curl_easy_setopt(curl, CURLOPT_PROGRESSFUNCTION, progress_callback);
curl_easy_setopt(curl, CURLOPT_PROGRESSDATA, this);
curl_easy_setopt(curl, CURLOPT_NOPROGRESS, false);
curl_easy_setopt(curl, CURLOPT_PROGRESSFUNCTION, progress_callback);
curl_easy_setopt(curl, CURLOPT_PROGRESSDATA, this);
curl_easy_setopt(curl, CURLOPT_NOPROGRESS, false);