1 | /* SPDX-License-Identifier: GPL-2.0 WITH Linux-syscall-note */ |
2 | #ifndef _LINUX_STDDEF_H |
3 | #define _LINUX_STDDEF_H |
4 | |
5 | |
6 | |
7 | #ifndef __always_inline |
8 | #define __always_inline __inline__ |
9 | #endif |
10 | |
11 | /** |
12 | * __struct_group() - Create a mirrored named and anonyomous struct |
13 | * |
14 | * @TAG: The tag name for the named sub-struct (usually empty) |
15 | * @NAME: The identifier name of the mirrored sub-struct |
16 | * @ATTRS: Any struct attributes (usually empty) |
17 | * @MEMBERS: The member declarations for the mirrored structs |
18 | * |
19 | * Used to create an anonymous union of two structs with identical layout |
20 | * and size: one anonymous and one named. The former's members can be used |
21 | * normally without sub-struct naming, and the latter can be used to |
22 | * reason about the start, end, and size of the group of struct members. |
23 | * The named struct can also be explicitly tagged for layer reuse, as well |
24 | * as both having struct attributes appended. |
25 | */ |
26 | #define __struct_group(TAG, NAME, ATTRS, MEMBERS...) \ |
27 | union { \ |
28 | struct { MEMBERS } ATTRS; \ |
29 | struct TAG { MEMBERS } ATTRS NAME; \ |
30 | } ATTRS |
31 | |
32 | /** |
33 | * __DECLARE_FLEX_ARRAY() - Declare a flexible array usable in a union |
34 | * |
35 | * @TYPE: The type of each flexible array element |
36 | * @NAME: The name of the flexible array member |
37 | * |
38 | * In order to have a flexible array member in a union or alone in a |
39 | * struct, it needs to be wrapped in an anonymous struct with at least 1 |
40 | * named member, but that member can be empty. |
41 | */ |
42 | #define __DECLARE_FLEX_ARRAY(TYPE, NAME) \ |
43 | struct { \ |
44 | struct { } __empty_ ## NAME; \ |
45 | TYPE NAME[]; \ |
46 | } |
47 | #endif |
48 | |