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Re: [PATCH 3/6] migration: Silence compiler warning in global_state_stor
From: |
Cleber Rosa |
Subject: |
Re: [PATCH 3/6] migration: Silence compiler warning in global_state_store_running() |
Date: |
Mon, 21 Sep 2020 16:39:02 -0400 |
On Fri, Sep 18, 2020 at 12:34:27PM +0200, Thomas Huth wrote:
> GCC 9.3.0 on Ubuntu complains:
>
> In file included from /usr/include/string.h:495,
> from /home/travis/build/huth/qemu/include/qemu/osdep.h:87,
> from ../migration/global_state.c:13:
> In function ‘strncpy’,
> inlined from ‘global_state_store_running’ at
> ../migration/global_state.c:47:5:
> /usr/include/x86_64-linux-gnu/bits/string_fortified.h:106:10: error:
> ‘__builtin_strncpy’ specified bound 100 equals destination size
> [-Werror=stringop-truncation]
> 106 | return __builtin___strncpy_chk (__dest, __src, __len, __bos
> (__dest));
> |
> ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
>
> ... but we apparently really want to do a strncpy here - the size is already
> checked with the assert() statement right in front of it. To silence the
> warning, simply replace it with our strpadcpy() function.
>
> Suggested-by: Philippe Mathieu-Daudé <philmd@redhat.com> (two years ago)
> Reviewed-by: Philippe Mathieu-Daudé <philmd@redhat.com>
> Signed-off-by: Thomas Huth <thuth@redhat.com>
> ---
> migration/global_state.c | 4 ++--
> 1 file changed, 2 insertions(+), 2 deletions(-)
>
> diff --git a/migration/global_state.c b/migration/global_state.c
> index 25311479a4..a33947ca32 100644
> --- a/migration/global_state.c
> +++ b/migration/global_state.c
> @@ -44,8 +44,8 @@ void global_state_store_running(void)
> {
> const char *state = RunState_str(RUN_STATE_RUNNING);
> assert(strlen(state) < sizeof(global_state.runstate));
> - strncpy((char *)global_state.runstate,
> - state, sizeof(global_state.runstate));
> + strpadcpy((char *)global_state.runstate, sizeof(global_state.runstate),
> + state, '\0');
> }
>
> bool global_state_received(void)
> --
> 2.18.2
>
>
Hi Thomas,
FIY, I couldn't reproduce the complaint from GCC. I've tested it on focal,
"gcc (Ubuntu 9.3.0-10ubuntu2) 9.3.0", with QEMU 5df6c87e8.
After a succesfull "configure --target-list=x86_64-softmmu && meson
compile" build, I tried to manually enable meson's "werror" option,
and found no difference.
Then, I manually ran gcc, with a couple of "-Werror" variations, such
as:
cc -Ilibcommon.fa.p -I. -I../../src/qemu -Iqapi -Itrace -Iui \
-Iui/shader -I/usr/include/libpng16 -I/usr/include/libmount \
-I/usr/include/blkid -I/usr/include/glib-2.0 \
-I/usr/lib/x86_64-linux-gnu/glib-2.0/include \
-I/usr/include/gio-unix-2.0 -I/root/src/qemu/slirp/src -Islirp/src \
-I/usr/include/pixman-1 -I/usr/include/gtk-3.0 \
-I/usr/include/at-spi2-atk/2.0 -I/usr/include/at-spi-2.0 \
-I/usr/include/dbus-1.0 -I/usr/lib/x86_64-linux-gnu/dbus-1.0/include \
-I/usr/include/cairo -I/usr/include/pango-1.0 -I/usr/include/fribidi \
-I/usr/include/harfbuzz -I/usr/include/atk-1.0 -I/usr/include/uuid \
-I/usr/include/freetype2 -I/usr/include/gdk-pixbuf-2.0 -Ilinux-headers \
-fdiagnostics-color=auto -pipe -Wall -Winvalid-pch -Werror \
-Werror=stringop-truncation -std=gnu99 -O2 -g -U_FORTIFY_SOURCE \
-D_FORTIFY_SOURCE=2 -m64 -mcx16 -D_GNU_SOURCE -D_FILE_OFFSET_BITS=64 \
-D_LARGEFILE_SOURCE -Wstrict-prototypes -Wredundant-decls -Wundef \
-Wwrite-strings -Wmissing-prototypes -fno-strict-aliasing -fno-common \
-fwrapv -Wold-style-declaration -Wold-style-definition -Wtype-limits \
-Wformat-security -Wformat-y2k -Winit-self -Wignored-qualifiers \
-Wempty-body -Wnested-externs -Wendif-labels -Wexpansion-to-defined \
-Wno-missing-include-dirs -Wno-shift-negative-value -Wno-psabi \
-fstack-protector-strong -iquote /root/src/qemu/tcg/i386 -isystem \
/root/src/qemu/linux-headers -iquote . -iquote /root/src/qemu -iquote \
/root/src/qemu/accel/tcg -iquote /root/src/qemu/include -iquote \
/root/src/qemu/disas/libvixl -pthread -fPIC -MD -MQ \
libcommon.fa.p/migration_global_state.c.o -MF \
libcommon.fa.p/migration_global_state.c.o.d -o \
libcommon.fa.p/migration_global_state.c.o -c \
../../src/qemu/migration/global_state.c
But I could not trigger the warning (and thus error). The change here
looks good, but I thought I should let you know, and maybe I'm missing
something obvious.
Thanks,
- Cleber.
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- [PATCH 0/6] Update Travis from Xenial to Bionic and Focal, Thomas Huth, 2020/09/18
- [PATCH 1/6] meson: move libudev test, Thomas Huth, 2020/09/18
- [PATCH 2/6] meson: move libmpathpersist test, Thomas Huth, 2020/09/18
- [PATCH 5/6] travis.yml: Update Travis to use Bionic and Focal instead of Xenial, Thomas Huth, 2020/09/18
- [PATCH 4/6] travis.yml: Drop the default softmmu builds, Thomas Huth, 2020/09/18
- [PATCH 3/6] migration: Silence compiler warning in global_state_store_running(), Thomas Huth, 2020/09/18
- Re: [PATCH 3/6] migration: Silence compiler warning in global_state_store_running(),
Cleber Rosa <=
- [PATCH 6/6] travis.yml: Drop the superfluous Python 3.6 build, Thomas Huth, 2020/09/18
- Re: [PATCH 0/6] Update Travis from Xenial to Bionic and Focal, Paolo Bonzini, 2020/09/18
- Re: [PATCH 0/6] Update Travis from Xenial to Bionic and Focal, Alex Bennée, 2020/09/21
- [PATCH 7/6] travis.yml: Drop the Python 3.5 build, Thomas Huth, 2020/09/22