Hi Pablo,
On 4/5/21 11:44 PM, Pablo Neira Ayuso wrote:
Then we still have the issue that ARRAY_SIZE is not defined in that
header (see a simple test below). You should probably include some
header that provides it.
SCTP_CHUNKMAP_IS_* macros are used from iptables/extensions/xt_sctp.h
(iptables userspace codebase). These macros are also used internally
from net/netfilter/xt_sctp.c. It's using a rather unorthodox trick to
share code between the kernel and userspace, otherwise iptables would
need to keep a copy of this code.
BTW, why do you need xt_sctp.h for the manpages? This header is rather
specific to the match on sctp from the xtables infrastructure, so it's
not so useful from a programmer perspective (manpages) I think.
I don't need it. Actually, I was fixing the includes in the SYNOPSIS,
and when I was grepping for some variable (I don't even remember which
one), the search brought me at some point to this header, where the use
of ARRAY_SIZE() caught my attention :-)
But again, if no one noticed this in more than a decade, either no one
used this macro, or they included other headers in the same file where
they used the macro. So I'd still rethink if maybe that macro (and
possibly others) is really needed.
Test 1:
[[
$ cat test.c
#include <linux/netfilter/xt_sctp.h>
int foo(int x)
{
int a[x];
return ARRAY_SIZE(a);
}
$ cc -Wall -Wextra -Werror test.c -S -o test.s
test.c: In function ‘foo’:
test.c:7:9: error: implicit declaration of function ‘ARRAY_SIZE’
[-Werror=implicit-function-declaration]
7 | return ARRAY_SIZE(a);
| ^~~~~~~~~~
cc1: all warnings being treated as errors
$
]]
I see, this is breaking self-compilation of the headers.
If there a need to remove xt_sctp.h from the ignore-list of the header
self-compilation infrastructure, it should be possible to fix
userspace to keep its own copy and probably add a #warn on the UAPI
header to let other possible consumers of this macro that this macro
will go away at some point.
Well, I ignore what is this header for; I was just reporting something
that I casually found and might be a bug. I'll leave the fix to you ;)
Cheers,
Alex
--
Alejandro Colomar
Linux man-pages comaintainer; https://www.kernel.org/doc/man-pages/
http://www.alejandro-colomar.es/
