diff options
Diffstat (limited to 'src/libs/7zip/unix/CPP/7zip/Archive/Common/FindSignature.cpp')
-rw-r--r-- | src/libs/7zip/unix/CPP/7zip/Archive/Common/FindSignature.cpp | 62 |
1 files changed, 62 insertions, 0 deletions
diff --git a/src/libs/7zip/unix/CPP/7zip/Archive/Common/FindSignature.cpp b/src/libs/7zip/unix/CPP/7zip/Archive/Common/FindSignature.cpp new file mode 100644 index 000000000..15aa6ceae --- /dev/null +++ b/src/libs/7zip/unix/CPP/7zip/Archive/Common/FindSignature.cpp @@ -0,0 +1,62 @@ +// FindSignature.cpp + +#include "StdAfx.h" + +#include "Common/Buffer.h" + +#include "FindSignature.h" + +#include "../../Common/StreamUtils.h" + +HRESULT FindSignatureInStream(ISequentialInStream *stream, + const Byte *signature, unsigned signatureSize, + const UInt64 *limit, UInt64 &resPos) +{ + resPos = 0; + CByteBuffer byteBuffer2; + byteBuffer2.SetCapacity(signatureSize); + RINOK(ReadStream_FALSE(stream, byteBuffer2, signatureSize)); + + if (memcmp(byteBuffer2, signature, signatureSize) == 0) + return S_OK; + + const UInt32 kBufferSize = (1 << 16); + CByteBuffer byteBuffer; + byteBuffer.SetCapacity(kBufferSize); + Byte *buffer = byteBuffer; + UInt32 numPrevBytes = signatureSize - 1; + memcpy(buffer, (const Byte *)byteBuffer2 + 1, numPrevBytes); + resPos = 1; + for (;;) + { + if (limit != NULL) + if (resPos > *limit) + return S_FALSE; + do + { + UInt32 numReadBytes = kBufferSize - numPrevBytes; + UInt32 processedSize; + RINOK(stream->Read(buffer + numPrevBytes, numReadBytes, &processedSize)); + numPrevBytes += processedSize; + if (processedSize == 0) + return S_FALSE; + } + while (numPrevBytes < signatureSize); + UInt32 numTests = numPrevBytes - signatureSize + 1; + for (UInt32 pos = 0; pos < numTests; pos++) + { + Byte b = signature[0]; + for (; buffer[pos] != b && pos < numTests; pos++); + if (pos == numTests) + break; + if (memcmp(buffer + pos, signature, signatureSize) == 0) + { + resPos += pos; + return S_OK; + } + } + resPos += numTests; + numPrevBytes -= numTests; + memmove(buffer, buffer + numTests, numPrevBytes); + } +} |