curl / libcurl / API / Examples / multi-double.c

multi-double.c

/***************************************************************************
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 *                            | (__| |_| |  _ <| |___
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 *
 * Copyright (C) Daniel Stenberg, <daniel@haxx.se>, et al.
 *
 * This software is licensed as described in the file COPYING, which
 * you should have received as part of this distribution. The terms
 * are also available at https://curl.se/docs/copyright.html.
 *
 * You may opt to use, copy, modify, merge, publish, distribute and/or sell
 * copies of the Software, and permit persons to whom the Software is
 * furnished to do so, under the terms of the COPYING file.
 *
 * This software is distributed on an "AS IS" basis, WITHOUT WARRANTY OF ANY
 * KIND, either express or implied.
 *
 * SPDX-License-Identifier: curl
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 ***************************************************************************/
/* <DESC>
 * multi interface code doing two parallel HTTP transfers
 * </DESC>
 */
#include <stdio.h>
#include <string.h>
 
/* somewhat unix-specific */
#include <sys/time.h>
#include <unistd.h>
 
/* curl stuff */
#include <curl/curl.h>
 
/*
 * Simply download two HTTP files!
 */
int main(void)
{
  CURL *http_handle;
  CURL *http_handle2;
  CURLM *multi_handle;
 
  int still_running = 1; /* keep number of running handles */
 
  http_handle = curl_easy_init();
  http_handle2 = curl_easy_init();
 
  /* set options */
  curl_easy_setopt(http_handle, CURLOPT_URL, "https://www.example.com/");
 
  /* set options */
  curl_easy_setopt(http_handle2, CURLOPT_URL, "http://localhost/");
 
  /* init a multi stack */
  multi_handle = curl_multi_init();
 
  /* add the individual transfers */
  curl_multi_add_handle(multi_handle, http_handle);
  curl_multi_add_handle(multi_handle, http_handle2);
 
  while(still_running) {
    CURLMsg *msg;
    int queued;
    CURLMcode mc = curl_multi_perform(multi_handle, &still_running);
 
    if(still_running)
      /* wait for activity, timeout or "nothing" */
      mc = curl_multi_poll(multi_handle, NULL, 0, 1000, NULL);
 
    if(mc)
      break;
 
    do {
      msg = curl_multi_info_read(multi_handle, &queued);
      if(msg) {
        if(msg->msg == CURLMSG_DONE) {
          /* a transfer ended */
          fprintf(stderr, "Transfer completed\n");
        }
      }
    } while(msg);
  }
 
  curl_multi_remove_handle(multi_handle, http_handle);
  curl_multi_remove_handle(multi_handle, http_handle2);
 
  curl_multi_cleanup(multi_handle);
 
  curl_easy_cleanup(http_handle);
  curl_easy_cleanup(http_handle2);
 
  return 0;
}

Notice

This source code example is simplified and ignores return codes and error checks to a large extent. We do this to highlight the libcurl function calls and related options and reduce unrelated code.

A real-world application will of course properly check every return value and exit correctly at the first serious error.