Archive_Tar::_readHeader PHP Method

    function _readHeader($v_binary_data, &$v_header)
    {
        if (strlen($v_binary_data) == 0) {
            $v_header['filename'] = '';
            return true;
        }
        if (strlen($v_binary_data) != 512) {
            $v_header['filename'] = '';
            $this->_error('Invalid block size : ' . strlen($v_binary_data));
            return false;
        }
        if (!is_array($v_header)) {
            $v_header = array();
        }
        // ----- Calculate the checksum
        $v_checksum = 0;
        // ..... First part of the header
        for ($i = 0; $i < 148; $i++) {
            $v_checksum += ord(substr($v_binary_data, $i, 1));
        }
        // ..... Ignore the checksum value and replace it by ' ' (space)
        for ($i = 148; $i < 156; $i++) {
            $v_checksum += ord(' ');
        }
        // ..... Last part of the header
        for ($i = 156; $i < 512; $i++) {
            $v_checksum += ord(substr($v_binary_data, $i, 1));
        }
        $v_data = unpack("a100filename/a8mode/a8uid/a8gid/a12size/a12mtime/" . "a8checksum/a1typeflag/a100link/a6magic/a2version/" . "a32uname/a32gname/a8devmajor/a8devminor", $v_binary_data);
        // ----- Extract the checksum
        $v_header['checksum'] = OctDec(trim($v_data['checksum']));
        if ($v_header['checksum'] != $v_checksum) {
            $v_header['filename'] = '';
            // ----- Look for last block (empty block)
            if ($v_checksum == 256 && $v_header['checksum'] == 0) {
                return true;
            }
            $this->_error('Invalid checksum for file "' . $v_data['filename'] . '" : ' . $v_checksum . ' calculated, ' . $v_header['checksum'] . ' expected');
            return false;
        }
        // ----- Extract the properties
        $v_header['filename'] = trim($v_data['filename']);
        if ($this->_maliciousFilename($v_header['filename'])) {
            $this->_error('Malicious .tar detected, file "' . $v_header['filename'] . '" will not install in desired directory tree');
            return false;
        }
        $v_header['mode'] = OctDec(trim($v_data['mode']));
        $v_header['uid'] = OctDec(trim($v_data['uid']));
        $v_header['gid'] = OctDec(trim($v_data['gid']));
        $v_header['size'] = OctDec(trim($v_data['size']));
        $v_header['mtime'] = OctDec(trim($v_data['mtime']));
        if (($v_header['typeflag'] = $v_data['typeflag']) == "5") {
            $v_header['size'] = 0;
        }
        $v_header['link'] = trim($v_data['link']);
        /* ----- All these fields are removed form the header because
        		they do not carry interesting info
                $v_header[magic] = trim($v_data[magic]);
                $v_header[version] = trim($v_data[version]);
                $v_header[uname] = trim($v_data[uname]);
                $v_header[gname] = trim($v_data[gname]);
                $v_header[devmajor] = trim($v_data[devmajor]);
                $v_header[devminor] = trim($v_data[devminor]);
                */
        return true;
    }

 function _readHeader($v_binary_data, &$v_header)
 {
     static $is_first = true;
     static $count = 0;
     static $block_performance = 32;
     $v_result = parent::_readHeader($v_binary_data, $v_header);
     if ($v_result && $this->resumeMode && (++$count > $block_performance || $is_first)) {
         $this->lastOffset = $this->_getOffset() - 1;
         $data = array('filename' => $v_header['filename'], 'size' => $v_header['size']);
         $performance = $this->setState($this->lastOffset);
         if ($is_first) {
             $is_first = false;
         } else {
             $count = 0;
             $block_performance = $performance;
         }
     }
     return $v_result;
 }