path: root/kfile-plugins/png/kfile_png.cpp

/* This file is part of the KDE project
 * Copyright (C) 2001, 2002 Rolf Magnus <ramagnus@kde.org>
 *
 * 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 version 2.
 *
 * 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; see the file COPYING.  If not, write to
 * the Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor,
 * Boston, MA 02110-1301, USA.
 *
 *  $Id$
 */

#include <stdlib.h>
#include "kfile_png.h"

#include <kurl.h>
#include <kprocess.h>
#include <klocale.h>
#include <kgenericfactory.h>
#include <kdebug.h>

#include <tqcstring.h>
#include <tqfile.h>
#include <tqdatetime.h>
#include <tqdict.h>
#include <tqvalidator.h>
#include <zlib.h>

// some defines to make it easier
// don't tell me anything about preprocessor usage :)
#define CHUNK_SIZE(data, index) ((data[index  ]<<24) + (data[index+1]<<16) + \
                                 (data[index+2]<< 8) +  data[index+3])
#define CHUNK_TYPE(data, index)  &data[index+4]
#define CHUNK_HEADER_SIZE 12
#define CHUNK_DATA(data, index, offset) data[8+index+offset]

// known translations for common png keys
static const char* knownTranslations[]
#ifdef __GNUC__
__attribute__((unused))
#endif
 = {
  I18N_NOOP("Title"),
  I18N_NOOP("Author"),
  I18N_NOOP("Description"),
  I18N_NOOP("Copyright"),
  I18N_NOOP("Creation Time"),
  I18N_NOOP("Software"),
  I18N_NOOP("Disclaimer"),
  I18N_NOOP("Warning"),
  I18N_NOOP("Source"),
  I18N_NOOP("Comment")
};

// and for the colors
static const char* colors[] = {
  I18N_NOOP("Grayscale"),
  I18N_NOOP("Unknown"),
  I18N_NOOP("RGB"),
  I18N_NOOP("Palette"),
  I18N_NOOP("Grayscale/Alpha"),
  I18N_NOOP("Unknown"),
  I18N_NOOP("RGB/Alpha")
};

  // and compressions
static const char* compressions[] =
{
  I18N_NOOP("Deflate")
};

  // interlaced modes
static const char* interlaceModes[] = {
  I18N_NOOP("None"),
  I18N_NOOP("Adam7")
};

typedef KGenericFactory<KPngPlugin> PngFactory;

K_EXPORT_COMPONENT_FACTORY(kfile_png, PngFactory("kfile_png"))

KPngPlugin::KPngPlugin(TQObject *tqparent, const char *name,
                       const TQStringList &args)
    : KFilePlugin(tqparent, name, args)
{
    kdDebug(7034) << "png plugin\n";

    // set up our mime type
    KFileMimeTypeInfo* info = addMimeTypeInfo( "image/png" );

    KFileMimeTypeInfo::GroupInfo* group = 0;
    KFileMimeTypeInfo::ItemInfo* item = 0;

    // comment group
    group = addGroupInfo(info, "Comment", i18n("Comment"));
    addVariableInfo(group, TQVariant::String, 0);

    // technical group
    group = addGroupInfo(info, "Technical", i18n("Technical Details"));

    item = addItemInfo(group, "Dimensions", i18n("Dimensions"), TQVariant::Size);
    setHint( item, KFileMimeTypeInfo::Size );
    setUnit(item, KFileMimeTypeInfo::Pixels);

    item = addItemInfo(group, "BitDepth", i18n("Bit Depth"), TQVariant::Int);
    setUnit(item, KFileMimeTypeInfo::BitsPerPixel);

    addItemInfo(group, "ColorMode", i18n("Color Mode"), TQVariant::String);
    addItemInfo(group, "Compression", i18n("Compression"), TQVariant::String);
    addItemInfo(group, "InterlaceMode", i18n("Interlace Mode"),TQVariant::String);
}

bool KPngPlugin::readInfo( KFileMetaInfo& info, uint what)
{
    if ( info.path().isEmpty() ) // remote file
        return false;
    TQFile f(info.path());
    if ( !f.open(IO_ReadOnly) )
        return false;

    TQIODevice::Offset fileSize = f.size();

    if (fileSize < 29) return false;
    // the technical group will be read from the first 29 bytes. If the file
    // is smaller, we can't even read this.

    bool readComments = false;
    if (what & (KFileMetaInfo::Fastest |
                KFileMetaInfo::DontCare |
                KFileMetaInfo::ContentInfo)) readComments = true;
    else
	fileSize = 29; // No need to read more

    uchar *data = new uchar[fileSize+1];
    f.readBlock(reinterpret_cast<char*>(data), fileSize);
    data[fileSize]='\n';

    // find the start
    if (data[0] == 137 && data[1] == 80 && data[2] == 78 && data[3] == 71 &&
        data[4] ==  13 && data[5] == 10 && data[6] == 26 && data[7] == 10 )
    {
        // ok
        // the IHDR chunk should be the first
        if (!strncmp((char*)&data[12], "IHDR", 4))
        {
            // we found it, get the dimensions
            ulong x,y;
            x = (data[16]<<24) + (data[17]<<16) + (data[18]<<8) + data[19];
            y = (data[20]<<24) + (data[21]<<16) + (data[22]<<8) + data[23];

            uint type = data[25];
            uint bpp =  data[24];
            kdDebug(7034) << "dimensions " << x << "*" << y << endl;

            // the bpp are only per channel, so we need to multiply the with
            // the channel count
            switch (type)
            {
                case 0: break;           // Grayscale
                case 2: bpp *= 3; break; // RGB
                case 3: break;           // palette
                case 4: bpp *= 2; break; // grayscale w. alpha
                case 6: bpp *= 4; break; // RGBA

                default: // we don't get any sensible value here
                    bpp = 0;
            }

            KFileMetaInfoGroup techgroup = appendGroup(info, "Technical");

            appendItem(techgroup, "Dimensions", TQSize(x, y));
            appendItem(techgroup, "BitDepth", bpp);
            appendItem(techgroup, "ColorMode",
                       (type < sizeof(colors)/sizeof(colors[0]))
                       ? i18n(colors[data[25]]) : i18n("Unknown"));

            appendItem(techgroup, "Compression",
                       (data[26] < sizeof(compressions)/sizeof(compressions[0]))
                       ? i18n(compressions[data[26]]) : i18n("Unknown"));

            appendItem(techgroup, "InterlaceMode",
                       (data[28] < sizeof(interlaceModes)/sizeof(interlaceModes[0]))
                       ? i18n(interlaceModes[data[28]]) : i18n("Unknown"));
        }

        // look for a tEXt chunk
        if (readComments)
        {
            uint index = 8;
            index += CHUNK_SIZE(data, index) + CHUNK_HEADER_SIZE;
            KFileMetaInfoGroup commentGroup = appendGroup(info, "Comment");

            while(index<fileSize-12)
            {
                while (index < fileSize - 12 &&
                       strncmp((char*)CHUNK_TYPE(data,index), "tEXt", 4) &&
                       strncmp((char*)CHUNK_TYPE(data,index), "zTXt", 4))

                {
                    if (!strncmp((char*)CHUNK_TYPE(data,index), "IEND", 4))
                        goto end;

                    index += CHUNK_SIZE(data, index) + CHUNK_HEADER_SIZE;
                }

                if (index < fileSize - 12)
                {
                    // we found a tEXt or zTXt field

                    // get the key, it's a null terminated string at the
                    //  chunk start

                    uchar* key = &CHUNK_DATA(data,index,0);

                    int keysize=0;
                    for (;key[keysize]!=0; keysize++)
                        // look if we reached the end of the file
                        // (it might be corrupted)
                        if (8+index+keysize>=fileSize)
                            goto end;

		    TQByteArray arr;
		    if(!strncmp((char*)CHUNK_TYPE(data,index), "zTXt", 4)) {
			kdDebug(7034) << "We found a zTXt field\n";
			// we get the compression method after the key
			uchar* compressionMethod = &CHUNK_DATA(data,index,keysize+1);
			if ( *compressionMethod != 0x00 ) {
			    // then it isn't zlib compressed and we are sunk
			    kdDebug(7034) << "Non-standard compression method." << endl;
			    goto end;
			}
			// compressed string after the compression technique spec
			uchar* compressedText = &CHUNK_DATA(data, index, keysize+2);
			uint compressedTextSize = CHUNK_SIZE(data, index)-keysize-2;

			// security check, also considering overflow wraparound from the addition --
			// we may endup with a /smaller/ index if we wrap all the way around
			uint firstIndex       = (uint)(compressedText - data);
			uint onePastLastIndex = firstIndex + compressedTextSize;
			if ( onePastLastIndex > fileSize || onePastLastIndex <= firstIndex)
			    goto end;

			uLongf uncompressedLen = compressedTextSize * 2; // just a starting point
			int zlibResult;
			do {
			    arr.resize(uncompressedLen);
			    zlibResult = uncompress((Bytef*)arr.data(), &uncompressedLen,
						    compressedText, compressedTextSize);
			    if (Z_OK == zlibResult) {
				// then it is all OK
				arr.resize(uncompressedLen);
			    } else if (Z_BUF_ERROR == zlibResult) {
				// the uncompressedArray needs to be larger
				// kdDebug(7034) << "doubling size for decompression" << endl;
				uncompressedLen *= 2;

                                // DoS protection. can't be bigger than 64k
                                if ( uncompressedLen > 131072 )
                                    break;
			    } else {
				// something bad happened
				goto end;
			    }
			} while (Z_BUF_ERROR == zlibResult);

			if (Z_OK != zlibResult)
			    goto end;
		    } else if (!strncmp((char*)CHUNK_TYPE(data,index), "tEXt", 4)) {
			kdDebug(7034) << "We found a tEXt field\n";
			// the text comes after the key, but isn't null terminated
			uchar* text = &CHUNK_DATA(data,index, keysize+1);
			uint textsize = CHUNK_SIZE(data, index)-keysize-1;

			// security check, also considering overflow wraparound from the addition --
			// we may endup with a /smaller/ index if we wrap all the way around
			uint firstIndex       = (uint)(text - data);
			uint onePastLastIndex = firstIndex + textsize;

			if ( onePastLastIndex > fileSize || onePastLastIndex <= firstIndex)
			    goto end;

			arr.resize(textsize);
			arr = TQByteArray(textsize).duplicate((const char*)text,
							     textsize);
			
		    } else {
			kdDebug(7034) << "We found a field, not expected though\n";
			goto end;
		    }
		    appendItem(commentGroup,
			       TQString(reinterpret_cast<char*>(key)),
			       TQString(arr));
		    
		    kdDebug(7034) << "adding " << key << " / "
				  << TQString(arr) << endl;

		    index += CHUNK_SIZE(data, index) + CHUNK_HEADER_SIZE;
                }
            }
        }
    }
end:
    delete[] data;
    return true;
}

#include "kfile_png.moc"