From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-6.8 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_PASS,URIBL_BLOCKED autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 3C322C00449 for ; Fri, 5 Oct 2018 15:31:01 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 0060521473 for ; Fri, 5 Oct 2018 15:31:00 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 0060521473 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=goodmis.org Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728594AbeJEWaK (ORCPT ); Fri, 5 Oct 2018 18:30:10 -0400 Received: from mail.kernel.org ([198.145.29.99]:43372 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726082AbeJEWaK (ORCPT ); Fri, 5 Oct 2018 18:30:10 -0400 Received: from gandalf.local.home (cpe-66-24-56-78.stny.res.rr.com [66.24.56.78]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id B08C020834; Fri, 5 Oct 2018 15:30:57 +0000 (UTC) Date: Fri, 5 Oct 2018 11:30:56 -0400 From: Steven Rostedt To: Arnaldo Carvalho de Melo Cc: LKML , Jiri Olsa , Ingo Molnar , Namhyung Kim , Tzvetomir Stoyanov , Linux Trace Devel , Colin Patrick McCabe Subject: Re: [PATCH v3] tools/lib/traceevent: Replace str_error_r() with an open coded implementation Message-ID: <20181005113056.55b23c31@gandalf.local.home> In-Reply-To: <20181002175539.2ac894c7@gandalf.local.home> References: <20181002175539.2ac894c7@gandalf.local.home> X-Mailer: Claws Mail 3.16.0 (GTK+ 2.24.32; x86_64-pc-linux-gnu) MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, 2 Oct 2018 17:55:39 -0400 Steven Rostedt wrote: > From: "Steven Rostedt (VMware)" > > While working on having PowerTop use libtracevent as a shared object > library, Tzvetomir hit "str_error_r not defined". This was added by commit > c3cec9e68f12d ("tools lib traceevent: Use str_error_r()") because > strerror_r() has two definitions, where one is GNU specific, and the other > is XSI complient. The strerror_r() is in a wrapper str_error_r() to keep the > code from having to worry about which compiler is being used. > > The problem is that str_error_r() is external to libtraceevent, and not part > of the library. If it is used as a shared object then the tools using it > will need to define that function. I do not want that function defined in > libtraceevent itself, as it is out of scope for that library. > > As there's only a single instance of this call, I replaced it with an open > coded algorithm that uses sys_nerr and sys_errlist error array with > strncpy() to place the error message in the given buffer. We don't need to > worry about the errors that strerror_r() returns. If the buffer isn't big > enough, we simply truncate it. > > The sys_nerr and sys_errlist idea was found here: > > http://www.club.cc.cmu.edu/~cmccabe/blog_strerror.html > > Cc: Colin Patrick McCabe > Reported-by: Tzvetomir Stoyanov > Signed-off-by: Steven Rostedt (VMware) > --- > Changes since v2: > > Use sys_nerr and sys_errlist idea. > > tools/lib/traceevent/event-parse.c | 9 +++++++-- > 1 file changed, 7 insertions(+), 2 deletions(-) > > diff --git a/tools/lib/traceevent/event-parse.c b/tools/lib/traceevent/event-parse.c > index 7980fc6c3bac..d23d10bc5314 100644 > --- a/tools/lib/traceevent/event-parse.c > +++ b/tools/lib/traceevent/event-parse.c > @@ -18,7 +18,6 @@ > #include > #include > #include > -#include > #include > > #include > @@ -6215,7 +6214,13 @@ int tep_strerror(struct tep_handle *pevent __maybe_unused, > const char *msg; > > if (errnum >= 0) { > - str_error_r(errnum, buf, buflen); > + if (buflen > 0) { > + if (errnum < sys_nerr) > + strncpy(buf, sys_errlist[errnum], buflen); > + else > + snprintf(buf, buflen, "Unknown error %d", errnum); > + buf[buflen - 1] = 0; > + } Bah, I now get warnings that sys_nerr and sys_errlist are deprecated. OK, so going back to just using the racy strerror() should be good enough, as this incompatibility with strerror_r() is a disaster! -- Steve > return 0; > } >