Swift_ByteStream_FileByteStream::_copyReadStream PHP Method

    private function _copyReadStream()
    {
        if ($tmpFile = fopen('php://temp/maxmemory:4096', 'w+b')) {
            /* We have opened a php:// Stream Should work without problem */
        } elseif (function_exists('sys_get_temp_dir') && is_writable(sys_get_temp_dir()) && ($tmpFile = tmpfile())) {
            /* We have opened a tmpfile */
        } else {
            throw new Swift_IoException('Unable to copy the file to make it seekable, sys_temp_dir is not writable, php://memory not available');
        }
        $currentPos = ftell($this->_reader);
        fclose($this->_reader);
        $source = fopen($this->_path, 'rb');
        if (!$source) {
            throw new Swift_IoException('Unable to open file for copying [' . $this->_path . ']');
        }
        fseek($tmpFile, 0, SEEK_SET);
        while (!feof($source)) {
            fwrite($tmpFile, fread($source, 4096));
        }
        fseek($tmpFile, $currentPos, SEEK_SET);
        fclose($source);
        $this->_reader = $tmpFile;
    }