From: David Sterba <dsterba@suse.cz>
To: Qu Wenruo <wqu@suse.com>
Cc: linux-btrfs@vger.kernel.org, Su Yanjun <suyj.fnst@cn.fujitsu.com>
Subject: Re: [PATCH 2/9] btrfs-progs: fix gcc8 default build warning caused by '-Wformat-truncation'
Date: Tue, 4 Dec 2018 12:10:19 +0100 [thread overview]
Message-ID: <20181204111018.GI17773@twin.jikos.cz> (raw)
In-Reply-To: <20181116075426.4142-3-wqu@suse.com>
On Fri, Nov 16, 2018 at 03:54:19PM +0800, Qu Wenruo wrote:
> From: Su Yanjun <suyj.fnst@cn.fujitsu.com>
>
> 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 <suyj.fnst@cn.fujitsu.com>
> [Use cc-disable-warning to fix the not working CFLAGS setting in configure.ac]
> Signed-off-by: Qu Wenruo <wqu@suse.com>
> ---
> 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
next prev parent reply other threads:[~2018-12-04 11:10 UTC|newest]
Thread overview: 33+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-11-16 7:54 [PATCH 0/9] btrfs-progs: Make W=1 clean (no "again") Qu Wenruo
2018-11-16 7:54 ` [PATCH 1/9] btrfs-progs: Makefile.extrawarn: Import cc-disable-warning Qu Wenruo
2018-12-04 11:04 ` David Sterba
2018-11-16 7:54 ` [PATCH 2/9] btrfs-progs: fix gcc8 default build warning caused by '-Wformat-truncation' Qu Wenruo
2018-12-04 11:10 ` David Sterba [this message]
2018-12-04 12:21 ` Qu Wenruo
2018-11-16 7:54 ` [PATCH 3/9] btrfs-progs: Makefile.extrawarn: Don't warn on sign compare Qu Wenruo
2018-11-16 8:00 ` [PATCH v1.1 " Qu Wenruo
2018-12-04 11:10 ` David Sterba
2018-11-16 7:54 ` [PATCH 4/9] btrfs-progs: Fix Wempty-body warning Qu Wenruo
2018-11-16 8:01 ` Nikolay Borisov
2018-11-16 7:54 ` [PATCH 5/9] btrfs-progs: Fix Wimplicit-fallthrough warning Qu Wenruo
2018-11-16 8:04 ` Nikolay Borisov
2018-11-16 8:10 ` Qu Wenruo
2018-11-16 7:54 ` [PATCH 6/9] btrfs-progs: Fix Wsuggest-attribute=format warning Qu Wenruo
2018-11-16 8:06 ` Nikolay Borisov
2018-11-16 7:54 ` [PATCH 7/9] btrfs-progs: Fix Wmaybe-uninitialized warning Qu Wenruo
2018-11-16 8:13 ` Nikolay Borisov
2018-11-16 8:16 ` Qu Wenruo
2018-11-16 8:22 ` [PATCH v1.1 " Qu Wenruo
2018-11-16 8:24 ` Nikolay Borisov
2018-12-04 12:17 ` [PATCH " David Sterba
2018-12-04 12:22 ` Adam Borowski
2018-12-04 12:42 ` Nikolay Borisov
2018-12-05 5:38 ` Qu Wenruo
2018-11-16 7:54 ` [PATCH 8/9] btrfs-progs: Fix Wtype-limits warning Qu Wenruo
2018-11-16 8:07 ` Nikolay Borisov
2018-11-16 7:54 ` [PATCH 9/9] btrfs-progs: Cleanup warning reported by -Wmissing-prototypes except free space tree Qu Wenruo
2018-11-16 8:04 ` [PATCH v1.1 9/9] btrfs-progs: Cleanup warning reported by -Wmissing-prototypes Qu Wenruo
2018-11-16 8:14 ` Nikolay Borisov
2018-12-04 12:22 ` David Sterba
2018-12-04 12:24 ` Qu Wenruo
2018-12-04 12:48 ` David Sterba
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