From owner-freebsd-hackers@FreeBSD.ORG  Fri Oct  8 03:35:39 2004
Return-Path: <owner-freebsd-hackers@FreeBSD.ORG>
Delivered-To: freebsd-hackers@freebsd.org
Received: from mx1.FreeBSD.org (mx1.freebsd.org [216.136.204.125])
	by hub.freebsd.org (Postfix) with ESMTP id B987616A4CE
	for <freebsd-hackers@freebsd.org>;
	Fri,  8 Oct 2004 03:35:39 +0000 (GMT)
Received: from harmony.village.org (rover.village.org [168.103.84.182])
	by mx1.FreeBSD.org (Postfix) with ESMTP id 1014A43D2F
	for <freebsd-hackers@freebsd.org>;
	Fri,  8 Oct 2004 03:35:39 +0000 (GMT)	(envelope-from imp@bsdimp.com)
Received: from localhost (harmony.village.org [10.0.0.6])
	by harmony.village.org (8.13.1/8.13.1) with ESMTP id i983YViA047196;
	Thu, 7 Oct 2004 21:34:31 -0600 (MDT)
	(envelope-from imp@bsdimp.com)
Date: Thu, 07 Oct 2004 21:36:13 -0600 (MDT)
Message-Id: <20041007.213613.34762646.imp@bsdimp.com>
To: marc@msys.ch
From: "M. Warner Losh" <imp@bsdimp.com>
In-Reply-To: <A3E829CE-1820-11D9-AB94-003065F9345A@msys.ch>
References: <FFEC3743-17A3-11D9-BB63-0003938168B2@msys.ch>
	<20041006144800.GB87201@dan.emsphone.com>
	<A3E829CE-1820-11D9-AB94-003065F9345A@msys.ch>
X-Mailer: Mew version 3.3 on Emacs 21.3 / Mule 5.0 (SAKAKI)
Mime-Version: 1.0
Content-Type: Text/Plain; charset=us-ascii
Content-Transfer-Encoding: 7bit
cc: freebsd-hackers@freebsd.org
cc: dnelson@allantgroup.com
Subject: Re: syslog() reentrant when compiling with -pthread?
X-BeenThere: freebsd-hackers@freebsd.org
X-Mailman-Version: 2.1.1
Precedence: list
List-Id: Technical Discussions relating to FreeBSD
	<freebsd-hackers.freebsd.org>
List-Unsubscribe: <http://lists.freebsd.org/mailman/listinfo/freebsd-hackers>,
	<mailto:freebsd-hackers-request@freebsd.org?subject=unsubscribe>
List-Archive: <http://lists.freebsd.org/pipermail/freebsd-hackers>
List-Post: <mailto:freebsd-hackers@freebsd.org>
List-Help: <mailto:freebsd-hackers-request@freebsd.org?subject=help>
List-Subscribe: <http://lists.freebsd.org/mailman/listinfo/freebsd-hackers>,
	<mailto:freebsd-hackers-request@freebsd.org?subject=subscribe>
X-List-Received-Date: Fri, 08 Oct 2004 03:35:39 -0000

In message: <A3E829CE-1820-11D9-AB94-003065F9345A@msys.ch>
            Marc Balmer <marc@msys.ch> writes:
: Am 06.10.2004 um 16:48 schrieb Dan Nelson:
: 
: > The only unsafe part is openlog(), so set that up before you start any
: > threads and you'll be okay.  Once the log fd is opened, the syslog()
: > call looks to be thread-safe.  Everything in there is done with local
: > variables and atomic writes.
: 
: At least on OpenBSD I can use "%m" in the syslog() format string.  This 
: results in a call to strerror(), which is not thread safe, AFAIK.  This 
: probably is true for FreeBSD as well, so we have the following three 
: conditions for thread safe syslog():
: 
: 1) openlog() must be called before any threads that use syslog() are 
: started.
: 2) The first argument to openlog() must not be NULL.
: 3) The "%m" Format String must not be used in syslog() calls.
: 
: Any comments?

strerror is thread safe, unless your errno is outside of the valid
range.

Warner