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 will be called 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 will 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 will be set to  zero  (like  if  you
       only download data, the upload size will remain 0). Many times the callback will be 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 will cause libcurl to
       continue executing the default progress function.

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

       If  you  transfer  data  with the multi interface, this function will not be 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 = (struct progress *)clientp;

          /* use the values */

          return 0; /* all is good */
        }

        struct progress data;

        /* pass struct to callback  */
        curl_easy_setopt(curl_handle, CURLOPT_PROGRESSDATA, &data);

        curl_easy_setopt(curl_handle, CURLOPT_PROGRESSFUNCTION, progress_callback);

AVAILABILITY

       Deprecated since 7.32.0.

RETURN VALUE

       Returns CURLE_OK.

SEE ALSO

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