On Mon, Sep 7, 2020 at 9:36 AM Quentin Monnet <quentin@xxxxxxxxxxxxx> wrote:
>
> The function used to dump a map entry in bpftool is a bit difficult to
> follow, as a consequence to earlier refactorings. There is a variable
> ("num_elems") which does not appear to be necessary, and the error
> handling would look cleaner if moved to its own function. Let's clean it
> up. No functional change.
>
> v2:
> - v1 was erroneously removing the check on fd maps in an attempt to get
> support for outer map dumps. This is already working. Instead, v2
> focuses on cleaning up the dump_map_elem() function, to avoid
> similar confusion in the future.
>
> Signed-off-by: Quentin Monnet <quentin@xxxxxxxxxxxxx>
> ---
> tools/bpf/bpftool/map.c | 101 +++++++++++++++++++++-------------------
> 1 file changed, 52 insertions(+), 49 deletions(-)
>
> diff --git a/tools/bpf/bpftool/map.c b/tools/bpf/bpftool/map.c
> index bc0071228f88..c8159cb4fb1e 100644
> --- a/tools/bpf/bpftool/map.c
> +++ b/tools/bpf/bpftool/map.c
> @@ -213,8 +213,9 @@ 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 *error_msg)
> +static void
> +print_entry_error_msg(struct bpf_map_info *info, unsigned char *key,
> + const char *error_msg)
> {
> int msg_size = strlen(error_msg);
> bool single_line, break_names;
> @@ -232,6 +233,40 @@ static void print_entry_error(struct bpf_map_info *info, unsigned char *key,
> printf("\n");
> }
>
> +static void
> +print_entry_error(struct bpf_map_info *map_info, void *key, int lookup_errno)
> +{
> + /* For prog_array maps or arrays of maps, failure to lookup the value
> + * means there is no entry for that key. Do not print an error message
> + * in that case.
> + */
this is the case when error is ENOENT, all the other ones should be
treated the same, no?
> + if (map_is_map_of_maps(map_info->type) ||
> + map_is_map_of_progs(map_info->type))
> + return;
> +
> + if (json_output) {
> + jsonw_start_object(json_wtr); /* entry */
> + jsonw_name(json_wtr, "key");
> + print_hex_data_json(key, map_info->key_size);
> + jsonw_name(json_wtr, "value");
> + jsonw_start_object(json_wtr); /* error */
> + jsonw_string_field(json_wtr, "error", strerror(lookup_errno));
> + jsonw_end_object(json_wtr); /* error */
> + jsonw_end_object(json_wtr); /* entry */
> + } else {
> + const char *msg = NULL;
> +
> + if (lookup_errno == ENOENT)
> + msg = "<no entry>";
> + else if (lookup_errno == ENOSPC &&
> + map_info->type == BPF_MAP_TYPE_REUSEPORT_SOCKARRAY)
> + msg = "<cannot read>";
> +
> + print_entry_error_msg(map_info, key,
> + msg ? : strerror(lookup_errno));
> + }
> +}
> +
[...]
