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@xxxxxx> > > > > > > > > > > Acked-by: Pablo Neira Ayuso <pablo@xxxxxxxxxxxxx> > > > > > > > > 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?
