On Sat, 2024-04-13 at 23:39 +0200, Quentin Deslandes wrote:
> Introduce the new print_strings flag in btf_dump_type_data_opts. If
> enabled, libbpf will print character arrays as strings if they meet the
> following conditions:
> - Contains a nul-termination character ('\0')
> - Contains only printable characters before the nul-termination character
>
> If print_strings is set to false (default value), the existing
> behavior remains unchanged.
>
> With print_strings=false:
> .str_array = (__u8[14])[
> 'H',
> 'e',
> 'l',
> 'l',
> 'o',
> ],
>
> With print_strings=true:
> .str_array = (__u8[14])"Hello",
>
> Signed-off-by: Quentin Deslandes <qde@xxxxxxxx>
> ---
Hi Quentin,
Thank you for this patch, sorry for the delay reviewing it.
Could you please also add a few tests in
tools/testing/selftests/bpf/prog_tests/btf_dump.c ?
[...]
> @@ -2021,6 +2022,21 @@ static int btf_dump_var_data(struct btf_dump *d,
> return btf_dump_dump_type_data(d, NULL, t, type_id, data, 0, 0);
> }
>
> +static bool btf_dump_isprint_str(const char *data, unsigned int len)
> +{
> + unsigned int i;
> +
> + for (i = 0; i < len; ++i) {
> + if (data[i] == '\0')
> + return true;
> +
> + if (!isprint(data[i]))
> + return false;
Would it make sense to use isprint_l() and specify something like C locale?
> + }
> +
> + return false;
> +}
> +
> static int btf_dump_array_data(struct btf_dump *d,
> const struct btf_type *t,
> __u32 id,
> @@ -2047,8 +2063,14 @@ static int btf_dump_array_data(struct btf_dump *d,
> * char arrays, so if size is 1 and element is
> * printable as a char, we'll do that.
> */
> - if (elem_size == 1)
> + if (elem_size == 1) {
> d->typed_dump->is_array_char = true;
> + if (d->typed_dump->print_strings &&
> + btf_dump_isprint_str(data, array->nelems)) {
> + btf_dump_type_values(d, "\"%s\"", data);
Note: this would have to deal with escape sequences,
otherwise strings containing '\' would be printed incorrectly.
> + return 0;
> + }
> + }
> }
>
> /* note that we increment depth before calling btf_dump_print() below;
[...]
