/* SPDX-License-Identifier: (LGPL-2.1 OR BSD-2-Clause) */

/*
 * Common user-facing libbpf helpers.
 *
 * Copyright (c) 2019 Facebook
 */

#ifndef __LIBBPF_LIBBPF_COMMON_H
#define __LIBBPF_LIBBPF_COMMON_H

#include <string.h>
#include "libbpf_version.h"

#ifndef LIBBPF_API
#define LIBBPF_API __attribute__((visibility("default")))
#endif

#define LIBBPF_DEPRECATED(msg) __attribute__((deprecated(msg)))

/* Mark a symbol as deprecated when libbpf version is >= {major}.{minor} */
#define LIBBPF_DEPRECATED_SINCE(major, minor, msg)                \
    __LIBBPF_MARK_DEPRECATED_ ## major ## _ ## minor            \
        (LIBBPF_DEPRECATED("libbpf v" # major "." # minor "+: " msg))

#define __LIBBPF_CURRENT_VERSION_GEQ(major, minor)                \
    (LIBBPF_MAJOR_VERSION > (major) ||                    \
     (LIBBPF_MAJOR_VERSION == (major) && LIBBPF_MINOR_VERSION >= (minor)))

/* Add checks for other versions below when planning deprecation of API symbols
 * with the LIBBPF_DEPRECATED_SINCE macro.
 */
#if __LIBBPF_CURRENT_VERSION_GEQ(1, 0)
#define __LIBBPF_MARK_DEPRECATED_1_0(X) X
#else
#define __LIBBPF_MARK_DEPRECATED_1_0(X)
#endif

/* This set of internal macros allows to do "function overloading" based on
 * number of arguments provided by used in backwards-compatible way during the
 * transition to libbpf 1.0
 * It's ugly but necessary evil that will be cleaned up when we get to 1.0.
 * See bpf_prog_load() overload for example.
 */
#define ___libbpf_cat(A, B) A ## B
#define ___libbpf_select(NAME, NUM) ___libbpf_cat(NAME, NUM)
#define ___libbpf_nth(_1, _2, _3, _4, _5, _6, N, ...) N
#define ___libbpf_cnt(...) ___libbpf_nth(__VA_ARGS__, 6, 5, 4, 3, 2, 1)
#define ___libbpf_overload(NAME, ...) ___libbpf_select(NAME, ___libbpf_cnt(__VA_ARGS__))(__VA_ARGS__)

/* Helper macro to declare and initialize libbpf options struct
 *
 * This dance with uninitialized declaration, followed by memset to zero,
 * followed by assignment using compound literal syntax is done to preserve
 * ability to use a nice struct field initialization syntax and **hopefully**
 * have all the padding bytes initialized to zero. It's not guaranteed though,
 * when copying literal, that compiler won't copy garbage in literal's padding
 * bytes, but that's the best way I've found and it seems to work in practice.
 *
 * Macro declares opts struct of given type and name, zero-initializes,
 * including any extra padding, it with memset() and then assigns initial
 * values provided by users in struct initializer-syntax as varargs.
 */
#define LIBBPF_OPTS(TYPE, NAME, ...)                        \
    struct TYPE NAME = ({                             \
        memset(&NAME, 0, sizeof(struct TYPE));                \
        (struct TYPE) {                            \
            .sz = sizeof(struct TYPE),                \
            __VA_ARGS__                        \
        };                                \
    })

#endif /* __LIBBPF_LIBBPF_COMMON_H */