gzfilebuf Class Reference

Gzipped file stream buffer class. More...

#include <zfstream.h>

Inheritance diagram for gzfilebuf:

Collaboration diagram for gzfilebuf:

Public Member Functions
	gzfilebuf ()
virtual	~gzfilebuf ()
gzfilebuf *	open (const char *name, int io_mode)
gzfilebuf *	attach (int file_descriptor, int io_mode)
gzfilebuf *	close ()
int	setcompressionlevel (int comp_level)
int	setcompressionstrategy (int comp_strategy)
int	is_open () const
virtual streampos	seekoff (streamoff, ios::seek_dir, int)
virtual int	sync ()
	gzfilebuf ()
virtual	~gzfilebuf ()
int	setcompression (int comp_level, int comp_strategy=Z_DEFAULT_STRATEGY)
	Set compression level and strategy on the fly. More...
bool	is_open () const
	Check if file is open. More...
gzfilebuf *	open (const char *name, std::ios_base::openmode mode)
	Open gzipped file. More...
gzfilebuf *	attach (int fd, std::ios_base::openmode mode)
	Attach to already open gzipped file. More...
gzfilebuf *	close ()
	Close gzipped file. More...

Protected Member Functions
virtual int	underflow ()
virtual int	overflow (int=EOF)
bool	open_mode (std::ios_base::openmode mode, char *c_mode) const
	Convert ios open mode int to mode string used by zlib. More...
virtual std::streamsize	showmanyc ()
	Number of characters available in stream buffer. More...
virtual int_type	underflow ()
	Fill get area from gzipped file. More...
virtual int_type	overflow (int_type c=traits_type::eof())
	Write put area to gzipped file. More...
virtual std::streambuf *	setbuf (char_type *p, std::streamsize n)
	Installs external stream buffer. More...
virtual int	sync ()
	Flush stream buffer to file. More...

Detailed Description

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.

Definition at line 8 of file zfstream.h.

Constructor & Destructor Documentation

gzfilebuf::gzfilebuf

(

)

Definition at line 4 of file zfstream.cpp.

gzfilebuf::~gzfilebuf ( )

virtual

Definition at line 10 of file zfstream.cpp.

gzfilebuf::gzfilebuf

(

)

virtual gzfilebuf::~gzfilebuf ( )

virtual

Member Function Documentation

gzfilebuf * gzfilebuf::attach	(	int	file_descriptor,
		int	io_mode
	)

Definition at line 60 of file zfstream.cpp.

gzfilebuf * gzfilebuf::attach	(	int	fd,
		std::ios_base::openmode	mode
	)

Attach to already open gzipped file.

Parameters

fd	File descriptor.
mode	Open mode flags.

Returns

this on success, NULL on failure.

Definition at line 79 of file zfstream.cc.

gzfilebuf * gzfilebuf::close

(

)

Definition at line 102 of file zfstream.cpp.

gzfilebuf* gzfilebuf::close

(

)

Close gzipped file.

Returns

this on success, NULL on failure.

int gzfilebuf::is_open ( ) const

inline

Definition at line 22 of file zfstream.h.

bool gzfilebuf::is_open ( ) const

inline

Check if file is open.

Returns

True if file is open.

Definition at line 57 of file zfstream.h.

gzfilebuf * gzfilebuf::open	(	const char *	name,
		int	io_mode
	)

Definition at line 18 of file zfstream.cpp.

gzfilebuf * gzfilebuf::open	(	const char *	name,
		std::ios_base::openmode	mode
	)

Open gzipped file.

Parameters

name	File name.
mode	Open mode flags.

Returns

this on success, NULL on failure.

Definition at line 51 of file zfstream.cc.

bool gzfilebuf::open_mode ( std::ios_base::openmode  mode, char *  c_mode  ) const

protected

Convert ios open mode int to mode string used by zlib.

Returns

True if valid mode flag combination.

Definition at line 131 of file zfstream.cc.

int gzfilebuf::overflow ( int  c = EOF )

protectedvirtual

Definition at line 173 of file zfstream.cpp.

gzfilebuf::int_type gzfilebuf::overflow ( int_type  c = traits_type::eof() )

protectedvirtual

Write put area to gzipped file.

Parameters

c	Extra character to add to buffer contents.

Returns

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.

Definition at line 214 of file zfstream.cc.

streampos gzfilebuf::seekoff ( streamoff  off, ios::seek_dir  dir, int  which  )

virtual

Definition at line 129 of file zfstream.cpp.

std::streambuf * gzfilebuf::setbuf ( char_type *  p, std::streamsize  n  )

protectedvirtual

Installs external stream buffer.

Parameters

p	Pointer to char buffer.
n	Size of external buffer.

Returns

this on success, NULL on failure.

Call setbuf(0,0) to enable unbuffered output.

Definition at line 266 of file zfstream.cc.

int gzfilebuf::setcompression	(	int	comp_level,
		int	comp_strategy = Z_DEFAULT_STRATEGY
	)

Set compression level and strategy on the fly.

Parameters

comp_level	Compression level (see zlib.h for allowed values)
comp_strategy	Compression strategy (see zlib.h for allowed values)

Returns

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).

Definition at line 43 of file zfstream.cc.

int gzfilebuf::setcompressionlevel

(

int

comp_level

)

Definition at line 116 of file zfstream.cpp.

int gzfilebuf::setcompressionstrategy

(

int

comp_strategy

)

Definition at line 122 of file zfstream.cpp.

std::streamsize gzfilebuf::showmanyc ( )

protectedvirtual

Number of characters available in stream buffer.

Returns

Number of characters.

This indicates number of characters in get area of stream buffer. These characters can be read without accessing the gzipped file.

Definition at line 169 of file zfstream.cc.

int gzfilebuf::sync ( )

virtual

Definition at line 206 of file zfstream.cpp.

virtual int gzfilebuf::sync ( )

protectedvirtual

Flush stream buffer to file.

Returns

0 on success, -1 on error.

This calls underflow(EOF) to do the job.

gzfilebuf::int_type gzfilebuf::underflow ( )

protectedvirtual

Definition at line 135 of file zfstream.cpp.

virtual int_type gzfilebuf::underflow ( )

protectedvirtual

Fill get area from gzipped file.

Returns

First character in get area on success, EOF on error.

This actually reads characters from gzipped file to stream buffer. Always buffered.

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The documentation for this class was generated from the following files:

• bial/zlib/contrib/iostream/zfstream.h
• bial/zlib/contrib/iostream/zfstream.cpp
• bial/zlib/contrib/iostream3/zfstream.cc