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 14 #ifndef LIBBPF_API 15 #define LIBBPF_API __attribute__((visibility("default"))) 16 #endif 17 18 /* Helper macro to declare and initialize libbpf options struct 19 * 20 * This dance with uninitialized declaration, followed by memset to zero, 21 * followed by assignment using compound literal syntax is done to preserve 22 * ability to use a nice struct field initialization syntax and **hopefully** 23 * have all the padding bytes initialized to zero. It's not guaranteed though, 24 * when copying literal, that compiler won't copy garbage in literal's padding 25 * bytes, but that's the best way I've found and it seems to work in practice. 26 * 27 * Macro declares opts struct of given type and name, zero-initializes, 28 * including any extra padding, it with memset() and then assigns initial 29 * values provided by users in struct initializer-syntax as varargs. 30 */ 31 #define DECLARE_LIBBPF_OPTS(TYPE, NAME, ...) \ 32 struct TYPE NAME = ({ \ 33 memset(&NAME, 0, sizeof(struct TYPE)); \ 34 (struct TYPE) { \ 35 .sz = sizeof(struct TYPE), \ 36 __VA_ARGS__ \ 37 }; \ 38 }) 39 40 #endif /* __LIBBPF_LIBBPF_COMMON_H */ 41