Re: [PATCH bpf-next 4/5] libbpf: Introduce a BPF_SNPRINTF helper macro

[Andrii Nakryiko]

On Wed, Mar 10, 2021 at 2:02 PM Florent Revest <revest@xxxxxxxxxxxx> wrote:
>
> Similarly to BPF_SEQ_PRINTF, this macro turns variadic arguments into an
> array of u64, making it more natural to call the bpf_snprintf helper.
>
> Signed-off-by: Florent Revest <revest@xxxxxxxxxxxx>
> ---
>  tools/lib/bpf/bpf_tracing.h | 15 +++++++++++++++
>  1 file changed, 15 insertions(+)
>
> diff --git a/tools/lib/bpf/bpf_tracing.h b/tools/lib/bpf/bpf_tracing.h
> index f6a2deb3cd5b..89e82da9b8a0 100644
> --- a/tools/lib/bpf/bpf_tracing.h
> +++ b/tools/lib/bpf/bpf_tracing.h
> @@ -457,4 +457,19 @@ static __always_inline typeof(name(0)) ____##name(struct pt_regs *ctx, ##args)
>                 ___ret;                                                     \
>         })
>
> +/*
> + * BPF_SNPRINTF wraps the bpf_snprintf helper with variadic arguments instead of
> + * an array of u64.
> + */
> +#define BPF_SNPRINTF(out, out_size, fmt, args...)                          \
> +       ({                                                                  \
> +               _Pragma("GCC diagnostic push")                              \
> +               _Pragma("GCC diagnostic ignored \"-Wint-conversion\"")      \
> +               ___bpf_build_param(args);                                   \
> +               _Pragma("GCC diagnostic pop")                               \
> +               int ___ret = bpf_snprintf(out, out_size, fmt,               \
> +                                           ___param, sizeof(___param));    \

same problem, mixing variable declarations and code

> +               ___ret;                                                     \
> +       })
> +
>  #endif
> --
> 2.30.1.766.gb4fecdf3b7-goog
>