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by weidai
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// gzip.cpp - written and placed in the public domain by Wei Dai
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#include "pch.h" |
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#include "gzip.h" |
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NAMESPACE_BEGIN(CryptoPP) |
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void Gzip::WritePrestreamHeader() |
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{
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m_totalLen = 0; |
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m_crc.Restart(); |
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AttachedTransformation()->Put(MAGIC1); |
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AttachedTransformation()->Put(MAGIC2); |
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AttachedTransformation()->Put(DEFLATED); |
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AttachedTransformation()->Put(0); // general flag |
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AttachedTransformation()->PutWord32(0); // time stamp |
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byte extra = (GetDeflateLevel() == 1) ? FAST : ((GetDeflateLevel() == 9) ? SLOW : 0); |
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AttachedTransformation()->Put(extra); |
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AttachedTransformation()->Put(GZIP_OS_CODE); |
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}
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void Gzip::ProcessUncompressedData(const byte *inString, unsigned int length) |
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{
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m_crc.Update(inString, length); |
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m_totalLen += length; |
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}
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void Gzip::WritePoststreamTail() |
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{
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SecByteBlock crc(4); |
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m_crc.Final(crc); |
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AttachedTransformation()->Put(crc, 4); |
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AttachedTransformation()->PutWord32(m_totalLen, LITTLE_ENDIAN_ORDER); |
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}
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// *************************************************************
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Gunzip::Gunzip(BufferedTransformation *attachment, bool repeat, int propagation) |
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: Inflator(attachment, repeat, propagation) |
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{
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}
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void Gunzip::ProcessPrestreamHeader() |
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{
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m_length = 0; |
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m_crc.Restart(); |
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byte buf[6]; |
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byte b, flags; |
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if (m_inQueue.Get(buf, 2)!=2) throw HeaderErr(); |
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if (buf[0] != MAGIC1 || buf[1] != MAGIC2) throw HeaderErr(); |
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if (!m_inQueue.Skip(1)) throw HeaderErr(); // skip extra flags |
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if (!m_inQueue.Get(flags)) throw HeaderErr(); |
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if (flags & (ENCRYPTED | CONTINUED)) throw HeaderErr(); |
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if (m_inQueue.Skip(6)!=6) throw HeaderErr(); // Skip file time, extra flags and OS type |
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if (flags & EXTRA_FIELDS) // skip extra fields |
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{
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word16 length; |
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if (m_inQueue.GetWord16(length, LITTLE_ENDIAN_ORDER) != 2) throw HeaderErr(); |
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if (m_inQueue.Skip(length)!=length) throw HeaderErr(); |
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}
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if (flags & FILENAME) // skip filename |
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do
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if(!m_inQueue.Get(b)) throw HeaderErr(); |
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while (b); |
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if (flags & COMMENTS) // skip comments |
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do
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if(!m_inQueue.Get(b)) throw HeaderErr(); |
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while (b); |
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}
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void Gunzip::ProcessDecompressedData(const byte *inString, unsigned int length) |
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{
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AttachedTransformation()->Put(inString, length); |
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m_crc.Update(inString, length); |
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m_length += length; |
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}
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void Gunzip::ProcessPoststreamTail() |
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{
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SecByteBlock crc(4); |
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if (m_inQueue.Get(crc, 4) != 4) |
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throw TailErr(); |
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if (!m_crc.Verify(crc)) |
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throw CrcErr(); |
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word32 lengthCheck; |
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if (m_inQueue.GetWord32(lengthCheck, LITTLE_ENDIAN_ORDER) != 4) |
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throw TailErr(); |
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if (lengthCheck != m_length) |
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throw LengthErr(); |
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}
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NAMESPACE_END
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