1/* SPDX-License-Identifier: GPL-2.0 WITH Linux-syscall-note */
2#ifndef _LINUX_STDDEF_H
3#define _LINUX_STDDEF_H
4
5
6#ifndef __always_inline
7#define __always_inline __inline__
8#endif
9
10/* Not all C++ standards support type declarations inside an anonymous union */
11#ifndef __cplusplus
12#define __struct_group_tag(TAG) TAG
13#else
14#define __struct_group_tag(TAG)
15#endif
16
17/**
18 * __struct_group() - Create a mirrored named and anonyomous struct
19 *
20 * @TAG: The tag name for the named sub-struct (usually empty)
21 * @NAME: The identifier name of the mirrored sub-struct
22 * @ATTRS: Any struct attributes (usually empty)
23 * @MEMBERS: The member declarations for the mirrored structs
24 *
25 * Used to create an anonymous union of two structs with identical layout
26 * and size: one anonymous and one named. The former's members can be used
27 * normally without sub-struct naming, and the latter can be used to
28 * reason about the start, end, and size of the group of struct members.
29 * The named struct can also be explicitly tagged for layer reuse (C only),
30 * as well as both having struct attributes appended.
31 */
32#define __struct_group(TAG, NAME, ATTRS, MEMBERS...) \
33 union { \
34 struct { MEMBERS } ATTRS; \
35 struct __struct_group_tag(TAG) { MEMBERS } ATTRS NAME; \
36 } ATTRS
37
38#ifdef __cplusplus
39/* sizeof(struct{}) is 1 in C++, not 0, can't use C version of the macro. */
40#define __DECLARE_FLEX_ARRAY(T, member) \
41 T member[0]
42#else
43/**
44 * __DECLARE_FLEX_ARRAY() - Declare a flexible array usable in a union
45 *
46 * @TYPE: The type of each flexible array element
47 * @NAME: The name of the flexible array member
48 *
49 * In order to have a flexible array member in a union or alone in a
50 * struct, it needs to be wrapped in an anonymous struct with at least 1
51 * named member, but that member can be empty.
52 */
53#define __DECLARE_FLEX_ARRAY(TYPE, NAME) \
54 struct { \
55 struct { } __empty_ ## NAME; \
56 TYPE NAME[]; \
57 }
58#endif
59
60#ifndef __counted_by
61#define __counted_by(m)
62#endif
63
64#ifndef __counted_by_le
65#define __counted_by_le(m)
66#endif
67
68#ifndef __counted_by_be
69#define __counted_by_be(m)
70#endif
71
72#define __kernel_nonstring
73
74#endif /* _LINUX_STDDEF_H */
75