Gzipped file stream buffer class. More...

#include "zfstream.h"

Inheritance diagram for gzfilebuf:

Collaboration diagram for gzfilebuf:

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

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

Private Member Functions
	gzfilebuf (const gzfilebuf &)
void	disable_buffer ()
	Destroy internal buffer.
void	enable_buffer ()
	Allocate internal buffer.
gzfilebuf &	operator= (const gzfilebuf &)

Private Attributes
char_type *	buffer
	Stream buffer.
std::streamsize	buffer_size
	Stream buffer size.
gzFile	file
	Underlying file pointer.
std::ios_base::openmode	io_mode
	Mode in which file was opened.
bool	own_buffer
	True if this object owns stream buffer.
bool	own_fd
	True if this object owns file descriptor.

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 52 of file zfstream.h.

Constructor & Destructor Documentation

gzfilebuf::gzfilebuf ( )

Definition at line 55 of file zfstream.cc.

References disable_buffer().

gzfilebuf::~gzfilebuf ( )

virtual

Definition at line 64 of file zfstream.cc.

References close(), disable_buffer(), own_fd, and sync().

gzfilebuf::gzfilebuf ( const gzfilebuf & )

private

Member Function Documentation

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 111 of file zfstream.cc.

References enable_buffer(), file, io_mode, is_open(), open_mode(), and own_fd.

Referenced by gzifstream::attach(), and gzofstream::attach().

gzfilebuf * gzfilebuf::close ( void )

Close gzipped file.

Returns: this on success, NULL on failure.

Definition at line 138 of file zfstream.cc.

References disable_buffer(), file, is_open(), own_fd, and sync().

Referenced by gzifstream::close(), gzofstream::close(), and ~gzfilebuf().

void gzfilebuf::disable_buffer ( )

private

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.

Definition at line 434 of file zfstream.cc.

References buffer, buffer_size, and own_buffer.

Referenced by close(), gzfilebuf(), setbuf(), and ~gzfilebuf().

void gzfilebuf::enable_buffer ( )

private

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.

Definition at line 394 of file zfstream.cc.

References buffer, buffer_size, own_buffer, and SMALLBUFSIZE.

Referenced by attach(), open(), pbackfail(), seekoff(), seekpos(), and setbuf().

bool gzfilebuf::is_open ( void ) const

inline

Check if file is open.

Returns: True if file is open.

Definition at line 82 of file zfstream.h.

References file.

Referenced by attach(), close(), gzifstream::is_open(), gzofstream::is_open(), open(), overflow(), pbackfail(), seekoff(), seekpos(), showmanyc(), and underflow().

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 84 of file zfstream.cc.

References enable_buffer(), file, io_mode, is_open(), open_mode(), and own_fd.

Referenced by gzifstream::open(), and gzofstream::open().

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 162 of file zfstream.cc.

Referenced by attach(), and open().

gzfilebuf& gzfilebuf::operator= ( const gzfilebuf & )

private

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 299 of file zfstream.cc.

References file, io_mode, and is_open().

Referenced by seekoff(), seekpos(), and sync().

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

protectedvirtual

Definition at line 218 of file zfstream.cc.

References buffer, buffer_size, enable_buffer(), file, is_open(), and SEEK_CUR.

gzfilebuf::pos_type gzfilebuf::seekoff	(	off_type	off,
		std::ios_base::seekdir	way,
		std::ios_base::openmode	mode = `std::ios_base::in\|std::ios_base::out`
	)

protectedvirtual

Alters the stream positions.

Each derived class provides its own appropriate behavior.

Definition at line 462 of file zfstream.cc.

References enable_buffer(), file, io_mode, is_open(), overflow(), SEEK_CUR, SEEK_END, and SEEK_SET.

gzfilebuf::pos_type gzfilebuf::seekpos	(	pos_type	sp,
		std::ios_base::openmode	mode = `std::ios_base::in\|std::ios_base::out`
	)

protectedvirtual

Alters the stream positions.

Each derived class provides its own appropriate behavior.

Definition at line 499 of file zfstream.cc.

References enable_buffer(), file, io_mode, is_open(), overflow(), and SEEK_SET.

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 351 of file zfstream.cc.

References buffer, buffer_size, disable_buffer(), enable_buffer(), own_buffer, and sync().

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 77 of file zfstream.cc.

References file.

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 201 of file zfstream.cc.

References io_mode, and is_open().

int gzfilebuf::sync ( void )

protectedvirtual

Flush stream buffer to file.

Returns: 0 on success, -1 on error.

This calls underflow(EOF) to do the job.

Definition at line 384 of file zfstream.cc.

References overflow().

Referenced by close(), setbuf(), and ~gzfilebuf().

gzfilebuf::int_type gzfilebuf::underflow ( void )

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.

Definition at line 256 of file zfstream.cc.

References buffer, buffer_size, file, io_mode, is_open(), and STASHED_CHARACTERS.

Member Data Documentation

char_type* gzfilebuf::buffer

private

Stream buffer.

For simplicity this remains allocated on the free store for the entire life span of the gzfilebuf object, unless replaced by setbuf.

Definition at line 254 of file zfstream.h.

Referenced by disable_buffer(), enable_buffer(), pbackfail(), setbuf(), and underflow().

std::streamsize gzfilebuf::buffer_size

private

Stream buffer size.

Defaults to system default buffer size (typically 8192 bytes). Modified by setbuf.

Definition at line 262 of file zfstream.h.

Referenced by disable_buffer(), enable_buffer(), pbackfail(), setbuf(), and underflow().

gzFile gzfilebuf::file

private

Underlying file pointer.

Definition at line 233 of file zfstream.h.

Referenced by attach(), close(), is_open(), open(), overflow(), pbackfail(), seekoff(), seekpos(), setcompression(), and underflow().

std::ios_base::openmode gzfilebuf::io_mode

private

Mode in which file was opened.

Definition at line 238 of file zfstream.h.

Referenced by attach(), open(), overflow(), seekoff(), seekpos(), showmanyc(), and underflow().

bool gzfilebuf::own_buffer

private

True if this object owns stream buffer.

This makes the class responsible for deleting the buffer upon destruction.

Definition at line 270 of file zfstream.h.

Referenced by disable_buffer(), enable_buffer(), and setbuf().

bool gzfilebuf::own_fd

private

True if this object owns file descriptor.

This makes the class responsible for closing the file upon destruction.

Definition at line 246 of file zfstream.h.

Referenced by attach(), close(), open(), and ~gzfilebuf().

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

libinterp/corefcn/zfstream.h
libinterp/corefcn/zfstream.cc

Public Member Functions

Protected Member Functions

Private Member Functions

Private Attributes

Detailed Description

Constructor & Destructor Documentation

Member Function Documentation

Member Data Documentation