After reading this article, I'm inclined to think that the right thing for this project to do is write their own library that wraps the Rust stdlib with a file-handle-based API along with one method to get a file handle from a Path; rewrite the code to use that library rather than rust stdlib methods, and then add a lint check that guards against any use of the Rust standard library file methods anywhere outside of that wrapper.

If that's the right approach, then it would be useful to make that library public as a crate, because writing such hardened code is generally useful. Possibly as a step before inclusion in the rust stdlib itself.