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>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
b42699547f