> > Lastly, the man page should not be fixed either - it should list all the
> > errors that might occur, and EFAULT is one of those.
> The application should check for a return value indicating failure
> before it looks at errno and the manual page should only document the
> return values that are possible.  EFAULT *cannot* possibly occur in any
> current NetBSD implementation of the pipe(2) call, no matter what, so
> far as I can see.

On the other hand, it always seems more troublesome to add new error returns
to system calls down the road than to have error returns which never happen
(mostly because the kind of application programmer who insists upon writing
code to handle each and every documented error return and codes a panic for
undocumented cases are exactly the kind of people who will gripe loudly when
future requirements cause system calls to become more communicative about
error returns...).