curl/docs/examples/progressfunc.c

/***************************************************************************
 *                                  _   _ ____  _
 *  Project                     ___| | | |  _ \| |
 *                             / __| | | | |_) | |
 *                            | (__| |_| |  _ <| |___
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 *
 * Copyright (C) 1998 - 2013, 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 http://curl.haxx.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.
 *
 ***************************************************************************/
#include <stdio.h>
#include <curl/curl.h>

#define STOP_DOWNLOAD_AFTER_THIS_MANY_BYTES         6000
#define MINIMAL_PROGRESS_FUNCTIONALITY_INTERVAL     3

struct myprogress {
  double lastruntime;
  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;
  double curtime = 0;

  curl_easy_getinfo(curl, CURLINFO_TOTAL_TIME, &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: %f \r\n", curtime);
  }

  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;
}

/* for libcurl older than 7.32.0 (CURLOPT_PROGRESSFUNCTION) */
static int older_progress(void *p,
                          double dltotal, double dlnow,
                          double ultotal, double ulnow)
{
  return xferinfo(p,
                  (curl_off_t)dltotal,
                  (curl_off_t)dlnow,
                  (curl_off_t)ultotal,
                  (curl_off_t)ulnow);
}


int main(void)
{
  CURL *curl;
  CURLcode res = CURLE_OK;
  struct myprogress prog;

  curl = curl_easy_init();
  if(curl) {
    prog.lastruntime = 0;
    prog.curl = curl;

    curl_easy_setopt(curl, CURLOPT_URL, "http://example.com/");

    curl_easy_setopt(curl, CURLOPT_PROGRESSFUNCTION, older_progress);
    /* pass the struct pointer into the progress function */
    curl_easy_setopt(curl, CURLOPT_PROGRESSDATA, &prog);

#if LIBCURL_VERSION_NUM >= 0x072000
    /* xferinfo was introduced in 7.32.0, no earlier libcurl versions will
       compile as they won't have the symbols around.

       If built with a newer libcurl, but running with an older libcurl:
       curl_easy_setopt() will fail in run-time trying to set the new
       callback, making the older callback get used.

       New libcurls will prefer the new callback and instead use that one even
       if both callbacks are set. */

    curl_easy_setopt(curl, CURLOPT_XFERINFOFUNCTION, xferinfo);
    /* pass the struct pointer into the xferinfo function, note that this is
       an alias to CURLOPT_PROGRESSDATA */
    curl_easy_setopt(curl, CURLOPT_XFERINFODATA, &prog);
#endif

    curl_easy_setopt(curl, CURLOPT_NOPROGRESS, 0L);
    res = curl_easy_perform(curl);

    if(res != CURLE_OK)
      fprintf(stderr, "%s\n", curl_easy_strerror(res));

    /* always cleanup */
    curl_easy_cleanup(curl);
  }
  return (int)res;
}