Subject: Re: [PATCH bpf-next] bpftool: btf: Support dumping a single type from file

From: Martin KaFai Lau <[email-masked]>
Date: Fri, 6 Dec 2024 17:50:51 -0800

On 12/6/24 3:29 PM, Daniel Xu wrote:
> diff --git a/tools/bpf/bpftool/btf.c b/tools/bpf/bpftool/btf.c
> index d005e4fd6128..668ff0d10469 100644
> --- a/tools/bpf/bpftool/btf.c
> +++ b/tools/bpf/bpftool/btf.c
> @@ -953,6 +953,7 @@ static int do_dump(int argc, char **argv)
>   		NEXT_ARG();
>   	} else if (is_prefix(src, "file")) {
>   		const char sysfs_prefix[] = "/sys/kernel/btf/";
> +		char *end;
>   
>   		if (!base_btf &&
>   		    strncmp(*argv, sysfs_prefix, sizeof(sysfs_prefix) - 1) == 0 &&
> @@ -967,6 +968,17 @@ static int do_dump(int argc, char **argv)
>   			goto done;
>   		}
>   		NEXT_ARG();
> +
> +		if (argc && is_prefix(*argv, "root_id")) {
> +			NEXT_ARG();
> +			root_type_ids[root_type_cnt++] = strtoul(*argv, &end, 0);

I only looked at the do_dump(). Other existing root_type_ids are from the kernel 
map_get_info and they should be valid. I haven't looked at the dump_btf_*, so 
ask a lazy question, is an invalid root_id handled properly?

Others lgtm.

> +			if (*end) {
> +				err = -1;
> +				p_err("can't parse %s as root ID", *argv);
> +				goto done;
> +			}
> +			NEXT_ARG();
> +		}
>   	} else {
>   		err = -1;
>   		p_err("unrecognized BTF source specifier: '%s'", src);