/* SPDX-License-Identifier: GPL-2.0 WITH Linux-syscall-note */ #ifndef _LINUX_STDDEF_H #define _LINUX_STDDEF_H #ifndef __always_inline #define __always_inline __inline__ #endif /* Not all C++ standards support type declarations inside an anonymous union */ #ifndef __cplusplus #define __struct_group_tag(TAG) TAG #else #define __struct_group_tag(TAG) #endif /** * __struct_group() - Create a mirrored named and anonyomous struct * * @TAG: The tag name for the named sub-struct (usually empty) * @NAME: The identifier name of the mirrored sub-struct * @ATTRS: Any struct attributes (usually empty) * @MEMBERS: The member declarations for the mirrored structs * * Used to create an anonymous union of two structs with identical layout * and size: one anonymous and one named. The former's members can be used * normally without sub-struct naming, and the latter can be used to * reason about the start, end, and size of the group of struct members. * The named struct can also be explicitly tagged for layer reuse (C only), * as well as both having struct attributes appended. */ #define __struct_group(TAG, NAME, ATTRS, MEMBERS...) \ union { \ struct { MEMBERS } ATTRS; \ struct __struct_group_tag(TAG) { MEMBERS } ATTRS NAME; \ } ATTRS /** * __DECLARE_FLEX_ARRAY() - Declare a flexible array usable in a union * * @TYPE: The type of each flexible array element * @NAME: The name of the flexible array member * * In order to have a flexible array member in a union or alone in a * struct, it needs to be wrapped in an anonymous struct with at least 1 * named member, but that member can be empty. */ #define __DECLARE_FLEX_ARRAY(TYPE, NAME) \ struct { \ struct { } __empty_ ## NAME; \ TYPE NAME[]; \ } #endif