Commit a20693b6 authored by Quentin Monnet's avatar Quentin Monnet Committed by Alexei Starovoitov
Browse files

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: default avatarQuentin Monnet <quentin@isovalent.com>
Signed-off-by: default avatarAlexei Starovoitov <ast@kernel.org>
Acked-by: default avatarAndrii Nakryiko <andriin@fb.com>
Link: https://lore.kernel.org/bpf/20200910102652.10509-2-quentin@isovalent.com
parent 2f7de986

tools/bpf/bpftool/map.c

+52 −49
Original line number Diff line number Diff line
@@ -213,7 +213,8 @@ 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,

static void

print_entry_error_msg(struct bpf_map_info *info, unsigned char *key,

		      const char *error_msg)

{

	int msg_size = strlen(error_msg);
@@ -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)

{
@@ -713,14 +748,14 @@ 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)) {

		print_entry_error(map_info, key, errno);

		return -1;

	}



	if (!bpf_map_lookup_elem(fd, key, value)) {

	if (json_output) {

		print_entry_json(map_info, key, value, btf);

		} else {

			if (btf) {

	} else if (btf) {

		struct btf_dumper d = {

			.btf = btf,

			.jw = btf_wtr,
@@ -731,39 +766,6 @@ static int dump_map_elem(int fd, void *key, void *value, 
	} else {

		print_entry_plain(map_info, key, value);

	}

			num_elems++;

		}

		return num_elems;

	}



	/* 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);

	} 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));

	}



	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;

	}