From mboxrd@z Thu Jan 1 00:00:00 1970 X-Msuck: nntp://news.gmane.org/gmane.linux.lib.musl.general/2750 Path: news.gmane.org!not-for-mail From: Rich Felker Newsgroups: gmane.linux.lib.musl.general Subject: Re: guard bug for strerror_r Date: Fri, 8 Feb 2013 13:59:18 -0500 Message-ID: <20130208185918.GJ20323@brightrain.aerifal.cx> References: <1360342098.2983.360.camel@eris.loria.fr> <20130208165542.GW6181@port70.net> <1360344600.2983.365.camel@eris.loria.fr> <20130208100125.0d6bf697.idunham@lavabit.com> Reply-To: musl@lists.openwall.com NNTP-Posting-Host: plane.gmane.org Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii X-Trace: ger.gmane.org 1360349970 23590 80.91.229.3 (8 Feb 2013 18:59:30 GMT) X-Complaints-To: usenet@ger.gmane.org NNTP-Posting-Date: Fri, 8 Feb 2013 18:59:30 +0000 (UTC) To: musl@lists.openwall.com Original-X-From: musl-return-2751-gllmg-musl=m.gmane.org@lists.openwall.com Fri Feb 08 19:59:51 2013 Return-path: Envelope-to: gllmg-musl@plane.gmane.org Original-Received: from mother.openwall.net ([195.42.179.200]) by plane.gmane.org with smtp (Exim 4.69) (envelope-from ) id 1U3tAr-0000xm-Ls for gllmg-musl@plane.gmane.org; Fri, 08 Feb 2013 19:59:49 +0100 Original-Received: (qmail 15383 invoked by uid 550); 8 Feb 2013 18:59:30 -0000 Mailing-List: contact musl-help@lists.openwall.com; run by ezmlm Precedence: bulk List-Post: List-Help: List-Unsubscribe: List-Subscribe: Original-Received: (qmail 15375 invoked from network); 8 Feb 2013 18:59:30 -0000 Content-Disposition: inline In-Reply-To: <20130208100125.0d6bf697.idunham@lavabit.com> User-Agent: Mutt/1.5.21 (2010-09-15) Xref: news.gmane.org gmane.linux.lib.musl.general:2750 Archived-At: On Fri, Feb 08, 2013 at 10:01:25AM -0800, Isaac Dunham wrote: > On Fri, 08 Feb 2013 18:30:00 +0100 > Jens Gustedt wrote: > > > > > __GNU_SOURCE is defined by the gnu platform to specify the > > availability of their extensions. Unfortunately they don't have a > > finer grained tool to distinguish different types of extensions they > > provide. (BTW the same holds for gcc, that you only can tune with > > version numbers.) > > > > If I, as a user, define __GNU_SOURCE I expect to have the gnu > > extension, if I then use strerror_r I expect to have their interface, > > since this is documented like this. At least as it is now, I don't > > think I have any means to distinguish the two platforms and to know > > which version of strerror_r I would receive. > > #ifdef __linux > #include /* this is partly for this purpose */ Use or similar -- it will include , but it's standard, so it won't break on systems that don't have it. > /*including would also work, and is more universal > * it's actually necessary with dietlibc, IIRC */ > #if defined(__GLIBC__) && defined(__USE_GNU) > ... I would simply avoid _ever_ using strerror_r on GNU systems. On any modern GNU or POSIX 2008 conforming system, you have the vastly superior strerror_l function. It does not require you to provide a buffer, and it's thread-safe (the buffer returned is either immutable static or thread-local). The logic I'd recommend is: #if _POSIX_VERSION >= 200809L || defined(__GLIBC__) /* use strerror_l */ #else /* use strerror_r and assume POSIX version of it */ #endif Rich