On Wed, 22 May 2019 12:50:51 -0700, Andrii Nakryiko wrote:
> Utilize new libbpf's btf_dump API to emit BTF as a C definitions.
>
> Signed-off-by: Andrii Nakryiko <andr...@fb.com>
> ---
> tools/bpf/bpftool/btf.c | 63 +++++++++++++++++++++++++++++++++++++++--
> 1 file changed, 60 insertions(+), 3 deletions(-)
>
> diff --git a/tools/bpf/bpftool/btf.c b/tools/bpf/bpftool/btf.c
> index a22ef6587ebe..ed3d3221cc78 100644
> --- a/tools/bpf/bpftool/btf.c
> +++ b/tools/bpf/bpftool/btf.c
> @@ -1,5 +1,12 @@
> // SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
> -/* Copyright (C) 2019 Facebook */
> +
> +/*
> + * BTF dumping command.
> + * Load BTF from multiple possible sources and outptu entirety or subset of
> + * types in either raw format or C-syntax format.
> + *
I don't think this header adds any value. Its very unlikely people
will remember to update it. And it's misspelled to begin with.
Please remove.
> + * Copyright (C) 2019 Facebook
> + */
>
> #include <errno.h>
> #include <fcntl.h>
> @@ -340,11 +347,48 @@ static int dump_btf_raw(const struct btf *btf,
> return 0;
> }
>
> +static void btf_dump_printf(void *ctx, const char *fmt, va_list args)
> +{
> + vfprintf(stdout, fmt, args);
> +}
> +
> +static int dump_btf_c(const struct btf *btf,
> + __u32 *root_type_ids, int root_type_cnt)
Please break the line after static int.
> +{
> + struct btf_dump *d;
> + int err = 0, i, id;
Hmm.. why do you have both i and id here? Maybe my eyes are failing me
but it seems either one or the other is used in different branches of
the main if () :)
> + d = btf_dump__new(btf, NULL, NULL, btf_dump_printf);
> + if (IS_ERR(d))
> + return PTR_ERR(d);
> +
> + if (root_type_cnt) {
> + for (i = 0; i < root_type_cnt; i++) {
> + err = btf_dump__dump_type(d, root_type_ids[i]);
> + if (err)
> + goto done;
> + }
> + } else {
> + int cnt = btf__get_nr_types(btf);
> +
> + for (id = 1; id <= cnt; id++) {
> + err = btf_dump__dump_type(d, id);
> + if (err)
> + goto done;
> + }
> + }
> +
> +done:
> + btf_dump__free(d);
> + return err;
What do we do for JSON output?
> +}
> +
> static int do_dump(int argc, char **argv)
> {
> struct btf *btf = NULL;
> __u32 root_type_ids[2];
> int root_type_cnt = 0;
> + bool dump_c = false;
> __u32 btf_id = -1;
> const char *src;
> int fd = -1;
> @@ -431,6 +475,16 @@ static int do_dump(int argc, char **argv)
> goto done;
> }
>
> + while (argc) {
> + if (strcmp(*argv, "c") == 0) {
> + dump_c = true;
> + NEXT_ARG();
> + } else {
> + p_err("unrecognized option: '%s'", *argv);
> + goto done;
> + }
> + }
This code should have checked there are no arguments and return an
error from the start :S
> if (!btf) {
> err = btf__get_from_id(btf_id, &btf);
> if (err) {
> @@ -444,7 +498,10 @@ static int do_dump(int argc, char **argv)
> }
> }
>
> - dump_btf_raw(btf, root_type_ids, root_type_cnt);
> + if (dump_c)
> + dump_btf_c(btf, root_type_ids, root_type_cnt);
> + else
> + dump_btf_raw(btf, root_type_ids, root_type_cnt);
>
> done:
> close(fd);
> @@ -460,7 +517,7 @@ static int do_help(int argc, char **argv)
> }
>
> fprintf(stderr,
> - "Usage: %s btf dump BTF_SRC\n"
> + "Usage: %s btf dump BTF_SRC [c]\n"
bpftool generally uses <key value> formats. So perhaps we could do
something like "[format raw|c]" here for consistency, defaulting to raw?
> " %s btf help\n"
> "\n"
> " BTF_SRC := { id BTF_ID | prog PROG | map MAP [{key |
> value | kv | all}] | file FILE }\n"
