Re: [PATCH dwarves] libbpf: allow to use packaged version

[Andrii Nakryiko <andrii.nakryiko@gmail.com>]

On Thu, Jan 21, 2021 at 5:29 AM Arnaldo Carvalho de Melo
<arnaldo.melo@gmail.com> wrote:
>
> Em Mon, Jan 04, 2021 at 10:17:36PM +0000, Luca Boccassi escreveu:
> > On Mon, 2021-01-04 at 12:23 -0800, Andrii Nakryiko wrote:
> > > On Sun, Jan 3, 2021 at 1:30 PM Luca Boccassi <bluca@debian.org>
> > > > > >  #include "dutil.h"
> > > > > > +#ifdef LIBBPF_FOUND
> > > > > > +#include <bpf/libbpf.h>
> > > > > > +#else
> > > > > >  #include "lib/bpf/src/libbpf.h"
> > > > > > +#endif
>
> > > > > this is horrible, are you sure there is no way to make
> > > > > <bpf/libbpf.h>
> > > > > work for both cases?
>
> > > > It really is, but unfortunately I don't see other ways that are
> > > > not just as horrible. Suggestions welcome. The only thing I can
> > > > think of, is if libbpf used the same directory hierarchy in-tree
> > > > as it does in the installed tree. Ie: move those headers from
> > > > libbpf/src/foo.h to libbpf/include/bpf/foo.h. Then we would just
> > > > have the - Ilib/bpf/include in CPPFLAGS for the embedded build
> > > > defined in the CMake files, and the sources would only use the
> > > > "system" includes everywhere, without ifdeffery.
>
> > > > Given you maintain libbpf, would that be something you'd accept?
> > > > It's quite a common pattern for libraries to store their public
> > > > headers in a separate directory in the git tree, after all.
>
> > > It's quite risky, as there are plenty of (sometimes private)
> > > integrations that assume such a layout of libbpf, so we'll be
> > > breaking them badly. Makefile-based projects do `make
> > > install_headers` to put *only exported* headers into the desired
> > > location. I'm not sure what's the best way to achieve the same with
> > > Cmake, though.
>
> > > One quick and easy hack would be to put a symlink lib/include/bpf ->
> > > lib/bpf/src into pahole repo. And add -Ilib/include to let compiler
> > > handle <bpf/*.h> properly.
>
> > Sure, that works for me if it's acceptable as a solution. Sent v3 that
> > implements it. Thanks for the suggestion.
>
> Andrii, can I have your Reviewed-by or Acked-by for v3?

Well, I still think it's not good and not necessary for pahole. pahole
doesn't run under root. It's not a networking application open to the
world either. So I don't buy security arguments in this case at all.
So no, feel free to push this, but without my ack.

>
> I have it in my local repo and will push publicly later today after I
> perform tests.

While on the subject, do you have plans to release 1.20 any time soon?
I'm holding off until 1.20 is available to sync it internally to be
used for our kernels. Would be nice to get this off my head :)

>
> - Arnaldo