From owner-freebsd-current@freebsd.org  Mon Jan 23 22:11:00 2017
Return-Path: <owner-freebsd-current@freebsd.org>
Delivered-To: freebsd-current@mailman.ysv.freebsd.org
Received: from mx1.freebsd.org (mx1.freebsd.org
 [IPv6:2001:1900:2254:206a::19:1])
 by mailman.ysv.freebsd.org (Postfix) with ESMTP id 10A18CBE227
 for <freebsd-current@mailman.ysv.freebsd.org>;
 Mon, 23 Jan 2017 22:11:00 +0000 (UTC) (envelope-from jilles@stack.nl)
Received: from mailout.stack.nl (mailout05.stack.nl [131.155.140.202])
 (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits))
 (Client CN "mailout.stack.nl",
 Issuer "CA Cert Signing Authority" (not verified))
 by mx1.freebsd.org (Postfix) with ESMTPS id D19B0257;
 Mon, 23 Jan 2017 22:10:59 +0000 (UTC) (envelope-from jilles@stack.nl)
Received: from snail.stack.nl (snail.stack.nl [IPv6:2001:610:1108:5010::131])
 by mailout.stack.nl (Postfix) with ESMTP id 2EAC53D;
 Mon, 23 Jan 2017 23:10:51 +0100 (CET)
Received: by snail.stack.nl (Postfix, from userid 1677)
 id 1FCF428494; Mon, 23 Jan 2017 23:10:51 +0100 (CET)
Date: Mon, 23 Jan 2017 23:10:51 +0100
From: Jilles Tjoelker <jilles@stack.nl>
To: "Simon J. Gerraty" <sjg@juniper.net>
Cc: Lu Tung-Pin <lutungpin@openmailbox.org>, freebsd-current@freebsd.org,
 des@freebsd.org
Subject: Re: Fix /etc/rc.d/random umask handling (/entropy permissions)
Message-ID: <20170123221050.GA77550@stack.nl>
References: <14f5a2fdf191c33e4ed1dc882b288e81@openmailbox.org>
 <20170121220136.GA59654@stack.nl> <43886.1485197541@kaos.jnpr.net>
MIME-Version: 1.0
Content-Type: text/plain; charset=us-ascii
Content-Disposition: inline
In-Reply-To: <43886.1485197541@kaos.jnpr.net>
User-Agent: Mutt/1.5.21 (2010-09-15)
X-BeenThere: freebsd-current@freebsd.org
X-Mailman-Version: 2.1.23
Precedence: list
List-Id: Discussions about the use of FreeBSD-current
 <freebsd-current.freebsd.org>
List-Unsubscribe: <https://lists.freebsd.org/mailman/options/freebsd-current>, 
 <mailto:freebsd-current-request@freebsd.org?subject=unsubscribe>
List-Archive: <http://lists.freebsd.org/pipermail/freebsd-current/>
List-Post: <mailto:freebsd-current@freebsd.org>
List-Help: <mailto:freebsd-current-request@freebsd.org?subject=help>
List-Subscribe: <https://lists.freebsd.org/mailman/listinfo/freebsd-current>, 
 <mailto:freebsd-current-request@freebsd.org?subject=subscribe>
X-List-Received-Date: Mon, 23 Jan 2017 22:11:00 -0000

On Mon, Jan 23, 2017 at 10:52:21AM -0800, Simon J. Gerraty wrote:
> Jilles Tjoelker <jilles@stack.nl> wrote:
> > Index: etc/rc.d/random
> > ===================================================================
> > --- etc/rc.d/random	(revision 311446)
> > +++ etc/rc.d/random	(working copy)
> > @@ -20,12 +20,14 @@
> >  
> >  save_dev_random()
> >  {
> > +	oumask=`umask`

> why not simply use a sub-shell to tighten umask

> (umask 077; what-ever)

With our /bin/sh, the save-restore method saves a fork. A command
substitution with a single umask command does not fork, while a subshell
containing umask and something else does.

The effect is fairly minor, but good performance is often the product of
many small optimizations.

-- 
Jilles Tjoelker