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tools: bpftool: Clean up function to dump map entry 

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@isovalent.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Andrii Nakryiko <andriin@fb.com>
Link: https://lore.kernel.org/bpf/20200910102652.10509-2-quentin@isovalent.com
This commit is contained in:
Quentin Monnet 2020-09-10 11:26:50 +01:00 committed by Alexei Starovoitov
parent 2f7de9865b
commit a20693b6e7
1 changed files with 52 additions and 49 deletions
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101
tools/bpf/bpftool/map.c
View File

@ -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.
*/
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));
}
}
static void print_entry_plain(struct bpf_map_info *info, unsigned char *key,
unsigned char *value)
{
@ -713,56 +748,23 @@ static int dump_map_elem(int fd, void *key, void *value,
struct bpf_map_info *map_info, struct btf *btf,
json_writer_t *btf_wtr)
{
int num_elems = 0;
int lookup_errno;
if (!bpf_map_lookup_elem(fd, key, value)) {
if (json_output) {
print_entry_json(map_info, key, value, btf);
} else {
if (btf) {
struct btf_dumper d = {
.btf = btf,
.jw = btf_wtr,
.is_plain_text = true,
};
do_dump_btf(&d, map_info, key, value);
} else {
print_entry_plain(map_info, key, value);
}
num_elems++;
}
return num_elems;
if (bpf_map_lookup_elem(fd, key, value)) {
print_entry_error(map_info, key, errno);
return -1;
}
/* 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;
if (json_output) {
jsonw_start_object(json_wtr);
jsonw_name(json_wtr, "key");
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", strerror(lookup_errno));
jsonw_end_object(json_wtr);
jsonw_end_object(json_wtr);
print_entry_json(map_info, key, value, btf);
} else if (btf) {
struct btf_dumper d = {
.btf = btf,
.jw = btf_wtr,
.is_plain_text = true,
};
do_dump_btf(&d, map_info, key, value);
} 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(map_info, key,
msg ? : strerror(lookup_errno));
print_entry_plain(map_info, key, value);
}
return 0;
@ -873,7 +875,8 @@ map_dump(int fd, struct bpf_map_info *info, json_writer_t *wtr,
err = 0;
break;
}
num_elems += dump_map_elem(fd, key, value, info, btf, wtr);
if (!dump_map_elem(fd, key, value, info, btf, wtr))
num_elems++;
prev_key = key;
}