curl / libcurl / API / Examples / progressfunc.c

progressfunc.c

/***************************************************************************
 *                                  _   _ ____  _
 *  Project                     ___| | | |  _ \| |
 *                             / __| | | | |_) | |
 *                            | (__| |_| |  _ <| |___
 *                             \___|\___/|_| \_\_____|
 *
 * 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
 *
 ***************************************************************************/
/* <DESC>
 * Use the progress callbacks, old and/or new one depending on available
 * libcurl version.
 * </DESC>
 */
#include <stdio.h>
 
#include <curl/curl.h>
 
#define MINIMAL_PROGRESS_FUNCTIONALITY_INTERVAL 3000000
#define STOP_DOWNLOAD_AFTER_THIS_MANY_BYTES     6000
 
struct myprogress {
  curl_off_t lastruntime; /* type depends on version, see above */
  CURL *curl;
};
 
/* this is how the CURLOPT_XFERINFOFUNCTION callback works */
static int xferinfo(void *p,
                    curl_off_t dltotal, curl_off_t dlnow,
                    curl_off_t ultotal, curl_off_t ulnow)
{
  struct myprogress *myp = (struct myprogress *)p;
  CURL *curl = myp->curl;
  curl_off_t curtime = 0;
 
  curl_easy_getinfo(curl, CURLINFO_TOTAL_TIME_T, &curtime);
 
  /* under certain circumstances it may be desirable for certain functionality
     to only run every N seconds, in order to do this the transaction time can
     be used */
  if((curtime - myp->lastruntime) >= MINIMAL_PROGRESS_FUNCTIONALITY_INTERVAL) {
    myp->lastruntime = curtime;
    fprintf(stderr, "TOTAL TIME: %" CURL_FORMAT_CURL_OFF_T
            ".%06" CURL_FORMAT_CURL_OFF_T "\r\n",
            curtime / 1000000,
            curtime % 1000000);
  }
 
  fprintf(stderr,
          "UP: "
          "%" CURL_FORMAT_CURL_OFF_T " of %" CURL_FORMAT_CURL_OFF_T "  "
          "DOWN: "
          "%" CURL_FORMAT_CURL_OFF_T " of %" CURL_FORMAT_CURL_OFF_T "\r\n",
          ulnow, ultotal,
          dlnow, dltotal);
 
  if(dlnow > STOP_DOWNLOAD_AFTER_THIS_MANY_BYTES)
    return 1;
  return 0;
}
 
int main(void)
{
  CURL *curl;
 
  CURLcode result = curl_global_init(CURL_GLOBAL_ALL);
  if(result != CURLE_OK)
    return (int)result;
 
  curl = curl_easy_init();
  if(curl) {
    struct myprogress prog;
 
    prog.lastruntime = 0;
    prog.curl = curl;
 
    curl_easy_setopt(curl, CURLOPT_URL, "https://example.com/");
 
    curl_easy_setopt(curl, CURLOPT_XFERINFOFUNCTION, xferinfo);
    /* pass the struct pointer into the xferinfo function */
    curl_easy_setopt(curl, CURLOPT_XFERINFODATA, &prog);
 
    curl_easy_setopt(curl, CURLOPT_NOPROGRESS, 0L);
    result = curl_easy_perform(curl);
 
    if(result != CURLE_OK)
      fprintf(stderr, "%s\n", curl_easy_strerror(result));
 
    /* always cleanup */
    curl_easy_cleanup(curl);
  }
  curl_global_cleanup();
  return (int)result;
}

Notice

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

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