LXR linux/tools/lib/bpf/libbpf

   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#define LIBBPF_DEPRECATED(msg) __attribute__((deprecated(msg)))
  19
  20/* Helper macro to declare and initialize libbpf options struct
  21 *
  22 * This dance with uninitialized declaration, followed by memset to zero,
  23 * followed by assignment using compound literal syntax is done to preserve
  24 * ability to use a nice struct field initialization syntax and **hopefully**
  25 * have all the padding bytes initialized to zero. It's not guaranteed though,
  26 * when copying literal, that compiler won't copy garbage in literal's padding
  27 * bytes, but that's the best way I've found and it seems to work in practice.
  28 *
  29 * Macro declares opts struct of given type and name, zero-initializes,
  30 * including any extra padding, it with memset() and then assigns initial
  31 * values provided by users in struct initializer-syntax as varargs.
  32 */
  33#define DECLARE_LIBBPF_OPTS(TYPE, NAME, ...)                                \
  34        struct TYPE NAME = ({                                               \
  35                memset(&NAME, 0, sizeof(struct TYPE));                      \
  36                (struct TYPE) {                                             \
  37                        .sz = sizeof(struct TYPE),                          \
  38                        __VA_ARGS__                                         \
  39                };                                                          \
  40        })
  41
  42#endif /* __LIBBPF_LIBBPF_COMMON_H */
  43