stddef.h

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/* SPDX-License-Identifier: GPL-2.0 */
#ifndef _LINUX_STDDEF_H
#define _LINUX_STDDEF_H
 
#include <uapi/linux/stddef.h>
 
#undef NULL
#define NULL ((void *)0)
 
/*
 * mainline spells these as an enum.  Under this tree <stdbool.h> has usually
 * been pulled in already (linux/atomic.h includes it) and defines true/false
 * as macros, so the enum body expands to `false = 0` -- an enumerator named
 * `0`, hence "expected identifier".  Guarded: with the macros present they
 * already mean 1 and 0, which is all the enum is saying, and without them the
 * enum is mainline's.
 */
#ifndef true
enum {
    false   = 0,
    true    = 1
};
#endif
 
#undef offsetof
#define offsetof(TYPE, MEMBER)  __builtin_offsetof(TYPE, MEMBER)
 
#define sizeof_field(TYPE, MEMBER) sizeof((((TYPE *)0)->MEMBER))
 
#define offsetofend(TYPE, MEMBER) \
    (offsetof(TYPE, MEMBER) + sizeof_field(TYPE, MEMBER))
 
#define struct_group(NAME, MEMBERS...)  \
    __struct_group(/* no tag */, NAME, /* no attrs */, MEMBERS)
 
#define struct_group_attr(NAME, ATTRS, MEMBERS...) \
    __struct_group(/* no tag */, NAME, ATTRS, MEMBERS)
 
#define struct_group_tagged(TAG, NAME, MEMBERS...) \
    __struct_group(TAG, NAME, /* no attrs */, MEMBERS)
 
#define DECLARE_FLEX_ARRAY(TYPE, NAME) \
    __DECLARE_FLEX_ARRAY(TYPE, NAME)
 
#define __TRAILING_OVERLAP(TYPE, NAME, FAM, ATTRS, MEMBERS)         \
    union {                                 \
        TYPE NAME;                          \
        struct {                            \
            unsigned char __offset_to_FAM[offsetof(TYPE, FAM)]; \
            MEMBERS                         \
        } ATTRS;                            \
    }
 
#define TRAILING_OVERLAP(TYPE, NAME, FAM, MEMBERS)              \
    __TRAILING_OVERLAP(TYPE, NAME, FAM, /* no attrs */, MEMBERS)
 
#endif