From: Pablo Neira Ayuso <pablo@netfilter.org>
To: Phil Sutter <phil@nwl.cc>, netfilter-devel@vger.kernel.org
Subject: Re: [iptables PATCH] nft: Use ARRAY_SIZE() macro in nft_strerror()
Date: Wed, 23 Oct 2019 22:41:49 +0200 [thread overview]
Message-ID: <20191023204149.vushra6ipmjqqd7c@salvia> (raw)
In-Reply-To: <20191023121627.GM26123@orbyte.nwl.cc>
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.
next prev parent reply other threads:[~2019-10-23 20:41 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-10-18 15:51 [iptables PATCH] nft: Use ARRAY_SIZE() macro in nft_strerror() Phil Sutter
2019-10-23 11:20 ` Pablo Neira Ayuso
2019-10-23 11:23 ` Pablo Neira Ayuso
2019-10-23 12:16 ` Phil Sutter
2019-10-23 20:41 ` Pablo Neira Ayuso [this message]
2019-10-24 8:45 ` Phil Sutter
2019-10-24 9:29 ` Pablo Neira Ayuso
2019-10-24 9:51 ` Phil Sutter
2019-10-24 10:01 ` Pablo Neira Ayuso
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