gzip.h

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// gzip.h - originally written and placed in the public domain by Wei Dai
 
/// \file gzip.h
/// \brief GZIP compression and decompression (RFC 1952)
 
#ifndef CRYPTOPP_GZIP_H
#define CRYPTOPP_GZIP_H
 
#include "cryptlib.h"
#include "zdeflate.h"
#include "zinflate.h"
#include "crc.h"
 
NAMESPACE_BEGIN(CryptoPP)
 
/// \brief GZIP Compression (RFC 1952)
class Gzip : public Deflator
{
public:
    /// \brief Construct a Gzip compressor
    /// \param attachment an attached transformation
    /// \param deflateLevel the deflate level
    /// \param log2WindowSize the window size
    /// \param detectUncompressible flag to detect if data is compressible
    /// \details detectUncompressible makes it faster to process uncompressible files, but
    ///   if a file has both compressible and uncompressible parts, it may fail to compress
    ///   some of the compressible parts.
    Gzip(BufferedTransformation *attachment=NULLPTR, unsigned int deflateLevel=DEFAULT_DEFLATE_LEVEL, unsigned int log2WindowSize=DEFAULT_LOG2_WINDOW_SIZE, bool detectUncompressible=true)
        : Deflator(attachment, deflateLevel, log2WindowSize, detectUncompressible), m_totalLen(0), m_filetime(0) { }
 
    /// \brief Construct a Gzip compressor
    /// \param parameters a set of NameValuePairs to initialize this object
    /// \param attachment an attached transformation
    /// \details Possible parameter names: Log2WindowSize, DeflateLevel, DetectUncompressible
    Gzip(const NameValuePairs &parameters, BufferedTransformation *attachment=NULLPTR)
        : Deflator(parameters, attachment), m_totalLen(0), m_filetime(0)
    {
        IsolatedInitialize(parameters);
    }
 
    /// \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);
 
    void IsolatedInitialize(const NameValuePairs &parameters);
 
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);
    void WritePoststreamTail();
 
    word32 m_totalLen;
    CRC32 m_crc;
 
    word32 m_filetime;
    std::string m_filename;
    std::string m_comment;
};
 
/// \brief GZIP Decompression (RFC 1952)
class Gunzip : public Inflator
{
public:
    typedef Inflator::Err Err;
 
    /// \brief Exception thrown when a header decoding error occurs
    class HeaderErr : public Err {public: HeaderErr() : Err(INVALID_DATA_FORMAT, "Gunzip: header decoding error") {}};
    /// \brief Exception thrown when the tail is too short
    class TailErr : public Err {public: TailErr() : Err(INVALID_DATA_FORMAT, "Gunzip: tail too short") {}};
    /// \brief Exception thrown when a CRC error occurs
    class CrcErr : public Err {public: CrcErr() : Err(DATA_INTEGRITY_CHECK_FAILED, "Gunzip: CRC check error") {}};
    /// \brief Exception thrown when a length error occurs
    class LengthErr : public Err {public: LengthErr() : Err(DATA_INTEGRITY_CHECK_FAILED, "Gunzip: length check error") {}};
 
    /// \brief Construct a Gunzip decompressor
    /// \param attachment an attached transformation
    /// \param repeat decompress multiple compressed streams in series
    /// \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
        MAGIC1=0x1f,
        /// \brief Second header magic value
        MAGIC2=0x8b,
        /// \brief Deflated flag
        DEFLATED=8
    };
 
    enum FLAG_MASKS {
        CONTINUED=2, EXTRA_FIELDS=4, FILENAME=8, COMMENTS=16, ENCRYPTED=32};
 
    unsigned int MaxPrestreamHeaderSize() const {return 1024;}
    void ProcessPrestreamHeader();
    void ProcessDecompressedData(const byte *string, size_t length);
    unsigned int MaxPoststreamTailSize() const {return 8;}
    void ProcessPoststreamTail();
 
    word32 m_length;
    CRC32 m_crc;
 
    word32 m_filetime;
    std::string m_filename;
    std::string m_comment;
};
 
NAMESPACE_END
 
#endif