From aff52e685eb39984f3a613e8a5c570d97e5d2414 Mon Sep 17 00:00:00 2001
From: YiFei Zhu <zhuyifei@google.com>
Date: Tue, 15 Sep 2020 16:45:42 -0700
Subject: bpftool: Support dumping metadata

Dump metadata in the 'bpftool prog' list if it's present.
For some formatting some BTF code is put directly in the
metadata dumping. Sanity checks on the map and the kind of the btf_type
to make sure we are actually dumping what we are expecting.

A helper jsonw_reset is added to json writer so we can reuse the same
json writer without having extraneous commas.

Sample output:

  $ bpftool prog
  6: cgroup_skb  name prog  tag bcf7977d3b93787c  gpl
  [...]
  	btf_id 4
  	metadata:
  		a = "foo"
  		b = 1

  $ bpftool prog --json --pretty
  [{
          "id": 6,
  [...]
          "btf_id": 4,
          "metadata": {
              "a": "foo",
              "b": 1
          }
      }
  ]

Signed-off-by: YiFei Zhu <zhuyifei@google.com>
Signed-off-by: Stanislav Fomichev <sdf@google.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Cc: YiFei Zhu <zhuyifei1999@gmail.com>
Link: https://lore.kernel.org/bpf/20200915234543.3220146-5-sdf@google.com
---
 tools/bpf/bpftool/json_writer.c | 6 ++++++
 1 file changed, 6 insertions(+)

(limited to 'tools/bpf/bpftool/json_writer.c')

diff --git a/tools/bpf/bpftool/json_writer.c b/tools/bpf/bpftool/json_writer.c
index 86501cd3c763..7fea83bedf48 100644
--- a/tools/bpf/bpftool/json_writer.c
+++ b/tools/bpf/bpftool/json_writer.c
@@ -119,6 +119,12 @@ void jsonw_pretty(json_writer_t *self, bool on)
 	self->pretty = on;
 }
 
+void jsonw_reset(json_writer_t *self)
+{
+	assert(self->depth == 0);
+	self->sep = '\0';
+}
+
 /* Basic blocks */
 static void jsonw_begin(json_writer_t *self, int c)
 {
-- 
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