Re: pipe

[Daiki Ueno <ueno@gnu.org>]

Eli Zaretskii <eliz@gnu.org> writes:

>> Related to:
>> https://lists.gnu.org/archive/html/emacs-devel/2014-09/msg00777.html
>> in which I proposed a generalization of start-process, in a similar way
>> to open-network-stream and make-network-process.
>
> I don't see the additional file descriptors mentioned there, did I
> miss something?

Sorry, I only mentioned it as a euphemism:

  * We could collect stderr output naturally.  'make-subprocess' could
    have a keyword, say :error, to prepare a pipe for stderr when spawning
    a process.

>> My motivation behind that was to avoid temporary files in epg.el, by
>> using file descriptors other than 0 and 1 (as you know, gpg has options
>> --status-fd, --command-fd, --attribute-fd, etc. for that).
>
> Can these features of gpg be used on MS-Windows?  IOW, how do you
> invoke a subprocess with redirected file descriptors beyond the 3
> standard ones, in a way that will work not only on Posix platforms
> that support the full 'fork' functionality?

Actually, I'm not sure, but there was a porting effort of the GPG stack
to Windows and Windows CE, and I think there should be a way to work
that around (added Werner to Cc).

> (I was about to ask why not use the existing feature of talking to
> localhost via sockets, but then realized that it would suffer from the
> same problem of how can we invoke a subprocess with more than just the
> standard handles redirected.)
>
> In any case, the Emacs side of this new process type, if it is added,
> will "need work" in w32proc.c.

Thanks for the info.

Regards,
--
Daiki Ueno