@pitrou, thanks for your PR! By analyzing the history of the files in this pull request, we identified @birkenfeld, @loewis and @taleinat to be potential reviewers.

@njsmith

Yeah, good idea and lgtm

If you want to get really fancy, I guess you could also mention that on unixes it's an arbitrary FD, but on Windows it should be a socket handle (not an FD at all).

If I'm reading signalmodule.c correctly (especially the functions signal_set_wakeup_fd and trip_signal), we support both regular file descriptors and sockets on Windows (but not native Windows handles).

we support both regular file descriptors and sockets on Windows (but not native Windows handles).

Ah, looks like you're right. In practice though I don't think there are any uses for passing in a regular file descriptor, because only sockets can be set in non-blocking mode, and python sockets are always represented as socket handles and not wrapped into an fd.