Re: proced: ppid of process ID 0 can be 0

[Eli Zaretskii <eliz@gnu.org>]

> From: Stefan Monnier <monnier@iro.umontreal.ca>
> Cc: Roland.Winkler@physik.uni-erlangen.de,  lekktu@gmail.com,  emacs-devel@gnu.org
> Date: Mon, 22 Dec 2008 17:24:24 -0500
> 
> >> To me the definition of "root" is "has no parent", so the two are
> >> equivalent.
> > Same here.  But "having no parent" and "found zero in /proc/NNN/stat"
> > is not necessarily the same.
> >> I could live with a predicate process-tree-root-p, but I'd expect it
> >> to just check for the absence of a parent.
> > Me too.  However, that check is OS-dependent, so I don't think it
> > should be in Lisp.
> 
> Indeed, it should be in system-process-attributes which is already
> OS-dependent.

If you mean by having no ppid attribute, then that's ambiguous, since
an attribute can be missing because it is inaccessible for some
reason, like some kind of failure unrelated to the fact that the
process is really a root of a tree.