pkg/47194: emacs24 does not work with ptyfs

[martin%NetBSD.org@localhost]

>Number:         47194
>Category:       pkg
>Synopsis:       emacs24 does not work with ptyfs
>Confidential:   no
>Severity:       serious
>Priority:       high
>Responsible:    pkg-manager
>State:          open
>Class:          sw-bug
>Submitter-Id:   net
>Arrival-Date:   Wed Nov 14 20:55:00 +0000 2012
>Originator:     Martin Husemann
>Release:        NetBSD 6.99.15
>Organization:
The NetBSD Foundation, Inc.
>Environment:
System: NetBSD night-owl.duskware.de 6.99.15 NetBSD 6.99.15 (NIGHT-OWL) #119: 
Sat Nov 10 15:17:07 CET 2012 
martin%night-owl.duskware.de@localhost:/usr/src/sys/arch/amd64/compile/NIGHT-OWL
 amd64
Architecture: x86_64
Machine: amd64
>Description:

On a system with ptyfs mounted and no legacy pty nodes, run emacs24 from
pkgsrc and try to invoke a subprocess, for example by running gdb from the
Tools/Debugger... menu item (just shorten the command line to a single "gdb"
and press enter): boom, emacs crashes and dumps core.

While the configure script recognizes /dev/ptmx and defines 
HAVE_DEV_PTMX, this is nowhere used in the code for *BSD*.
With the legacy pty nodes gone, it fails big time.

The src/process.c code should be changed to use openpty() probably, but I
don't understand how the client gets its tty in the emacs code (I fear
by numeric identity to the master node).

>How-To-Repeat:
s/a

>Fix: