On Sun, Mar 15, 2020 at 5:57 PM Martin KaFai Lau <kafai@xxxxxx> wrote:
>
> A char[] is currently printed as an integer array.
> This patch will print it as a string when
> 1) The array element type is an one byte int
> 2) The array element type has a BTF_INT_CHAR encoding or
> the array element type's name is "char"
> 3) All characters is between (0x1f, 0x7f) and it is terminated
> by a null character.
>
> Signed-off-by: Martin KaFai Lau <kafai@xxxxxx>
> ---
> tools/bpf/bpftool/btf_dumper.c | 41 ++++++++++++++++++++++++++++++++++
> 1 file changed, 41 insertions(+)
>
> diff --git a/tools/bpf/bpftool/btf_dumper.c b/tools/bpf/bpftool/btf_dumper.c
> index 57bd6c0fafc9..1d2d8d2cedea 100644
> --- a/tools/bpf/bpftool/btf_dumper.c
> +++ b/tools/bpf/bpftool/btf_dumper.c
> @@ -77,6 +77,42 @@ static void btf_dumper_enum(const struct btf_dumper *d,
> jsonw_int(d->jw, value);
> }
>
> +static bool is_str_array(const struct btf *btf, const struct btf_array *arr,
> + const char *s)
> +{
> + const struct btf_type *elem_type;
> + const char *end_s;
> +
> + if (!arr->nelems)
> + return false;
> +
> + elem_type = btf__type_by_id(btf, arr->type);
> + /* Not skipping typedef. typedef to char does not count as
> + * a string now.
> + */
> + while (elem_type && btf_is_mod(elem_type))
> + elem_type = btf__type_by_id(btf, elem_type->type);
> +
> + if (!elem_type || !btf_is_int(elem_type) || elem_type->size != 1)
> + return false;
> +
> + if (btf_int_encoding(elem_type) != BTF_INT_CHAR &&
> + strcmp("char", btf__name_by_offset(btf, elem_type->name_off)))
> + return false;
> +
> + end_s = s + arr->nelems;
> + while (s < end_s) {
> + if (!*s)
> + return true;
> + if (*s <= 0x1f || *s >= 0x7f)
> + return false;
> + s++;
> + }
> +
> + /* '\0' is not found */
> + return false;
> +}
> +
> static int btf_dumper_array(const struct btf_dumper *d, __u32 type_id,
> const void *data)
> {
> @@ -86,6 +122,11 @@ static int btf_dumper_array(const struct btf_dumper *d, __u32 type_id,
> int ret = 0;
> __u32 i;
>
> + if (is_str_array(d->btf, arr, data)) {
> + jsonw_string(d->jw, data);
> + return 0;
> + }
> +
Looks good, but curious how the string that contains ' or " will be
output in json? Will it be escaped properly or will result in
malformed JSON?
Acked-by: Andrii Nakryiko <andriin@xxxxxx>
> elem_size = btf__resolve_size(d->btf, arr->type);
> if (elem_size < 0)
> return elem_size;
> --
> 2.17.1
>
