Provided by: libcurl4-doc_7.68.0-1ubuntu2.25_all bug

NAME

       CURLOPT_PROGRESSFUNCTION - callback to progress meter function

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.

       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 very 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's rarely wanted by users.

PROTOCOLS

       All

EXAMPLE

       https://curl.haxx.se/libcurl/c/progressfunc.html

AVAILABILITY

       Always

RETURN VALUE

       Returns CURLE_OK.

SEE ALSO

       CURLOPT_VERBOSE(3), CURLOPT_NOPROGRESS(3),