bpftool: add C output format option to btf dump subcommand

Utilize new libbpf's btf_dump API to emit BTF as a C definitions.

Acked-by: Jakub Kicinski <jakub.kicinski@netronome.com>
Signed-off-by: Andrii Nakryiko <andriin@fb.com>
Reviewed-by: Quentin Monnet <quentin.monnet@netronome.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>

diff --git a/tools/bpf/bpftool/btf.c b/tools/bpf/bpftool/btf.c
index a22ef65..1b8ec91 100644 (file)
--- a/tools/bpf/bpftool/btf.c
+++ b/tools/bpf/bpftool/btf.c
@@ -340,11 +340,49 @@ static int dump_btf_raw(const struct btf *btf,
        return 0;
 }
 
+static void __printf(2, 0) 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)
+{
+       struct btf_dump *d;
+       int err = 0, i;
+
+       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 (i = 1; i <= cnt; i++) {
+                       err = btf_dump__dump_type(d, i);
+                       if (err)
+                               goto done;
+               }
+       }
+
+done:
+       btf_dump__free(d);
+       return err;
+}
+
 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 +469,29 @@ static int do_dump(int argc, char **argv)
                goto done;
        }
 
+       while (argc) {
+               if (is_prefix(*argv, "format")) {
+                       NEXT_ARG();
+                       if (argc < 1) {
+                               p_err("expecting value for 'format' option\n");
+                               goto done;
+                       }
+                       if (strcmp(*argv, "c") == 0) {
+                               dump_c = true;
+                       } else if (strcmp(*argv, "raw") == 0) {
+                               dump_c = false;
+                       } else {
+                               p_err("unrecognized format specifier: '%s', possible values: raw, c",
+                                     *argv);
+                               goto done;
+                       }
+                       NEXT_ARG();
+               } else {
+                       p_err("unrecognized option: '%s'", *argv);
+                       goto done;
+               }
+       }
+
        if (!btf) {
                err = btf__get_from_id(btf_id, &btf);
                if (err) {
@@ -444,7 +505,16 @@ static int do_dump(int argc, char **argv)
                }
        }
 
-       dump_btf_raw(btf, root_type_ids, root_type_cnt);
+       if (dump_c) {
+               if (json_output) {
+                       p_err("JSON output for C-syntax dump is not supported");
+                       err = -ENOTSUP;
+                       goto done;
+               }
+               err = dump_btf_c(btf, root_type_ids, root_type_cnt);
+       } else {
+               err = dump_btf_raw(btf, root_type_ids, root_type_cnt);
+       }
 
 done:
        close(fd);
@@ -460,10 +530,11 @@ static int do_help(int argc, char **argv)
        }
 
        fprintf(stderr,
-               "Usage: %s btf dump BTF_SRC\n"
+               "Usage: %s btf dump BTF_SRC [format FORMAT]\n"
                "       %s btf help\n"
                "\n"
                "       BTF_SRC := { id BTF_ID | prog PROG | map MAP [{key | value | kv | all}] | file FILE }\n"
+               "       FORMAT  := { raw | c }\n"
                "       " HELP_SPEC_MAP "\n"
                "       " HELP_SPEC_PROGRAM "\n"
                "       " HELP_SPEC_OPTIONS "\n"