>This is because the stdin of an init-spawned getty is null; login will exit,
>and init will subsequently restart it.  The tty is given as a command line
>option.

[...]

>This sounds like a job for "extra options to login" - say, let it pop up a
>login on a given tty if argv[optind + 2] exists.

Or just use a script to set up the file descriptors, exec login, and
return an error if that fails.