bug#14474: 24.3.50; Zombie subprocesses (again)

[Paul Eggert]

On 05/27/2013 05:46 AM, Colin Walters wrote:
>> One possibility is to see if we can get Emacs to use
>> > glib's child watcher.
> That'd be best obviously.

I looked into this a bit, and found a problem.
Emacs wants to be notified about child processes
that are stopped, so it invokes waitpid with the
WUNTRACED option, but glib never uses WUNTRACED
when invoking waitpid.  If Emacs used glib to watch for
child processes, Emacs will not be informed about
a child process changing state because it has
stopped.  (Similarly for WCONTINUED and processes
that have been continued.)

Perhaps glib needs a new function, which lets the
caller specify additional options to be given to
waitpid?  Something like this, say:

   g_child_watch_source_new_full (pid, WUNTRACED | WCONTINUED)

Then, g_child_watch_source_new (pid) would be equivalent to
g_child_watch_source_new_full (pid, 0).