Re: nftables-20140407 compilation error

[Florian Westphal <fw@strlen.de>]

Pablo Neira Ayuso <pablo@netfilter.org> wrote:
> > > src/scanner.o: In function `nft_realloc':
> > > /home/nwd/lab/nftables/nftables-20140407/<stdout>:4260: undefined
> > > reference to `rpl_realloc'
> > 
> > This happens when configure thinks malloc/realloc are missing.
> > 
> > Any objetions wrt. removing AC_FUNC_MALLOC/AC_FUNC_REALLOC from
> > nftables configure.ac?
> 
> If that resolves the problem, please go ahead, thanks Florian.

The problem is two-fold.  When libnftnl has just been installed and
is not yet in linker path, the malloc/realloc test will fail:

configure:4557: gcc -o conftest -I/usr/local/libnftnl/include
-L/usr/local/libnftnl/lib conftest.c -lreadline -lgmp -lnftnl -lmnl  >&5
configure:4557: $? = 0
configure:4557: ./conftest
./conftest: error while loading shared libraries: libnftnl.so.0: cannot
open shared object file: No such file or directory

That error is only in config.log, and config.h redefines malloc/realloc
with rpl_ prefix, which then yields the mysterious
'undefined reference to `rpl_realloc'' error when compiling nftables.

The 2nd problem is that the macro executes the built program, which has
the usual cross-compiling issue.

AFAIU these macros are only useful to check if malloc(0) returns
non-NULL and that realloc(NULL, .. works, hence the question if these
should just be removed.