epoll_wait implementation can silently produce wrong results #2800
Description
This is to track the concerns I raised in #2764 (comment): currently it is possible to run Rust code in Miri that calls epoll_wait and the call returns, but its behavior is just wrong. That should never happen. The call should either halt execution (e.g. via throw_unsup) or return with correct behavior. It's okay to only support a tiny fragment of what epoll_wait can do, but in that case it is IMO mandatory to fail loudly when the code being run falls outside that fragment.
This looks like it might also affect the write implementation for Event.
@DebugSteven can you look into adding the necessary checks in epoll_wait and Event::write?