On 09/09/2020 04:25, Andrii Nakryiko wrote:
> 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?
Do you mean all map types should be treated the same? If so, I can
remove the check below, as in v1. Or do you mean there is a missing
check on the error value? In which case I can extend this check to
verify we have ENOENT.
>> + 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));
>> + }
>> +}
>> +
>
> [...]
>
