Compression support

[Erik Søe Sørensen]

Jonas Bähr wrote:
> Am Sonntag, 11. April 2004 11:32 schrieb David Philippi:
>>Do you really believe that it hurts to have the uncompressed on disk?
> storing on disk is not the problem...

Disk space may be cheap these days - but for individual users it may 
still be a problem.
Right now the level may only constitute 16% of the installed size, but 
when the planned levels are there this will rise to a significant part 
of the space (50%+).

David Philippi wrote:
> Am Mo, den 12.04.2004 schrieb Jonas Bähr um 23:04:
>
> > An easy alternative could be to write a little shell-script (ex: 'pingusgz' or 
> > so) which pipes the recived file throgh gzip and calls pingus afterwards. So 
> > you only need to tell your browser to open .pingusgz with this script instead 
> > of pingus itself....
>
> Yes, that's a viable solution. I didn't think of .pingusgz and
> .pingus.gz doesn't help you very much. We surely could even add support
> for something like detecting wheter a .pingus level is gzipped or plain
> text but I don't have the time to code such a thing at the moment. Or to
> put it into other words, I don't see it as important enough as to take
> the time.

I did (and this is my last vacation day :)
And it so happens that zlib already has that detection ("if this file 
has as GZ header, then treat it as a gzipped file, otherwise treat it as 
a raw file").
No shell stuff needed (an even easier alternative might have been to 
create a pipe and run system('gzip -c <name-of-file>') so that the main 
program could read the output. I don't understand why the libxml 
interface doesn't have a parse-from-FILE* function?).

My 40 lines (new file) and a patch attached - C++-code, that is.
Enjoy - and proof-read, bitte!

/Erik

Index: src/Makefile.am
===================================================================
RCS file: /var/lib/cvs/Games/Pingus/src/Makefile.am,v
retrieving revision 1.153
diff -r1.153 Makefile.am
300a301,302
> xmlgz_reader.hxx \
> xmlgz_reader.cxx \
Index: src/xml_plf.cxx
===================================================================
RCS file: /var/lib/cvs/Games/Pingus/src/xml_plf.cxx,v
retrieving revision 1.38
diff -r1.38 xml_plf.cxx
21a22
> #include "xmlgz_reader.hxx"
40c41
<   doc = xmlParseFile(filename.c_str());
---
>   doc = xmlgzParseFile(filename.c_str());

/*  $Id: xml_plf.cxx,v 1.38 2003/04/19 10:23:17 torangan Exp $
 *
 *  Pingus - A free Lemmings clone
 *  Copyright (C) 2000 Ingo Ruhnke <address@hidden>
 *
 *  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., 59 Temple Place - Suite 330, Boston, MA  02111-1307, USA.
 */

#include "xmlgz_reader.hxx"
#include <iostream>
#include <stdio.h>
#include <zlib.h>

using namespace std;

/** This file implements parsing of gzipped XML files.
 *  The main function for this is  xmlgzParseFile(),
 *  which should behave like libxml's  xmlParseFile() except that
 *  it is capable of handling both gzipped and raw XML.
 */

xmlDocPtr xmlgzParseFile(const char * filename) {
    gzFile in = NULL;
    char* buf = NULL; 
    xmlDocPtr doc = NULL;
    try {
        // 1: Open file.
        in = gzopen(filename, "rb"); // Works for both gzipped and raw files.
        
        if (!in) throw "Cannot open file.";
    
        // 2: Read file:
        int length;
        {
            int bufsize = 8192; // For starters.
            buf = (char*) malloc(bufsize);
            if (!buf) throw "Allocation of buffer memory failed.";
            int pos=0, status;
            while (1) {
                status = gzread(in, buf+pos, bufsize-pos);
                if (status <= 0) break; // Error or EOF
                pos += status;
                if (pos==bufsize) {
                    int newbufsize = bufsize*2;
                    buf = (char*) realloc(buf, newbufsize);     
                    if (!buf) throw "Expansion of buffer memory failed.";
                    bufsize = newbufsize;
                }
            }
            if (status < 0) throw "Uncompression error.";
            length = pos;
        }

        // 3: Parse:
        doc = xmlParseMemory(buf, length);
    } catch (const char* str) {
        cout << "Reading the file " << filename << " failed: " << str << endl;
    }

    // Finally, clean up:
    if (buf) free(buf);
    if (in) gzclose(in);
    return doc;
}

/*  $Id: xml_plf.cxx,v 1.38 2003/04/19 10:23:17 torangan Exp $
 *
 *  Pingus - A free Lemmings clone
 *  Copyright (C) 2000 Ingo Ruhnke <address@hidden>
 *
 *  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., 59 Temple Place - Suite 330, Boston, MA  02111-1307, USA.
 */

#ifndef HEADER_PINGUS_XMLGZ_READER_HXX
#define HEADER_PINGUS_XMLGZ_READER_HXX

#include "xml_helper.hxx"

xmlDocPtr xmlgzParseFile(const char * filename);

#endif // Double-inclusion protection

/* EOF */