1.1 --- /dev/null	Thu Jan 01 00:00:00 1970 +0000
     1.2 +++ b/src/win32/7zip/7z/CPP/7zip/Archive/Common/FindSignature.cpp	Sat Mar 03 10:31:27 2012 -0600
     1.3 @@ -0,0 +1,62 @@
     1.4 +// FindSignature.cpp
     1.5 +
     1.6 +#include "StdAfx.h"
     1.7 +
     1.8 +#include "Common/Buffer.h"
     1.9 +
    1.10 +#include "FindSignature.h"
    1.11 +
    1.12 +#include "../../Common/StreamUtils.h"
    1.13 +
    1.14 +HRESULT FindSignatureInStream(ISequentialInStream *stream,
    1.15 +    const Byte *signature, unsigned signatureSize,
    1.16 +    const UInt64 *limit, UInt64 &resPos)
    1.17 +{
    1.18 +  resPos = 0;
    1.19 +  CByteBuffer byteBuffer2;
    1.20 +  byteBuffer2.SetCapacity(signatureSize);
    1.21 +  RINOK(ReadStream_FALSE(stream, byteBuffer2, signatureSize));
    1.22 +
    1.23 +  if (memcmp(byteBuffer2, signature, signatureSize) == 0)
    1.24 +    return S_OK;
    1.25 +
    1.26 +  const UInt32 kBufferSize = (1 << 16);
    1.27 +  CByteBuffer byteBuffer;
    1.28 +  byteBuffer.SetCapacity(kBufferSize);
    1.29 +  Byte *buffer = byteBuffer;
    1.30 +  UInt32 numPrevBytes = signatureSize - 1;
    1.31 +  memcpy(buffer, (const Byte *)byteBuffer2 + 1, numPrevBytes);
    1.32 +  resPos = 1;
    1.33 +  for (;;)
    1.34 +  {
    1.35 +    if (limit != NULL)
    1.36 +      if (resPos > *limit)
    1.37 +        return S_FALSE;
    1.38 +    do
    1.39 +    {
    1.40 +      UInt32 numReadBytes = kBufferSize - numPrevBytes;
    1.41 +      UInt32 processedSize;
    1.42 +      RINOK(stream->Read(buffer + numPrevBytes, numReadBytes, &processedSize));
    1.43 +      numPrevBytes += processedSize;
    1.44 +      if (processedSize == 0)
    1.45 +        return S_FALSE;
    1.46 +    }
    1.47 +    while (numPrevBytes < signatureSize);
    1.48 +    UInt32 numTests = numPrevBytes - signatureSize + 1;
    1.49 +    for (UInt32 pos = 0; pos < numTests; pos++)
    1.50 +    {
    1.51 +      Byte b = signature[0];
    1.52 +      for (; buffer[pos] != b && pos < numTests; pos++);
    1.53 +      if (pos == numTests)
    1.54 +        break;
    1.55 +      if (memcmp(buffer + pos, signature, signatureSize) == 0)
    1.56 +      {
    1.57 +        resPos += pos;
    1.58 +        return S_OK;
    1.59 +      }
    1.60 +    }
    1.61 +    resPos += numTests;
    1.62 +    numPrevBytes -= numTests;
    1.63 +    memmove(buffer, buffer + numTests, numPrevBytes);
    1.64 +  }
    1.65 +}