libbpf: Add bpf_map__pin_path function

Add bpf_map__pin_path, so that the inconsistently named
bpf_map__get_pin_path can be deprecated later. This is part of the
effort towards libbpf v1.0: https://github.com/libbpf/libbpf/issues/307

Also, add a selftest for the new function.
Signed-off-by: NEvgeniy Litvinenko <evgeniyl@fb.com>
Signed-off-by: NAndrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/bpf/20210723221511.803683-1-evgeniyl@fb.com

tools/lib/bpf/libbpf.c

@@ -8511,6 +8511,11 @@ const char *bpf_map__get_pin_path(const struct bpf_map *map)
 	return map->pin_path;
 }
 
+const char *bpf_map__pin_path(const struct bpf_map *map)
+{
+	return map->pin_path;
+}
+
 bool bpf_map__is_pinned(const struct bpf_map *map)
 {
 	return map->pinned;

tools/lib/bpf/libbpf.h

@@ -499,6 +499,7 @@ LIBBPF_API bool bpf_map__is_offload_neutral(const struct bpf_map *map);
 LIBBPF_API bool bpf_map__is_internal(const struct bpf_map *map);
 LIBBPF_API int bpf_map__set_pin_path(struct bpf_map *map, const char *path);
 LIBBPF_API const char *bpf_map__get_pin_path(const struct bpf_map *map);
+LIBBPF_API const char *bpf_map__pin_path(const struct bpf_map *map);
 LIBBPF_API bool bpf_map__is_pinned(const struct bpf_map *map);
 LIBBPF_API int bpf_map__pin(struct bpf_map *map, const char *path);
 LIBBPF_API int bpf_map__unpin(struct bpf_map *map, const char *path);

tools/lib/bpf/libbpf.map

@@ -371,6 +371,7 @@ LIBBPF_0.4.0 {
 LIBBPF_0.5.0 {
 	global:
 		bpf_map__initial_value;
+		bpf_map__pin_path;
 		bpf_map_lookup_and_delete_elem_flags;
 		bpf_program__attach_kprobe_opts;
 		bpf_object__gen_loader;

tools/testing/selftests/bpf/prog_tests/pinning.c

@@ -125,6 +125,10 @@ void test_pinning(void)
 	if (CHECK(err, "pin maps", "err %d errno %d\n", err, errno))
 		goto out;
 
+	/* get pinning path */
+	if (!ASSERT_STREQ(bpf_map__pin_path(map), pinpath, "get pin path"))
+		goto out;
+
 	/* set pinning path of other map and re-pin all */
 	map = bpf_object__find_map_by_name(obj, "nopinmap");
 	if (CHECK(!map, "find map", "NULL map"))
@@ -134,6 +138,11 @@ void test_pinning(void)
 	if (CHECK(err, "set pin path", "err %d errno %d\n", err, errno))
 		goto out;
 
+	/* get pinning path after set */
+	if (!ASSERT_STREQ(bpf_map__pin_path(map), custpinpath,
+			  "get pin path after set"))
+		goto out;
+
 	/* should only pin the one unpinned map */
 	err = bpf_object__pin_maps(obj, NULL);
 	if (CHECK(err, "pin maps", "err %d errno %d\n", err, errno))