[PATCH v14 bpf-next 6/6] selftests/bpf: Add test that uses fsverity and xattr to sign a file

[Alexei Starovoitov]

On Tue, Nov 28, 2023 at 4:37 PM Song Liu <song at kernel.org> wrote:
> +char digest[MAGIC_SIZE + sizeof(struct fsverity_digest) + SHA256_DIGEST_SIZE];

when vmlinux is built without CONFIG_FS_VERITY the above fails
in a weird way:
  CLNG-BPF [test_maps] test_sig_in_xattr.bpf.o
progs/test_sig_in_xattr.c:36:26: error: invalid application of
'sizeof' to an incomplete type 'struct fsverity_digest'
   36 | char digest[MAGIC_SIZE + sizeof(struct fsverity_digest) +
SHA256_DIGEST_SIZE];
      |                          ^     ~~~~~~~~~~~~~~~~~~~~~~~~

Is there a way to somehow print a hint during the build what
configs users need to enable to pass the build ?