Re: [PATCH v1 00/10] Define _GNU_SOURCE for sources using

[Kees Cook <keescook@xxxxxxxxxxxx>]

On Wed, May 01, 2024 at 06:24:36AM -0700, Sean Christopherson wrote:
> On Wed, May 01, 2024, Mark Brown wrote:
> > On Tue, Apr 30, 2024 at 11:50:09PM +0000, Edward Liaw wrote:
> > > 809216233555 ("selftests/harness: remove use of LINE_MAX") introduced
> > > asprintf into kselftest_harness.h, which is a GNU extension and needs
> > > _GNU_SOURCE to either be defined prior to including headers or with the
> > > -D_GNU_SOURCE flag passed to the compiler.
> > 
> > This seems like something that should be handled centrally rather than
> > having to go round and audit the users every time some update is made.
> 
> +1.
> 
> And if for some reason unilaterally defining _GNU_SOURCE in
> tools/testing/selftests/lib.mk isn't an option, we should at least have
> kselftest_harness.h assert instead of making a futile attempt to provide its own
> definition, e.g.
> 
> diff --git a/tools/testing/selftests/kselftest_harness.h b/tools/testing/selftests/kselftest_harness.h
> index 4fd735e48ee7..6741b4f20f25 100644
> --- a/tools/testing/selftests/kselftest_harness.h
> +++ b/tools/testing/selftests/kselftest_harness.h
> @@ -51,7 +51,7 @@
>  #define __KSELFTEST_HARNESS_H
>  
>  #ifndef _GNU_SOURCE
> -#define _GNU_SOURCE
> +static_assert(0, "Using the kselftests harness requires building with _GNU_SOURCE");
>  #endif
>  #include <asm/types.h>
>  #include <ctype.h>

Yeah, let's fix centrally. I like this approach.

-- 
Kees Cook