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bpftool: Improve handling of ENOENT on map dumps

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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>
This commit is contained in:
David Ahern 2018-11-08 13:00:07 -08:00 committed by Daniel Borkmann
parent 435f90a338
commit bf598a8f0f
1 changed files with 14 additions and 4 deletions
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18
tools/bpf/bpftool/map.c
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@ -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;