Is there literally no other code in the application?
Rust has plenty of situations where you do unsafe things but wrap that in safe APIs. If you’re returning regions of that mmapped file, for example, a lifetime can be associated to those references to ensure that those are valid for the duration of the file being mmapped in the program.
It can be used to ensure that if you need to write back to that mmapped file (inside the same program) that there are no existing references to it, because those would be invalid after an update to the file. You need to do the same in C, but there are no guardrails you can build in C to make that same assurance.
