From mboxrd@z Thu Jan 1 00:00:00 1970 X-Msuck: nntp://news.gmane.org/gmane.linux.lib.musl.general/8627 Path: news.gmane.org!not-for-mail From: Rich Felker Newsgroups: gmane.linux.lib.musl.general Subject: Re: Bug in macro LOG_MAKEPRI in syslog.h Date: Tue, 6 Oct 2015 17:14:28 -0400 Message-ID: <20151006211428.GS8645@brightrain.aerifal.cx> References: <20151006210931.GR8645@brightrain.aerifal.cx> 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 1444166090 24695 80.91.229.3 (6 Oct 2015 21:14:50 GMT) X-Complaints-To: usenet@ger.gmane.org NNTP-Posting-Date: Tue, 6 Oct 2015 21:14:50 +0000 (UTC) To: musl@lists.openwall.com Original-X-From: musl-return-8639-gllmg-musl=m.gmane.org@lists.openwall.com Tue Oct 06 23:14:44 2015 Return-path: 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 ) id 1ZjZZK-0004g2-SE for gllmg-musl@m.gmane.org; Tue, 06 Oct 2015 23:14:42 +0200 Original-Received: (qmail 1939 invoked by uid 550); 6 Oct 2015 21:14:41 -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 1918 invoked from network); 6 Oct 2015 21:14:40 -0000 Content-Disposition: inline In-Reply-To: <20151006210931.GR8645@brightrain.aerifal.cx> User-Agent: Mutt/1.5.21 (2010-09-15) Original-Sender: Rich Felker Xref: news.gmane.org gmane.linux.lib.musl.general:8627 Archived-At: On Tue, Oct 06, 2015 at 05:09:31PM -0400, Rich Felker wrote: > On Tue, Oct 06, 2015 at 09:06:49PM +0200, Pepe Aracil wrote: > > Hi all. > > > > > > Now the macro is defined as: > > #define LOG_MAKEPRI(f, p) (((f)<<3) | (p)) > > And must be: > > #define LOG_MAKEPRI(f, p) ((f) | (p)) > > > > The next example posts wrong facility (LOG_LOCAL1) because LOG_LOCAL1 is > > already rotated ( #define LOG_LOCAL1 (17<<3) ). > > > > syslog (LOG_MAKEPRI(LOG_LOCAL1, LOG_ERROR), > > "Unable to make network connection to %s. Error=%m", host); > > LOG_MAKEPRI is not supposed to be used for this; it's not even a > standard API. The documented way to use syslog is to pass > LOG_LOCAL1|LOG_ERROR. See the specification at > http://pubs.opengroup.org/onlinepubs/9699919799/functions/syslog.html > > I agree with your reasoning that the <<3 does not make sense, but > glibc and other historical systems, where the nonstandard macro was > copied from, do the same, and there does not seem to be any value in > offering an incompatible version of a nonstandard/legacy macro like > this. Presumably you're supposed to use LOG_FAC() first to do the >>3 > if you want to use these legacy macros, as in: > > LOG_MAKEPRI(LOG_FAC(LOG_LOCAL1), LOG_ERROR) > > Yes this is ugly.. Hmm, Alexander Monakov just pointed me to this: https://sourceware.org/bugzilla/show_bug.cgi?id=14347 So maybe we should change it. In any case I think it's a really bad idea to use this macro since it was "wrong" for a very long time on glibc (and on musl). The documented correct way to achieve the same thing is simply the | operator. Rich