Variable 'table' is an array of type struct table_struct, so this is a classical use-case for ARRAY_SIZE() macro. Signed-off-by: Phil Sutter <phil@nwl.cc> --- iptables/nft.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/iptables/nft.c b/iptables/nft.c index 89b1c7a808f57..3c230c121f8b9 100644 --- a/iptables/nft.c +++ b/iptables/nft.c @@ -2888,7 +2888,7 @@ const char *nft_strerror(int err) { NULL, ENOENT, "No chain/target/match by that name" }, }; - for (i = 0; i < sizeof(table)/sizeof(struct table_struct); i++) { + for (i = 0; i < ARRAY_SIZE(table); i++) { if ((!table[i].fn || table[i].fn == nft_fn) && table[i].err == err) return table[i].message; -- 2.23.0
On Fri, Oct 18, 2019 at 05:51:14PM +0200, Phil Sutter wrote:
> Variable 'table' is an array of type struct table_struct, so this is a
> classical use-case for ARRAY_SIZE() macro.
>
> Signed-off-by: Phil Sutter <phil@nwl.cc>
Acked-by: Pablo Neira Ayuso <pablo@netfilter.org>
On Wed, Oct 23, 2019 at 01:20:24PM +0200, Pablo Neira Ayuso wrote: > On Fri, Oct 18, 2019 at 05:51:14PM +0200, Phil Sutter wrote: > > Variable 'table' is an array of type struct table_struct, so this is a > > classical use-case for ARRAY_SIZE() macro. > > > > Signed-off-by: Phil Sutter <phil@nwl.cc> > > Acked-by: Pablo Neira Ayuso <pablo@netfilter.org> BTW, probably good to add the array check? https://sourceforge.net/p/libhx/libhx/ci/master/tree/include/libHX/defs.h#l152
Hi Pablo,
On Wed, Oct 23, 2019 at 01:23:11PM +0200, Pablo Neira Ayuso wrote:
> On Wed, Oct 23, 2019 at 01:20:24PM +0200, Pablo Neira Ayuso wrote:
> > On Fri, Oct 18, 2019 at 05:51:14PM +0200, Phil Sutter wrote:
> > > Variable 'table' is an array of type struct table_struct, so this is a
> > > classical use-case for ARRAY_SIZE() macro.
> > >
> > > Signed-off-by: Phil Sutter <phil@nwl.cc>
> >
> > Acked-by: Pablo Neira Ayuso <pablo@netfilter.org>
>
> BTW, probably good to add the array check?
>
> https://sourceforge.net/p/libhx/libhx/ci/master/tree/include/libHX/defs.h#l152
Copying from kernel sources, do you think that's fine?
| # ifndef ARRAY_SIZE
| -# define ARRAY_SIZE(x) (sizeof(x) / sizeof(*(x)))
| +# define BUILD_BUG_ON_ZERO(e) (sizeof(struct { int:(-!!(e)); }))
| +# define __same_type(a, b) \
| + __builtin_types_compatible_p(typeof(a), typeof(b))
| +/* &a[0] degrades to a pointer: a different type from an array */
| +# define __must_be_array(a) \
| + BUILD_BUG_ON_ZERO(__same_type((a), &(a)[0]))
| +# define ARRAY_SIZE(x) (sizeof(x) / sizeof(*(x))) + __must_be_array(x)
| # endif
Cheers, Phil
On Wed, Oct 23, 2019 at 02:16:27PM +0200, Phil Sutter wrote:
> Hi Pablo,
>
> On Wed, Oct 23, 2019 at 01:23:11PM +0200, Pablo Neira Ayuso wrote:
> > On Wed, Oct 23, 2019 at 01:20:24PM +0200, Pablo Neira Ayuso wrote:
> > > On Fri, Oct 18, 2019 at 05:51:14PM +0200, Phil Sutter wrote:
> > > > Variable 'table' is an array of type struct table_struct, so this is a
> > > > classical use-case for ARRAY_SIZE() macro.
> > > >
> > > > Signed-off-by: Phil Sutter <phil@nwl.cc>
> > >
> > > Acked-by: Pablo Neira Ayuso <pablo@netfilter.org>
> >
> > BTW, probably good to add the array check?
> >
> > https://sourceforge.net/p/libhx/libhx/ci/master/tree/include/libHX/defs.h#l152
>
> Copying from kernel sources, do you think that's fine?
>
> | # ifndef ARRAY_SIZE
> | -# define ARRAY_SIZE(x) (sizeof(x) / sizeof(*(x)))
> | +# define BUILD_BUG_ON_ZERO(e) (sizeof(struct { int:(-!!(e)); }))
> | +# define __same_type(a, b) \
> | + __builtin_types_compatible_p(typeof(a), typeof(b))
> | +/* &a[0] degrades to a pointer: a different type from an array */
> | +# define __must_be_array(a) \
> | + BUILD_BUG_ON_ZERO(__same_type((a), &(a)[0]))
> | +# define ARRAY_SIZE(x) (sizeof(x) / sizeof(*(x))) + __must_be_array(x)
> | # endif
At quick glance I would say that's fine.
Hi,
On Wed, Oct 23, 2019 at 10:41:49PM +0200, Pablo Neira Ayuso wrote:
> On Wed, Oct 23, 2019 at 02:16:27PM +0200, Phil Sutter wrote:
> > Hi Pablo,
> >
> > On Wed, Oct 23, 2019 at 01:23:11PM +0200, Pablo Neira Ayuso wrote:
> > > On Wed, Oct 23, 2019 at 01:20:24PM +0200, Pablo Neira Ayuso wrote:
> > > > On Fri, Oct 18, 2019 at 05:51:14PM +0200, Phil Sutter wrote:
> > > > > Variable 'table' is an array of type struct table_struct, so this is a
> > > > > classical use-case for ARRAY_SIZE() macro.
> > > > >
> > > > > Signed-off-by: Phil Sutter <phil@nwl.cc>
> > > >
> > > > Acked-by: Pablo Neira Ayuso <pablo@netfilter.org>
> > >
> > > BTW, probably good to add the array check?
> > >
> > > https://sourceforge.net/p/libhx/libhx/ci/master/tree/include/libHX/defs.h#l152
> >
> > Copying from kernel sources, do you think that's fine?
> >
> > | # ifndef ARRAY_SIZE
> > | -# define ARRAY_SIZE(x) (sizeof(x) / sizeof(*(x)))
> > | +# define BUILD_BUG_ON_ZERO(e) (sizeof(struct { int:(-!!(e)); }))
> > | +# define __same_type(a, b) \
> > | + __builtin_types_compatible_p(typeof(a), typeof(b))
> > | +/* &a[0] degrades to a pointer: a different type from an array */
> > | +# define __must_be_array(a) \
> > | + BUILD_BUG_ON_ZERO(__same_type((a), &(a)[0]))
> > | +# define ARRAY_SIZE(x) (sizeof(x) / sizeof(*(x))) + __must_be_array(x)
> > | # endif
>
> At quick glance I would say that's fine.
While testing it, I noticed that gcc has a builtin check already:
| ../include/xtables.h:640:36: warning: division 'sizeof (const uint32_t * {aka const unsigned int *}) / sizeof (uint32_t {aka const unsigned int})' does not compute the number of array elements [-Wsizeof-pointer-div]
| 640 | # define ARRAY_SIZE(x) (sizeof(x) / sizeof(*(x)))
| | ^
| nft.c:914:18: note: in expansion of macro 'ARRAY_SIZE'
| 914 | for (i = 1; i < ARRAY_SIZE(multp); i++) {
| | ^~~~~~~~~~
| nft.c:906:25: note: first 'sizeof' operand was declared here
| 906 | static const uint32_t *multp = mult;
| | ^~~~~
AFAICT, the only benefit the above brings is that it causes an error
instead of warning. Do you think we still need it? Maybe instead enable
-Werror? ;)
Cheers, Phil
On Thu, Oct 24, 2019 at 10:45:03AM +0200, Phil Sutter wrote:
> Hi,
>
> On Wed, Oct 23, 2019 at 10:41:49PM +0200, Pablo Neira Ayuso wrote:
> > On Wed, Oct 23, 2019 at 02:16:27PM +0200, Phil Sutter wrote:
> > > Hi Pablo,
> > >
> > > On Wed, Oct 23, 2019 at 01:23:11PM +0200, Pablo Neira Ayuso wrote:
> > > > On Wed, Oct 23, 2019 at 01:20:24PM +0200, Pablo Neira Ayuso wrote:
> > > > > On Fri, Oct 18, 2019 at 05:51:14PM +0200, Phil Sutter wrote:
> > > > > > Variable 'table' is an array of type struct table_struct, so this is a
> > > > > > classical use-case for ARRAY_SIZE() macro.
> > > > > >
> > > > > > Signed-off-by: Phil Sutter <phil@nwl.cc>
> > > > >
> > > > > Acked-by: Pablo Neira Ayuso <pablo@netfilter.org>
> > > >
> > > > BTW, probably good to add the array check?
> > > >
> > > > https://sourceforge.net/p/libhx/libhx/ci/master/tree/include/libHX/defs.h#l152
> > >
> > > Copying from kernel sources, do you think that's fine?
> > >
> > > | # ifndef ARRAY_SIZE
> > > | -# define ARRAY_SIZE(x) (sizeof(x) / sizeof(*(x)))
> > > | +# define BUILD_BUG_ON_ZERO(e) (sizeof(struct { int:(-!!(e)); }))
> > > | +# define __same_type(a, b) \
> > > | + __builtin_types_compatible_p(typeof(a), typeof(b))
> > > | +/* &a[0] degrades to a pointer: a different type from an array */
> > > | +# define __must_be_array(a) \
> > > | + BUILD_BUG_ON_ZERO(__same_type((a), &(a)[0]))
> > > | +# define ARRAY_SIZE(x) (sizeof(x) / sizeof(*(x))) + __must_be_array(x)
> > > | # endif
> >
> > At quick glance I would say that's fine.
>
> While testing it, I noticed that gcc has a builtin check already:
>
> | ../include/xtables.h:640:36: warning: division 'sizeof (const uint32_t * {aka const unsigned int *}) / sizeof (uint32_t {aka const unsigned int})' does not compute the number of array elements [-Wsizeof-pointer-div]
> | 640 | # define ARRAY_SIZE(x) (sizeof(x) / sizeof(*(x)))
> | | ^
> | nft.c:914:18: note: in expansion of macro 'ARRAY_SIZE'
> | 914 | for (i = 1; i < ARRAY_SIZE(multp); i++) {
> | | ^~~~~~~~~~
> | nft.c:906:25: note: first 'sizeof' operand was declared here
> | 906 | static const uint32_t *multp = mult;
> | | ^~~~~
>
> AFAICT, the only benefit the above brings is that it causes an error
> instead of warning. Do you think we still need it? Maybe instead enable
> -Werror? ;)
If gcc is already checking for this. Warning should be fine.
Regarding -Werror, we would at least need to keep the autogenerated C
code by bison away from it.
IIRC I enabled this in conntrack-tools long time ago, and I started
getting reports on it breaking compilation with new gcc versions that
were actually spewing new warnings. That was stopping users to install
latest, probably -Werror is too agressive?
Hey, On Thu, Oct 24, 2019 at 11:29:03AM +0200, Pablo Neira Ayuso wrote: [...] > If gcc is already checking for this. Warning should be fine. > > Regarding -Werror, we would at least need to keep the autogenerated C > code by bison away from it. In nftables there is libparser_la_CFLAGS which holds quite some exclusions already and could be used to pass -Wno-error as well. (Maybe a good idea to add this regardless of whether we set -Werror by default or not.) > IIRC I enabled this in conntrack-tools long time ago, and I started > getting reports on it breaking compilation with new gcc versions that > were actually spewing new warnings. That was stopping users to install > latest, probably -Werror is too agressive? Yes, I wasn't completely serious. Breaking users' builds for things they may not be in control of is not the best idea. We could instead add a configure option to enable strict mode, but checking for warnings is something I usually do so probably not that important after all. Cheers, Phil
On Thu, Oct 24, 2019 at 11:51:01AM +0200, Phil Sutter wrote:
> Hey,
>
> On Thu, Oct 24, 2019 at 11:29:03AM +0200, Pablo Neira Ayuso wrote:
> [...]
> > If gcc is already checking for this. Warning should be fine.
> >
> > Regarding -Werror, we would at least need to keep the autogenerated C
> > code by bison away from it.
>
> In nftables there is libparser_la_CFLAGS which holds quite some
> exclusions already and could be used to pass -Wno-error as well. (Maybe
> a good idea to add this regardless of whether we set -Werror by default
> or not.)
>
> > IIRC I enabled this in conntrack-tools long time ago, and I started
> > getting reports on it breaking compilation with new gcc versions that
> > were actually spewing new warnings. That was stopping users to install
> > latest, probably -Werror is too agressive?
>
> Yes, I wasn't completely serious. Breaking users' builds for things they
> may not be in control of is not the best idea. We could instead add a
> configure option to enable strict mode, but checking for warnings is
> something I usually do so probably not that important after all.
Indeed. So let's leave things as is then.