From mboxrd@z Thu Jan 1 00:00:00 1970 Path: news.gmane.org!not-for-mail From: Eli Zaretskii Newsgroups: gmane.emacs.devel Subject: Re: proced: ppid of process ID 0 can be 0 Date: Wed, 31 Dec 2008 00:02:54 +0200 Message-ID: References: <18765.19040.568030.246241@tfkp04.physik.uni-erlangen.de> <18765.29820.997276.703222@tfkp04.physik.uni-erlangen.de> <18765.51840.943986.608296@tfkp04.physik.uni-erlangen.de> Reply-To: Eli Zaretskii NNTP-Posting-Host: lo.gmane.org X-Trace: ger.gmane.org 1230674727 23673 80.91.229.12 (30 Dec 2008 22:05:27 GMT) X-Complaints-To: usenet@ger.gmane.org NNTP-Posting-Date: Tue, 30 Dec 2008 22:05:27 +0000 (UTC) Cc: lekktu@gmail.com, emacs-devel@gnu.org, Roland.Winkler@physik.uni-erlangen.de To: Stefan Monnier Original-X-From: emacs-devel-bounces+ged-emacs-devel=m.gmane.org@gnu.org Tue Dec 30 23:06:33 2008 Return-path: Envelope-to: ged-emacs-devel@m.gmane.org Original-Received: from lists.gnu.org ([199.232.76.165]) by lo.gmane.org with esmtp (Exim 4.50) id 1LHmjE-0000CX-Uz for ged-emacs-devel@m.gmane.org; Tue, 30 Dec 2008 23:06:21 +0100 Original-Received: from localhost ([127.0.0.1]:40314 helo=lists.gnu.org) by lists.gnu.org with esmtp (Exim 4.43) id 1LHmi1-0005Yh-EU for ged-emacs-devel@m.gmane.org; Tue, 30 Dec 2008 17:05:05 -0500 Original-Received: from mailman by lists.gnu.org with tmda-scanned (Exim 4.43) id 1LHmhx-0005Yc-Uw for emacs-devel@gnu.org; Tue, 30 Dec 2008 17:05:01 -0500 Original-Received: from exim by lists.gnu.org with spam-scanned (Exim 4.43) id 1LHmhw-0005YQ-Bo for emacs-devel@gnu.org; Tue, 30 Dec 2008 17:05:00 -0500 Original-Received: from [199.232.76.173] (port=40096 helo=monty-python.gnu.org) by lists.gnu.org with esmtp (Exim 4.43) id 1LHmhw-0005YN-61 for emacs-devel@gnu.org; Tue, 30 Dec 2008 17:05:00 -0500 Original-Received: from mtaout1.012.net.il ([84.95.2.1]:12837) by monty-python.gnu.org with esmtp (Exim 4.60) (envelope-from ) id 1LHmhv-0002Sx-Ka for emacs-devel@gnu.org; Tue, 30 Dec 2008 17:04:59 -0500 Original-Received: from conversion-daemon.i-mtaout1.012.net.il by i-mtaout1.012.net.il (HyperSendmail v2007.08) id <0KCP00J00MP3PM00@i-mtaout1.012.net.il> for emacs-devel@gnu.org; Wed, 31 Dec 2008 00:05:33 +0200 (IST) Original-Received: from HOME-C4E4A596F7 ([77.126.82.236]) by i-mtaout1.012.net.il (HyperSendmail v2007.08) with ESMTPA id <0KCP00DFXMP8XIH0@i-mtaout1.012.net.il>; Wed, 31 Dec 2008 00:05:33 +0200 (IST) In-reply-to: X-012-Sender: halo1@inter.net.il X-detected-operating-system: by monty-python.gnu.org: Solaris 9.1 X-BeenThere: emacs-devel@gnu.org X-Mailman-Version: 2.1.5 Precedence: list List-Id: "Emacs development discussions." List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Original-Sender: emacs-devel-bounces+ged-emacs-devel=m.gmane.org@gnu.org Errors-To: emacs-devel-bounces+ged-emacs-devel=m.gmane.org@gnu.org Xref: news.gmane.org gmane.emacs.devel:107428 Archived-At: > From: Stefan Monnier > Cc: Roland.Winkler@physik.uni-erlangen.de, lekktu@gmail.com, emacs-devel@gnu.org > Date: Tue, 30 Dec 2008 12:11:15 -0500 > > >> AFAIK we're talking about ppid, and this info is always present, so if > >> it's absent, don't return the process. > > > Can you find any authoritative reference that says we can rely on > > this? I couldn't even find a decent documentation of /proc when I was > > working on these primitives, let alone some information about what > > attributes are always present or how that changes with the kernel > > version. > > The ppid is in the /proc/NNN/stat file, those attributes are > distinguished by their order, so if it's missing the ordering gets > messed up, so it can't be missing. As for the /proc/NNN/stat file > missing, that would mean that pretty much all the attributes returned by > `ps' would be missing, so we can definitely count on its presence. Sorry, this doesn't even come close to being an "authoritative reference". These are just deliberations based on some concept of how /proc is implemented in the Linux kernel, and I have no idea how close is this concept to the truth.