From: Mark Kettenis Subject: Re: [PATCH, RFC] random: introduce getrandom(2) system call Date: Thu, 17 Jul 2014 20:48:11 +0200 (CEST) Message-ID: <201407171848.s6HImBb4027900@glazunov.sibelius.xs4all.nl> Cc: linux-kernel@vger.kernel.org, linux-crypto@vger.kernel.org, beck@openbsd.org To: "Theodore Ts'o" Return-path: Received: from sibelius.xs4all.nl ([83.163.83.176]:26022 "EHLO glazunov.sibelius.xs4all.nl" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1752118AbaGQTWM (ORCPT ); Thu, 17 Jul 2014 15:22:12 -0400 Sender: linux-crypto-owner@vger.kernel.org List-ID: On Thu, Jul 17, 2014, Theodore Ts'o wrote: > > The getrandom(2) system call is a superset of getentropy(2). When we > add the support for this into glibc, it won't be terribly difficult > nor annoying to drop the following in alongside the standard support > needed for any new system call: > > int getentropy(void *buf, size_t buflen) > { > int ret; > > ret = getentropy(buf, buflen, 0); > return (ret > 0) ? 0 : ret; > } I'm sure you meant to use getrandom() there ;) Since for LibreSSL we'd want a getentropy() that cannot fail the getrandom() call should use GRND_BLOCK flag. Actually it makes sense (to me) to make blocking the default behaviour and have a BRND_NONBLOCK flag. Much in the same way as you need to specify O_NONBLOCK if you want non-blocking behaviour for files.