CURLOPT_PROGRESSFUNCTION(3)curl_easy_setopt optionsCURLOPT_PROGRESSFUNCTION(3)

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 proto-
       type 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  call-
       back.

       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.

       Returning  a  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),

libcurl 7.54.0                 February 03, 2016   CURLOPT_PROGRESSFUNCTION(3)