From mboxrd@z Thu Jan  1 00:00:00 1970
X-Msuck: nntp://news.gmane.org/gmane.linux.lib.musl.general/6902
Path: news.gmane.org!not-for-mail
From: Rich Felker <dalias@libc.org>
Newsgroups: gmane.linux.lib.musl.general
Subject: Re: getrandom syscall
Date: Wed, 28 Jan 2015 11:21:04 -0500
Message-ID: <20150128162104.GJ4574@brightrain.aerifal.cx>
References: <CAPLrYERojt8q5JDKG5UZJxoouKvN+OgAZz6ixhuFB85EPZzF6A@mail.gmail.com>
 <20150128145410.GH4574@brightrain.aerifal.cx>
 <20150128154108.GH32318@port70.net>
 <CAPLrYEQEfZyaAbcC3NbTdzc-TdJ-B-hz1iqBYb5f=sMAvxdJig@mail.gmail.com>
 <20150128160352.GI32318@port70.net>
 <CAPLrYETf1wLOvzng3+YsGpfD+ouj5A8WQJUFeU2nkKbAd83+Eg@mail.gmail.com>
Reply-To: musl@lists.openwall.com
NNTP-Posting-Host: plane.gmane.org
Mime-Version: 1.0
Content-Type: text/plain; charset=utf-8
Content-Transfer-Encoding: 8bit
X-Trace: ger.gmane.org 1422462080 32532 80.91.229.3 (28 Jan 2015 16:21:20 GMT)
X-Complaints-To: usenet@ger.gmane.org
NNTP-Posting-Date: Wed, 28 Jan 2015 16:21:20 +0000 (UTC)
To: musl@lists.openwall.com
Original-X-From: musl-return-6915-gllmg-musl=m.gmane.org@lists.openwall.com Wed Jan 28 17:21:19 2015
Return-path: <musl-return-6915-gllmg-musl=m.gmane.org@lists.openwall.com>
Envelope-to: gllmg-musl@m.gmane.org
Original-Received: from mother.openwall.net ([195.42.179.200])
	by plane.gmane.org with smtp (Exim 4.69)
	(envelope-from <musl-return-6915-gllmg-musl=m.gmane.org@lists.openwall.com>)
	id 1YGVMk-0001dw-OM
	for gllmg-musl@m.gmane.org; Wed, 28 Jan 2015 17:21:18 +0100
Original-Received: (qmail 16215 invoked by uid 550); 28 Jan 2015 16:21:17 -0000
Mailing-List: contact musl-help@lists.openwall.com; run by ezmlm
Precedence: bulk
List-Post: <mailto:musl@lists.openwall.com>
List-Help: <mailto:musl-help@lists.openwall.com>
List-Unsubscribe: <mailto:musl-unsubscribe@lists.openwall.com>
List-Subscribe: <mailto:musl-subscribe@lists.openwall.com>
Original-Received: (qmail 16201 invoked from network); 28 Jan 2015 16:21:16 -0000
Content-Disposition: inline
In-Reply-To: <CAPLrYETf1wLOvzng3+YsGpfD+ouj5A8WQJUFeU2nkKbAd83+Eg@mail.gmail.com>
User-Agent: Mutt/1.5.21 (2010-09-15)
Original-Sender: Rich Felker <dalias@aerifal.cx>
Xref: news.gmane.org gmane.linux.lib.musl.general:6902
Archived-At: <http://permalink.gmane.org/gmane.linux.lib.musl.general/6902>

On Wed, Jan 28, 2015 at 05:12:31PM +0100, Daniel Cegiełka wrote:
> 
> int getentropy(void *buf, size_t buflen)
> {
> 	int ret;
> 
> 	if (buflen > 256)
> 		goto failure;
> 	ret = getrandom(buf, buflen, 0);
> 	if (ret < 0)
> 		return ret;
> 	if (ret == buflen)
> 		return 0;
> failure:
> 	errno = EIO;
> 	return -1;
> }

Is it intentional to fall through to failure when ret is positive but
less than buflen? Can this happen?

> #include "syscall.h"
> 
> int getrandom(void *buf, size_t buflen, unsigned int flags)
> {
> 	return syscall(SYS_getrandom, buf, buflen, flags);
> }

If I read the documentation correctly, the removed EINTR handling is
irrelevant since the kernel guarantees not to EINTR for <=256 bytes
with the default flags, right?

Rich