Andrii Nakryiko <andr...@fb.com> writes:
> Add new set of bpf_object__open APIs using new approach to optional
> parameters extensibility allowing simpler ABI compatibility approach.
>
> This patch demonstrates an approach to implementing libbpf APIs that
> makes it easy to extend existing APIs with extra optional parameters in
> such a way, that ABI compatibility is preserved without having to do
> symbol versioning and generating lots of boilerplate code to handle it.
> To facilitate succinct code for working with options, add OPTS_VALID,
> OPTS_HAS, and OPTS_GET macros that hide all the NULL, size, and zero
> checks.
>
> Additionally, newly added libbpf APIs are encouraged to follow similar
> pattern of having all mandatory parameters as formal function parameters
> and always have optional (NULL-able) xxx_opts struct, which should
> always have real struct size as a first field and the rest would be
> optional parameters added over time, which tune the behavior of existing
> API, if specified by user.
>
> Signed-off-by: Andrii Nakryiko <andr...@fb.com>
> ---
> tools/lib/bpf/libbpf.c | 51 ++++++++++++++++++++++++++++-----
> tools/lib/bpf/libbpf.h | 36 +++++++++++++++++++++--
> tools/lib/bpf/libbpf.map | 3 ++
> tools/lib/bpf/libbpf_internal.h | 32 +++++++++++++++++++++
> 4 files changed, 112 insertions(+), 10 deletions(-)
>
> diff --git a/tools/lib/bpf/libbpf.c b/tools/lib/bpf/libbpf.c
> index 056769ce4fd0..503fba903e99 100644
> --- a/tools/lib/bpf/libbpf.c
> +++ b/tools/lib/bpf/libbpf.c
> @@ -3620,16 +3620,33 @@ struct bpf_object *bpf_object__open(const char *path)
> return bpf_object__open_xattr(&attr);
> }
>
> -struct bpf_object *bpf_object__open_buffer(void *obj_buf,
> - size_t obj_buf_sz,
> - const char *name)
> +struct bpf_object *
> +bpf_object__open_file(const char *path, struct bpf_object_open_opts *opts)
> +{
> + if (!OPTS_VALID(opts, bpf_object_open_opts))
> + return ERR_PTR(-EINVAL);
> + if (!path)
> + return ERR_PTR(-EINVAL);
> +
> + pr_debug("loading %s\n", path);
> +
> + return __bpf_object__open(path, NULL, 0, 0);
> +}
This is not doing anything with opts...
[...]
> +struct bpf_object_open_opts {
> + /* size of this struct, for forward/backward compatiblity */
> + size_t sz;
> + /* object name override, if provided:
> + * - for object open from file, this will override setting object
> + * name from file path's base name;
... but this says it should be, no?
-Toke
