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 memset(&NAME, 0, sizeof(NAME)); \ 83 NAME = (typeof(NAME)) { \ 84 .sz = sizeof(NAME), \ 85 __VA_ARGS__ \ 86 }; \ 87 } while (0) 88 89 #endif /* __LIBBPF_LIBBPF_COMMON_H */ 90