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Re: [Qemu-devel] [PATCH] configure: add -Wno-format-truncation to QEMU_C
From: |
Daniel P. Berrange |
Subject: |
Re: [Qemu-devel] [PATCH] configure: add -Wno-format-truncation to QEMU_CFLAGS |
Date: |
Thu, 20 Jul 2017 16:33:28 +0100 |
User-agent: |
Mutt/1.8.3 (2017-05-23) |
On Thu, Jul 20, 2017 at 04:57:29PM +0200, Eduardo Otubo wrote:
> Compilation breaks on GCC 7.1.1 20170622 (Fedora 26), thus adding
> -Wno-format-truncation to QEMU_CFLAGS on configure script is neecssary.
>
> hw/usb/bus.c: In function ‘usb_port_location’:
> hw/usb/bus.c:410:66: error: ‘%d’ directive output may be truncated
> writing between 1 and 11 bytes into a region of size between 0 and 15
> [-Werror=format-truncation=]
> snprintf(downstream->path, sizeof(downstream->path), "%s.%d",
> ^~
> In file included from /usr/include/stdio.h:939:0,
> from
> /home/otubo/develop/qemu/otubo/include/qemu/osdep.h:68,
> from hw/usb/bus.c:1:
> /usr/include/bits/stdio2.h:64:10: note: ‘__builtin___snprintf_chk’ output
> between 3 and 28 bytes into a destination of size 16
> return __builtin___snprintf_chk (__s, __n, __USE_FORTIFY_LEVEL - 1,
> ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
> __bos (__s), __fmt, __va_arg_pack ());
> ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
> cc1: all warnings being treated as errors
> make: *** [/home/otubo/develop/qemu/otubo/rules.mak:66: hw/usb/bus.o]
> Error 1
> make: *** Waiting for unfinished jobs....
>
> Signed-off-by: Eduardo Otubo <address@hidden>
> ---
> This warning looks pretty much bogus to me. Since building with -Werror is
> essential, we should add this flag to configure. If someone thinks this
> warning
> is not a false positive, feel free to drop this patch.
This particular case of the warning may be a false positive, but the
-Wformat-truncation warning *can* detect serious real bugs so turning
it off is not appropriate. In any case there's a patch this problem
queued for merge already:
https://lists.gnu.org/archive/html/qemu-devel/2017-07/msg06455.html
Regards,
Daniel
--
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