/* $NetBSD: zfstream.h,v 1.1.1.1 2006/01/14 20:10:54 christos Exp $ */ /* * A C++ I/O streams interface to the zlib gz* functions * * by Ludwig Schwardt * original version by Kevin Ruland * * This version is standard-compliant and compatible with gcc 3.x. */ #ifndef ZFSTREAM_H #define ZFSTREAM_H #include // not iostream, since we don't need cin/cout #include #include "zlib.h" /*****************************************************************************/ /** * @brief Gzipped file stream buffer class. * * This class implements basic_filebuf for gzipped files. It doesn't yet support * seeking (allowed by zlib but slow/limited), putback and read/write access * (tricky). Otherwise, it attempts to be a drop-in replacement for the standard * file streambuf. */ class gzfilebuf : public std::streambuf { public: // Default constructor. gzfilebuf(); // Destructor. virtual ~gzfilebuf(); /** * @brief Set compression level and strategy on the fly. * @param comp_level Compression level (see zlib.h for allowed values) * @param comp_strategy Compression strategy (see zlib.h for allowed values) * @return Z_OK on success, Z_STREAM_ERROR otherwise. * * Unfortunately, these parameters cannot be modified separately, as the * previous zfstream version assumed. Since the strategy is seldom changed, * it can default and setcompression(level) then becomes like the old * setcompressionlevel(level). */ int setcompression(int comp_level, int comp_strategy = Z_DEFAULT_STRATEGY); /** * @brief Check if file is open. * @return True if file is open. */ bool is_open() const { return (file != NULL); } /** * @brief Open gzipped file. * @param name File name. * @param mode Open mode flags. * @return @c this on success, NULL on failure. */ gzfilebuf* open(const char* name, std::ios_base::openmode mode); /** * @brief Attach to already open gzipped file. * @param fd File descriptor. * @param mode Open mode flags. * @return @c this on success, NULL on failure. */ gzfilebuf* attach(int fd, std::ios_base::openmode mode); /** * @brief Close gzipped file. * @return @c this on success, NULL on failure. */ gzfilebuf* close(); protected: /** * @brief Convert ios open mode int to mode string used by zlib. * @return True if valid mode flag combination. */ bool open_mode(std::ios_base::openmode mode, char* c_mode) const; /** * @brief Number of characters available in stream buffer. * @return Number of characters. * * This indicates number of characters in get area of stream buffer. * These characters can be read without accessing the gzipped file. */ virtual std::streamsize showmanyc(); /** * @brief Fill get area from gzipped file. * @return First character in get area on success, EOF on error. * * This actually reads characters from gzipped file to stream * buffer. Always buffered. */ virtual int_type underflow(); /** * @brief Write put area to gzipped file. * @param c Extra character to add to buffer contents. * @return Non-EOF on success, EOF on error. * * This actually writes characters in stream buffer to * gzipped file. With unbuffered output this is done one * character at a time. */ virtual int_type overflow(int_type c = traits_type::eof()); /** * @brief Installs external stream buffer. * @param p Pointer to char buffer. * @param n Size of external buffer. * @return @c this on success, NULL on failure. * * Call setbuf(0,0) to enable unbuffered output. */ virtual std::streambuf* setbuf(char_type* p, std::streamsize n); /** * @brief Flush stream buffer to file. * @return 0 on success, -1 on error. * * This calls underflow(EOF) to do the job. */ virtual int sync(); // // Some future enhancements // // virtual int_type uflow(); // virtual int_type pbackfail(int_type c = traits_type::eof()); // virtual pos_type // seekoff(off_type off, // std::ios_base::seekdir way, // std::ios_base::openmode mode = std::ios_base::in|std::ios_base::out); // virtual pos_type // seekpos(pos_type sp, // std::ios_base::openmode mode = std::ios_base::in|std::ios_base::out); private: /** * @brief Allocate internal buffer. * * This function is safe to call multiple times. It will ensure * that a proper internal buffer exists if it is required. If the * buffer already exists or is external, the buffer pointers will be * reset to their original state. */ void enable_buffer(); /** * @brief Destroy internal buffer. * * This function is safe to call multiple times. It will ensure * that the internal buffer is deallocated if it exists. In any * case, it will also reset the buffer pointers. */ void disable_buffer(); /** * Underlying file pointer. */ gzFile file; /** * Mode in which file was opened. */ std::ios_base::openmode io_mode; /** * @brief True if this object owns file descriptor. * * This makes the class responsible for closing the file * upon destruction. */ bool own_fd; /** * @brief Stream buffer. * * For simplicity this remains allocated on the free store for the * entire life span of the gzfilebuf object, unless replaced by setbuf. */ char_type* buffer; /** * @brief Stream buffer size. * * Defaults to system default buffer size (typically 8192 bytes). * Modified by setbuf. */ std::streamsize buffer_size; /** * @brief True if this object owns stream buffer. * * This makes the class responsible for deleting the buffer * upon destruction. */ bool own_buffer; }; /*****************************************************************************/ /** * @brief Gzipped file input stream class. * * This class implements ifstream for gzipped files. Seeking and putback * is not supported yet. */ class gzifstream : public std::istream { public: // Default constructor gzifstream(); /** * @brief Construct stream on gzipped file to be opened. * @param name File name. * @param mode Open mode flags (forced to contain ios::in). */ explicit gzifstream(const char* name, std::ios_base::openmode mode = std::ios_base::in); /** * @brief Construct stream on already open gzipped file. * @param fd File descriptor. * @param mode Open mode flags (forced to contain ios::in). */ explicit gzifstream(int fd, std::ios_base::openmode mode = std::ios_base::in); /** * Obtain underlying stream buffer. */ gzfilebuf* rdbuf() const { return const_cast(&sb); } /** * @brief Check if file is open. * @return True if file is open. */ bool is_open() { return sb.is_open(); } /** * @brief Open gzipped file. * @param name File name. * @param mode Open mode flags (forced to contain ios::in). * * Stream will be in state good() if file opens successfully; * otherwise in state fail(). This differs from the behavior of * ifstream, which never sets the state to good() and therefore * won't allow you to reuse the stream for a second file unless * you manually clear() the state. The choice is a matter of * convenience. */ void open(const char* name, std::ios_base::openmode mode = std::ios_base::in); /** * @brief Attach to already open gzipped file. * @param fd File descriptor. * @param mode Open mode flags (forced to contain ios::in). * * Stream will be in state good() if attach succeeded; otherwise * in state fail(). */ void attach(int fd, std::ios_base::openmode mode = std::ios_base::in); /** * @brief Close gzipped file. * * Stream will be in state fail() if close failed. */ void close(); private: /** * Underlying stream buffer. */ gzfilebuf sb; }; /*****************************************************************************/ /** * @brief Gzipped file output stream class. * * This class implements ofstream for gzipped files. Seeking and putback * is not supported yet. */ class gzofstream : public std::ostream { public: // Default constructor gzofstream(); /** * @brief Construct stream on gzipped file to be opened. * @param name File name. * @param mode Open mode flags (forced to contain ios::out). */ explicit gzofstream(const char* name, std::ios_base::openmode mode = std::ios_base::out); /** * @brief Construct stream on already open gzipped file. * @param fd File descriptor. * @param mode Open mode flags (forced to contain ios::out). */ explicit gzofstream(int fd, std::ios_base::openmode mode = std::ios_base::out); /** * Obtain underlying stream buffer. */ gzfilebuf* rdbuf() const { return const_cast(&sb); } /** * @brief Check if file is open. * @return True if file is open. */ bool is_open() { return sb.is_open(); } /** * @brief Open gzipped file. * @param name File name. * @param mode Open mode flags (forced to contain ios::out). * * Stream will be in state good() if file opens successfully; * otherwise in state fail(). This differs from the behavior of * ofstream, which never sets the state to good() and therefore * won't allow you to reuse the stream for a second file unless * you manually clear() the state. The choice is a matter of * convenience. */ void open(const char* name, std::ios_base::openmode mode = std::ios_base::out); /** * @brief Attach to already open gzipped file. * @param fd File descriptor. * @param mode Open mode flags (forced to contain ios::out). * * Stream will be in state good() if attach succeeded; otherwise * in state fail(). */ void attach(int fd, std::ios_base::openmode mode = std::ios_base::out); /** * @brief Close gzipped file. * * Stream will be in state fail() if close failed. */ void close(); private: /** * Underlying stream buffer. */ gzfilebuf sb; }; /*****************************************************************************/ /** * @brief Gzipped file output stream manipulator class. * * This class defines a two-argument manipulator for gzofstream. It is used * as base for the setcompression(int,int) manipulator. */ template class gzomanip2 { public: // Allows insertor to peek at internals template friend gzofstream& operator<<(gzofstream&, const gzomanip2&); // Constructor gzomanip2(gzofstream& (*f)(gzofstream&, T1, T2), T1 v1, T2 v2); private: // Underlying manipulator function gzofstream& (*func)(gzofstream&, T1, T2); // Arguments for manipulator function T1 val1; T2 val2; }; /*****************************************************************************/ // Manipulator function thunks through to stream buffer inline gzofstream& setcompression(gzofstream &gzs, int l, int s = Z_DEFAULT_STRATEGY) { (gzs.rdbuf())->setcompression(l, s); return gzs; } // Manipulator constructor stores arguments template inline gzomanip2::gzomanip2(gzofstream &(*f)(gzofstream &, T1, T2), T1 v1, T2 v2) : func(f), val1(v1), val2(v2) { } // Insertor applies underlying manipulator function to stream template inline gzofstream& operator<<(gzofstream& s, const gzomanip2& m) { return (*m.func)(s, m.val1, m.val2); } // Insert this onto stream to simplify setting of compression level inline gzomanip2 setcompression(int l, int s = Z_DEFAULT_STRATEGY) { return gzomanip2(&setcompression, l, s); } #endif // ZFSTREAM_H