On Mon, Oct 8, 2018 at 6:06 PM Prashant Bhole
<bhole_prashant...@lab.ntt.co.jp> wrote:
>
> Since map lookup error can be ENOENT or EOPNOTSUPP, let's print
> strerror() as error message in normal and JSON output.
>
> This patch adds helper function print_entry_error() to print
> entry from lookup error occurs
>
> Example: Following example dumps a map which does not support lookup.
>
> Output before:
> root# bpftool map -jp dump id 40
> [
> "key": ["0x0a","0x00","0x00","0x00"
> ],
> "value": {
> "error": "can\'t lookup element"
> },
> "key": ["0x0b","0x00","0x00","0x00"
> ],
> "value": {
> "error": "can\'t lookup element"
> }
> ]
>
> root# bpftool map dump id 40
> can't lookup element with key:
> 0a 00 00 00
> can't lookup element with key:
> 0b 00 00 00
> Found 0 elements
>
> Output after changes:
> root# bpftool map dump -jp id 45
> [
> "key": ["0x0a","0x00","0x00","0x00"
> ],
> "value": {
> "error": "Operation not supported"
> },
> "key": ["0x0b","0x00","0x00","0x00"
> ],
> "value": {
> "error": "Operation not supported"
> }
> ]
>
> root# bpftool map dump id 45
> key:
> 0a 00 00 00
> value:
> Operation not supported
> key:
> 0b 00 00 00
> value:
> Operation not supported
> Found 0 elements
>
> Signed-off-by: Prashant Bhole <bhole_prashant...@lab.ntt.co.jp>
> Acked-by: Jakub Kicinski <jakub.kicin...@netronome.com>
> Acked-by: Alexei Starovoitov <a...@kernel.org>
Acked-by: Song Liu <songliubrav...@fb.com>
> ---
> tools/bpf/bpftool/map.c | 29 ++++++++++++++++++++++++-----
> 1 file changed, 24 insertions(+), 5 deletions(-)
>
> diff --git a/tools/bpf/bpftool/map.c b/tools/bpf/bpftool/map.c
> index 28d365435fea..9f5de48f8a99 100644
> --- a/tools/bpf/bpftool/map.c
> +++ b/tools/bpf/bpftool/map.c
> @@ -336,6 +336,25 @@ static void print_entry_json(struct bpf_map_info *info,
> unsigned char *key,
> jsonw_end_object(json_wtr);
> }
>
> +static void print_entry_error(struct bpf_map_info *info, unsigned char *key,
> + const char *value)
> +{
> + int value_size = strlen(value);
> + bool single_line, break_names;
> +
> + break_names = info->key_size > 16 || value_size > 16;
> + single_line = info->key_size + value_size <= 24 && !break_names;
> +
> + printf("key:%c", break_names ? '\n' : ' ');
> + fprint_hex(stdout, key, info->key_size, " ");
> +
> + printf(single_line ? " " : "\n");
> +
> + printf("value:%c%s", break_names ? '\n' : ' ', value);
> +
> + printf("\n");
> +}
> +
> static void print_entry_plain(struct bpf_map_info *info, unsigned char *key,
> unsigned char *value)
> {
> @@ -663,6 +682,7 @@ static int dump_map_elem(int fd, void *key, void *value,
> json_writer_t *btf_wtr)
> {
> int num_elems = 0;
> + int lookup_errno;
>
> if (!bpf_map_lookup_elem(fd, key, value)) {
> if (json_output) {
> @@ -685,6 +705,8 @@ static int dump_map_elem(int fd, void *key, void *value,
> }
>
> /* lookup error handling */
> + lookup_errno = errno;
> +
> if (map_is_map_of_maps(map_info->type) ||
> map_is_map_of_progs(map_info->type))
> return 0;
> @@ -694,13 +716,10 @@ static int dump_map_elem(int fd, void *key, void *value,
> print_hex_data_json(key, map_info->key_size);
> jsonw_name(json_wtr, "value");
> jsonw_start_object(json_wtr);
> - jsonw_string_field(json_wtr, "error",
> - "can't lookup element");
> + jsonw_string_field(json_wtr, "error", strerror(lookup_errno));
> jsonw_end_object(json_wtr);
> } else {
> - p_info("can't lookup element with key: ");
> - fprint_hex(stderr, key, map_info->key_size, " ");
> - fprintf(stderr, "\n");
> + print_entry_error(map_info, key, strerror(lookup_errno));
> }
>
> return 0;
> --
> 2.17.1
>
>
