Manipulate the files uploaded via Gravity Forms before they are stored
I would like to make changes to files (for e.g. compress them into a zip) uploaded via Gravity Forms File upload field before they are uploaded to the webserver.
Do you know of any hook or workaround to modify the (temporary) file before it is sent to and stored on the webserver?
(I have found a solution to do it after the files are uploaded, but that is not what I am looking for.)