1 /* SPDX-License-Identifier: GPL-2.0 */ 2 #ifndef _LINUX_STDDEF_H 3 #define _LINUX_STDDEF_H 4 5 /* SPDX-License-Identifier: GPL-2.0 WITH Linux-syscall-note */ 6 #ifndef _UAPI_LINUX_STDDEF_H 7 #define _UAPI_LINUX_STDDEF_H 8 9 #include "../compiler_types.h" 10 11 #ifndef __always_inline 12 #define __always_inline inline 13 #endif 14 15 /** 16 * __struct_group() - Create a mirrored named and anonyomous struct 17 * 18 * @TAG: The tag name for the named sub-struct (usually empty) 19 * @NAME: The identifier name of the mirrored sub-struct 20 * @ATTRS: Any struct attributes (usually empty) 21 * @MEMBERS: The member declarations for the mirrored structs 22 * 23 * Used to create an anonymous union of two structs with identical layout 24 * and size: one anonymous and one named. The former's members can be used 25 * normally without sub-struct naming, and the latter can be used to 26 * reason about the start, end, and size of the group of struct members. 27 * The named struct can also be explicitly tagged for layer reuse, as well 28 * as both having struct attributes appended. 29 */ 30 #define __struct_group(TAG, NAME, ATTRS, MEMBERS...) \ 31 union { \ 32 struct { MEMBERS } ATTRS; \ 33 struct TAG { MEMBERS } ATTRS NAME; \ 34 } 35 36 #ifdef __cplusplus 37 /* sizeof(struct{}) is 1 in C++, not 0, can't use C version of the macro. */ 38 #define __DECLARE_FLEX_ARRAY(T, member) \ 39 T member[0] 40 #else 41 /** 42 * __DECLARE_FLEX_ARRAY() - Declare a flexible array usable in a union 43 * 44 * @TYPE: The type of each flexible array element 45 * @NAME: The name of the flexible array member 46 * 47 * In order to have a flexible array member in a union or alone in a 48 * struct, it needs to be wrapped in an anonymous struct with at least 1 49 * named member, but that member can be empty. 50 */ 51 #define __DECLARE_FLEX_ARRAY(TYPE, NAME) \ 52 struct { \ 53 struct { } __empty_ ## NAME; \ 54 TYPE NAME[]; \ 55 } 56 #endif 57 58 #ifndef __counted_by 59 #define __counted_by(m) 60 #endif 61 62 #endif /* _UAPI_LINUX_STDDEF_H */ 63 64 65 #undef NULL 66 #define NULL ((void *)0) 67 68 // enum { 69 // false = 0, 70 // true = 1 71 // }; 72 73 #undef offsetof 74 #define offsetof(TYPE, MEMBER) __builtin_offsetof(TYPE, MEMBER) 75 76 /** 77 * sizeof_field() - Report the size of a struct field in bytes 78 * 79 * @TYPE: The structure containing the field of interest 80 * @MEMBER: The field to return the size of 81 */ 82 #define sizeof_field(TYPE, MEMBER) sizeof((((TYPE *)0)->MEMBER)) 83 84 /** 85 * offsetofend() - Report the offset of a struct field within the struct 86 * 87 * @TYPE: The type of the structure 88 * @MEMBER: The member within the structure to get the end offset of 89 */ 90 #define offsetofend(TYPE, MEMBER) \ 91 (offsetof(TYPE, MEMBER) + sizeof_field(TYPE, MEMBER)) 92 93 /** 94 * struct_group() - Wrap a set of declarations in a mirrored struct 95 * 96 * @NAME: The identifier name of the mirrored sub-struct 97 * @MEMBERS: The member declarations for the mirrored structs 98 * 99 * Used to create an anonymous union of two structs with identical 100 * layout and size: one anonymous and one named. The former can be 101 * used normally without sub-struct naming, and the latter can be 102 * used to reason about the start, end, and size of the group of 103 * struct members. 104 */ 105 #define struct_group(NAME, MEMBERS...) \ 106 __struct_group(/* no tag */, NAME, /* no attrs */, MEMBERS) 107 108 /** 109 * struct_group_attr() - Create a struct_group() with trailing attributes 110 * 111 * @NAME: The identifier name of the mirrored sub-struct 112 * @ATTRS: Any struct attributes to apply 113 * @MEMBERS: The member declarations for the mirrored structs 114 * 115 * Used to create an anonymous union of two structs with identical 116 * layout and size: one anonymous and one named. The former can be 117 * used normally without sub-struct naming, and the latter can be 118 * used to reason about the start, end, and size of the group of 119 * struct members. Includes structure attributes argument. 120 */ 121 #define struct_group_attr(NAME, ATTRS, MEMBERS...) \ 122 __struct_group(/* no tag */, NAME, ATTRS, MEMBERS) 123 124 /** 125 * struct_group_tagged() - Create a struct_group with a reusable tag 126 * 127 * @TAG: The tag name for the named sub-struct 128 * @NAME: The identifier name of the mirrored sub-struct 129 * @MEMBERS: The member declarations for the mirrored structs 130 * 131 * Used to create an anonymous union of two structs with identical 132 * layout and size: one anonymous and one named. The former can be 133 * used normally without sub-struct naming, and the latter can be 134 * used to reason about the start, end, and size of the group of 135 * struct members. Includes struct tag argument for the named copy, 136 * so the specified layout can be reused later. 137 */ 138 #define struct_group_tagged(TAG, NAME, MEMBERS...) \ 139 __struct_group(TAG, NAME, /* no attrs */, MEMBERS) 140 141 /** 142 * DECLARE_FLEX_ARRAY() - Declare a flexible array usable in a union 143 * 144 * @TYPE: The type of each flexible array element 145 * @NAME: The name of the flexible array member 146 * 147 * In order to have a flexible array member in a union or alone in a 148 * struct, it needs to be wrapped in an anonymous struct with at least 1 149 * named member, but that member can be empty. 150 */ 151 #define DECLARE_FLEX_ARRAY(TYPE, NAME) \ 152 __DECLARE_FLEX_ARRAY(TYPE, NAME) 153 154 #endif 155