CURL retrieve HTML into string

Weather.cpp

size_t weather_write_data(void* ptr, size_t size, size_t nmemb, void* str) {
  std::string* s = static_cast<std::string*>(str);
  std::copy((char*)ptr, (char*)ptr + (size + nmemb), std::back_inserter(*s));
  return size * nmemb;
}

std::string weather_download_yahoo_rss() {
  std::string result;
  std::string url = "http://weather.yahooapis.com/forecastrss?w=10242&u=c"; // w=10242 is Aberaron
  CURL* curl = NULL;

  CURLcode res;
  curl = curl_easy_init();
  if(!curl) {
    printf("Error: cannot initialize CURL.\n");
    return result;
  }

  res = curl_easy_setopt(curl, CURLOPT_URL, url.c_str());
  if(res != CURLE_OK) {
    printf("Cannot set curl url.\n");
    goto curl_error;
  }

  res = curl_easy_setopt(curl, CURLOPT_FOLLOWLOCATION, 1L);
  if(res != CURLE_OK) {
    printf("Cannot set curl follow location flag.\n");
    goto curl_error;
  }

  res = curl_easy_setopt(curl, CURLOPT_WRITEFUNCTION, weather_write_data);
  if(res != CURLE_OK) {
    printf("Cannot set the weather write function.\n");
    goto curl_error;
  }
  
  res = curl_easy_setopt(curl, CURLOPT_WRITEDATA, &result);
  if(res != CURLE_OK) {
    printf("Cannot set the curl write data.\n");
    goto curl_error;
  }

  res = curl_easy_perform(curl);
  if(res != CURLE_OK) {
    printf("Cannot perform curl.\n");
    goto curl_error;
  }
  printf("Got: %s\n", result.c_str());
  printf("performed!\n");

  return result;
  
 curl_error: 
    curl_easy_cleanup(curl);
    curl = NULL;
    return result;
}

void weather_thread(void* user) {
  Weather* w = static_cast<Weather*>(user);
  std::vector<WeatherTask*> work;
  bool must_stop = false;

  printf("weather thread.\n");
  while(true) {
    
    uv_mutex_lock(&w->task_mutex);
    while(w->tasks.size() == 0) {
      uv_cond_wait(&w->task_cv, &w->task_mutex);
    }
    std::copy(w->tasks.begin(), w->tasks.end(), std::back_inserter(work));
    w->tasks.clear();
    uv_mutex_unlock(&w->task_mutex);
    
    for(std::vector<WeatherTask*>::iterator it = work.begin(); it != work.end(); ++it) {
      WeatherTask* task = *it;
      if(task->type == WEATHER_TASK_FETCH_RSS) {
        weather_download_yahoo_rss();
        delete task;
        task = NULL;
      }
      else if(task->type == WEATHER_TASK_STOP) {
        must_stop = true;
        delete task;
        task = NULL;
        break;
      }
    }

    work.clear();
    
    if(must_stop) {
      break;
    }

  }

  printf("Weather thread stopped.\n");
}