_readBlock example

if (is_resource($this->_file)) {
            if ($p_len === null) {
                $p_len = 1;
            }

            if ($this->_compress_type == 'gz') {
                @gzseek($this->_file, gztell($this->_file) + ($p_len * 512));
            } else {
                if ($this->_compress_type == 'bz2') {
                    // ----- Replace missing bztell() and bzseek()                     for ($i = 0; $i < $p_len; $i++) {
                        $this->_readBlock();
                    }
                } else {
                    if ($this->_compress_type == 'lzma2') {
                        // ----- Replace missing xztell() and xzseek()                         for ($i = 0; $i < $p_len; $i++) {
                            $this->_readBlock();
                        }
                    } else {
                        if ($this->_compress_type == 'none') {
                            @fseek($this->_file, $p_len * 512, SEEK_CUR);
                        } else {