CURLOPT_XFERINFOFUNCTION(3)				     curl_easy_setopt options				       CURLOPT_XFERINFOFUNCTION(3)

NAME

       CURLOPT_XFERINFOFUNCTION - callback to progress meter function

SYNOPSIS

       #include <curl/curl.h>

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

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

DESCRIPTION

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

       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_XFERINFODATA(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.

       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

       Added in 7.32.0. This callback replaces CURLOPT_PROGRESSFUNCTION(3)

RETURN VALUE

       Returns CURLE_OK.

SEE ALSO

       CURLOPT_XFERINFODATA(3), CURLOPT_NOPROGRESS(3),

libcurl 7.54.0							 February 03, 2016				       CURLOPT_XFERINFOFUNCTION(3)