1 /* SPDX-License-Identifier: GPL-2.0 */ 2 #ifndef _LINUX_STDDEF_H 3 #define _LINUX_STDDEF_H 4 5 #include <uapi/linux/stddef.h> 6 7 #undef NULL 8 #define NULL ((void *)0) 9 10 enum { 11 false = 0, 12 true = 1 13 }; 14 15 #undef offsetof 16 #ifdef __compiler_offsetof 17 #define offsetof(TYPE, MEMBER) __compiler_offsetof(TYPE, MEMBER) 18 #else 19 #define offsetof(TYPE, MEMBER) ((size_t)&((TYPE *)0)->MEMBER) 20 #endif 21 22 /** 23 * sizeof_field() - Report the size of a struct field in bytes 24 * 25 * @TYPE: The structure containing the field of interest 26 * @MEMBER: The field to return the size of 27 */ 28 #define sizeof_field(TYPE, MEMBER) sizeof((((TYPE *)0)->MEMBER)) 29 30 /** 31 * offsetofend() - Report the offset of a struct field within the struct 32 * 33 * @TYPE: The type of the structure 34 * @MEMBER: The member within the structure to get the end offset of 35 */ 36 #define offsetofend(TYPE, MEMBER) \ 37 (offsetof(TYPE, MEMBER) + sizeof_field(TYPE, MEMBER)) 38 39 /** 40 * struct_group() - Wrap a set of declarations in a mirrored struct 41 * 42 * @NAME: The identifier name of the mirrored sub-struct 43 * @MEMBERS: The member declarations for the mirrored structs 44 * 45 * Used to create an anonymous union of two structs with identical 46 * layout and size: one anonymous and one named. The former can be 47 * used normally without sub-struct naming, and the latter can be 48 * used to reason about the start, end, and size of the group of 49 * struct members. 50 */ 51 #define struct_group(NAME, MEMBERS...) \ 52 __struct_group(/* no tag */, NAME, /* no attrs */, MEMBERS) 53 54 /** 55 * struct_group_attr() - Create a struct_group() with trailing attributes 56 * 57 * @NAME: The identifier name of the mirrored sub-struct 58 * @ATTRS: Any struct attributes to apply 59 * @MEMBERS: The member declarations for the mirrored structs 60 * 61 * Used to create an anonymous union of two structs with identical 62 * layout and size: one anonymous and one named. The former can be 63 * used normally without sub-struct naming, and the latter can be 64 * used to reason about the start, end, and size of the group of 65 * struct members. Includes structure attributes argument. 66 */ 67 #define struct_group_attr(NAME, ATTRS, MEMBERS...) \ 68 __struct_group(/* no tag */, NAME, ATTRS, MEMBERS) 69 70 /** 71 * struct_group_tagged() - Create a struct_group with a reusable tag 72 * 73 * @TAG: The tag name for the named sub-struct 74 * @NAME: The identifier name of the mirrored sub-struct 75 * @MEMBERS: The member declarations for the mirrored structs 76 * 77 * Used to create an anonymous union of two structs with identical 78 * layout and size: one anonymous and one named. The former can be 79 * used normally without sub-struct naming, and the latter can be 80 * used to reason about the start, end, and size of the group of 81 * struct members. Includes struct tag argument for the named copy, 82 * so the specified layout can be reused later. 83 */ 84 #define struct_group_tagged(TAG, NAME, MEMBERS...) \ 85 __struct_group(TAG, NAME, /* no attrs */, MEMBERS) 86 87 /** 88 * DECLARE_FLEX_ARRAY() - Declare a flexible array usable in a union 89 * 90 * @TYPE: The type of each flexible array element 91 * @NAME: The name of the flexible array member 92 * 93 * In order to have a flexible array member in a union or alone in a 94 * struct, it needs to be wrapped in an anonymous struct with at least 1 95 * named member, but that member can be empty. 96 */ 97 #define DECLARE_FLEX_ARRAY(TYPE, NAME) \ 98 __DECLARE_FLEX_ARRAY(TYPE, NAME) 99 100 #endif 101