From #2244513: Replace old managed and unmanaged file APIs with testable services (file.inc)
- file_munge_filename() is a pretty weird one, maybe we should have something like a file upload service, with functions related to handling uploads, which this clearly is. (That said, drupal_move_uploaded_file() was already moved to the file_system service, so we could also just move those to that as well)
- Same for file_unmunge_filename(), which is actually used only once in a test.
- file_upload_max_size(), another upload related thingy.