zip.php

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        return $before - $this->offset;
    }
    /**
     * @see File_Archive_Reader::tell()
     */
    function tell()
    {
        return $this->offset;
    }

    function uncompressData()
    {
        if ($this->data !== null)
            return;

        $this->data = $this->source->getData($this->header['CLen']);
        if (PEAR::isError($this->data)) {
            return $this->data;
        }
        if ($this->header['Method'] == 8) {
            $this->data = gzinflate($this->data);
        }
        if ($this->header['Method'] == 12) {
            $this->data = bzdecompress($this->data);
        }

        if (crc32($this->data) != $this->header['CRC']) {
            return PEAR::raiseError("Zip archive: CRC fails on entry ".
                                    $this->currentFilename);
        }
    }

    /**
     * @see File_Archive_Reader::makeWriterRemoveFiles()
     */
    function makeWriterRemoveFiles($pred)
    {
        require_once "File/Archive/Writer/Zip.php";

        $blocks = array();
        $seek = null;
        $gap = 0;
        if ($this->currentFilename !== null && $pred->isTrue($this)) {
            $seek = 30 + $this->header['File'] + $this->header['Extra'] + $this->header['CLen'];
            $blocks[] = $seek; //Remove this file
            array_pop($this->files);
        }

        while (($error = $this->nextWithFolders()) === true) {
            $size = 30 + $this->header['File'] + $this->header['Extra'] + $this->header['CLen'];
            if (substr($this->getFilename(), -1) == '/' || $pred->isTrue($this)) {
                array_pop($this->files);
                if ($seek === null) {
                    $seek = $size;
                    $blocks[] = $size;
                } else if ($gap > 0) {
                    $blocks[] = $gap; //Don't remove the files between the gap
                    $blocks[] = $size;
                    $seek += $size;
                } else {
                    $blocks[count($blocks)-1] += $size;   //Also remove this file
                    $seek += $size;
                }
                $gap = 0;
            } else {
                if ($seek !== null) {
                    $seek += $size;
                    $gap += $size;
                }
            }
        }
        if (PEAR::isError($error)) {
            return $error;
        }

        if ($seek === null) {
            $seek = 4;
        } else {
            $seek += 4;
            if ($gap == 0) {
                array_pop($blocks);
            } else {
                $blocks[] = $gap;
            }
        }

        $writer = new File_Archive_Writer_Zip(null,
            $this->source->makeWriterRemoveBlocks($blocks, -$seek)
        );
        if (PEAR::isError($writer)) {
            return $writer;
        }

        foreach ($this->files as $file) {
            $writer->alreadyWrittenFile($file['name'], $file['stat'], $file['CRC'], $file['CLen']);
        }

        $this->close();
        return $writer;
    }

    /**
     * @see File_Archive_Reader::makeWriterRemoveBlocks()
     */
    function makeWriterRemoveBlocks($blocks, $seek = 0)
    {
        if ($this->currentFilename === null) {
            return PEAR::raiseError('No file selected');
        }

        $keep = false;

        $this->uncompressData();
        $newData = substr($this->data, 0, $this->offset + $seek);
        $this->data = substr($this->data, $this->offset + $seek);
        foreach ($blocks as $length) {
            if ($keep) {
                $newData .= substr($this->data, 0, $length);
            }
            $this->data = substr($this->data, $length);
            $keep = !$keep;
        }
        if ($keep) {
            $newData .= $this->data;
        }

        $filename = $this->currentFilename;
        $stat = $this->currentStat;

        $writer = $this->makeWriterRemove();
        if (PEAR::isError($writer)) {
            return $writer;
        }

        unset($stat[7]);
        $stat[9] = $stat['mtime'] = time();
        $writer->newFile($filename, $stat);
        $writer->writeData($newData);
        return $writer;
    }

    /**
     * @see File_Archive_Reader::makeAppendWriter
     */
    function makeAppendWriter()
    {
        require_once "File/Archive/Writer/Zip.php";

        while (($error = $this->next()) === true) { }
        if (PEAR::isError($error)) {
            $this->close();
            return $error;
        }

        $writer = new File_Archive_Writer_Zip(null,
            $this->source->makeWriterRemoveBlocks(array(), -4)
        );

        foreach ($this->files as $file) {
            $writer->alreadyWrittenFile($file['name'], $file['stat'], $file['CRC'], $file['CLen']);
        }

        $this->close();
        return $writer;
    }

    /**
     * This function seeks to the start of the [end of central directory] field,
     * just after the \x50\x4b\x05\x06 signature and returns the number of bytes
     * skipped
     *
     * The stream must initially be positioned before the end of central directory
     */
    function seekToEndOfCentralDirectory()
    {
        $nbSkipped = $this->source->skip();

        $nbSkipped -= $this->source->rewind(22) - 4;
        if ($this->source->getData(4) == "\x50\x4b\x05\x06") {
            return $nbSkipped;
        }

        while ($nbSkipped > 0) {

            $nbRewind = $this->source->rewind(min(100, $nbSkipped));
            while ($nbRewind >= -4) {
                if ($nbRewind-- && $this->source->getData(1) == "\x50" &&
                    $nbRewind-- && $this->source->getData(1) == "\x4b" &&
                    $nbRewind-- && $this->source->getData(1) == "\x05" &&
                    $nbRewind-- && $this->source->getData(1) == "\x06") {
                    //We finally found it!
                    return $nbSkipped - $nbRewind;
                }
            }
            $nbSkipped -= $nbRewind;
        }

        return PEAR::raiseError('End of central directory not found. The file is probably not a zip archive');
    }

    /**
     * This function will fill the central directory variable
     * and seek back to where it was called
     */
    function readCentralDirectory()
    {
        $nbSkipped = $this->seekToEndOfCentralDirectory();
        if (PEAR::isError($nbSkipped)) {
            return $nbSkipped;
        }

        $this->source->skip(12);
        $offset = $this->source->getData(4);
        $nbSkipped += 16;
        if (PEAR::isError($offset)) {
            return $offset;
        }

        $offset = unpack("Vvalue", $offset);
        $offset = $offset['value'];

        $current = $this->source->tell();
        $nbSkipped -= $this->source->rewind($current - $offset);

        //Now we are the right pos to read the central directory
        $this->centralDirectory = array();
        while ($this->source->getData(4) == "\x50\x4b\x01\x02") {
            $this->source->skip(12);
            $header = $this->source->getData(16);
            $nbSkipped += 32;

            if (PEAR::isError($header)) {
                return $header;
            }

            $header = unpack('VCRC/VCLen/VNLen/vFileLength/vExtraLength', $header);
            $this->centralDirectory[] = array('CRC'  => $header['CRC'],
                                              'CLen' => $header['CLen'],
                                              'NLen' => $header['NLen']);
            $nbSkipped += $this->source->skip(14 + $header['FileLength'] + $header['ExtraLength']);
        }

        $this->source->rewind($nbSkipped+4);
    }
}
?>