I'm uploading information to a server using a post call (using curlpp, but libcurl directly is fine too).
CURLOPT_PROGRESSFUNCTION callback gets called from time to time with reports on how much data was send until now. When I upload a file, I see this call being made with very small delta between calls.
I want to get a callback BEFORE each part of data is sent, with the information of how much data is going to be transmitted now.
There is no such callbacks in libcurl. CURLOPT_DEBUGFUNCTION will tell you basically that info, but after it was sent...