flightgear/Lib/Misc/zfstream.cxx

//  A C++ I/O streams interface to the zlib gz* functions
//
// Written by Bernie Bright, 1998
// Based on zlib/contrib/iostream/ by Kevin Ruland <kevin@rodin.wustl.edu>
//
// Copyright (C) 1998  Bernie Bright - bbright@c031.aone.net.au
//
// This program is free software; you can redistribute it and/or
// modify it under the terms of the GNU General Public License as
// published by the Free Software Foundation; either version 2 of the
// License, or (at your option) any later version.
//
// This program is distributed in the hope that it will be useful, but
// WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
// General Public License for more details.
//
// You should have received a copy of the GNU General Public License
// along with this program; if not, write to the Free Software
// Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
//
// $Id$

#include <memory.h>
#include "zfstream.hxx"

//
// Construct a gzfilebuf object.
// Allocate memory for 'get' buffer and zero all buffer pointers.
//
gzfilebuf::gzfilebuf()
    : streambuf(),
      file(NULL),
      mode(0),
      own_file_descriptor(false),
      ibuf_size(0),
      ibuffer(0)
{
//     try {
    ibuf_size = page_size / sizeof(char);
    ibuffer = new char [ibuf_size];
//     } catch (...) {
// 	delete [] ibuffer;
//     }

    // Null get and set pointers.
    this->setg(0,0,0);
    this->setp(0,0);
}

gzfilebuf::~gzfilebuf()
{
    sync();
    if ( own_file_descriptor )
	this->close();
    delete [] ibuffer;
}

void
gzfilebuf::cvt_iomode( char* p, ios_openmode io_mode )
{
//     memset( char_mode, '\0', 10 );
//     char* p = char_mode;

    if ( io_mode & ios_in )
    {
	mode = ios_in;
	*p++ = 'r';
    }
    else if ( io_mode & ios_app )
    {
	mode = ios_app;
	*p++ = 'a';
    }
    else
    {
	mode = ios_out;
	*p++ = 'w';
    }

    if ( io_mode & ios_binary )
    {
	mode |= ios_binary;
	*p++ = 'b';
    }

    // Hard code the compression level
    if ( io_mode & (ios_out | ios_app) )
    {
	*p++ = '9';
    }

    *p = '\0';
}

gzfilebuf*
gzfilebuf::open( const char *name, ios_openmode io_mode )
{
    if ( is_open() )
	return NULL;

    char char_mode[10];
    cvt_iomode( char_mode, io_mode );
    if ( (file = gzopen(name, char_mode)) == NULL )
	return NULL;

    own_file_descriptor = true;

    return this;
}

gzfilebuf*
gzfilebuf::attach( int file_descriptor, ios_openmode io_mode )
{
    if ( is_open() )
	return NULL;

    char char_mode[10];
    cvt_iomode( char_mode, io_mode );
    if ( (file = gzdopen(file_descriptor, char_mode)) == NULL )
	return NULL;

    own_file_descriptor = false;

    return this;
}

gzfilebuf*
gzfilebuf::close()
{
    if ( is_open() )
    {
	sync();
	gzclose( file );
	file = NULL;
    }

    return this;
}

// int
// gzfilebuf::setcompressionlevel( int comp_level )
// {
//     return gzsetparams(file, comp_level, -2);
// }

// int
// gzfilebuf::setcompressionstrategy( int comp_strategy )
// {
//     return gzsetparams(file, -2, comp_strategy);
// }


streampos
gzfilebuf::seekoff( streamoff, ios_seekdir, int )
{
    return streampos(EOF);
}

gzfilebuf::int_type
gzfilebuf::overflow( int_type )
{
#if 0
    if ( !is_open() || !(mode & ios::out) )
	return EOF;

    if ( !base() )
    {
	if ( allocate() == EOF )
	    return EOF;
	setg(0,0,0);
    }
    else
    {
	if (in_avail())
	{
	    return EOF;
	}

	if (out_waiting())
	{
	    if (flushbuf() == EOF)
		return EOF;
	}
    }

    int bl = blen();
    setp( base(), base() + bl);

    if ( c != EOF )
    {
	*pptr() = c;
	pbump(1);
    }
#endif
    return 0;
}

int
gzfilebuf::sync()
{
    if ( !is_open() )
	return EOF;

    if ( pptr() != 0 && pptr() > pbase() )
	return flushbuf();

    return 0;
}

gzfilebuf::int_type
gzfilebuf::flushbuf()
{
    char* q = pbase();
    int n = pptr() - q;

    if ( gzwrite( file, q, n) < n )
	return traits_type::eof();

    setp(0,0);

    return 0;
}

gzfilebuf::int_type
gzfilebuf::underflow()
{
//     cerr << "gzfilebuf::underflow(): gptr()=" << (void*)gptr() << endl;
    // Error if the file not open for reading.
    if ( !is_open() || !(mode & ios_in) )
	return traits_type::eof();

    // If the input buffer is empty then try to fill it.
    if ( gptr() != 0 && gptr() < egptr() )
    {
	return int_type(*gptr());
    }
    else
    {
	return fillbuf() == EOF ? traits_type::eof() : int_type(*gptr());
    }
}

//
// Load the input buffer from the underlying gz file.
// Returns number of characters read, or EOF.
//
int
gzfilebuf::fillbuf()
{
    int t = gzread( file, ibuffer, ibuf_size );
    if ( t <= 0)
    {
	// disable get area
	setg(0,0,0);
	return EOF;
    }

    // Set the input (get) pointers
    setg( ibuffer, ibuffer, ibuffer+t );

//     cerr << "gzfilebuf::fillbuf():"
// 	 << " t=" << t
// 	 << ", ibuffer=" << (void*)ibuffer
// 	 << ", ibuffer+t=" << (void*)(ibuffer+t) << endl;

    return t;
}

#if 0
gzifstream::gzifstream()
    : istream(&buffer), buffer()
{
    clear( ios_badbit );
}

gzifstream::gzifstream( const char *name, ios_openmode io_mode )
    : istream(&buffer), buffer()
{
    this->open( name, io_mode );
}

gzifstream::gzifstream( int fd, ios_openmode io_mode )
    : istream(&buffer), buffer()
{
    buffer.attach( fd, io_mode );
}

gzifstream::~gzifstream()
{
}

void
gzifstream::open( const char *name, ios_openmode io_mode )
{
    if ( !buffer.open( name, io_mode ) )
	clear( ios_failbit | ios_badbit );
    else
	clear();
}

void
gzifstream::close()
{
    if ( !buffer.close() )
	clear( ios_failbit | ios_badbit );
}
#endif