NAME

       CURLOPT_PROGRESSFUNCTION - progress meter callback

SYNOPSIS

       #include <curl/curl.h>

       int progress_callback(void *clientp,
                             double dltotal,
                             double dlnow,
                             double ultotal,
                             double ulnow);

       CURLcode curl_easy_setopt(CURL *handle, CURLOPT_PROGRESSFUNCTION,
                                 progress_callback);

DESCRIPTION

       Pass a pointer to your callback function, which should match the prototype shown above.

       This option is deprecated and we encourage users to use the newer CURLOPT_XFERINFOFUNCTION(3) instead, if
       you can.

       This  function  gets called by libcurl instead of its internal equivalent with a frequent interval. While
       data is being transferred it is invoked frequently, and during slow periods like when  nothing  is  being
       transferred it can slow down to about one call per second.

       clientp  is  the  pointer  set with CURLOPT_PROGRESSDATA(3), it is not used by libcurl but is only passed
       along from the application to the callback.

       The callback gets told how much data libcurl is about to transfer  and  has  transferred,  in  number  of
       bytes.  dltotal  is  the total number of bytes libcurl expects to download in this transfer. dlnow is the
       number of bytes downloaded so far. ultotal is the total number of bytes libcurl expects to upload in this
       transfer. ulnow is the number of bytes uploaded so far.

       Unknown/unused argument values passed to the callback are be set to zero (like if you only download data,
       the upload size remains 0). Many times the callback is called one or more times first,  before  it  knows
       the data sizes so a program must be made to handle that.

       If  your callback function returns CURL_PROGRESSFUNC_CONTINUE it causes libcurl to continue executing the
       default progress function.

       Returning any other non-zero value from this  callback  makes  libcurl  abort  the  transfer  and  return
       CURLE_ABORTED_BY_CALLBACK.

       If  you  transfer  data  with the multi interface, this function is not called during periods of idleness
       unless you call the appropriate libcurl function that performs transfers.

       CURLOPT_NOPROGRESS(3) must be set to 0 to make this function actually get called.

DEFAULT

       By default, libcurl has an internal progress meter. That is rarely wanted by users.

PROTOCOLS

       All

EXAMPLE

       struct progress {
         char *private;
         size_t size;
       };

       static size_t progress_callback(void *clientp,
                                       double dltotal,
                                       double dlnow,
                                       double ultotal,
                                       double ulnow)
       {
         struct progress *memory = clientp;
         printf("private: %p\n", memory->private);

         /* use the values */

         return 0; /* all is good */
       }

       int main(void)
       {
         struct progress data;

         CURL *curl = curl_easy_init();
         if(curl) {
           /* pass struct to callback  */
           curl_easy_setopt(curl, CURLOPT_PROGRESSDATA, &data);
           curl_easy_setopt(curl, CURLOPT_PROGRESSFUNCTION, progress_callback);

           curl_easy_perform(curl);
         }
       }

AVAILABILITY

       Deprecated since 7.32.0.

RETURN VALUE

       Returns CURLE_OK.

SEE ALSO

       CURLOPT_VERBOSE(3), CURLOPT_NOPROGRESS(3), CURLOPT_XFERINFOFUNCTION(3)

ibcurl 8.5.0                                    December 04, 2023                    CURLOPT_PROGRESSFUNCTION(3)