White-list file types for media upload

Question

I'd like to attach files that aren't on the list of supported file types. In this case I'd like to upload files from the media manager that have the .RWP extension (which is used to package files in the Train Simulator 2012 game).

Answer 1

You can hook the upload_mimes filter to accomplish this:

add_filter('upload_mimes', 'wpse_43657_upload_mimes');
function wpse_43657_upload_mimes($mime_types){
     $mime_types['rwp'] = 'application/octet-stream';
     return $mime_types;
}