I was wondering if it's possible to get a hook anywhere before media_handle_upload in /wp-admin/async-upload.php??
The reason for this is because I need to get a handle of the temporary upload file before it's moved into the wordpress uploads folder.
Looking through the code the closest I can come up with is adding a filter to wp_handle_upload, but by the time apply_filters is called the file has already been moved.
Even a hook at the start of wp_handle_upload would do the trick.