Re: emacsclient in elisp

[Eli Zaretskii <eliz@gnu.org>]

> From: Stefan Monnier <monnier@iro.umontreal.ca>
> Cc: Daniel Mendler <mail@daniel-mendler.de>,  emacs-devel@gnu.org
> Date: Sat, 22 May 2021 09:55:20 -0400
> 
> > What do you mean by "at the same time"?  If I have a stdin-process
> > active, we watch it via pselect and read from it using the machinery
> > in wait_reading_process_output and accept-process-output.  During all
> > the time such a process is active, I see no way to also read from the
> > same descriptor bypassing the above mechanisms, in a way that won't
> > cause trouble on the Lisp level, due toe the basic inability to decide
> > which input should go what way.
> 
> AFAIK we watch this description only when we're inside
> "wait_reading_process_output and accept-process-output".  If we're
> inside `read-from-minibuffer` then we're not inside
> "wait_reading_process_output and accept-process-output" (and
> vice-versa), so I don't think there should be much trouble (at least for
> my understanding of POSIX file descriptors, which is admittedly somewhat
> limited; for Windows, I have no idea).

So we will enter read-from-minibuffer, and read the stuff from stdin
till the first newline.  How do we know what's there is for us, not
for the stdin-process?

The scenario is that we have the process for reading from stdin, but
some function we called decides to ask the user.