On Tue, Mar 17, 2020 at 8:15 PM Martin KaFai Lau <kafai@xxxxxx> wrote:
>
> This patch prints the enum's name if there is one found in
> the array of btf_enum.
>
> The commit 9eea98497951 ("bpf: fix BTF verification of enums")
> has details about an enum could have any power-of-2 size (up to 8 bytes).
> This patch also takes this chance to accommodate these non 4 byte
> enums.
>
> Acked-by: Quentin Monnet <quentin@xxxxxxxxxxxxx>
> Signed-off-by: Martin KaFai Lau <kafai@xxxxxx>
> ---
> tools/bpf/bpftool/btf_dumper.c | 39 +++++++++++++++++++++++++++++++---
> 1 file changed, 36 insertions(+), 3 deletions(-)
>
> diff --git a/tools/bpf/bpftool/btf_dumper.c b/tools/bpf/bpftool/btf_dumper.c
> index 01cc52b834fa..079f9171b1a3 100644
> --- a/tools/bpf/bpftool/btf_dumper.c
> +++ b/tools/bpf/bpftool/btf_dumper.c
> @@ -43,9 +43,42 @@ static int btf_dumper_modifier(const struct btf_dumper *d, __u32 type_id,
> return btf_dumper_do_type(d, actual_type_id, bit_offset, data);
> }
>
> -static void btf_dumper_enum(const void *data, json_writer_t *jw)
> +static void btf_dumper_enum(const struct btf_dumper *d,
> + const struct btf_type *t,
> + const void *data)
> {
> - jsonw_printf(jw, "%d", *(int *)data);
> + const struct btf_enum *enums = btf_enum(t);
> + __s64 value;
> + __u16 i;
> +
> + switch (t->size) {
> + case 8:
> + value = *(__s64 *)data;
> + break;
> + case 4:
> + value = *(__s32 *)data;
> + break;
> + case 2:
> + value = *(__s16 *)data;
> + break;
> + case 1:
> + value = *(__s8 *)data;
> + break;
> + default:
> + jsonw_string(d->jw, "<invalid_enum_size>");
Why not return error and let it propagate, similar to how
btf_dumper_array() can return an error? BTF is malformed if this
happened, so there is no point in continuing dumping, it's most
probably going to be a garbage.
> + return;
> + }
> +
> + for (i = 0; i < btf_vlen(t); i++) {
> + if (value == enums[i].val) {
> + jsonw_string(d->jw,
> + btf__name_by_offset(d->btf,
> + enums[i].name_off));
nit: local variable will make it cleaner
> + return;
> + }
> + }
> +
> + jsonw_int(d->jw, value);
> }
>
> static int btf_dumper_array(const struct btf_dumper *d, __u32 type_id,
> @@ -366,7 +399,7 @@ static int btf_dumper_do_type(const struct btf_dumper *d, __u32 type_id,
> case BTF_KIND_ARRAY:
> return btf_dumper_array(d, type_id, data);
> case BTF_KIND_ENUM:
> - btf_dumper_enum(data, d->jw);
> + btf_dumper_enum(d, t, data);
> return 0;
> case BTF_KIND_PTR:
> btf_dumper_ptr(data, d->jw, d->is_plain_text);
> --
> 2.17.1
>
