Initial revision

1 files changed, 99 insertions, 0 deletions

diff --git a/gzip.cpp b/gzip.cpp
new file mode 100644
index 00000000..2cfee9c5
--- /dev/null
+++ b/gzip.cpp
@@ -0,0 +1,99 @@
+// gzip.cpp - written and placed in the public domain by Wei Dai
+
+#include "pch.h"
+#include "gzip.h"
+
+NAMESPACE_BEGIN(CryptoPP)
+
+void Gzip::WritePrestreamHeader()
+{
+	m_totalLen = 0;
+	m_crc.Restart();
+
+	AttachedTransformation()->Put(MAGIC1);
+	AttachedTransformation()->Put(MAGIC2);
+	AttachedTransformation()->Put(DEFLATED);
+	AttachedTransformation()->Put(0);		// general flag
+	AttachedTransformation()->PutWord32(0);	// time stamp
+	byte extra = (GetDeflateLevel() == 1) ? FAST : ((GetDeflateLevel() == 9) ? SLOW : 0);
+	AttachedTransformation()->Put(extra);
+	AttachedTransformation()->Put(GZIP_OS_CODE);
+}
+
+void Gzip::ProcessUncompressedData(const byte *inString, unsigned int length)
+{
+	m_crc.Update(inString, length);
+	m_totalLen += length;
+}
+
+void Gzip::WritePoststreamTail()
+{
+	SecByteBlock crc(4);
+	m_crc.Final(crc);
+	AttachedTransformation()->Put(crc, 4);
+	AttachedTransformation()->PutWord32(m_totalLen, LITTLE_ENDIAN_ORDER);
+}
+
+// *************************************************************
+
+Gunzip::Gunzip(BufferedTransformation *attachment, bool repeat, int propagation)
+	: Inflator(attachment, repeat, propagation)
+{
+}
+
+void Gunzip::ProcessPrestreamHeader()
+{
+	m_length = 0;
+	m_crc.Restart();
+
+	byte buf[6];
+	byte b, flags;
+
+	if (m_inQueue.Get(buf, 2)!=2) throw HeaderErr();
+	if (buf[0] != MAGIC1 || buf[1] != MAGIC2) throw HeaderErr();
+	if (!m_inQueue.Skip(1)) throw HeaderErr();	 // skip extra flags
+	if (!m_inQueue.Get(flags)) throw HeaderErr();
+	if (flags & (ENCRYPTED | CONTINUED)) throw HeaderErr();
+	if (m_inQueue.Skip(6)!=6) throw HeaderErr();    // Skip file time, extra flags and OS type
+
+	if (flags & EXTRA_FIELDS)	// skip extra fields
+	{
+		word16 length;
+		if (m_inQueue.GetWord16(length, LITTLE_ENDIAN_ORDER) != 2) throw HeaderErr();
+		if (m_inQueue.Skip(length)!=length) throw HeaderErr();
+	}
+
+	if (flags & FILENAME)	// skip filename
+		do
+			if(!m_inQueue.Get(b)) throw HeaderErr();
+		while (b);
+
+	if (flags & COMMENTS)	// skip comments
+		do
+			if(!m_inQueue.Get(b)) throw HeaderErr();
+		while (b);
+}
+
+void Gunzip::ProcessDecompressedData(const byte *inString, unsigned int length)
+{
+	AttachedTransformation()->Put(inString, length);
+	m_crc.Update(inString, length);
+	m_length += length;
+}
+
+void Gunzip::ProcessPoststreamTail()
+{
+	SecByteBlock crc(4);
+	if (m_inQueue.Get(crc, 4) != 4)
+		throw TailErr();
+	if (!m_crc.Verify(crc))
+		throw CrcErr();
+
+	word32 lengthCheck;
+	if (m_inQueue.GetWord32(lengthCheck, LITTLE_ENDIAN_ORDER) != 4)
+		throw TailErr();
+	if (lengthCheck != m_length)
+		throw LengthErr();
+}
+
+NAMESPACE_END