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100 lines
2.5 KiB
100 lines
2.5 KiB
5 years ago
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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 = byte((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, size_t length)
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{
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m_crc.Update(inString, length);
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m_totalLen += (word32)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), m_length(0)
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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, size_t 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 += (word32)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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