zinflate.cpp

提供rsa、 des、 md5等加密和hash算法

	return false;
}

void Inflator::ProcessInput(bool flush)
{
	while (true)
	{
		switch (m_state)
		{
		case PRE_STREAM:
			if (!flush && m_inQueue.CurrentSize() < MaxPrestreamHeaderSize())
				return;
			ProcessPrestreamHeader();
			m_state = WAIT_HEADER;
			m_wrappedAround = false;
			m_current = 0;
			m_lastFlush = 0;
			m_window.New(1 << GetLog2WindowSize());
			break;
		case WAIT_HEADER:
			{
			// maximum number of bytes before actual compressed data starts
			const unsigned int MAX_HEADER_SIZE = BitsToBytes(3+5+5+4+19*7+286*15+19*15);
			if (m_inQueue.CurrentSize() < (flush ? 1 : MAX_HEADER_SIZE))
				return;
			DecodeHeader();
			break;
			}
		case DECODING_BODY:
			if (!DecodeBody())
				return;
			break;
		case POST_STREAM:
			if (!flush && m_inQueue.CurrentSize() < MaxPoststreamTailSize())
				return;
			ProcessPoststreamTail();
			m_state = m_repeat ? PRE_STREAM : AFTER_END;
			Output(0, NULL, 0, GetAutoSignalPropagation(), true);	// TODO: non-blocking
			if (m_inQueue.IsEmpty())
				return;
			break;
		case AFTER_END:
			m_inQueue.TransferTo(*AttachedTransformation());
			return;
		}
	}
}

void Inflator::DecodeHeader()
{
	if (!m_reader.FillBuffer(3))
		throw UnexpectedEndErr();
	m_eof = m_reader.GetBits(1) != 0;
	m_blockType = (byte)m_reader.GetBits(2);
	switch (m_blockType)
	{
	case 0:	// stored
		{
		m_reader.SkipBits(m_reader.BitsBuffered() % 8);
		if (!m_reader.FillBuffer(32))
			throw UnexpectedEndErr();
		m_storedLen = (word16)m_reader.GetBits(16);
		word16 nlen = (word16)m_reader.GetBits(16);
		if (nlen != (word16)~m_storedLen)
			throw BadBlockErr();
		break;
		}
	case 1:	// fixed codes
		m_nextDecode = LITERAL;
		break;
	case 2:	// dynamic codes
		{
		if (!m_reader.FillBuffer(5+5+4))
			throw UnexpectedEndErr();
		unsigned int hlit = m_reader.GetBits(5);
		unsigned int hdist = m_reader.GetBits(5);
		unsigned int hclen = m_reader.GetBits(4);

		FixedSizeSecBlock<unsigned int, 286+32> codeLengths;
		unsigned int i;
		static const unsigned int border[] = {    // Order of the bit length code lengths
			16, 17, 18, 0, 8, 7, 9, 6, 10, 5, 11, 4, 12, 3, 13, 2, 14, 1, 15};
		std::fill(codeLengths.begin(), codeLengths+19, 0);
		for (i=0; i<hclen+4; i++)
			codeLengths[border[i]] = m_reader.GetBits(3);

		try
		{
			HuffmanDecoder codeLengthDecoder(codeLengths, 19);
			for (i = 0; i < hlit+257+hdist+1; )
			{
				unsigned int k, count, repeater;
				bool result = codeLengthDecoder.Decode(m_reader, k);
				if (!result)
					throw UnexpectedEndErr();
				if (k <= 15)
				{
					count = 1;
					repeater = k;
				}
				else switch (k)
				{
				case 16:
					if (!m_reader.FillBuffer(2))
						throw UnexpectedEndErr();
					count = 3 + m_reader.GetBits(2);
					if (i == 0)
						throw BadBlockErr();
					repeater = codeLengths[i-1];
					break;
				case 17:
					if (!m_reader.FillBuffer(3))
						throw UnexpectedEndErr();
					count = 3 + m_reader.GetBits(3);
					repeater = 0;
					break;
				case 18:
					if (!m_reader.FillBuffer(7))
						throw UnexpectedEndErr();
					count = 11 + m_reader.GetBits(7);
					repeater = 0;
					break;
				}
				if (i + count > hlit+257+hdist+1)
					throw BadBlockErr();
				std::fill(codeLengths + i, codeLengths + i + count, repeater);
				i += count;
			}
			m_dynamicLiteralDecoder.Initialize(codeLengths, hlit+257);
			if (hdist == 0 && codeLengths[hlit+257] == 0)
			{
				if (hlit != 0)	// a single zero distance code length means all literals
					throw BadBlockErr();
			}
			else
				m_dynamicDistanceDecoder.Initialize(codeLengths+hlit+257, hdist+1);
			m_nextDecode = LITERAL;
		}
		catch (HuffmanDecoder::Err &)
		{
			throw BadBlockErr();
		}
		break;
		}
	default:
		throw BadBlockErr();	// reserved block type
	}
	m_state = DECODING_BODY;
}

bool Inflator::DecodeBody()
{
	bool blockEnd = false;
	switch (m_blockType)
	{
	case 0:	// stored
		assert(m_reader.BitsBuffered() == 0);
		while (!m_inQueue.IsEmpty() && !blockEnd)
		{
			unsigned int size;
			const byte *block = m_inQueue.Spy(size);
			size = STDMIN(size, (unsigned int)m_storedLen);
			OutputString(block, size);
			m_inQueue.Skip(size);
			m_storedLen -= size;
			if (m_storedLen == 0)
				blockEnd = true;
		}
		break;
	case 1:	// fixed codes
	case 2:	// dynamic codes
		static const unsigned int lengthStarts[] = {
			3, 4, 5, 6, 7, 8, 9, 10, 11, 13, 15, 17, 19, 23, 27, 31,
			35, 43, 51, 59, 67, 83, 99, 115, 131, 163, 195, 227, 258};
		static const unsigned int lengthExtraBits[] = {
			0, 0, 0, 0, 0, 0, 0, 0, 1, 1, 1, 1, 2, 2, 2, 2,
			3, 3, 3, 3, 4, 4, 4, 4, 5, 5, 5, 5, 0};
		static const unsigned int distanceStarts[] = {
			1, 2, 3, 4, 5, 7, 9, 13, 17, 25, 33, 49, 65, 97, 129, 193,
			257, 385, 513, 769, 1025, 1537, 2049, 3073, 4097, 6145,
			8193, 12289, 16385, 24577};
		static const unsigned int distanceExtraBits[] = {
			0, 0, 0, 0, 1, 1, 2, 2, 3, 3, 4, 4, 5, 5, 6, 6,
			7, 7, 8, 8, 9, 9, 10, 10, 11, 11,
			12, 12, 13, 13};

		const HuffmanDecoder& literalDecoder = GetLiteralDecoder();
		const HuffmanDecoder& distanceDecoder = GetDistanceDecoder();

		switch (m_nextDecode)
		{
		case LITERAL:
			while (true)
			{
				if (!literalDecoder.Decode(m_reader, m_literal))
				{
					m_nextDecode = LITERAL;
					break;
				}
				if (m_literal < 256)
					OutputByte((byte)m_literal);
				else if (m_literal == 256)	// end of block
				{
					blockEnd = true;
					break;
				}
				else
				{
					if (m_literal > 285)
						throw BadBlockErr();
					unsigned int bits;
		case LENGTH_BITS:
					bits = lengthExtraBits[m_literal-257];
					if (!m_reader.FillBuffer(bits))
					{
						m_nextDecode = LENGTH_BITS;
						break;
					}
					m_literal = m_reader.GetBits(bits) + lengthStarts[m_literal-257];
		case DISTANCE:
					if (!distanceDecoder.Decode(m_reader, m_distance))
					{
						m_nextDecode = DISTANCE;
						break;
					}
		case DISTANCE_BITS:
					bits = distanceExtraBits[m_distance];
					if (!m_reader.FillBuffer(bits))
					{
						m_nextDecode = DISTANCE_BITS;
						break;
					}
					m_distance = m_reader.GetBits(bits) + distanceStarts[m_distance];
					OutputPast(m_literal, m_distance);
				}
			}
		}
	}
	if (blockEnd)
	{
		if (m_eof)
		{
			FlushOutput();
			m_reader.SkipBits(m_reader.BitsBuffered()%8);
			if (m_reader.BitsBuffered())
			{
				// undo too much lookahead
				SecBlockWithHint<byte, 4> buffer(m_reader.BitsBuffered() / 8);
				for (unsigned int i=0; i<buffer.size(); i++)
					buffer[i] = (byte)m_reader.GetBits(8);
				m_inQueue.Unget(buffer, buffer.size());
			}
			m_state = POST_STREAM;
		}
		else
			m_state = WAIT_HEADER;
	}
	return blockEnd;
}

void Inflator::FlushOutput()
{
	if (m_state != PRE_STREAM)
	{
		assert(m_current >= m_lastFlush);
		ProcessDecompressedData(m_window + m_lastFlush, m_current - m_lastFlush);
		m_lastFlush = m_current;
	}
}

struct NewFixedLiteralDecoder
{
	HuffmanDecoder * operator()() const
	{
		unsigned int codeLengths[288];
		std::fill(codeLengths + 0, codeLengths + 144, 8);
		std::fill(codeLengths + 144, codeLengths + 256, 9);
		std::fill(codeLengths + 256, codeLengths + 280, 7);
		std::fill(codeLengths + 280, codeLengths + 288, 8);
		std::auto_ptr<HuffmanDecoder> pDecoder(new HuffmanDecoder);
		pDecoder->Initialize(codeLengths, 288);
		return pDecoder.release();
	}
};

struct NewFixedDistanceDecoder
{
	HuffmanDecoder * operator()() const
	{
		unsigned int codeLengths[32];
		std::fill(codeLengths + 0, codeLengths + 32, 5);
		std::auto_ptr<HuffmanDecoder> pDecoder(new HuffmanDecoder);
		pDecoder->Initialize(codeLengths, 32);
		return pDecoder.release();
	}
};

const HuffmanDecoder& Inflator::GetLiteralDecoder() const
{
	return m_blockType == 1 ? Singleton<HuffmanDecoder, NewFixedLiteralDecoder>().Ref() : m_dynamicLiteralDecoder;
}

const HuffmanDecoder& Inflator::GetDistanceDecoder() const
{
	return m_blockType == 1 ? Singleton<HuffmanDecoder, NewFixedDistanceDecoder>().Ref() : m_dynamicDistanceDecoder;
}

NAMESPACE_END