libbpf: hide and discourage inconsistently named getters

Move a bunch of "getters" into libbpf_legacy.h to keep them there in
libbpf 1.0. See [0] for discussion of "Discouraged APIs". These getters
don't add any maintenance burden and are simple alias, but they are
inconsistent in naming. So keep them in libbpf_legacy.h instead of
libbpf.h to "hide" them in favor of preferred getters ([1]). Also add two
missing getters: bpf_program__type() and bpf_program__expected_attach_type().

  [0] https://github.com/libbpf/libbpf/wiki/Libbpf:-the-road-to-v1.0#handling-deprecation-of-apis-and-functionality
  [1] Closes: https://github.com/libbpf/libbpf/issues/307

Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/r/20220124194254.2051434-2-andrii@kernel.org
Signed-off-by: Alexei Starovoitov <ast@kernel.org>

tools/lib/bpf/btf.h

@@ -147,8 +147,6 @@ LIBBPF_API int btf__resolve_type(const struct btf *btf, __u32 type_id);
 LIBBPF_API int btf__align_of(const struct btf *btf, __u32 id);
 LIBBPF_API int btf__fd(const struct btf *btf);
 LIBBPF_API void btf__set_fd(struct btf *btf, int fd);
-LIBBPF_DEPRECATED_SINCE(0, 7, "use btf__raw_data() instead")
-LIBBPF_API const void *btf__get_raw_data(const struct btf *btf, __u32 *size);
 LIBBPF_API const void *btf__raw_data(const struct btf *btf, __u32 *size);
 LIBBPF_API const char *btf__name_by_offset(const struct btf *btf, __u32 offset);
 LIBBPF_API const char *btf__str_by_offset(const struct btf *btf, __u32 offset);
@@ -159,8 +157,7 @@ LIBBPF_API int btf__get_map_kv_tids(const struct btf *btf, const char *map_name,
 
 LIBBPF_API struct btf_ext *btf_ext__new(const __u8 *data, __u32 size);
 LIBBPF_API void btf_ext__free(struct btf_ext *btf_ext);
-LIBBPF_API const void *btf_ext__get_raw_data(const struct btf_ext *btf_ext,
-					     __u32 *size);
+LIBBPF_API const void *btf_ext__raw_data(const struct btf_ext *btf_ext, __u32 *size);
 LIBBPF_API LIBBPF_DEPRECATED("btf_ext__reloc_func_info was never meant as a public API and has wrong assumptions embedded in it; it will be removed in the future libbpf versions")
 int btf_ext__reloc_func_info(const struct btf *btf,
 			     const struct btf_ext *btf_ext,

tools/lib/bpf/libbpf.c

@@ -7896,10 +7896,8 @@ int bpf_map__set_pin_path(struct bpf_map *map, const char *path)
 	return 0;
 }
 
-const char *bpf_map__get_pin_path(const struct bpf_map *map)
-{
-	return map->pin_path;
-}
+__alias(bpf_map__pin_path)
+const char *bpf_map__get_pin_path(const struct bpf_map *map);
 
 const char *bpf_map__pin_path(const struct bpf_map *map)
 {
@@ -8464,7 +8462,10 @@ static int bpf_program_nth_fd(const struct bpf_program *prog, int n)
 	return fd;
 }
 
-enum bpf_prog_type bpf_program__get_type(const struct bpf_program *prog)
+__alias(bpf_program__type)
+enum bpf_prog_type bpf_program__get_type(const struct bpf_program *prog);
+
+enum bpf_prog_type bpf_program__type(const struct bpf_program *prog)
 {
 	return prog->type;
 }
@@ -8508,8 +8509,10 @@ BPF_PROG_TYPE_FNS(struct_ops, BPF_PROG_TYPE_STRUCT_OPS);
 BPF_PROG_TYPE_FNS(extension, BPF_PROG_TYPE_EXT);
 BPF_PROG_TYPE_FNS(sk_lookup, BPF_PROG_TYPE_SK_LOOKUP);
 
-enum bpf_attach_type
-bpf_program__get_expected_attach_type(const struct bpf_program *prog)
+__alias(bpf_program__expected_attach_type)
+enum bpf_attach_type bpf_program__get_expected_attach_type(const struct bpf_program *prog);
+
+enum bpf_attach_type bpf_program__expected_attach_type(const struct bpf_program *prog)
 {
 	return prog->expected_attach_type;
 }
@@ -9477,7 +9480,7 @@ static int bpf_prog_load_xattr2(const struct bpf_prog_load_attr *attr,
 			bpf_program__set_expected_attach_type(prog,
 							      attach_type);
 		}
-		if (bpf_program__get_type(prog) == BPF_PROG_TYPE_UNSPEC) {
+		if (bpf_program__type(prog) == BPF_PROG_TYPE_UNSPEC) {
 			/*
 			 * we haven't guessed from section name and user
 			 * didn't provide a fallback type, too bad...
@@ -10528,7 +10531,7 @@ bpf_program__attach_fd(const struct bpf_program *prog, int target_fd, int btf_id
 		return libbpf_err_ptr(-ENOMEM);
 	link->detach = &bpf_link__detach_fd;
 
-	attach_type = bpf_program__get_expected_attach_type(prog);
+	attach_type = bpf_program__expected_attach_type(prog);
 	link_fd = bpf_link_create(prog_fd, target_fd, attach_type, &opts);
 	if (link_fd < 0) {
 		link_fd = -errno;

tools/lib/bpf/libbpf.h

@@ -607,12 +607,12 @@ LIBBPF_API int bpf_program__set_struct_ops(struct bpf_program *prog);
 LIBBPF_API int bpf_program__set_extension(struct bpf_program *prog);
 LIBBPF_API int bpf_program__set_sk_lookup(struct bpf_program *prog);
 
-LIBBPF_API enum bpf_prog_type bpf_program__get_type(const struct bpf_program *prog);
+LIBBPF_API enum bpf_prog_type bpf_program__type(const struct bpf_program *prog);
 LIBBPF_API void bpf_program__set_type(struct bpf_program *prog,
 				      enum bpf_prog_type type);
 
 LIBBPF_API enum bpf_attach_type
-bpf_program__get_expected_attach_type(const struct bpf_program *prog);
+bpf_program__expected_attach_type(const struct bpf_program *prog);
 LIBBPF_API void
 bpf_program__set_expected_attach_type(struct bpf_program *prog,
 				      enum bpf_attach_type type);
@@ -760,7 +760,6 @@ 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);

tools/lib/bpf/libbpf.map

@@ -424,10 +424,12 @@ LIBBPF_0.6.0 {
 LIBBPF_0.7.0 {
 	global:
 		bpf_btf_load;
+		bpf_program__expected_attach_type;
 		bpf_program__log_buf;
 		bpf_program__log_level;
 		bpf_program__set_log_buf;
 		bpf_program__set_log_level;
+		bpf_program__type;
 		bpf_xdp_attach;
 		bpf_xdp_detach;
 		bpf_xdp_query;

tools/lib/bpf/libbpf_internal.h

@@ -92,6 +92,9 @@
 # define offsetofend(TYPE, FIELD) \
 	(offsetof(TYPE, FIELD) + sizeof(((TYPE *)0)->FIELD))
 #endif
+#ifndef __alias
+#define __alias(symbol) __attribute__((alias(#symbol)))
+#endif
 
 /* Check whether a string `str` has prefix `pfx`, regardless if `pfx` is
  * a string literal known at compilation time or char * pointer known only at

tools/lib/bpf/libbpf_legacy.h

@@ -86,6 +86,23 @@ LIBBPF_API int libbpf_set_strict_mode(enum libbpf_strict_mode mode);
 
 #define DECLARE_LIBBPF_OPTS LIBBPF_OPTS
 
+/* "Discouraged" APIs which don't follow consistent libbpf naming patterns.
+ * They are normally a trivial aliases or wrappers for proper APIs and are
+ * left to minimize unnecessary disruption for users of libbpf. But they
+ * shouldn't be used going forward.
+ */
+
+struct bpf_program;
+struct bpf_map;
+struct btf;
+struct btf_ext;
+
+LIBBPF_API enum bpf_prog_type bpf_program__get_type(const struct bpf_program *prog);
+LIBBPF_API enum bpf_attach_type bpf_program__get_expected_attach_type(const struct bpf_program *prog);
+LIBBPF_API const char *bpf_map__get_pin_path(const struct bpf_map *map);
+LIBBPF_API const void *btf__get_raw_data(const struct btf *btf, __u32 *size);
+LIBBPF_API const void *btf_ext__get_raw_data(const struct btf_ext *btf_ext, __u32 *size);
+
 #ifdef __cplusplus
 } /* extern "C" */
 #endif