1/* SPDX-License-Identifier: (LGPL-2.1 OR BSD-2-Clause) */
2
3/*
4 * Common user-facing libbpf helpers.
5 *
6 * Copyright (c) 2019 Facebook
7 */
8
9#ifndef __LIBBPF_LIBBPF_COMMON_H
10#define __LIBBPF_LIBBPF_COMMON_H
11
12#include <string.h>
13#include "libbpf_version.h"
14
15#ifndef LIBBPF_API
16#define LIBBPF_API __attribute__((visibility("default")))
17#endif
18
19#define LIBBPF_DEPRECATED(msg) __attribute__((deprecated(msg)))
20
21/* Mark a symbol as deprecated when libbpf version is >= {major}.{minor} */
22#define LIBBPF_DEPRECATED_SINCE(major, minor, msg) \
23 __LIBBPF_MARK_DEPRECATED_ ## major ## _ ## minor \
24 (LIBBPF_DEPRECATED("libbpf v" # major "." # minor "+: " msg))
25
26#define __LIBBPF_CURRENT_VERSION_GEQ(major, minor) \
27 (LIBBPF_MAJOR_VERSION > (major) || \
28 (LIBBPF_MAJOR_VERSION == (major) && LIBBPF_MINOR_VERSION >= (minor)))
29
30/* Add checks for other versions below when planning deprecation of API symbols
31 * with the LIBBPF_DEPRECATED_SINCE macro.
32 */
33#if __LIBBPF_CURRENT_VERSION_GEQ(1, 0)
34#define __LIBBPF_MARK_DEPRECATED_1_0(X) X
35#else
36#define __LIBBPF_MARK_DEPRECATED_1_0(X)
37#endif
38
39/* This set of internal macros allows to do "function overloading" based on
40 * number of arguments provided by used in backwards-compatible way during the
41 * transition to libbpf 1.0
42 * It's ugly but necessary evil that will be cleaned up when we get to 1.0.
43 * See bpf_prog_load() overload for example.
44 */
45#define ___libbpf_cat(A, B) A ## B
46#define ___libbpf_select(NAME, NUM) ___libbpf_cat(NAME, NUM)
47#define ___libbpf_nth(_1, _2, _3, _4, _5, _6, N, ...) N
48#define ___libbpf_cnt(...) ___libbpf_nth(__VA_ARGS__, 6, 5, 4, 3, 2, 1)
49#define ___libbpf_overload(NAME, ...) ___libbpf_select(NAME, ___libbpf_cnt(__VA_ARGS__))(__VA_ARGS__)
50
51/* Helper macro to declare and initialize libbpf options struct
52 *
53 * This dance with uninitialized declaration, followed by memset to zero,
54 * followed by assignment using compound literal syntax is done to preserve
55 * ability to use a nice struct field initialization syntax and **hopefully**
56 * have all the padding bytes initialized to zero. It's not guaranteed though,
57 * when copying literal, that compiler won't copy garbage in literal's padding
58 * bytes, but that's the best way I've found and it seems to work in practice.
59 *
60 * Macro declares opts struct of given type and name, zero-initializes,
61 * including any extra padding, it with memset() and then assigns initial
62 * values provided by users in struct initializer-syntax as varargs.
63 */
64#define LIBBPF_OPTS(TYPE, NAME, ...) \
65 struct TYPE NAME = ({ \
66 memset(&NAME, 0, sizeof(struct TYPE)); \
67 (struct TYPE) { \
68 .sz = sizeof(struct TYPE), \
69 __VA_ARGS__ \
70 }; \
71 })
72
73/* Helper macro to clear and optionally reinitialize libbpf options struct
74 *
75 * Small helper macro to reset all fields and to reinitialize the common
76 * structure size member. Values provided by users in struct initializer-
77 * syntax as varargs can be provided as well to reinitialize options struct
78 * specific members.
79 */
80#define LIBBPF_OPTS_RESET(NAME, ...) \
81 do { \
82 typeof(NAME) ___##NAME = ({ \
83 memset(&___##NAME, 0, sizeof(NAME)); \
84 (typeof(NAME)) { \
85 .sz = sizeof(NAME), \
86 __VA_ARGS__ \
87 }; \
88 }); \
89 memcpy(&NAME, &___##NAME, sizeof(NAME)); \
90 } while (0)
91
92#endif /* __LIBBPF_LIBBPF_COMMON_H */
93

source code of linux/tools/lib/bpf/libbpf_common.h