First Commit

externals/cryptopp/zlib.cpp

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+// zlib.cpp - originally written and placed in the public domain by Wei Dai
+
+// "zlib" is the name of a well known C language compression library
+// (http://www.zlib.org) and also the name of a compression format
+// (RFC 1950) that the library implements. This file is part of a
+// complete reimplementation of the zlib compression format.
+
+#include "pch.h"
+#include "zlib.h"
+#include "zdeflate.h"
+#include "zinflate.h"
+#include "secblock.h"
+
+NAMESPACE_BEGIN(CryptoPP)
+
+static const byte DEFLATE_METHOD = 8;
+static const byte FDICT_FLAG = (1 << 5);
+
+// *************************************************************
+
+void ZlibCompressor::WritePrestreamHeader()
+{
+	m_adler32.Restart();
+	CRYPTOPP_ASSERT(((GetLog2WindowSize()-8) << 4) <= 255);
+	byte cmf = byte(DEFLATE_METHOD | ((GetLog2WindowSize()-8) << 4));
+	CRYPTOPP_ASSERT((GetCompressionLevel() << 6) <= 255);
+	byte flags = byte(GetCompressionLevel() << 6);
+	AttachedTransformation()->PutWord16(RoundUpToMultipleOf(word16(cmf*256+flags), word16(31)));
+}
+
+void ZlibCompressor::ProcessUncompressedData(const byte *inString, size_t length)
+{
+	m_adler32.Update(inString, length);
+}
+
+void ZlibCompressor::WritePoststreamTail()
+{
+	FixedSizeSecBlock<byte, 4> adler32;
+	m_adler32.Final(adler32);
+	AttachedTransformation()->Put(adler32, 4);
+}
+
+unsigned int ZlibCompressor::GetCompressionLevel() const
+{
+	static const unsigned int deflateToCompressionLevel[] = {0, 1, 1, 1, 2, 2, 2, 2, 2, 3};
+	return deflateToCompressionLevel[GetDeflateLevel()];
+}
+
+// *************************************************************
+
+ZlibDecompressor::ZlibDecompressor(BufferedTransformation *attachment, bool repeat, int propagation)
+	: Inflator(attachment, repeat, propagation), m_log2WindowSize(0)
+{
+}
+
+void ZlibDecompressor::ProcessPrestreamHeader()
+{
+	m_adler32.Restart();
+
+	byte cmf;
+	byte flags;
+
+	if (!m_inQueue.Get(cmf) || !m_inQueue.Get(flags))
+		throw HeaderErr();
+
+	if ((cmf*256+flags) % 31 != 0)
+		throw HeaderErr();	// if you hit this exception, you're probably trying to decompress invalid data
+
+	if ((cmf & 0xf) != DEFLATE_METHOD)
+		throw UnsupportedAlgorithm();
+
+	if (flags & FDICT_FLAG)
+		throw UnsupportedPresetDictionary();
+
+	m_log2WindowSize = 8 + (cmf >> 4);
+}
+
+void ZlibDecompressor::ProcessDecompressedData(const byte *inString, size_t length)
+{
+	AttachedTransformation()->Put(inString, length);
+	m_adler32.Update(inString, length);
+}
+
+void ZlibDecompressor::ProcessPoststreamTail()
+{
+	FixedSizeSecBlock<byte, 4> adler32;
+	if (m_inQueue.Get(adler32, 4) != 4)
+		throw Adler32Err();
+	if (!m_adler32.Verify(adler32))
+		throw Adler32Err();
+}
+
+NAMESPACE_END