bug#56606: Acknowledgement (29.0.50; recent master fails with "creating pipe: too many open files")

[Eli Zaretskii]

> Cc: 56606@debbugs.gnu.org
> Date: Sun, 17 Jul 2022 13:20:12 +0300
> From: Eli Zaretskii <eliz@gnu.org>
> 
> > From: Stephen Leake <stephen_leake@stephe-leake.org>
> > Date: Sun, 17 Jul 2022 02:42:04 -0700
> > 
> > On emacs-devel, Eli said:
> > 
> > AFAICT, this loop in deactivate_process:
> > 
> >   /* Beware SIGCHLD hereabouts.  */
> > 
> >   for (i = 0; i < PROCESS_OPEN_FDS; i++)
> >     close_process_fd (&p->open_fd[i]);
> > 
> > doesn't close the last of the 4 descriptors opened by the 2 emacs_pipe
> > calls in make-pipe-process.  It calls 'close' with the right value,
> > and close returns zero, but the pipe stays open.  In Emacs 28, this
> > same loop successfully closes the descriptor.  I don't know why.
> > 
> > Perhaps bisecting could help.
> 
> I think commit a81669c could be the culprit.

I hope I fixed this now on master.