plucky (3) CURLOPT_PROGRESSFUNCTION.3.gz

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.

       Return zero from the callback if everything is fine.

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

       Return 1 from this callback to make 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

       NULL. libcurl has an internal progress meter. That is rarely wanted by users.

PROTOCOLS

       This functionality affects all supported protocols

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);
         }
       }

DEPRECATED

       Deprecated since 7.32.0.

AVAILABILITY

       Added in curl 7.1

RETURN VALUE

       curl_easy_setopt(3) returns a CURLcode indicating success or error.

       CURLE_OK (0) means everything was OK, non-zero means an error occurred, see libcurl-errors(3).

SEE ALSO

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