Re: [PATCH v3] Add systemd socket launching support

[Stefan Monnier]

> And I object to exposing file descriptors to Lisp, certainly when that
> is not necessary.

In other similar functionality I've seen over the years, an alternative
was to pass the fd as an additional argument on the command line, but in
any case whether it's received from the environment or the command line,
the file-descriptor to use will just be an integer, and it's already
exposed to Lisp.

So, AFAICT we just need 3 elements:
- a function to get the FD number from systemd (which we could write in
  Elisp, but is much better implemented as a call to systemd's support
  library).
- a way to create a process-object from an existing file-descriptor number.
- changes in server.el to connect the previous 2 elements together.

AFAICT, only the first part is systemd-specific, so I think it would
make sense to try and avoid having systemd-specific details leak to the
other parts.


        Stefan