From: Stefan Monnier <monnier@iro.umontreal.ca>
To: Eli Zaretskii <eliz@gnu.org>
Cc: lekktu@gmail.com, emacs-devel@gnu.org,
Roland.Winkler@physik.uni-erlangen.de
Subject: Re: proced: ppid of process ID 0 can be 0
Date: Mon, 22 Dec 2008 07:23:05 -0500 [thread overview]
Message-ID: <jwvtz8w5rqe.fsf-monnier+emacs@gnu.org> (raw)
In-Reply-To: <u1vw0etsp.fsf@gnu.org> (Eli Zaretskii's message of "Mon, 22 Dec 2008 06:08:06 +0200")
>> The primitives should ensure that what they return forms a forest.
> You mean a tree.
No, I meant a forest. It may consist of a single tree, but I see no
reason to impose such a constraint.
>> I.e. under POSIX, they should treat a "ppid == 0" as meaning that
>> there's no parent (i.e. the data returned to Elisp should never say "the
>> parent is process 0" but should instead say "this process doesn't have
>> a parent").
> For me, code that calls process-tree-root-p (say) is much more
> self-explanatory than a test for a missing parent pid attribute.
To me the definition of "root" is "has no parent", so the two are
equivalent. I could live with a predicate process-tree-root-p, but I'd
expect it to just check for the absence of a parent.
> It is also more reliable, since ppid attribute could be missing for
> some other reason, like failure to access the attribute.
And what would your process-tree-root-p say in that case?
> Btw, is the above really mandated by Posix? Any references to that?
I don't know, but whatever it is POSIX say, it should be handled in the
POSIX implementation of system-process-attributes.
On my GNU/Linux system, 0 is not a process, so a ppid of 0 is not
a parent but rather the mark of the absence of a parent.
Stefan
next prev parent reply other threads:[~2008-12-22 12:23 UTC|newest]
Thread overview: 53+ messages / expand[flat|nested] mbox.gz Atom feed top
2008-12-20 2:52 proced: ppid of process ID 0 can be 0 Juanma Barranquero
2008-12-20 3:27 ` Stefan Monnier
2008-12-20 4:31 ` Chong Yidong
2008-12-20 19:10 ` Stefan Monnier
2008-12-20 10:20 ` Juanma Barranquero
2008-12-20 11:34 ` Eli Zaretskii
2008-12-20 19:41 ` Roland Winkler
2008-12-20 21:02 ` Juanma Barranquero
2008-12-20 22:02 ` Eli Zaretskii
2008-12-20 22:41 ` Roland Winkler
2008-12-21 4:15 ` Eli Zaretskii
2008-12-21 4:48 ` Roland Winkler
2008-12-21 19:17 ` Eli Zaretskii
2008-12-21 21:26 ` Juanma Barranquero
2008-12-22 4:09 ` Eli Zaretskii
2008-12-22 10:41 ` Juanma Barranquero
2008-12-22 19:17 ` Eli Zaretskii
2008-12-22 19:26 ` Juanma Barranquero
2008-12-22 2:45 ` Stefan Monnier
2008-12-22 4:08 ` Eli Zaretskii
2008-12-22 4:17 ` Miles Bader
2008-12-22 19:10 ` Eli Zaretskii
2008-12-22 8:54 ` Harald Hanche-Olsen
2008-12-22 10:43 ` Juanma Barranquero
2008-12-22 10:50 ` Harald Hanche-Olsen
2008-12-22 18:03 ` Giorgos Keramidas
2008-12-22 10:59 ` Andreas Schwab
2008-12-22 19:22 ` Eli Zaretskii
2008-12-22 19:37 ` David De La Harpe Golden
2008-12-22 19:59 ` Andreas Schwab
2008-12-22 12:23 ` Stefan Monnier [this message]
2008-12-22 19:57 ` Eli Zaretskii
2008-12-22 22:24 ` Stefan Monnier
2008-12-23 4:02 ` Eli Zaretskii
2008-12-23 12:28 ` Roland Winkler
2008-12-23 14:44 ` Stefan Monnier
2008-12-23 19:12 ` Eli Zaretskii
2008-12-23 20:41 ` Stefan Monnier
2008-12-23 22:34 ` Giorgos Keramidas
2008-12-24 2:34 ` Stefan Monnier
2008-12-24 4:14 ` Eli Zaretskii
2008-12-24 16:47 ` Stefan Monnier
2008-12-24 4:15 ` Eli Zaretskii
2008-12-24 16:47 ` Stefan Monnier
2008-12-24 18:29 ` Eli Zaretskii
2008-12-24 18:55 ` Stefan Monnier
2008-12-24 21:12 ` Eli Zaretskii
2008-12-30 17:11 ` Stefan Monnier
2008-12-30 22:02 ` Eli Zaretskii
2008-12-31 1:40 ` Stefan Monnier
2008-12-22 8:28 ` Ulrich Mueller
2008-12-21 2:18 ` Stefan Monnier
-- strict thread matches above, loose matches on Subject: below --
2008-12-24 7:42 grischka
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