function Archive_Tar($p_tarname, $p_compress = null)
    {
        $this->PEAR();
        $this->_compress = false;
        $this->_compress_type = 'none';
        if (($p_compress === null) || ($p_compress == '')) {
            if (@file_exists($p_tarname)) {
                if ($fp = @fopen($p_tarname, "rb")) {
                    // look for gzip magic cookie
                    $data = fread($fp, 2);
                    fclose($fp);
                    if ($data == "\37\213") {
                        $this->_compress = true;
                        $this->_compress_type = 'gz';
                        // No sure it's enought for a magic code ....
                    } elseif ($data == "BZ") {
                        $this->_compress = true;
                        $this->_compress_type = 'bz2';
                    }
                }
            } else {
                // probably a remote file or some file accessible
                // through a stream interface
                if (substr($p_tarname, -2) == 'gz') {
                    $this->_compress = true;
                    $this->_compress_type = 'gz';
                } elseif ((substr($p_tarname, -3) == 'bz2') ||
                          (substr($p_tarname, -2) == 'bz')) {
                    $this->_compress = true;
                    $this->_compress_type = 'bz2';
                }
            }
        } else {
            if (($p_compress === true) || ($p_compress == 'gz')) {
                $this->_compress = true;
                $this->_compress_type = 'gz';
            } else if ($p_compress == 'bz2') {
                $this->_compress = true;
                $this->_compress_type = 'bz2';
            } else {
                $this->_error("Unsupported compression type '$p_compress'\n".
                    "Supported types are 'gz' and 'bz2'.\n");
                return false;
            }
        }
        $this->_tarname = $p_tarname;
        if ($this->_compress) { // assert zlib or bz2 extension support
            if ($this->_compress_type == 'gz')
                $extname = 'zlib';
            else if ($this->_compress_type == 'bz2')
                $extname = 'bz2';

            if (!extension_loaded($extname)) {
                PEAR::loadExtension($extname);
            }
            if (!extension_loaded($extname)) {
                $this->_error("The extension '$extname' couldn't be found.\n".
                    "Please make sure your version of PHP was built ".
                    "with '$extname' support.\n");
                return false;
            }
        }
    }