kzip.cpp

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/* This file is part of the KDE libraries
   Copyright (C) 2000 David Faure <faure@kde.org>
   Copyright (C) 2002 Holger Schroeder <holger-kde@holgis.net>

   This library is free software; you can redistribute it and/or
   modify it under the terms of the GNU Library General Public
   License version 2 as published by the Free Software Foundation.

   This library 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
   Library General Public License for more details.

   You should have received a copy of the GNU Library General Public License
   along with this library; see the file COPYING.LIB.  If not, write to
   the Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor,
   Boston, MA 02110-1301, USA.
*/

#include "kzip.h"
#include "kfilterdev.h"
#include "klimitediodevice_p.h"
#include <kdebug.h>

#include <QtCore/QHash>
#include <QtCore/QByteArray>
#include <QtCore/QFile>
#include <QtCore/QDir>
#include <QtCore/QDate>
#include <QtCore/QList>

#include <zlib.h>
#include <time.h>
#include <string.h>

const int max_path_len = 4095;  // maximum number of character a path may contain

static void transformToMsDos(const QDateTime& dt, char* buffer)
{
    if ( dt.isValid() )
    {
        const quint16 time =
             ( dt.time().hour() << 11 )    // 5 bit hour
           | ( dt.time().minute() << 5 )   // 6 bit minute
           | ( dt.time().second() >> 1 );  // 5 bit double seconds

        buffer[0] = char(time);
        buffer[1] = char(time >> 8);

        const quint16 date =
             ( ( dt.date().year() - 1980 ) << 9 ) // 7 bit year 1980-based
           | ( dt.date().month() << 5 )           // 4 bit month
           | ( dt.date().day() );                 // 5 bit day

        buffer[2] = char(date);
        buffer[3] = char(date >> 8);
    }
    else // !dt.isValid(), assume 1980-01-01 midnight
    {
        buffer[0] = 0;
        buffer[1] = 0;
        buffer[2] = 33;
        buffer[3] = 0;
    }
}

static time_t transformFromMsDos(const char* buffer)
{
    quint16 time = (uchar)buffer[0] | ( (uchar)buffer[1] << 8 );
    int h = time >> 11;
    int m = ( time & 0x7ff ) >> 5;
    int s = ( time & 0x1f ) * 2 ;
    QTime qt(h, m, s);

    quint16 date = (uchar)buffer[2] | ( (uchar)buffer[3] << 8 );
    int y = ( date >> 9 ) + 1980;
    int o = ( date & 0x1ff ) >> 5;
    int d = ( date & 0x1f );
    QDate qd(y, o, d);

    QDateTime dt( qd, qt );
    return dt.toTime_t();
}

// == parsing routines for zip headers

struct ParseFileInfo {
  // file related info
  mode_t perm;          // permissions of this file
  time_t atime;         // last access time (UNIX format)
  time_t mtime;         // modification time (UNIX format)
  time_t ctime;         // creation time (UNIX format)
  int uid;          // user id (-1 if not specified)
  int gid;          // group id (-1 if not specified)
  QByteArray guessed_symlink;   // guessed symlink target
  int extralen;         // length of extra field

  // parsing related info
  bool exttimestamp_seen;   // true if extended timestamp extra field
                // has been parsed
  bool newinfounix_seen;    // true if Info-ZIP Unix New extra field has
                // been parsed

  ParseFileInfo() : perm(0100644), uid(-1), gid(-1), extralen(0),
    exttimestamp_seen(false), newinfounix_seen(false) {
    ctime = mtime = atime = time(0);
  }
};

static bool parseExtTimestamp(const char *buffer, int size, bool islocal,
            ParseFileInfo &pfi) {
  if (size < 1) {
    kDebug(7040) << "premature end of extended timestamp (#1)";
    return false;
  }/*end if*/
  int flags = *buffer;      // read flags
  buffer += 1;
  size -= 1;

  if (flags & 1) {      // contains modification time
    if (size < 4) {
      kDebug(7040) << "premature end of extended timestamp (#2)";
      return false;
    }/*end if*/
    pfi.mtime = time_t((uchar)buffer[0] | (uchar)buffer[1] << 8
                | (uchar)buffer[2] << 16 | (uchar)buffer[3] << 24);
    buffer += 4;
    size -= 4;
  }/*end if*/
  // central extended field cannot contain more than the modification time
  // even if other flags are set
  if (!islocal) {
    pfi.exttimestamp_seen = true;
    return true;
  }/*end if*/

  if (flags & 2) {      // contains last access time
    if (size < 4) {
      kDebug(7040) << "premature end of extended timestamp (#3)";
      return true;
    }/*end if*/
    pfi.atime = time_t((uchar)buffer[0] | (uchar)buffer[1] << 8
                | (uchar)buffer[2] << 16 | (uchar)buffer[3] << 24);
    buffer += 4;
    size -= 4;
  }/*end if*/

  if (flags & 4) {      // contains creation time
    if (size < 4) {
      kDebug(7040) << "premature end of extended timestamp (#4)";
      return true;
    }/*end if*/
    pfi.ctime = time_t((uchar)buffer[0] | (uchar)buffer[1] << 8
                | (uchar)buffer[2] << 16 | (uchar)buffer[3] << 24);
    buffer += 4;
  }/*end if*/

  pfi.exttimestamp_seen = true;
  return true;
}

static bool parseInfoZipUnixOld(const char *buffer, int size, bool islocal,
            ParseFileInfo &pfi) {
  // spec mandates to omit this field if one of the newer fields are available
  if (pfi.exttimestamp_seen || pfi.newinfounix_seen) return true;

  if (size < 8) {
    kDebug(7040) << "premature end of Info-ZIP unix extra field old";
    return false;
  }/*end if*/

  pfi.atime = time_t((uchar)buffer[0] | (uchar)buffer[1] << 8
                | (uchar)buffer[2] << 16 | (uchar)buffer[3] << 24);
  buffer += 4;
  pfi.mtime = time_t((uchar)buffer[0] | (uchar)buffer[1] << 8
                | (uchar)buffer[2] << 16 | (uchar)buffer[3] << 24);
  buffer += 4;
  if (islocal && size >= 12) {
    pfi.uid = (uchar)buffer[0] | (uchar)buffer[1] << 8;
    buffer += 2;
    pfi.gid = (uchar)buffer[0] | (uchar)buffer[1] << 8;
    buffer += 2;
  }/*end if*/
  return true;
}

#if 0 // not needed yet

static bool parseInfoZipUnixNew(const char *buffer, int size, bool islocal,
            ParseFileInfo &pfi) {
  if (!islocal) {   // contains nothing in central field
    pfi.newinfounix = true;
    return true;
  }/*end if*/

  if (size < 4) {
    kDebug(7040) << "premature end of Info-ZIP unix extra field new";
    return false;
  }/*end if*/

  pfi.uid = (uchar)buffer[0] | (uchar)buffer[1] << 8;
  buffer += 2;
  pfi.gid = (uchar)buffer[0] | (uchar)buffer[1] << 8;
  buffer += 2;

  pfi.newinfounix = true;
  return true;
}
#endif

static bool parseExtraField(const char *buffer, int size, bool islocal,
            ParseFileInfo &pfi) {
  // extra field in central directory doesn't contain useful data, so we
  // don't bother parsing it
  if (!islocal) return true;

  while (size >= 4) {   // as long as a potential extra field can be read
    int magic = (uchar)buffer[0] | (uchar)buffer[1] << 8;
    buffer += 2;
    int fieldsize = (uchar)buffer[0] | (uchar)buffer[1] << 8;
    buffer += 2;
    size -= 4;

    if (fieldsize > size) {
      //kDebug(7040) << "fieldsize: " << fieldsize << " size: " << size;
      kDebug(7040) << "premature end of extra fields reached";
      break;
    }/*end if*/

    switch (magic) {
      case 0x5455:      // extended timestamp
        if (!parseExtTimestamp(buffer, fieldsize, islocal, pfi)) return false;
    break;
      case 0x5855:      // old Info-ZIP unix extra field
        if (!parseInfoZipUnixOld(buffer, fieldsize, islocal, pfi)) return false;
    break;
#if 0   // not needed yet
      case 0x7855:      // new Info-ZIP unix extra field
        if (!parseInfoZipUnixNew(buffer, fieldsize, islocal, pfi)) return false;
    break;
#endif
      default:
        /* ignore everything else */;
    }/*end switch*/

    buffer += fieldsize;
    size -= fieldsize;
  }/*wend*/
  return true;
}

static bool handlePossibleHeaderBegin(const char* buffer, QIODevice *dev)
{
    // we have to detect three magic tokens here:
    // PK34 for the next local header in case there is no data descriptor
    // PK12 for the central header in case there is no data descriptor
    // PK78 for the data descriptor in case it is following the compressed data
    // TODO: optimize using 32bit const data for comparison instead of byte-wise,
    // given we run at least on 32bit CPUs

    if (buffer[0] == 'K') {
        if (buffer[1] == 7 && buffer[2] == 8) {
            // data descriptor token found
            dev->seek(dev->pos() + 12); // skip the 'data_descriptor'
            return true;
        }

        if ((buffer[1] == 1 && buffer[2] == 2)
            || (buffer[1] == 3 && buffer[2] == 4)) {
            // central/local header token found
            dev->seek(dev->pos() - 4);
            // go back 4 bytes, so that the magic bytes can be found
            // in the next cycle...
            return true;
        }
    }
    return false;
}

static bool seekToNextHeaderToken(QIODevice *dev)
{
    bool headerTokenFound = false;
    char buffer[3];

    while (!headerTokenFound) {
        int n = dev->read(buffer, 1);
        if (n < 1) {
            //qWarning() << "Invalid ZIP file. Unexpected end of file. (#2)";
            return false;
        }

        if (buffer[0] != 'P') {
            continue;
        }

        n = dev->read(buffer, 3);
        if (n < 3) {
            //qWarning() << "Invalid ZIP file. Unexpected end of file. (#3)";
            return false;
        }

        if (handlePossibleHeaderBegin(buffer, dev)) {
            headerTokenFound = true;
        } else {
            for (int i = 0; i < 3; ++i) {
                if (buffer[i] == 'P') {
                    // We have another P character so we must go back a little to check if it is a magic
                    dev->seek(dev->pos() - 3 + i);
                    break;
                }
            }
        }
    }
    return true;
}


class KZip::KZipPrivate
{
public:
    KZipPrivate()
        : m_crc( 0 ),
          m_currentFile( 0 ),
          m_currentDev( 0 ),
          m_compression( 8 ),
          m_extraField( KZip::NoExtraField ),
      m_offset( 0 )
    {}

    unsigned long           m_crc;         // checksum
    KZipFileEntry*          m_currentFile; // file currently being written
    QIODevice*              m_currentDev;  // filterdev used to write to the above file
    QList<KZipFileEntry*> m_fileList;    // flat list of all files, for the index (saves a recursive method ;)
    int                     m_compression;
    KZip::ExtraField        m_extraField;
    // m_offset holds the offset of the place in the zip,
    // where new data can be appended. after openarchive it points to 0, when in
    // writeonly mode, or it points to the beginning of the central directory.
    // each call to writefile updates this value.
    quint64                 m_offset;
};

KZip::KZip( const QString& fileName )
    : KArchive( fileName ),d(new KZipPrivate)
{
}

KZip::KZip( QIODevice * dev )
    : KArchive( dev ),d(new KZipPrivate)
{
}

KZip::~KZip()
{
    //kDebug(7040) << this;
    if( isOpen() )
        close();
    delete d;
}

bool KZip::openArchive( QIODevice::OpenMode mode )
{
    //kDebug(7040);
    d->m_fileList.clear();

    if ( mode == QIODevice::WriteOnly )
        return true;

    char buffer[47];

    // Check that it's a valid ZIP file
    // KArchive::open() opened the underlying device already.

    quint64 offset = 0; // holds offset, where we read
    int n;

    // contains information gathered from the local file headers
    QHash<QByteArray, ParseFileInfo> pfi_map;

    QIODevice* dev = device();

    // We set a bool for knowing if we are allowed to skip the start of the file
    bool startOfFile = true;

    for (;;) // repeat until 'end of entries' signature is reached
    {
        //kDebug(7040) << "loop starts";
        //kDebug(7040) << "dev->pos() now : " << dev->pos();
        n = dev->read( buffer, 4 );

        if (n < 4)
        {
            kWarning(7040) << "Invalid ZIP file. Unexpected end of file. (#1)";

            return false;
        }

        if ( !memcmp( buffer, "PK\5\6", 4 ) ) // 'end of entries'
        {
        //kDebug(7040) << "PK56 found end of archive";
            startOfFile = false;
        break;
    }

    if ( !memcmp( buffer, "PK\3\4", 4 ) ) // local file header
        {
        //kDebug(7040) << "PK34 found local file header";
            startOfFile = false;
            // can this fail ???
        dev->seek( dev->pos() + 2 ); // skip 'version needed to extract'

        // read static header stuff
            n = dev->read( buffer, 24 );
        if (n < 24) {
                kWarning(7040) << "Invalid ZIP file. Unexpected end of file. (#4)";
                return false;
        }

        int gpf = (uchar)buffer[0]; // "general purpose flag" not "general protection fault" ;-)
        int compression_mode = (uchar)buffer[2] | (uchar)buffer[3] << 8;
        time_t mtime = transformFromMsDos( buffer+4 );

            const qint64 compr_size = uint(uchar(buffer[12])) | uint(uchar(buffer[13])) << 8 |
                                      uint(uchar(buffer[14])) << 16 | uint(uchar(buffer[15])) << 24;
            const qint64 uncomp_size = uint(uchar(buffer[16])) | uint(uchar(buffer[17])) << 8 |
                                      uint(uchar(buffer[18])) << 16 | uint(uchar(buffer[19])) << 24;
            const int namelen = uint(uchar(buffer[20])) | uint(uchar(buffer[21])) << 8;
            const int extralen = uint(uchar(buffer[22])) | uint(uchar(buffer[23])) << 8;

            /*
        kDebug(7040) << "general purpose bit flag: " << gpf;
        kDebug(7040) << "compressed size: " << compr_size;
        kDebug(7040) << "uncompressed size: " << uncomp_size;
        kDebug(7040) << "namelen: " << namelen;
        kDebug(7040) << "extralen: " << extralen;
        kDebug(7040) << "archive size: " << dev->size();
        */

        // read fileName
            Q_ASSERT( namelen > 0 );
        QByteArray fileName = dev->read(namelen);
            if ( fileName.size() < namelen ) {
                kWarning(7040) << "Invalid ZIP file. Name not completely read (#2)";
        return false;
        }

        ParseFileInfo pfi;
        pfi.mtime = mtime;

            // read and parse the beginning of the extra field,
            // skip rest of extra field in case it is too long
            unsigned int extraFieldEnd = dev->pos() + extralen;
        pfi.extralen = extralen;
        int handledextralen = qMin(extralen, (int)sizeof buffer);

            //if ( handledextralen )
            //    kDebug(7040) << "handledextralen: " << handledextralen;

        n = dev->read(buffer, handledextralen);
        // no error msg necessary as we deliberately truncate the extra field
        if (!parseExtraField(buffer, handledextralen, true, pfi))
        {
            kWarning(7040) << "Invalid ZIP File. Broken ExtraField.";
            return false;
        }

            // jump to end of extra field
            dev->seek( extraFieldEnd );

        // we have to take care of the 'general purpose bit flag'.
            // if bit 3 is set, the header doesn't contain the length of
            // the file and we look for the signature 'PK\7\8'.
            if ( gpf & 8 )
            {
            // here we have to read through the compressed data to find
        // the next PKxx
                if (!seekToNextHeaderToken(dev)) {
                    return false;
                }
            }
            else
            {
            // here we skip the compressed data and jump to the next header
            //kDebug(7040) << "general purpose bit flag indicates, that local file header contains valid size";
                bool foundSignature = false;
        // check if this could be a symbolic link
        if (compression_mode == NoCompression
                && uncomp_size <= max_path_len
            && uncomp_size > 0) {
            // read content and store it
                    // If it's not a symlink, then we'll just discard the data for now.
            pfi.guessed_symlink = dev->read(uncomp_size);
            if (pfi.guessed_symlink.size() < uncomp_size) {
            kWarning(7040) << "Invalid ZIP file. Unexpected end of file. (#5)";
            return false;
            }
        } else {

                if ( compr_size > dev->size() )
            {
                // here we cannot trust the compressed size, so scan through the compressed
            // data to find the next header

                        if (!seekToNextHeaderToken(dev)) {
                            return false;
                        }
                        foundSignature = true;
            }
            else
            {
//          kDebug(7040) << "before interesting dev->pos(): " << dev->pos();
          bool success = dev->seek( dev->pos() + compr_size ); // can this fail ???
          Q_UNUSED( success ); // prevent warning in release builds.
          Q_ASSERT( success ); // let's see...
/*          kDebug(7040) << "after interesting dev->pos(): " << dev->pos();
            if ( success )
                kDebug(7040) << "dev->at was successful... ";
            else
                kDebug(7040) << "dev->at failed... ";*/
            }

        }
                // test for optional data descriptor
                if (!foundSignature) {
//                     qDebug() << "Testing for optional data descriptor";
                    // read static data descriptor
                    n = dev->read(buffer, 4);
                    if (n < 4) {
//                         qWarning() << "Invalid ZIP file. Unexpected end of file. (#1)";
                        return false;
                    }

                    if (buffer[0] != 'P' || !handlePossibleHeaderBegin(buffer+1, dev)) {
                        // assume data descriptor without signature
                        dev->seek(dev->pos() + 8); // skip rest of the 'data_descriptor'
                    }
                }

// not needed any more
/*                // here we calculate the length of the file in the zip
                // with headers and jump to the next header.
                uint skip = compr_size + namelen + extralen;
                offset += 30 + skip;*/
            }
            pfi_map.insert(fileName, pfi);
        }
        else if ( !memcmp( buffer, "PK\1\2", 4 ) ) // central block
        {
        //kDebug(7040) << "PK12 found central block";
            startOfFile = false;

            // so we reached the central header at the end of the zip file
            // here we get all interesting data out of the central header
            // of a file
            offset = dev->pos() - 4;

            //set offset for appending new files
            if ( d->m_offset == 0L ) d->m_offset = offset;

            n = dev->read( buffer + 4, 42 );
            if (n < 42) {
                kWarning(7040) << "Invalid ZIP file, central entry too short"; // not long enough for valid entry
                return false;
            }

            //int gpf = (uchar)buffer[9] << 8 | (uchar)buffer[10];
            //kDebug() << "general purpose flag=" << gpf;
            // length of the fileName (well, pathname indeed)
            int namelen = (uchar)buffer[29] << 8 | (uchar)buffer[28];
            Q_ASSERT( namelen > 0 );
            QByteArray bufferName = dev->read( namelen );
            if ( bufferName.size() < namelen )
                kWarning(7040) << "Invalid ZIP file. Name not completely read";

            ParseFileInfo pfi = pfi_map.value( bufferName, ParseFileInfo() );

            QString name( QFile::decodeName(bufferName) );

            //kDebug(7040) << "name: " << name;
            // only in central header ! see below.
            // length of extra attributes
            int extralen = (uchar)buffer[31] << 8 | (uchar)buffer[30];
            // length of comment for this file
            int commlen =  (uchar)buffer[33] << 8 | (uchar)buffer[32];
            // compression method of this file
            int cmethod =  (uchar)buffer[11] << 8 | (uchar)buffer[10];

            //kDebug(7040) << "cmethod: " << cmethod;
            //kDebug(7040) << "extralen: " << extralen;

            // crc32 of the file
            uint crc32 = (uchar)buffer[19] << 24 | (uchar)buffer[18] << 16 |
                       (uchar)buffer[17] << 8 | (uchar)buffer[16];

            // uncompressed file size
            uint ucsize = (uchar)buffer[27] << 24 | (uchar)buffer[26] << 16 |
                (uchar)buffer[25] << 8 | (uchar)buffer[24];
            // compressed file size
            uint csize = (uchar)buffer[23] << 24 | (uchar)buffer[22] << 16 |
                (uchar)buffer[21] << 8 | (uchar)buffer[20];

            // offset of local header
            uint localheaderoffset = (uchar)buffer[45] << 24 | (uchar)buffer[44] << 16 |
                (uchar)buffer[43] << 8 | (uchar)buffer[42];

            // some clever people use different extra field lengths
            // in the central header and in the local header... funny.
            // so we need to get the localextralen to calculate the offset
            // from localheaderstart to dataoffset
            int localextralen = pfi.extralen; // FIXME: this will not work if
                            // no local header exists

            //kDebug(7040) << "localextralen: " << localextralen;

            // offset, where the real data for uncompression starts
            uint dataoffset = localheaderoffset + 30 + localextralen + namelen; //comment only in central header

            //kDebug(7040) << "esize: " << esize;
            //kDebug(7040) << "eoffset: " << eoffset;
            //kDebug(7040) << "csize: " << csize;

        int os_madeby = (uchar)buffer[5];
            bool isdir = false;
            int access = 0100644;

        if (os_madeby == 3) {   // good ole unix
            access = (uchar)buffer[40] | (uchar)buffer[41] << 8;
        }

            QString entryName;

            if (name.endsWith(QLatin1Char('/'))) { // Entries with a trailing slash are directories
                isdir = true;
                name = name.left( name.length() - 1 );
                if (os_madeby != 3) access = S_IFDIR | 0755;
        else Q_ASSERT(access & S_IFDIR);
            }

            int pos = name.lastIndexOf(QLatin1Char('/'));
            if ( pos == -1 )
                entryName = name;
            else
                entryName = name.mid( pos + 1 );
            Q_ASSERT( !entryName.isEmpty() );

            KArchiveEntry* entry;
            if ( isdir )
            {
                QString path = QDir::cleanPath( name );
                const KArchiveEntry* ent = rootDir()->entry( path );
                if ( ent && ent->isDirectory() )
                {
                    //kDebug(7040) << "Directory already exists, NOT going to add it again";
                    entry = 0;
                }
                else
                {
                    entry = new KArchiveDirectory( this, entryName, access, (int)pfi.mtime, rootDir()->user(), rootDir()->group(), QString() );
                    //kDebug(7040) << "KArchiveDirectory created, entryName= " << entryName << ", name=" << name;
                }
        }
            else
            {
            QString symlink;
        if (S_ISLNK(access)) {
            symlink = QFile::decodeName(pfi.guessed_symlink);
        }
                entry = new KZipFileEntry( this, entryName, access, pfi.mtime,
                    rootDir()->user(), rootDir()->group(),
                    symlink, name, dataoffset,
                    ucsize, cmethod, csize );
                static_cast<KZipFileEntry *>(entry)->setHeaderStart( localheaderoffset );
                static_cast<KZipFileEntry*>(entry)->setCRC32(crc32);
                //kDebug(7040) << "KZipFileEntry created, entryName= " << entryName << ", name=" << name;
                d->m_fileList.append( static_cast<KZipFileEntry *>( entry ) );
            }

            if ( entry )
            {
                if ( pos == -1 )
                {
                    rootDir()->addEntry(entry);
                }
                else
                {
                    // In some tar files we can find dir/./file => call cleanPath
                    QString path = QDir::cleanPath( name.left( pos ) );
                    // Ensure container directory exists, create otherwise
                    KArchiveDirectory * tdir = findOrCreate( path );
                    tdir->addEntry(entry);
                }
            }

            //calculate offset to next entry
            offset += 46 + commlen + extralen + namelen;
            bool b = dev->seek(offset);
            Q_ASSERT( b );
            if ( !b )
              return false;
        }
        else if ( startOfFile )
        {
            // The file does not start with any ZIP header (e.g. self-extractable ZIP files)
            // Therefore we need to find the first PK\003\004 (local header)
            //kDebug(7040) << "Try to skip start of file";
            startOfFile = false;
            bool foundSignature = false;

            while (!foundSignature)
            {
                n = dev->read( buffer, 1 );
                if (n < 1)
                {
                    kWarning(7040) << "Invalid ZIP file. Unexpected end of file. " ;
                    return false;
                }

                if ( buffer[0] != 'P' )
                    continue;

                n = dev->read( buffer, 3 );
                if (n < 3)
                {
                    kWarning(7040) << "Invalid ZIP file. Unexpected end of file. " ;
                    return false;
                }

                // We have to detect the magic token for a local header: PK\003\004
                /*
                 * Note: we do not need to check the other magics, if the ZIP file has no
                 * local header, then it has not any files!
                 */
                if ( buffer[0] == 'K' && buffer[1] == 3 && buffer[2] == 4 )
                {
                    foundSignature = true;
                    dev->seek( dev->pos() - 4 ); // go back 4 bytes, so that the magic bytes can be found...
                } else {
                    for (int i = 0; i < 3; ++i) {
                        if (buffer[i] == 'P') {
                            // We have another P character so we must go back a little to check if it is a magic
                            dev->seek(dev->pos() - 3 + i);
                            break;
                        }
                    }
                }
            }
        }
        else
        {
            kWarning(7040) << "Invalid ZIP file. Unrecognized header at offset " << offset;

            return false;
        }
    }
    //kDebug(7040) << "*** done *** ";
    return true;
}

bool KZip::closeArchive()
{
    if ( ! ( mode() & QIODevice::WriteOnly ) )
    {
        //kDebug(7040) << "readonly";
        return true;
    }

    //ReadWrite or WriteOnly
    //write all central dir file entries

    // to be written at the end of the file...
    char buffer[ 22 ]; // first used for 12, then for 22 at the end
    uLong crc = crc32(0L, Z_NULL, 0);

    qint64 centraldiroffset = device()->pos();
    //kDebug(7040) << "closearchive: centraldiroffset: " << centraldiroffset;
    qint64 atbackup = centraldiroffset;
    QMutableListIterator<KZipFileEntry*> it( d->m_fileList );

    while(it.hasNext())
    {   //set crc and compressed size in each local file header
        it.next();
        if ( !device()->seek( it.value()->headerStart() + 14 ) )
            return false;
    //kDebug(7040) << "closearchive setcrcandcsize: fileName:"
    //    << it.current()->path()
    //    << "encoding:" << it.current()->encoding();

        uLong mycrc = it.value()->crc32();
        buffer[0] = char(mycrc); // crc checksum, at headerStart+14
        buffer[1] = char(mycrc >> 8);
        buffer[2] = char(mycrc >> 16);
        buffer[3] = char(mycrc >> 24);

        int mysize1 = it.value()->compressedSize();
        buffer[4] = char(mysize1); // compressed file size, at headerStart+18
        buffer[5] = char(mysize1 >> 8);
        buffer[6] = char(mysize1 >> 16);
        buffer[7] = char(mysize1 >> 24);

        int myusize = it.value()->size();
        buffer[8] = char(myusize); // uncompressed file size, at headerStart+22
        buffer[9] = char(myusize >> 8);
        buffer[10] = char(myusize >> 16);
        buffer[11] = char(myusize >> 24);

        if ( device()->write( buffer, 12 ) != 12 )
            return false;
    }
    device()->seek( atbackup );

    it.toFront();
    while (it.hasNext())
    {
    it.next();
        //kDebug(7040) << "fileName:" << it.current()->path()
        //              << "encoding:" << it.current()->encoding();

        QByteArray path = QFile::encodeName(it.value()->path());

    const int extra_field_len = 9;
        int bufferSize = extra_field_len + path.length() + 46;
        char* buffer = new char[ bufferSize ];

        memset(buffer, 0, 46); // zero is a nice default for most header fields

        const char head[] =
        {
            'P', 'K', 1, 2, // central file header signature
            0x14, 3,        // version made by (3 == UNIX)
            0x14, 0         // version needed to extract
        };

    // I do not know why memcpy is not working here
        //memcpy(buffer, head, sizeof(head));
        memmove(buffer, head, sizeof(head));

        buffer[ 10 ] = char(it.value()->encoding()); // compression method
        buffer[ 11 ] = char(it.value()->encoding() >> 8);

        transformToMsDos( it.value()->datetime(), &buffer[ 12 ] );

        uLong mycrc = it.value()->crc32();
        buffer[ 16 ] = char(mycrc); // crc checksum
        buffer[ 17 ] = char(mycrc >> 8);
        buffer[ 18 ] = char(mycrc >> 16);
        buffer[ 19 ] = char(mycrc >> 24);

        int mysize1 = it.value()->compressedSize();
        buffer[ 20 ] = char(mysize1); // compressed file size
        buffer[ 21 ] = char(mysize1 >> 8);
        buffer[ 22 ] = char(mysize1 >> 16);
        buffer[ 23 ] = char(mysize1 >> 24);

        int mysize = it.value()->size();
        buffer[ 24 ] = char(mysize); // uncompressed file size
        buffer[ 25 ] = char(mysize >> 8);
        buffer[ 26 ] = char(mysize >> 16);
        buffer[ 27 ] = char(mysize >> 24);

        buffer[ 28 ] = char(path.length()); // fileName length
        buffer[ 29 ] = char(path.length() >> 8);

    buffer[ 30 ] = char(extra_field_len);
    buffer[ 31 ] = char(extra_field_len >> 8);

    buffer[ 40 ] = char(it.value()->permissions());
    buffer[ 41 ] = char(it.value()->permissions() >> 8);

        int myhst = it.value()->headerStart();
        buffer[ 42 ] = char(myhst); //relative offset of local header
        buffer[ 43 ] = char(myhst >> 8);
        buffer[ 44 ] = char(myhst >> 16);
        buffer[ 45 ] = char(myhst >> 24);

        // file name
        strncpy( buffer + 46, path, path.length() );
    //kDebug(7040) << "closearchive length to write: " << bufferSize;

    // extra field
    char *extfield = buffer + 46 + path.length();
    extfield[0] = 'U';
    extfield[1] = 'T';
    extfield[2] = 5;
    extfield[3] = 0;
    extfield[4] = 1 | 2 | 4;    // specify flags from local field
                    // (unless I misread the spec)
    // provide only modification time
    unsigned long time = (unsigned long)it.value()->date();
    extfield[5] = char(time);
    extfield[6] = char(time >> 8);
    extfield[7] = char(time >> 16);
    extfield[8] = char(time >> 24);

        crc = crc32(crc, (Bytef *)buffer, bufferSize );
        bool ok = ( device()->write( buffer, bufferSize ) == bufferSize );
        delete[] buffer;
        if ( !ok )
            return false;
    }
    qint64 centraldirendoffset = device()->pos();
    //kDebug(7040) << "closearchive: centraldirendoffset: " << centraldirendoffset;
    //kDebug(7040) << "closearchive: device()->pos(): " << device()->pos();

    //write end of central dir record.
    buffer[ 0 ] = 'P'; //end of central dir signature
    buffer[ 1 ] = 'K';
    buffer[ 2 ] = 5;
    buffer[ 3 ] = 6;

    buffer[ 4 ] = 0; // number of this disk
    buffer[ 5 ] = 0;

    buffer[ 6 ] = 0; // number of disk with start of central dir
    buffer[ 7 ] = 0;

    int count = d->m_fileList.count();
    //kDebug(7040) << "number of files (count): " << count;


    buffer[ 8 ] = char(count); // total number of entries in central dir of
    buffer[ 9 ] = char(count >> 8); // this disk

    buffer[ 10 ] = buffer[ 8 ]; // total number of entries in the central dir
    buffer[ 11 ] = buffer[ 9 ];

    int cdsize = centraldirendoffset - centraldiroffset;
    buffer[ 12 ] = char(cdsize); // size of the central dir
    buffer[ 13 ] = char(cdsize >> 8);
    buffer[ 14 ] = char(cdsize >> 16);
    buffer[ 15 ] = char(cdsize >> 24);

    //kDebug(7040) << "end : centraldiroffset: " << centraldiroffset;
    //kDebug(7040) << "end : centraldirsize: " << cdsize;

    buffer[ 16 ] = char(centraldiroffset); // central dir offset
    buffer[ 17 ] = char(centraldiroffset >> 8);
    buffer[ 18 ] = char(centraldiroffset >> 16);
    buffer[ 19 ] = char(centraldiroffset >> 24);

    buffer[ 20 ] = 0; //zipfile comment length
    buffer[ 21 ] = 0;

    if ( device()->write( buffer, 22 ) != 22 )
        return false;

    return true;
}

bool KZip::doWriteDir( const QString &name, const QString &user, const QString &group,
                       mode_t perm, time_t atime, time_t mtime, time_t ctime ) {
    // Zip files have no explicit directories, they are implicitly created during extraction time
    // when file entries have paths in them.
    // However, to support empty directories, we must create a dummy file entry which ends with '/'.
    QString dirName = name;
    if (!name.endsWith(QLatin1Char('/')))
        dirName = dirName.append(QLatin1Char('/'));
    return writeFile(dirName, user, group, 0, 0, perm, atime, mtime, ctime);
}

bool KZip::doPrepareWriting(const QString &name, const QString &user,
                               const QString &group, qint64 /*size*/, mode_t perm,
                               time_t atime, time_t mtime, time_t ctime) {
    //kDebug(7040);
    if ( !isOpen() )
    {
        qWarning( "KZip::writeFile: You must open the zip file before writing to it\n");
        return false;
    }

    if ( ! ( mode() & QIODevice::WriteOnly ) ) // accept WriteOnly and ReadWrite
    {
        qWarning( "KZip::writeFile: You must open the zip file for writing\n");
        return false;
    }

    Q_ASSERT( device() );

    // set right offset in zip.
    if ( !device()->seek( d->m_offset ) ) {
        kWarning(7040) << "doPrepareWriting: cannot seek in ZIP file. Disk full?";
        return false;
    }

    // Find or create parent dir
    KArchiveDirectory* parentDir = rootDir();
    QString fileName( name );
    int i = name.lastIndexOf(QLatin1Char('/'));
    if (i != -1) {
        QString dir = name.left( i );
        fileName = name.mid( i + 1 );
        //kDebug(7040) << "ensuring" << dir << "exists. fileName=" << fileName;
        parentDir = findOrCreate( dir );
    }

    // delete entries in the filelist with the same fileName as the one we want
    // to save, so that we don't have duplicate file entries when viewing the zip
    // with konqi...
    // CAUTION: the old file itself is still in the zip and won't be removed !!!
    QMutableListIterator<KZipFileEntry*> it( d->m_fileList );
    //kDebug(7040) << "fileName to write: " << name;
    while(it.hasNext())
    {
        it.next();
        //kDebug(7040) << "prepfileName: " << it.current()->path();
        if (name == it.value()->path() )
        {
            // also remove from the parentDir
            parentDir->removeEntry(it.value());
            //kDebug(7040) << "removing following entry: " << it.current()->path();
            delete it.value();
            it.remove();
        }

    }

    // construct a KZipFileEntry and add it to list
    KZipFileEntry * e = new KZipFileEntry( this, fileName, perm, mtime, user, group, QString(),
                                           name, device()->pos() + 30 + name.length(), // start
                                           0 /*size unknown yet*/, d->m_compression, 0 /*csize unknown yet*/ );
    e->setHeaderStart( device()->pos() );
    //kDebug(7040) << "wrote file start: " << e->position() << " name: " << name;
    parentDir->addEntry( e );

    d->m_currentFile = e;
    d->m_fileList.append( e );

    int extra_field_len = 0;
    if ( d->m_extraField == ModificationTime )
        extra_field_len = 17;   // value also used in finishWriting()

    // write out zip header
    QByteArray encodedName = QFile::encodeName(name);
    int bufferSize = extra_field_len + encodedName.length() + 30;
    //kDebug(7040) << "bufferSize=" << bufferSize;
    char* buffer = new char[ bufferSize ];

    buffer[ 0 ] = 'P'; //local file header signature
    buffer[ 1 ] = 'K';
    buffer[ 2 ] = 3;
    buffer[ 3 ] = 4;

    buffer[ 4 ] = 0x14; // version needed to extract
    buffer[ 5 ] = 0;

    buffer[ 6 ] = 0; // general purpose bit flag
    buffer[ 7 ] = 0;

    buffer[ 8 ] = char(e->encoding()); // compression method
    buffer[ 9 ] = char(e->encoding() >> 8);

    transformToMsDos( e->datetime(), &buffer[ 10 ] );

    buffer[ 14 ] = 'C'; //dummy crc
    buffer[ 15 ] = 'R';
    buffer[ 16 ] = 'C';
    buffer[ 17 ] = 'q';

    buffer[ 18 ] = 'C'; //compressed file size
    buffer[ 19 ] = 'S';
    buffer[ 20 ] = 'I';
    buffer[ 21 ] = 'Z';

    buffer[ 22 ] = 'U'; //uncompressed file size
    buffer[ 23 ] = 'S';
    buffer[ 24 ] = 'I';
    buffer[ 25 ] = 'Z';

    buffer[ 26 ] = (uchar)(encodedName.length()); //fileName length
    buffer[ 27 ] = (uchar)(encodedName.length() >> 8);

    buffer[ 28 ] = (uchar)(extra_field_len); // extra field length
    buffer[ 29 ] = (uchar)(extra_field_len >> 8);

    // file name
    strncpy( buffer + 30, encodedName, encodedName.length() );

    // extra field
    if ( d->m_extraField == ModificationTime )
    {
        char *extfield = buffer + 30 + encodedName.length();
        // "Extended timestamp" header (0x5455)
        extfield[0] = 'U';
        extfield[1] = 'T';
        extfield[2] = 13; // data size
        extfield[3] = 0;
        extfield[4] = 1 | 2 | 4;    // contains mtime, atime, ctime

        extfield[5] = char(mtime);
        extfield[6] = char(mtime >> 8);
        extfield[7] = char(mtime >> 16);
        extfield[8] = char(mtime >> 24);

        extfield[9] = char(atime);
        extfield[10] = char(atime >> 8);
        extfield[11] = char(atime >> 16);
        extfield[12] = char(atime >> 24);

        extfield[13] = char(ctime);
        extfield[14] = char(ctime >> 8);
        extfield[15] = char(ctime >> 16);
        extfield[16] = char(ctime >> 24);
    }

    // Write header
    bool b = (device()->write( buffer, bufferSize ) == bufferSize );
    d->m_crc = 0L;
    delete[] buffer;

    Q_ASSERT( b );
    if (!b) {
        return false;
    }

    // Prepare device for writing the data
    // Either device() if no compression, or a KFilterDev to compress
    if ( d->m_compression == 0 ) {
        d->m_currentDev = device();
        return true;
    }

    d->m_currentDev = KFilterDev::device( device(), QString::fromLatin1("application/x-gzip"), false );
    Q_ASSERT( d->m_currentDev );
    if ( !d->m_currentDev ) {
        return false; // ouch
    }
    static_cast<KFilterDev *>(d->m_currentDev)->setSkipHeaders(); // Just zlib, not gzip

    b = d->m_currentDev->open( QIODevice::WriteOnly );
    Q_ASSERT( b );
    return b;
}

bool KZip::doFinishWriting( qint64 size )
{
    if ( d->m_currentFile->encoding() == 8 ) {
        // Finish
        (void)d->m_currentDev->write( 0, 0 );
        delete d->m_currentDev;
    }
    // If 0, d->m_currentDev was device() - don't delete ;)
    d->m_currentDev = 0L;

    Q_ASSERT( d->m_currentFile );
    //kDebug(7040) << "fileName: " << d->m_currentFile->path();
    //kDebug(7040) << "getpos (at): " << device()->pos();
    d->m_currentFile->setSize(size);
    int extra_field_len = 0;
    if ( d->m_extraField == ModificationTime )
        extra_field_len = 17;   // value also used in finishWriting()

    const QByteArray encodedName = QFile::encodeName(d->m_currentFile->path());
    int csize = device()->pos() -
        d->m_currentFile->headerStart() - 30 -
        encodedName.length() - extra_field_len;
    d->m_currentFile->setCompressedSize(csize);
    //kDebug(7040) << "usize: " << d->m_currentFile->size();
    //kDebug(7040) << "csize: " << d->m_currentFile->compressedSize();
    //kDebug(7040) << "headerstart: " << d->m_currentFile->headerStart();

    //kDebug(7040) << "crc: " << d->m_crc;
    d->m_currentFile->setCRC32( d->m_crc );

    d->m_currentFile = 0L;

    // update saved offset for appending new files
    d->m_offset = device()->pos();
    return true;
}

bool KZip::doWriteSymLink(const QString &name, const QString &target,
                          const QString &user, const QString &group,
                          mode_t perm, time_t atime, time_t mtime, time_t ctime) {
  // reassure that symlink flag is set, otherwise strange things happen on
  // extraction
  perm |= S_IFLNK;
  Compression c = compression();
  setCompression(NoCompression);    // link targets are never compressed

  if (!doPrepareWriting(name, user, group, 0, perm, atime, mtime, ctime)) {
    kWarning() << "prepareWriting failed";
    setCompression(c);
    return false;
  }

  QByteArray symlink_target = QFile::encodeName(target);
  if (!writeData(symlink_target, symlink_target.length())) {
    kWarning() << "writeData failed";
    setCompression(c);
    return false;
  }

  if (!finishWriting(symlink_target.length())) {
    kWarning() << "finishWriting failed";
    setCompression(c);
    return false;
  }

  setCompression(c);
  return true;
}

void KZip::virtual_hook( int id, void* data )
{
    KArchive::virtual_hook( id, data );
}

bool KZip::writeData(const char * data, qint64 size)
{
    Q_ASSERT( d->m_currentFile );
    Q_ASSERT( d->m_currentDev );
    if (!d->m_currentFile || !d->m_currentDev) {
        return false;
    }

    // crc to be calculated over uncompressed stuff...
    // and they didn't mention it in their docs...
    d->m_crc = crc32(d->m_crc, (const Bytef *) data , size);

    qint64 written = d->m_currentDev->write( data, size );
    //kDebug(7040) << "wrote" << size << "bytes.";
    return written == size;
}

void KZip::setCompression( Compression c )
{
    d->m_compression = ( c == NoCompression ) ? 0 : 8;
}

KZip::Compression KZip::compression() const
{
   return ( d->m_compression == 8 ) ? DeflateCompression : NoCompression;
}

void KZip::setExtraField( ExtraField ef )
{
    d->m_extraField = ef;
}

KZip::ExtraField KZip::extraField() const
{
    return d->m_extraField;
}

class KZipFileEntry::KZipFileEntryPrivate
{
public:
    KZipFileEntryPrivate()
    : crc(0),
      compressedSize(0),
      headerStart(0),
      encoding(0)
    {}
    unsigned long crc;
    qint64        compressedSize;
    qint64        headerStart;
    int           encoding;
    QString       path;
};

KZipFileEntry::KZipFileEntry(KZip* zip, const QString& name, int access, int date,
                             const QString& user, const QString& group, const QString& symlink,
                             const QString& path, qint64 start, qint64 uncompressedSize,
                             int encoding, qint64 compressedSize)
 : KArchiveFile(zip, name, access, date, user, group, symlink, start, uncompressedSize ),
   d(new KZipFileEntryPrivate)
{
    d->path = path;
    d->encoding = encoding;
    d->compressedSize = compressedSize;
}

KZipFileEntry::~KZipFileEntry()
{
    delete d;
}

int KZipFileEntry::encoding() const
{
    return d->encoding;
}

qint64 KZipFileEntry::compressedSize() const
{
    return d->compressedSize;
}

void KZipFileEntry::setCompressedSize(qint64 compressedSize)
{
    d->compressedSize = compressedSize;
}

void KZipFileEntry::setHeaderStart(qint64 headerstart)
{
    d->headerStart = headerstart;
}

qint64 KZipFileEntry::headerStart() const
{
    return d->headerStart;
}

unsigned long KZipFileEntry::crc32() const
{
    return d->crc;
}

void KZipFileEntry::setCRC32(unsigned long crc32)
{
    d->crc=crc32;
}

const QString &KZipFileEntry::path() const
{
    return d->path;
}

QByteArray KZipFileEntry::data() const
{
    QIODevice* dev = createDevice();
    QByteArray arr;
    if ( dev ) {
        arr = dev->readAll();
        delete dev;
    }
    return arr;
}

QIODevice* KZipFileEntry::createDevice() const
{
    //kDebug(7040) << "creating iodevice limited to pos=" << position() << ", csize=" << compressedSize();
    // Limit the reading to the appropriate part of the underlying device (e.g. file)
    KLimitedIODevice* limitedDev = new KLimitedIODevice( archive()->device(), position(), compressedSize() );
    if ( encoding() == 0 || compressedSize() == 0 ) // no compression (or even no data)
        return limitedDev;

    if ( encoding() == 8 )
    {
        // On top of that, create a device that uncompresses the zlib data
        QIODevice* filterDev = KFilterDev::device( limitedDev, QString::fromLatin1("application/x-gzip") );
        if ( !filterDev )
            return 0L; // ouch
        static_cast<KFilterDev *>(filterDev)->setSkipHeaders(); // Just zlib, not gzip
        bool b = filterDev->open( QIODevice::ReadOnly );
        Q_UNUSED( b );
        Q_ASSERT( b );
        return filterDev;
    }

    kError() << "This zip file contains files compressed with method"
              << encoding() << ", this method is currently not supported by KZip,"
              << "please use a command-line tool to handle this file.";
    return 0L;
}