[PATCH bpf-next 10/12] bpftool: add C output format option to btf dump subcommand

[Andrii Nakryiko]

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.
+ *
+ * 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)
+{
+       struct btf_dump *d;
+       int err = 0, i, id;
+
+       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;
+}
+
 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;
+               }
+       }
+
        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"
                "       %s btf help\n"
                "\n"
                "       BTF_SRC := { id BTF_ID | prog PROG | map MAP [{key | 
value | kv | all}] | file FILE }\n"
-- 
2.17.1