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Subject[PATCH 5.1 030/138] tools: bpftool: Fix JSON output when lookup fails
[ Upstream commit 1884c066579a7a274dd981a4d9639ca63db66a23 ]

In commit 9a5ab8bf1d6d ("tools: bpftool: turn err() and info() macros
into functions") one case of error reporting was special cased, so it
could report a lookup error for a specific key when dumping the map
element. What the code forgot to do is to wrap the key and value keys
into a JSON object, so an example output of pretty JSON dump of a
sockhash map (which does not support looking up its values) is:

"key": ["0x0a","0x41","0x00","0x02","0x1f","0x78","0x00","0x00"
"value": {
"error": "Operation not supported"
"key": ["0x0a","0x41","0x00","0x02","0x1f","0x78","0x00","0x01"
"value": {
"error": "Operation not supported"

Note the key-value pairs inside the toplevel array. They should be
wrapped inside a JSON object, otherwise it is an invalid JSON. This
commit fixes this, so the output now is:

"key": ["0x0a","0x41","0x00","0x02","0x1f","0x78","0x00","0x00"
"value": {
"error": "Operation not supported"
"key": ["0x0a","0x41","0x00","0x02","0x1f","0x78","0x00","0x01"
"value": {
"error": "Operation not supported"

Fixes: 9a5ab8bf1d6d ("tools: bpftool: turn err() and info() macros into functions")
Cc: Quentin Monnet <>
Signed-off-by: Krzesimir Nowak <>
Acked-by: Andrii Nakryiko <>
Signed-off-by: Daniel Borkmann <>
Signed-off-by: Sasha Levin <>
tools/bpf/bpftool/map.c | 2 ++
1 file changed, 2 insertions(+)

diff --git a/tools/bpf/bpftool/map.c b/tools/bpf/bpftool/map.c
index 994a7e0d16fb..14f581b562bd 100644
--- a/tools/bpf/bpftool/map.c
+++ b/tools/bpf/bpftool/map.c
@@ -713,12 +713,14 @@ static int dump_map_elem(int fd, void *key, void *value,
return 0;

if (json_output) {
+ jsonw_start_object(json_wtr);
jsonw_name(json_wtr, "key");
print_hex_data_json(key, map_info->key_size);
jsonw_name(json_wtr, "value");
jsonw_string_field(json_wtr, "error", strerror(lookup_errno));
+ jsonw_end_object(json_wtr);
} else {
if (errno == ENOENT)
print_entry_plain(map_info, key, NULL);

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