From mboxrd@z Thu Jan  1 00:00:00 1970
From: Ludovic =?UTF-8?Q?Court=C3=A8s?= <ludo@gnu.org>
Subject: bug#36380: service urandom-seed takes too long on boot
Date: Thu, 11 Jul 2019 23:33:07 +0200
Message-ID: <87k1contnw.fsf@gnu.org>
References: <F88CEF04-9BFA-4886-8A2D-AD84AE278D07@vllmrt.net>
 <20190626154721.GA2999@jasmine.lan> <87zhm3xdfu.fsf@gnu.org>
 <20190627190314.GA7403@jasmine.lan>
 <EA773339-2CC9-486E-99B8-A2E71B34467E@vllmrt.net>
 <20190628172401.GA17073@jasmine.lan>
 <20190711174455.GA30457@jasmine.lan>
Mime-Version: 1.0
Content-Type: text/plain; charset=utf-8
Content-Transfer-Encoding: quoted-printable
Return-path: <bug-guix-bounces+gcggb-bug-guix=m.gmane.org@gnu.org>
Received: from eggs.gnu.org ([2001:470:142:3::10]:52933)
 by lists.gnu.org with esmtp (Exim 4.86_2)
 (envelope-from <Debian-debbugs@debbugs.gnu.org>) id 1hlghX-0007Cm-Lg
 for bug-guix@gnu.org; Thu, 11 Jul 2019 17:34:04 -0400
Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71)
 (envelope-from <Debian-debbugs@debbugs.gnu.org>) id 1hlghW-0006Px-OM
 for bug-guix@gnu.org; Thu, 11 Jul 2019 17:34:03 -0400
Received: from debbugs.gnu.org ([209.51.188.43]:58345)
 by eggs.gnu.org with esmtps (TLS1.0:RSA_AES_128_CBC_SHA1:16)
 (Exim 4.71) (envelope-from <Debian-debbugs@debbugs.gnu.org>)
 id 1hlghW-0006Pm-Ks
 for bug-guix@gnu.org; Thu, 11 Jul 2019 17:34:02 -0400
Received: from Debian-debbugs by debbugs.gnu.org with local (Exim 4.84_2)
 (envelope-from <Debian-debbugs@debbugs.gnu.org>) id 1hlghW-0002YG-Ef
 for bug-guix@gnu.org; Thu, 11 Jul 2019 17:34:02 -0400
Sender: "Debbugs-submit" <debbugs-submit-bounces@debbugs.gnu.org>
Resent-Message-ID: <handler.36380.B36380.15628808009755@debbugs.gnu.org>
In-Reply-To: <20190711174455.GA30457@jasmine.lan> (Leo Famulari's message of
 "Thu, 11 Jul 2019 13:44:55 -0400")
List-Id: Bug reports for GNU Guix <bug-guix.gnu.org>
List-Unsubscribe: <https://lists.gnu.org/mailman/options/bug-guix>,
 <mailto:bug-guix-request@gnu.org?subject=unsubscribe>
List-Archive: <https://lists.gnu.org/archive/html/bug-guix>
List-Post: <mailto:bug-guix@gnu.org>
List-Help: <mailto:bug-guix-request@gnu.org?subject=help>
List-Subscribe: <https://lists.gnu.org/mailman/listinfo/bug-guix>,
 <mailto:bug-guix-request@gnu.org?subject=subscribe>
Errors-To: bug-guix-bounces+gcggb-bug-guix=m.gmane.org@gnu.org
Sender: "bug-Guix" <bug-guix-bounces+gcggb-bug-guix=m.gmane.org@gnu.org>
To: Leo Famulari <leo@famulari.name>
Cc: 36380@debbugs.gnu.org, Robert Vollmert <rob@vllmrt.net>

Hi Leo,

Leo Famulari <leo@famulari.name> skribis:

> On Fri, Jun 28, 2019 at 01:24:01PM -0400, Leo Famulari wrote:
>> So, I suggest we add a 1 second timeout to this read.
>>=20
>> I can work on that next week.
>
> I did try working on this, after reading the code in (guix scripts
> offload (call-with-timeout)).

The =E2=80=98start=E2=80=99 method of the =E2=80=98urandom-seed=E2=80=99 Sh=
epherd service runs in PID=C2=A01,
so we certainly don=E2=80=99t want to fiddle with SIGALRM in that context, =
which
is what =E2=80=98call-with-timeout=E2=80=99 does.

Instead, I think we should use =E2=80=98select=E2=80=99 with a timeout:

  (call-with-input-file "/dev/hwrng"
    (lambda (port)
      (match (select (list port) '() '() 3)
        =E2=80=A6)))

I think we can then use =E2=80=98get-bytevector-n!=E2=80=99, assuming it do=
esn=E2=80=99t block
if less than COUNT bytes are available (I=E2=80=99m not sure this is the ca=
se.)

HTH!

Ludo=E2=80=99.