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Date:      Sat, 04 Feb 2012 20:16:42 +0200
From:      Mikolaj Golub <trociny@freebsd.org>
To:        Guy Helmer <ghelmer@palisadesystems.com>
Cc:        svn-src-head@FreeBSD.org, svn-src-all@FreeBSD.org, Andrey Zonov <andrey@zonov.org>, Pawel Jakub Dawidek <pjd@FreeBSD.org>, src-committers@FreeBSD.org
Subject:   Re: svn commit: r230869 - head/usr.sbin/daemon
Message-ID:  <86zkcy5ur9.fsf@kopusha.home.net>
In-Reply-To: <27A0A960-F767-4D2C-BF3E-31F73FBF4E28@palisadesystems.com> (Guy Helmer's message of "Sat, 4 Feb 2012 10:30:00 -0600")
References:  <201202011641.q11Gf0j6095461@svn.freebsd.org> <20120204074201.GA1694@garage.freebsd.pl> <4F2CEB1D.10607@zonov.org> <27A0A960-F767-4D2C-BF3E-31F73FBF4E28@palisadesystems.com>

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On Sat, 4 Feb 2012 10:30:00 -0600 Guy Helmer wrote:

 GH> On Feb 4, 2012, at 2:23 AM, Andrey Zonov wrote:

 >> On 04.02.2012 11:42, Pawel Jakub Dawidek wrote:
 >>> On Wed, Feb 01, 2012 at 04:41:00PM +0000, Guy Helmer wrote:
 >>>> Author: ghelmer
 >>>> Date: Wed Feb  1 16:40:59 2012
 >>>> New Revision: 230869
 >>>> URL: http://svn.freebsd.org/changeset/base/230869
 >>>> 
 >>>> Log:
 >>>>   Change the notes about the pidfile to include Doug's preference
 >>>>   for pre-creating the pidfile with appropriate owner and permissions.
 >>>> 
 >>>>   Requested by dougb
 >>> 
 >>> Pre-creating pidfiles? That sounds weird. The common practise is to turn
 >>> eg. /var/run/<name>.pid into /var/run/<name>/pid where<name>  directory
 >>> has appropriate permissions. Pre-creating pidfiles is simply wrong,
 >>> because applications create pidfile on start and unlink it on exit.
 >>> If application has no permission to remove files from /var/run/ it will
 >>> leave pidfile with stale PID in it, which is bad. Changing application
 >>> to truncate pidfile on exit instead of unlinking it also is a bad idea
 >>> especially because there is working solution - pid directory.
 >>> 
 >> 
 >> Hi,
 >> 
 >> There's even worse problem - kernel closes pidfile in execvp() because of
 >> FD_CLOEXEC flag is set and daemon doesn't hold lock on pidfile.
 >> 
 >> I reported about that earlier, but was ignored.

 GH> I don't understand your concern about this -- the daemon(8) program
 GH> exists to start a program that does not manage its own user authority or
 GH> pid file, and it is inappropriate to leak the open pidfile descriptor to
 GH> the program that daemon(8) execs.

ref8-amd64:/home/trociny% uname -r
8.2-STABLE
ref8-amd64:/home/trociny% daemon -p /tmp/sleep.pid sleep 10
ref8-amd64:/home/trociny% daemon -p /tmp/sleep.pid sleep 10
daemon: process already running, pid: 19799

kopusha:~% uname -r                         
10.0-CURRENT
kopusha:~% daemon -p /tmp/sleep.pid sleep 10
kopusha:~% daemon -p /tmp/sleep.pid sleep 10
kopusha:~% 

-- 
Mikolaj Golub



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