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=-8.5 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_PASS,URIBL_BLOCKED, USER_AGENT_MUTT 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 C5C2DC04EB8 for ; Tue, 4 Dec 2018 11:10:42 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 960FF2082D for ; Tue, 4 Dec 2018 11:10:42 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 960FF2082D Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=suse.cz Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-btrfs-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728306AbeLDLKl (ORCPT ); Tue, 4 Dec 2018 06:10:41 -0500 Received: from mx2.suse.de ([195.135.220.15]:46680 "EHLO mx1.suse.de" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1728382AbeLDLKk (ORCPT ); Tue, 4 Dec 2018 06:10:40 -0500 X-Virus-Scanned: by amavisd-new at test-mx.suse.de Received: from relay2.suse.de (unknown [195.135.220.254]) by mx1.suse.de (Postfix) with ESMTP id B93ABAC7A; Tue, 4 Dec 2018 11:10:37 +0000 (UTC) Received: by ds.suse.cz (Postfix, from userid 10065) id 53476DA7A3; Tue, 4 Dec 2018 12:10:19 +0100 (CET) Date: Tue, 4 Dec 2018 12:10:19 +0100 From: David Sterba To: Qu Wenruo Cc: linux-btrfs@vger.kernel.org, Su Yanjun Subject: Re: [PATCH 2/9] btrfs-progs: fix gcc8 default build warning caused by '-Wformat-truncation' Message-ID: <20181204111018.GI17773@twin.jikos.cz> Reply-To: dsterba@suse.cz Mail-Followup-To: dsterba@suse.cz, Qu Wenruo , linux-btrfs@vger.kernel.org, Su Yanjun References: <20181116075426.4142-1-wqu@suse.com> <20181116075426.4142-3-wqu@suse.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20181116075426.4142-3-wqu@suse.com> User-Agent: Mutt/1.5.23.1 (2014-03-12) Sender: linux-btrfs-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-btrfs@vger.kernel.org On Fri, Nov 16, 2018 at 03:54:19PM +0800, Qu Wenruo wrote: > From: Su Yanjun > > When using gcc8 compiles utils.c, it complains as below: > > utils.c:852:45: warning: '%s' directive output may be truncated writing > up to 4095 bytes into a region of size 4084 [-Wformat-truncation=] > snprintf(path, sizeof(path), "/dev/mapper/%s", name); > ^~ ~~~~ > In file included from /usr/include/stdio.h:873, > from utils.c:20: > /usr/include/bits/stdio2.h:67:10: note: '__builtin___snprintf_chk' > output between 13 and 4108 bytes into a destination of size 4096 > return __builtin___snprintf_chk (__s, __n, __USE_FORTIFY_LEVEL - 1, > ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ > __bos (__s), __fmt, __va_arg_pack ()); > ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ > > This isn't a type of warning we care about, particularly when PATH_MAX > is much less than either. > > Using the GCC option -Wno-format-truncation to disable this for default > build. > > Signed-off-by: Su Yanjun > [Use cc-disable-warning to fix the not working CFLAGS setting in configure.ac] > Signed-off-by: Qu Wenruo > --- > Makefile | 1 + > Makefile.extrawarn | 1 + > 2 files changed, 2 insertions(+) > > diff --git a/Makefile b/Makefile > index f4ab14ea74c8..252299f8869f 100644 > --- a/Makefile > +++ b/Makefile > @@ -49,6 +49,7 @@ CSCOPE_CMD := cscope -u -b -c -q > include Makefile.extrawarn > > EXTRA_CFLAGS := > +EXTRA_CFLAGS += $(call cc-disable-warning, format-truncation) Please don't touch EXTRA_CFLAGS, this is for users who want to override any defaults that are set by build. This should go to CFLAGS. > EXTRA_LDFLAGS := > > DEBUG_CFLAGS_DEFAULT = -O0 -U_FORTIFY_SOURCE -ggdb3 > diff --git a/Makefile.extrawarn b/Makefile.extrawarn > index 5849036fd166..bbb2d5173846 100644 > --- a/Makefile.extrawarn > +++ b/Makefile.extrawarn > @@ -53,6 +53,7 @@ warning-1 += -Wold-style-definition > warning-1 += $(call cc-option, -Wmissing-include-dirs) > warning-1 += $(call cc-option, -Wunused-but-set-variable) > warning-1 += $(call cc-disable-warning, missing-field-initializers) > +warning-1 += $(call cc-disable-warning, format-truncation) It's ok to disable for W=1 but eg. the W=3 level could take all previously disabled warnings. > > warning-2 := -Waggregate-return > warning-2 += -Wcast-align > -- > 2.19.1