From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754863Ab2GWVGF (ORCPT ); Mon, 23 Jul 2012 17:06:05 -0400 Received: from shutemov.name ([176.9.204.213]:44246 "EHLO shutemov.name" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754576Ab2GWVGD (ORCPT ); Mon, 23 Jul 2012 17:06:03 -0400 Date: Tue, 24 Jul 2012 00:06:54 +0300 From: "Kirill A. Shutemov" To: Ulrich Drepper Cc: Peter Zijlstra , Paul Mackerras , Ingo Molnar , Arnaldo Carvalho de Melo , linux-kernel@vger.kernel.org Subject: Re: [PATCH 2/2] perf: use XSI-complaint version of strerror_r() instead of GNU-specific Message-ID: <20120723210654.GA25248@shutemov.name> References: <1343055645-24083-1-git-send-email-kirill@shutemov.name> <1343055645-24083-2-git-send-email-kirill@shutemov.name> <20120723203120.GA25072@shutemov.name> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: User-Agent: Mutt/1.5.21 (2010-09-15) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon, Jul 23, 2012 at 04:48:22PM -0400, Ulrich Drepper wrote: > On Mon, Jul 23, 2012 at 4:31 PM, Kirill A. Shutemov > wrote: > > + const char *err = strerror_r(errnum, buf, buflen); > > + > > + if (err != buf && buflen > 0) { > > + size_t len = strlen(err); > > + char *c = mempcpy(buf, err, min(buflen - 1, len)); > > + *c = '\0'; > > + } > > No need to check for err == NULL. There's no such check. > buflen == 0 is a possibility given > the interface but I'd say this is an error and should be tested for at > the beginning of the function and the call should fail or even abort > the program. >>From 11d62205ee3c534aa9b0e9a24a312438ac726ffb Mon Sep 17 00:00:00 2001 From: "Kirill A. Shutemov" Date: Mon, 23 Jul 2012 17:41:05 +0300 Subject: [PATCH 2/2] perf: fix strerror_r() usage MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Perf uses GNU-specific version of strerror_r(). The GNU-specific strerror_r() returns a pointer to a string containing the error message. This may be either a pointer to a string that the function stores in buf, or a pointer to some (immutable) static string (in which case buf is unused). In glibc-2.16 GNU version was marked with attribute warn_unused_result. It triggers few warnings in perf: util/target.c: In function ‘perf_target__strerror’: util/target.c:114:13: error: ignoring return value of ‘strerror_r’, declared with attribute warn_unused_result [-Werror=unused-result] ui/browsers/hists.c: In function ‘hist_browser__dump’: ui/browsers/hists.c:981:13: error: ignoring return value of ‘strerror_r’, declared with attribute warn_unused_result [-Werror=unused-result] They are bugs. Let's fix strerror_r() usage. Signed-off-by: Kirill A. Shutemov --- tools/perf/ui/browsers/hists.c | 4 ++-- tools/perf/util/target.c | 12 +++++++++++- 2 files changed, 13 insertions(+), 3 deletions(-) diff --git a/tools/perf/ui/browsers/hists.c b/tools/perf/ui/browsers/hists.c index 482f051..413bd62 100644 --- a/tools/perf/ui/browsers/hists.c +++ b/tools/perf/ui/browsers/hists.c @@ -978,8 +978,8 @@ static int hist_browser__dump(struct hist_browser *browser) fp = fopen(filename, "w"); if (fp == NULL) { char bf[64]; - strerror_r(errno, bf, sizeof(bf)); - ui_helpline__fpush("Couldn't write to %s: %s", filename, bf); + const char *err = strerror_r(errno, bf, sizeof(bf)); + ui_helpline__fpush("Couldn't write to %s: %s", filename, err); return -1; } diff --git a/tools/perf/util/target.c b/tools/perf/util/target.c index 1064d5b..5c4b3b1 100644 --- a/tools/perf/util/target.c +++ b/tools/perf/util/target.c @@ -9,6 +9,7 @@ #include "target.h" #include "debug.h" +#include #include #include @@ -110,8 +111,17 @@ int perf_target__strerror(struct perf_target *target, int errnum, int idx; const char *msg; + assert(buflen > 0); + if (errnum >= 0) { - strerror_r(errnum, buf, buflen); + const char *err = strerror_r(errnum, buf, buflen); + + if (err != buf) { + size_t len = strlen(err); + char *c = mempcpy(buf, err, min(buflen - 1, len)); + *c = '\0'; + } + return 0; } -- Kirill A. Shutemov