Gunzip: added GetFilename() and GetComment() methods (#418)

Add Filename, Filtetime and Comment support to Gzip classes

2 files changed, 146 insertions, 8 deletions

diff --git a/gzip.cpp b/gzip.cpp
index 04568386..4b4869b4 100644
--- a/gzip.cpp
+++ b/gzip.cpp
@@ -5,19 +5,39 @@
 

 NAMESPACE_BEGIN(CryptoPP)

 

+// Checks whether the character is valid for ISO/IEC 8859-1 as required by RFC 1952

+static inline bool Is8859Character(char c) {

+	const unsigned char cc = static_cast<unsigned char>(c);

+	return (cc >= 32 && cc <= 126) || (cc >= 160 && cc <= 255);

+}

+

 void Gzip::WritePrestreamHeader()

 {

 	m_totalLen = 0;

 	m_crc.Restart();

 

+	int flags = 0;

+	if(!m_filename.empty())

+		flags |= FILENAME;

+	if(!m_comment.empty())

+		flags |= COMMENTS;

+

 	AttachedTransformation()->Put(MAGIC1);

 	AttachedTransformation()->Put(MAGIC2);

 	AttachedTransformation()->Put(DEFLATED);

-	AttachedTransformation()->Put(0);		// general flag

-	AttachedTransformation()->PutWord32(0);	// time stamp

-	byte extra = byte((GetDeflateLevel() == 1) ? FAST : ((GetDeflateLevel() == 9) ? SLOW : 0));

+	AttachedTransformation()->Put((byte)flags);		// general flag

+	AttachedTransformation()->PutWord32(m_filetime, LITTLE_ENDIAN_ORDER);	// time stamp

+	byte extra = (GetDeflateLevel() == 1) ? FAST : ((GetDeflateLevel() == 9) ? SLOW : 0);

 	AttachedTransformation()->Put(extra);

 	AttachedTransformation()->Put(GZIP_OS_CODE);

+

+	// Filename is NULL terminated, hence the +1

+	if(!m_filename.empty())

+		AttachedTransformation()->Put((const unsigned char*)m_filename.data(), m_filename.size() +1);

+

+	// Comment is NULL terminated, hence the +1

+	if(!m_comment.empty())

+		AttachedTransformation()->Put((const unsigned char*)m_comment.data(), m_comment.size() +1);

 }

 

 void Gzip::ProcessUncompressedData(const byte *inString, size_t length)

@@ -32,12 +52,44 @@ void Gzip::WritePoststreamTail()
 	m_crc.Final(crc);

 	AttachedTransformation()->Put(crc, 4);

 	AttachedTransformation()->PutWord32(m_totalLen, LITTLE_ENDIAN_ORDER);

+

+	m_filetime = 0;

+	m_filename.clear();

+	m_comment.clear();

+}

+

+void Gzip::SetComment(const std::string& comment, bool throwOnEncodingError)

+{

+	if(throwOnEncodingError)

+	{

+		for(size_t i = 0; i < comment.length(); i++) {

+			const char c = comment[i];

+			if(!Is8859Character(c))

+				throw InvalidDataFormat("The comment is not ISO/IEC 8859-1 encoded");

+		}

+	}

+

+	m_comment = comment;

+}

+

+void Gzip::SetFilename(const std::string& filename, bool throwOnEncodingError)

+{

+	if(throwOnEncodingError)

+	{

+		for(size_t i = 0; i < filename.length(); i++) {

+			const char c = filename[i];

+			if(!Is8859Character(c))

+				throw InvalidDataFormat("The filename is not ISO/IEC 8859-1 encoded");

+		}

+	}

+

+	m_filename = filename;

 }

 

 // *************************************************************

 

 Gunzip::Gunzip(BufferedTransformation *attachment, bool repeat, int propagation)

-	: Inflator(attachment, repeat, propagation), m_length(0)

+	: Inflator(attachment, repeat, propagation), m_length(0), m_filetime(0)

 {

 }

 

@@ -46,15 +98,20 @@ void Gunzip::ProcessPrestreamHeader()
 	m_length = 0;

 	m_crc.Restart();

 

+	m_filetime = 0;

+	m_filename.clear();

+	m_comment.clear();

+

 	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(b) || (b != DEFLATED)) throw HeaderErr();	 // skip CM flag

 	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 (m_inQueue.GetWord32(m_filetime, LITTLE_ENDIAN_ORDER) != 4) throw HeaderErr();

+	if (m_inQueue.Skip(2)!=2) throw HeaderErr();    // Skip extra flags and OS type

 

 	if (flags & EXTRA_FIELDS)	// skip extra fields

 	{

@@ -63,15 +120,25 @@ void Gunzip::ProcessPrestreamHeader()
 		if (m_inQueue.Skip(length)!=length) throw HeaderErr();

 	}

 

-	if (flags & FILENAME)	// skip filename

+	if (flags & FILENAME)	// extract filename

+	{

 		do

+		{

 			if(!m_inQueue.Get(b)) throw HeaderErr();

+			if(b) m_filename.append( 1, (char)b );

+		}

 		while (b);

+	}

 

-	if (flags & COMMENTS)	// skip comments

+	if (flags & COMMENTS)	// extract comments

+	{

 		do

+		{

 			if(!m_inQueue.Get(b)) throw HeaderErr();

+			if(b) m_comment.append( 1, (char)b );

+		}

 		while (b);

+	}

 }

 

 void Gunzip::ProcessDecompressedData(const byte *inString, size_t length)

@@ -96,4 +163,32 @@ void Gunzip::ProcessPoststreamTail()
 		throw LengthErr();

 }

 

+const std::string& Gunzip::GetComment(bool throwOnEncodingError) const

+{

+	if(throwOnEncodingError)

+	{

+		for(size_t i = 0; i < m_comment.length(); i++) {

+			const char c = m_comment[i];

+			if(!Is8859Character(c))

+				throw InvalidDataFormat("The comment is not ISO/IEC 8859-1 encoded");

+		}

+	}

+

+	return m_comment;

+}

+

+const std::string& Gunzip::GetFilename(bool throwOnEncodingError) const

+{

+	if(throwOnEncodingError)

+	{

+		for(size_t i = 0; i < m_filename.length(); i++) {

+			const char c = m_filename[i];

+			if(!Is8859Character(c))

+				throw InvalidDataFormat("The filename is not ISO/IEC 8859-1 encoded");

+		}

+	}

+

+	return m_filename;

+}

+

 NAMESPACE_END

diff --git a/gzip.h b/gzip.h
index a53a23e4..3f7b7cdc 100644
--- a/gzip.h
+++ b/gzip.h
@@ -35,9 +35,29 @@ public:
 	Gzip(const NameValuePairs &parameters, BufferedTransformation *attachment=NULLPTR)

 		: Deflator(parameters, attachment), m_totalLen(0) {}

 

+	//! \param filetime the filetime to set in the header. The application is responsible for setting it.

+	void SetFiletime(word32 filetime) { m_filetime = filetime; }

+    

+	//! \param filename the original filename to set in the header. The application is responsible for setting it.

+	//!        RFC 1952 requires a ISO/IEC 8859-1 encoding.

+	//! \param throwOnEncodingError if throwOnEncodingError is true, then the filename is checked to ensure it is

+	//!        ISO/IEC 8859-1 encoded. If the filename does not adhere to ISO/IEC 8859-1, then a InvalidDataFormat

+	//!        is thrown. If throwOnEncodingError is false then the filename is not checked.

+	void SetFilename(const std::string& filename, bool throwOnEncodingError = false);

+    

+	//! \param comment the comment to set in the header. The application is responsible for setting it.

+	//!        RFC 1952 requires a ISO/IEC 8859-1 encoding.

+	//! \param throwOnEncodingError if throwOnEncodingError is true, then the comment is checked to ensure it is

+	//!        ISO/IEC 8859-1 encoded. If the comment does not adhere to ISO/IEC 8859-1, then a InvalidDataFormat

+	//!        is thrown. If throwOnEncodingError is false then the comment is not checked.

+	void SetComment(const std::string& comment, bool throwOnEncodingError = false);

+

 protected:

 	enum {MAGIC1=0x1f, MAGIC2=0x8b,   // flags for the header

 		  DEFLATED=8, FAST=4, SLOW=2};

+    

+	enum FLAG_MASKS {

+		FILENAME=8, COMMENTS=16};

 

 	void WritePrestreamHeader();

 	void ProcessUncompressedData(const byte *string, size_t length);

@@ -45,6 +65,10 @@ protected:
 

 	word32 m_totalLen;

 	CRC32 m_crc;

+    

+	word32 m_filetime;

+	std::string m_filename;

+	std::string m_comment;

 };

 

 //! \class Gunzip

@@ -73,6 +97,21 @@ public:
 	//! \param autoSignalPropagation 0 to turn off MessageEnd signal

 	Gunzip(BufferedTransformation *attachment = NULLPTR, bool repeat = false, int autoSignalPropagation = -1);

 

+	//! \return the filetime of the stream as set in the header. The application is responsible for setting it on the decompressed file.

+	word32 GetFiletime() const { return m_filetime; }

+    

+	//! \return the filename of the stream as set in the header. The application is responsible for setting it on the decompressed file.

+	//! \param throwOnEncodingError if throwOnEncodingError is true, then the filename is checked to ensure it is

+	//!        ISO/IEC 8859-1 encoded. If the filename does not adhere to ISO/IEC 8859-1, then a InvalidDataFormat is thrown.

+	//!        If throwOnEncodingError is false then the filename is not checked.

+	const std::string& GetFilename(bool throwOnEncodingError = false) const;

+    

+	//! \return the comment of the stream as set in the header.

+	//! \param throwOnEncodingError if throwOnEncodingError is true, then the comment is checked to ensure it is

+	//!        ISO/IEC 8859-1 encoded. If the comment does not adhere to ISO/IEC 8859-1, then a InvalidDataFormat is thrown.

+	//!        If throwOnEncodingError is false then the comment is not checked.

+	const std::string& GetComment(bool throwOnEncodingError = false) const;

+

 protected:

 	enum {

 		//! \brief First header magic value

@@ -94,6 +133,10 @@ protected:
 

 	word32 m_length;

 	CRC32 m_crc;

+

+	word32 m_filetime;

+	std::string m_filename;

+	std::string m_comment;

 };

 

 NAMESPACE_END