Re: [PATCH bpf-next v2] tools/bpf: make libbpf _GNU_SOURCE friendly

[Jakub Kicinski <jakub.kicinski@netronome.com>]

On Thu, 29 Nov 2018 15:31:45 -0800, Yonghong Song wrote:
> During porting libbpf to bcc, I got some warnings like below:
>   ...
>   [  2%] Building C object src/cc/CMakeFiles/bpf-shared.dir/libbpf/src/libbpf.c.o
>   /home/yhs/work/bcc2/src/cc/libbpf/src/libbpf.c:12:0:
>   warning: "_GNU_SOURCE" redefined [enabled by default]
>    #define _GNU_SOURCE
>   ...
>   [  3%] Building C object src/cc/CMakeFiles/bpf-shared.dir/libbpf/src/libbpf_errno.c.o
>   /home/yhs/work/bcc2/src/cc/libbpf/src/libbpf_errno.c: In function ‘libbpf_strerror’:
>   /home/yhs/work/bcc2/src/cc/libbpf/src/libbpf_errno.c:45:7:
>   warning: assignment makes integer from pointer without a cast [enabled by default]
>      ret = strerror_r(err, buf, size);
>   ...
> 
> bcc is built with _GNU_SOURCE defined and this caused the above warning.
> This patch intends to make libpf _GNU_SOURCE friendly by
>   . define _GNU_SOURCE in libbpf.c unless it is not defined
>   . undefine _GNU_SOURCE as non-gnu version of strerror_r is expected.
> 
> Signed-off-by: Yonghong Song <yhs@fb.com>

Acked-by: Jakub Kicinski <jakub.kicinski@netronome.com>

FWIW :)