace N7z {

class CInArchiveException {};

static void ThrowException() { throw CInArchiveException(); }
static inline void ThrowEndOfData()   { ThrowException(); }
static inline void ThrowUnsupported() { ThrowException(); }
static inline void ThrowIncorrect()   { ThrowException(); }
static inline void ThrowUnsupportedVersion() { ThrowException(); }

/*
class CInArchiveException
{
public:
  enum CCauseType
  {
    kUnsupportedVersion = 0,
    kUnsupported,
    kIncorrect, 
    kEndOfData,
  } Cause;
  CInArchiveException(CCauseType cause): Cause(cause) {};
};

static void ThrowException(CInArchiveException::CCauseType c) { throw CInArchiveException(c); }
static void ThrowEndOfData()   { ThrowException(CInArchiveException::kEndOfData); }
static void ThrowUnsupported() { ThrowException(CInArchiveException::kUnsupported); }
static void ThrowIncorrect()   { ThrowException(CInArchiveException::kIncorrect); }
static void ThrowUnsupportedVersion() { ThrowException(CInArchiveException::kUnsupportedVersion); }
*/

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);
  void 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());
}

void CStreamSwitch::Set(CInArchive *archive, const CObjectVector<CByteBuffer> *dataVector)
{
  Remove();
  Byte external = archive->ReadByte();
  if (external != 0)
  {
    int dataIndex = (int)archive->ReadNum();
    if (dataIndex < 0 || dataIndex >= dataVector->Size())
      ThrowIncorrect();
    Set(archive, (*dataVector)[dataIndex]);
  }
}

#if defined(_M_IX86) || defined(_M_X64) || defined(_M_AMD64) || defined(__i386__) || defined(__x86_64__)
#define SZ_LITTLE_ENDIAN_UNALIGN
#endif

#ifdef SZ_LITTLE_ENDIAN_UNALIGN
static inline UInt16 GetUInt16FromMem(const Byte *p) { return *(const UInt16 *)p; }
static inline UInt32 GetUInt32FromMem(const Byte *p) { return *(const UInt32 *)p; }
static inline UInt64 GetUInt64FromMem(const Byte *p) { return *(const UInt64 *)p; }
#else
static inline UInt16 GetUInt16FromMem(const Byte *p) { return p[0] | ((UInt16)p[1] << 8); }
static inline UInt32 GetUInt32FromMem(const Byte *p) { return p[0] | ((UInt32)p[1] << 8) | ((UInt32)p[2] << 16) | ((UInt32)p[3] << 24); }
static inline UInt64 GetUInt64FromMem(const Byte *p) { return GetUInt32FromMem(p) | ((UInt64)GetUInt32FromMem(p + 4) << 32); }
#endif

Byte CInByte2::ReadByte()
{
  if (_pos >= _size)
    ThrowEndOfData();
  return _buffer[_pos++];
}

void CInByte2::ReadBytes(Byte *data, size_t size)
{
  if (size > _size - _pos)
    ThrowEndOfData();
  for (size_t i = 0; i < size; i++)
    data[i] = _buffer[_pos++];
}

void CInByte2::SkeepData(UInt64 size)
{
  if (size > _size - _pos)
    ThrowEndOfData();
}

void CInByte2::SkeepData()
{
  SkeepData(ReadNumber());
}

UInt64 CInByte2::ReadNumber()
{
  if (_pos >= _size)
    ThrowEndOfData();
  Byte firstByte = _buffer[_pos++];
  Byte mask = 0x80;
  UInt64 value = 0;
  for (int i = 0; i < 8; i++)
  {
    if ((firstByte & mask) == 0)
    {
      UInt64 highPart = firstByte & (mask - 1);
      value += (highPart << (i * 8));
      return value;
    }
    if (_pos >= _size)
      ThrowEndOfData();
    value |= ((UInt64)_buffer[_pos++] << (8 * i));
    mask >>= 1;
  }
  return value;
}

CNum CInByte2::ReadNum()
{ 
  UInt64 value = ReadNumber(); 
  if (value > kNumMax)
    ThrowUnsupported();
  return (CNum)value;
}

UInt32 CInByte2::ReadUInt32()
{
  if (_pos + 4 > _size)
    ThrowEndOfData();
  UInt32 res = GetUInt32FromMem(_buffer + _pos);
  _pos += 4;
  return res;
}

UInt64 CInByte2::ReadUInt64()
{
  if (_pos + 8 > _size)
    ThrowEndOfData();
  UInt64 res = GetUInt64FromMem(_buffer + _pos);
  _pos += 8;
  return res;
}

void CInByte2::ReadString(UString &s)
{
  const Byte *buf = _buffer + _pos;
  size_t rem = (_size - _pos) / 2 * 2;
  {
    size_t i;
    for (i = 0; i < rem; i += 2)
      if (buf[i] == 0 && buf[i + 1] == 0)
        break;
    if (i == rem)
      ThrowEndOfData();
    rem = i;
  }
  int len = (int)(rem / 2);
  if (len < 0 || (size_t)len * 2 != rem)
    ThrowUnsupported();
  wchar_t *p = s.GetBuffer(len);
  int i;
  for (i = 0; i < len; i++, buf += 2) 
    p[i] = (wchar_t)GetUInt16FromMem(buf);
  p[i] = 0;
  s.ReleaseBuffer(len);
  _pos += rem + 2;
}

static inline bool TestSignatureCandidate(const Byte *p)
{
  for (int i = 0; i < kSignatureSize; i++)
    if (p[i] != kSignature[i])
      return false;
  return (p[0x1A] == 0 && p[0x1B] == 0);
}

HRESULT CInArchive::FindAndReadSignature(IInStream *stream, const UInt64 *searchHeaderSizeLimit)
{
  UInt32 processedSize; 
  RINOK(ReadStream(stream, _header, kHeaderSize, &processedSize));
  if (processedSize != kHeaderSize)
    return S_FALSE;
  if (TestSignatureCandidate(_header))
    return S_OK;

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

// 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))
  RINOK(FindAndReadSignature(stream, searchHeaderSizeLimit));
  _stream = stream;
  return S_OK;
}
  
void CInArchive::Close()
{
  _stream.Release();
}

void CInArchive::ReadArchiveProperties(CInArchiveInfo & /* archiveInfo */)
{
  for (;;)
  {
    if (ReadID() == NID::kEnd)
      break;
    SkeepData();
  }
}

void CInArchive::GetNextFolderItem(CFolder &folder)
{
  CNum numCoders = ReadNum();

  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();

    {
      Byte mainByte = ReadByte();
      int idSize = (mainByte & 0xF);
      Byte longID[15];
      ReadBytes(longID, idSize);
      if (idSize > 8)
        ThrowUnsupported();
      UInt64 id = 0;
      for (int j = 0; j < idSize; j++)
        id |= (UInt64)longID[idSize - 1 - j] << (8 * j);
      coder.MethodID = id;

      if ((mainByte & 0x10) != 0)
      {
        coder.NumInStreams = ReadNum();
        coder.NumOutStreams = ReadNum();
      }
      else
      {
        coder.NumInStreams = 1;
        coder.NumOutStreams = 1;
      }
      if ((mainByte & 0x20) != 0)
      {
        CNum propertiesSize = ReadNum();
        coder.Properties.SetCapacity((size_t)propertiesSize);
        ReadBytes((Byte *)coder.Properties, (size_t)propertiesSize);
      }
      if ((mainByte & 0x80) != 0)
        ThrowUnsupported();
    }
    numInStreams += coder.NumInStreams;
    numOutStreams += coder.NumOutStreams;
  }

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

void CInArchive::WaitAttribute(UInt64 attribute)
{
  for (;;)
  {
    UInt64 type = ReadID();
    if (type == attribute)
      return;
    if (type == NID::kEnd)
      ThrowIncorrect();
    SkeepData();
  }
}

void CInArchive::ReadHashDigests(int numItems,
    CRecordVector<bool> &digestsDefined, 
    CRecordVector<UInt32> &digests)
{
  ReadBoolVector2(numItems, digestsDefined);
  digests.Clear();
  digests.Reserve(numItems);
  for(int i = 0; i < numItems; i++)
  {
    UInt32 crc = 0;
    if (digestsDefined[i])
      crc = ReadUInt32();
    digests.Add(crc);
  }
}

void CInArchive::ReadPackInfo(
    UInt64 &dataOffset,
    CRecordVector<UInt64> &packSizes,
    CRecordVector<bool> &packCRCsDefined,
    CRecordVector<UInt32> &packCRCs)
{
  dataOffset = ReadNumber();
  CNum numPackStreams = ReadNum();

  WaitAttribute(NID::kSize);