[PATCH AUTOSEL 4.20 030/304] bpftool: Improve handling of ENOENT on map dumps

Sasha Levin
2019-01-28T17:50:35Z

From: David Ahern <dsahern@gmail.com>

[ Upstream commit bf598a8f0f771302d4ecb0ef0003c54732221597 ]

bpftool output is not user friendly when dumping a map with only a few
populated entries:

$ bpftool map
1: devmap name tx_devmap flags 0x0
key 4B value 4B max_entries 64 memlock 4096B
2: array name tx_idxmap flags 0x0
key 4B value 4B max_entries 64 memlock 4096B

$ bpftool map dump id 1
key:
00 00 00 00
value:
No such file or directory
key:
01 00 00 00
value:
No such file or directory
key:
02 00 00 00
value:
No such file or directory
key: 03 00 00 00 value: 03 00 00 00

Handle ENOENT by keeping the line format sane and dumping
"<no entry>" for the value

$ bpftool map dump id 1
key: 00 00 00 00 value: <no entry>
key: 01 00 00 00 value: <no entry>
key: 02 00 00 00 value: <no entry>
key: 03 00 00 00 value: 03 00 00 00
...

Signed-off-by: David Ahern <dsahern@gmail.com>
Acked-by: Jakub Kicinski <jakub.kicinski@netronome.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
tools/bpf/bpftool/map.c | 18 ++++++++++++++----
1 file changed, 14 insertions(+), 4 deletions(-)

diff --git a/tools/bpf/bpftool/map.c b/tools/bpf/bpftool/map.c
index 7bf38f0e152e..9988d5c126b6 100644
--- a/tools/bpf/bpftool/map.c
+++ b/tools/bpf/bpftool/map.c
@@ -383,7 +383,10 @@ static void print_entry_plain(struct bpf_map_info *info, unsigned char *key,
printf(single_line ? " " : "\n");

printf("value:%c", break_names ? '\n' : ' ');
- fprint_hex(stdout, value, info->value_size, " ");
+ if (value)
+ fprint_hex(stdout, value, info->value_size, " ");
+ else
+ printf("<no entry>");

printf("\n");
} else {
@@ -398,8 +401,11 @@ static void print_entry_plain(struct bpf_map_info *info, unsigned char *key,
for (i = 0; i < n; i++) {
printf("value (CPU %02d):%c",
i, info->value_size > 16 ? '\n' : ' ');
- fprint_hex(stdout, value + i * step,
- info->value_size, " ");
+ if (value)
+ fprint_hex(stdout, value + i * step,
+ info->value_size, " ");
+ else
+ printf("<no entry>");
printf("\n");
}
}
@@ -731,7 +737,11 @@ static int dump_map_elem(int fd, void *key, void *value,
jsonw_string_field(json_wtr, "error", strerror(lookup_errno));
jsonw_end_object(json_wtr);
} else {
- print_entry_error(map_info, key, strerror(lookup_errno));
+ if (errno == ENOENT)
+ print_entry_plain(map_info, key, NULL);
+ else
+ print_entry_error(map_info, key,
+ strerror(lookup_errno));
}

return 0;
--
2.19.1