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/*-
 * SPDX-License-Identifier: BSD-3-Clause
 *
 * Copyright (c) 1991, 1993
 *	The Regents of the University of California.  All rights reserved.
 *
 * This code is derived from software contributed to Berkeley by
 * Berkeley Software Design, Inc.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 * 3. Neither the name of the University nor the names of its contributors
 *    may be used to endorse or promote products derived from this software
 *    without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 *
 *	@(#)cdefs.h	8.8 (Berkeley) 1/9/95
 * $FreeBSD$
 */

#ifndef	_SYS_CDEFS_H_
#define	_SYS_CDEFS_H_

#if defined(_KERNEL) && defined(_STANDALONE)
#error "_KERNEL and _STANDALONE are mutually exclusive"
#endif

/*
 * Testing against Clang-specific extensions.
 */
#ifndef	__has_attribute
#define	__has_attribute(x)	0
#endif
#ifndef	__has_extension
#define	__has_extension		__has_feature
#endif
#ifndef	__has_feature
#define	__has_feature(x)	0
#endif
#ifndef	__has_include
#define	__has_include(x)	0
#endif
#ifndef	__has_builtin
#define	__has_builtin(x)	0
#endif

#if defined(__cplusplus)
#define	__BEGIN_DECLS	extern "C" {
#define	__END_DECLS	}
#else
#define	__BEGIN_DECLS
#define	__END_DECLS
#endif

/*
 * This code has been put in place to help reduce the addition of
 * compiler specific defines in FreeBSD code.  It helps to aid in
 * having a compiler-agnostic source tree.
 */

#if defined(__GNUC__)

#if __GNUC__ >= 3
#define	__GNUCLIKE_ASM 3
#define	__GNUCLIKE_MATH_BUILTIN_CONSTANTS
#else
#define	__GNUCLIKE_ASM 2
#endif
#define	__GNUCLIKE___TYPEOF 1
#define	__GNUCLIKE___OFFSETOF 1
#define	__GNUCLIKE___SECTION 1

#define	__GNUCLIKE_CTOR_SECTION_HANDLING 1

#define	__GNUCLIKE_BUILTIN_CONSTANT_P 1

#if (__GNUC_MINOR__ > 95 || __GNUC__ >= 3)
#define	__GNUCLIKE_BUILTIN_VARARGS 1
#define	__GNUCLIKE_BUILTIN_STDARG 1
#define	__GNUCLIKE_BUILTIN_VAALIST 1
#endif

#if defined(__GNUC__)
#define	__GNUC_VA_LIST_COMPATIBILITY 1
#endif

/*
 * Compiler memory barriers, specific to gcc and clang.
 */
#if defined(__GNUC__)
#define	__compiler_membar()	__asm __volatile(" " : : : "memory")
#endif

#define	__GNUCLIKE_BUILTIN_NEXT_ARG 1
#define	__GNUCLIKE_MATH_BUILTIN_RELOPS

#define	__GNUCLIKE_BUILTIN_MEMCPY 1

/* XXX: if __GNUC__ >= 2: not tested everywhere originally, where replaced */
#define	__CC_SUPPORTS_INLINE 1
#define	__CC_SUPPORTS___INLINE 1
#define	__CC_SUPPORTS___INLINE__ 1

#define	__CC_SUPPORTS___FUNC__ 1
#define	__CC_SUPPORTS_WARNING 1

#define	__CC_SUPPORTS_VARADIC_XXX 1 /* see varargs.h */

#define	__CC_SUPPORTS_DYNAMIC_ARRAY_INIT 1

#endif /* __GNUC__ */

/*
 * Macro to test if we're using a specific version of gcc or later.
 */
#if defined(__GNUC__)
#define	__GNUC_PREREQ__(ma, mi)	\
	(__GNUC__ > (ma) || __GNUC__ == (ma) && __GNUC_MINOR__ >= (mi))
#else
#define	__GNUC_PREREQ__(ma, mi)	0
#endif

/*
 * The __CONCAT macro is used to concatenate parts of symbol names, e.g.
 * with "#define OLD(foo) __CONCAT(old,foo)", OLD(foo) produces oldfoo.
 * The __CONCAT macro is a bit tricky to use if it must work in non-ANSI
 * mode -- there must be no spaces between its arguments, and for nested
 * __CONCAT's, all the __CONCAT's must be at the left.  __CONCAT can also
 * concatenate double-quoted strings produced by the __STRING macro, but
 * this only works with ANSI C.
 *
 * __XSTRING is like __STRING, but it expands any macros in its argument
 * first.  It is only available with ANSI C.
 */
#if defined(__STDC__) || defined(__cplusplus)
#define	__P(protos)	protos		/* full-blown ANSI C */
#define	__CONCAT1(x,y)	x ## y
#define	__CONCAT(x,y)	__CONCAT1(x,y)
#define	__STRING(x)	#x		/* stringify without expanding x */
#define	__XSTRING(x)	__STRING(x)	/* expand x, then stringify */

#define	__const		const		/* define reserved names to standard */
#define	__signed	signed
#define	__volatile	volatile
#if defined(__cplusplus)
#define	__inline	inline		/* convert to C++ keyword */
#else
#if !(defined(__CC_SUPPORTS___INLINE))
#define	__inline			/* delete GCC keyword */
#endif /* ! __CC_SUPPORTS___INLINE */
#endif /* !__cplusplus */

#else	/* !(__STDC__ || __cplusplus) */
#define	__P(protos)	()		/* traditional C preprocessor */
#define	__CONCAT(x,y)	x/**/y
#define	__STRING(x)	"x"

#if !defined(__CC_SUPPORTS___INLINE)
#define	__const				/* delete pseudo-ANSI C keywords */
#define	__inline
#define	__signed
#define	__volatile
/*
 * In non-ANSI C environments, new programs will want ANSI-only C keywords
 * deleted from the program and old programs will want them left alone.
 * When using a compiler other than gcc, programs using the ANSI C keywords
 * const, inline etc. as normal identifiers should define -DNO_ANSI_KEYWORDS.
 * When using "gcc -traditional", we assume that this is the intent; if
 * __GNUC__ is defined but __STDC__ is not, we leave the new keywords alone.
 */
#ifndef	NO_ANSI_KEYWORDS
#define	const				/* delete ANSI C keywords */
#define	inline
#define	signed
#define	volatile
#endif	/* !NO_ANSI_KEYWORDS */
#endif	/* !__CC_SUPPORTS___INLINE */
#endif	/* !(__STDC__ || __cplusplus) */

/*
 * Compiler-dependent macros to help declare dead (non-returning) and
 * pure (no side effects) functions, and unused variables.  They are
 * null except for versions of gcc that are known to support the features
 * properly (old versions of gcc-2 supported the dead and pure features
 * in a different (wrong) way).  If we do not provide an implementation
 * for a given compiler, let the compile fail if it is told to use
 * a feature that we cannot live without.
 */
#define	__weak_symbol	__attribute__((__weak__))
#if !__GNUC_PREREQ__(2, 5)
#define	__dead2
#define	__pure2
#define	__unused
#endif
#if __GNUC__ == 2 && __GNUC_MINOR__ >= 5 && __GNUC_MINOR__ < 7
#define	__dead2		__attribute__((__noreturn__))
#define	__pure2		__attribute__((__const__))
#define	__unused
/* XXX Find out what to do for __packed, __aligned and __section */
#endif
#if __GNUC_PREREQ__(2, 7)
#define	__dead2		__attribute__((__noreturn__))
#define	__pure2		__attribute__((__const__))
#define	__unused	__attribute__((__unused__))
#define	__used		__attribute__((__used__))
#define	__packed	__attribute__((__packed__))
#define	__aligned(x)	__attribute__((__aligned__(x)))
#define	__section(x)	__attribute__((__section__(x)))
#endif
#if __GNUC_PREREQ__(4, 3) || __has_attribute(__alloc_size__)
#define	__alloc_size(x)	__attribute__((__alloc_size__(x)))
#define	__alloc_size2(n, x)	__attribute__((__alloc_size__(n, x)))
#else
#define	__alloc_size(x)
#define	__alloc_size2(n, x)
#endif
#if __GNUC_PREREQ__(4, 9) || __has_attribute(__alloc_align__)
#define	__alloc_align(x)	__attribute__((__alloc_align__(x)))
#else
#define	__alloc_align(x)
#endif

#if !__GNUC_PREREQ__(2, 95)
#define	__alignof(x)	__offsetof(struct { char __a; x __b; }, __b)
#endif

/*
 * Keywords added in C11.
 */

#if !defined(__STDC_VERSION__) || __STDC_VERSION__ < 201112L

#if !__has_extension(c_alignas)
#if (defined(__cplusplus) && __cplusplus >= 201103L) || \
    __has_extension(cxx_alignas)
#define	_Alignas(x)		alignas(x)
#else
/* XXX: Only emulates _Alignas(constant-expression); not _Alignas(type-name). */
#define	_Alignas(x)		__aligned(x)
#endif
#endif

#if defined(__cplusplus) && __cplusplus >= 201103L
#define	_Alignof(x)		alignof(x)
#else
#define	_Alignof(x)		__alignof(x)
#endif

#if !defined(__cplusplus) && !__has_extension(c_atomic) && \
	!__has_extension(cxx_atomic) && !__GNUC_PREREQ__(4, 7)
/*
 * No native support for _Atomic(). Place object in structure to prevent
 * most forms of direct non-atomic access.
 */
#define	_Atomic(T)		struct { T volatile __val; }
#endif

#if defined(__cplusplus) && __cplusplus >= 201103L
#define	_Noreturn		[[noreturn]]
#else
#define	_Noreturn		__dead2
#endif

#if !__has_extension(c_static_assert)
#if (defined(__cplusplus) && __cplusplus >= 201103L) || \
    __has_extension(cxx_static_assert)
#define	_Static_assert(x, y)	static_assert(x, y)
#elif __GNUC_PREREQ__(4,6) && !defined(__cplusplus)
/* Nothing, gcc 4.6 and higher has _Static_assert built-in */
#elif defined(__COUNTER__)
#define	_Static_assert(x, y)	__Static_assert(x, __COUNTER__)
#define	__Static_assert(x, y)	___Static_assert(x, y)
#define	___Static_assert(x, y)	typedef char __assert_ ## y[(x) ? 1 : -1] \
				__unused
#else
#define	_Static_assert(x, y)	struct __hack
#endif
#endif

#if !__has_extension(c_thread_local)
/*
 * XXX: Some compilers (Clang 3.3, GCC 4.7) falsely announce C++11 mode
 * without actually supporting the thread_local keyword. Don't check for
 * the presence of C++11 when defining _Thread_local.
 */
#if /* (defined(__cplusplus) && __cplusplus >= 201103L) || */ \
    __has_extension(cxx_thread_local)
#define	_Thread_local		thread_local
#else
#define	_Thread_local		__thread
#endif
#endif

#endif /* __STDC_VERSION__ || __STDC_VERSION__ < 201112L */

/*
 * Emulation of C11 _Generic().  Unlike the previously defined C11
 * keywords, it is not possible to implement this using exactly the same
 * syntax.  Therefore implement something similar under the name
 * __generic().  Unlike _Generic(), this macro can only distinguish
 * between a single type, so it requires nested invocations to
 * distinguish multiple cases.
 */

#if (defined(__STDC_VERSION__) && __STDC_VERSION__ >= 201112L) || \
    __has_extension(c_generic_selections)
#define	__generic(expr, t, yes, no)					\
	_Generic(expr, t: yes, default: no)
#elif __GNUC_PREREQ__(3, 1) && !defined(__cplusplus)
#define	__generic(expr, t, yes, no)					\
	__builtin_choose_expr(						\
	    __builtin_types_compatible_p(__typeof(expr), t), yes, no)
#endif

/*
 * C99 Static array indices in function parameter declarations.  Syntax such as:
 * void bar(int myArray[static 10]);
 * is allowed in C99 but not in C++.  Define __min_size appropriately so
 * headers using it can be compiled in either language.  Use like this:
 * void bar(int myArray[__min_size(10)]);
 */
#if !defined(__cplusplus) && \
    (defined(__clang__) || __GNUC_PREREQ__(4, 6)) && \
    (!defined(__STDC_VERSION__) || (__STDC_VERSION__ >= 199901))
#define __min_size(x)	static (x)
#else
#define __min_size(x)	(x)
#endif

#if __GNUC_PREREQ__(2, 96)
#define	__malloc_like	__attribute__((__malloc__))
#define	__pure		__attribute__((__pure__))
#else
#define	__malloc_like
#define	__pure
#endif

#if __GNUC_PREREQ__(3, 1)
#define	__always_inline	__attribute__((__always_inline__))
#else
#define	__always_inline
#endif

#if __GNUC_PREREQ__(3, 1)
#define	__noinline	__attribute__ ((__noinline__))
#else
#define	__noinline
#endif

#if __GNUC_PREREQ__(3, 4)
#define	__fastcall	__attribute__((__fastcall__))
#define	__result_use_check	__attribute__((__warn_unused_result__))
#else
#define	__fastcall
#define	__result_use_check
#endif

#if __GNUC_PREREQ__(4, 1)
#define	__returns_twice	__attribute__((__returns_twice__))
#else
#define	__returns_twice
#endif

#if __GNUC_PREREQ__(4, 6) || __has_builtin(__builtin_unreachable)
#define	__unreachable()	__builtin_unreachable()
#else
#define	__unreachable()	((void)0)
#endif

/* XXX: should use `#if __STDC_VERSION__ < 199901'. */
#if !__GNUC_PREREQ__(2, 7)
#define	__func__	NULL
#endif

#if (defined(__GNUC__) && __GNUC__ >= 2) && !defined(__STRICT_ANSI__) || __STDC_VERSION__ >= 199901
#define	__LONG_LONG_SUPPORTED
#endif

/* C++11 exposes a load of C99 stuff */
#if defined(__cplusplus) && __cplusplus >= 201103L
#define	__LONG_LONG_SUPPORTED
#ifndef	__STDC_LIMIT_MACROS
#define	__STDC_LIMIT_MACROS
#endif
#ifndef	__STDC_CONSTANT_MACROS
#define	__STDC_CONSTANT_MACROS
#endif
#endif

/*
 * GCC 2.95 provides `__restrict' as an extension to C90 to support the
 * C99-specific `restrict' type qualifier.  We happen to use `__restrict' as
 * a way to define the `restrict' type qualifier without disturbing older
 * software that is unaware of C99 keywords.
 */
#if !(__GNUC__ == 2 && __GNUC_MINOR__ == 95)
#if !defined(__STDC_VERSION__) || __STDC_VERSION__ < 199901
#define	__restrict
#else
#define	__restrict	restrict
#endif
#endif

/*
 * GNU C version 2.96 adds explicit branch prediction so that
 * the CPU back-end can hint the processor and also so that
 * code blocks can be reordered such that the predicted path
 * sees a more linear flow, thus improving cache behavior, etc.
 *
 * The following two macros provide us with a way to utilize this
 * compiler feature.  Use __predict_true() if you expect the expression
 * to evaluate to true, and __predict_false() if you expect the
 * expression to evaluate to false.
 *
 * A few notes about usage:
 *
 *	* Generally, __predict_false() error condition checks (unless
 *	  you have some _strong_ reason to do otherwise, in which case
 *	  document it), and/or __predict_true() `no-error' condition
 *	  checks, assuming you want to optimize for the no-error case.
 *
 *	* Other than that, if you don't know the likelihood of a test
 *	  succeeding from empirical or other `hard' evidence, don't
 *	  make predictions.
 *
 *	* These are meant to be used in places that are run `a lot'.
 *	  It is wasteful to make predictions in code that is run
 *	  seldomly (e.g. at subsystem initialization time) as the
 *	  basic block reordering that this affects can often generate
 *	  larger code.
 */
#if __GNUC_PREREQ__(2, 96)
#define	__predict_true(exp)     __builtin_expect((exp), 1)
#define	__predict_false(exp)    __builtin_expect((exp), 0)
#else
#define	__predict_true(exp)     (exp)
#define	__predict_false(exp)    (exp)
#endif

#if __GNUC_PREREQ__(4, 0)
#define	__null_sentinel	__attribute__((__sentinel__))
#define	__exported	__attribute__((__visibility__("default")))
#define	__hidden	__attribute__((__visibility__("hidden")))
#else
#define	__null_sentinel
#define	__exported
#define	__hidden
#endif

/*
 * We define this here since <stddef.h>, <sys/queue.h>, and <sys/types.h>
 * require it.
 */
#if __GNUC_PREREQ__(4, 1)
#define	__offsetof(type, field)	 __builtin_offsetof(type, field)
#else
#ifndef __cplusplus
#define	__offsetof(type, field) \
	((__size_t)(__uintptr_t)((const volatile void *)&((type *)0)->field))
#else
#define	__offsetof(type, field)					\
  (__offsetof__ (reinterpret_cast <__size_t>			\
                 (&reinterpret_cast <const volatile char &>	\
                  (static_cast<type *> (0)->field))))
#endif
#endif
#define	__rangeof(type, start, end) \
	(__offsetof(type, end) - __offsetof(type, start))

/*
 * Given the pointer x to the member m of the struct s, return
 * a pointer to the containing structure.  When using GCC, we first
 * assign pointer x to a local variable, to check that its type is
 * compatible with member m.
 */
#if __GNUC_PREREQ__(3, 1)
#define	__containerof(x, s, m) ({					\
	const volatile __typeof(((s *)0)->m) *__x = (x);		\
	__DEQUALIFY(s *, (const volatile char *)__x - __offsetof(s, m));\
})
#else
#define	__containerof(x, s, m)						\
	__DEQUALIFY(s *, (const volatile char *)(x) - __offsetof(s, m))
#endif

/*
 * Compiler-dependent macros to declare that functions take printf-like
 * or scanf-like arguments.  They are null except for versions of gcc
 * that are known to support the features properly (old versions of gcc-2
 * didn't permit keeping the keywords out of the application namespace).
 */
#if !__GNUC_PREREQ__(2, 7)
#define	__printflike(fmtarg, firstvararg)
#define	__scanflike(fmtarg, firstvararg)
#define	__format_arg(fmtarg)
#define	__strfmonlike(fmtarg, firstvararg)
#define	__strftimelike(fmtarg, firstvararg)
#else
#define	__printflike(fmtarg, firstvararg) \
	    __attribute__((__format__ (__printf__, fmtarg, firstvararg)))
#define	__scanflike(fmtarg, firstvararg) \
	    __attribute__((__format__ (__scanf__, fmtarg, firstvararg)))
#define	__format_arg(fmtarg)	__attribute__((__format_arg__ (fmtarg)))
#define	__strfmonlike(fmtarg, firstvararg) \
	    __attribute__((__format__ (__strfmon__, fmtarg, firstvararg)))
#define	__strftimelike(fmtarg, firstvararg) \
	    __attribute__((__format__ (__strftime__, fmtarg, firstvararg)))
#endif

/* Compiler-dependent macros that rely on FreeBSD-specific extensions. */
#if defined(__FreeBSD_cc_version) && __FreeBSD_cc_version >= 300001 && \
    defined(__GNUC__)
#define	__printf0like(fmtarg, firstvararg) \
	    __attribute__((__format__ (__printf0__, fmtarg, firstvararg)))
#else
#define	__printf0like(fmtarg, firstvararg)
#endif

#if defined(__GNUC__)
#define	__strong_reference(sym,aliassym)	\
	extern __typeof (sym) aliassym __attribute__ ((__alias__ (#sym)))
#ifdef __STDC__
#define	__weak_reference(sym,alias)	\
	__asm__(".weak " #alias);	\
	__asm__(".equ "  #alias ", " #sym)
#define	__warn_references(sym,msg)	\
	__asm__(".section .gnu.warning." #sym);	\
	__asm__(".asciz \"" msg "\"");	\
	__asm__(".previous")
#define	__sym_compat(sym,impl,verid)	\
	__asm__(".symver " #impl ", " #sym "@" #verid)
#define	__sym_default(sym,impl,verid)	\
	__asm__(".symver " #impl ", " #sym "@@@" #verid)
#else
#define	__weak_reference(sym,alias)	\
	__asm__(".weak alias");		\
	__asm__(".equ alias, sym")
#define	__warn_references(sym,msg)	\
	__asm__(".section .gnu.warning.sym"); \
	__asm__(".asciz \"msg\"");	\
	__asm__(".previous")
#define	__sym_compat(sym,impl,verid)	\
	__asm__(".symver impl, sym@verid")
#define	__sym_default(impl,sym,verid)	\
	__asm__(".symver impl, sym@@@verid")
#endif	/* __STDC__ */
#endif	/* __GNUC__ */

#define	__GLOBL1(sym)	__asm__(".globl " #sym)
#define	__GLOBL(sym)	__GLOBL1(sym)

#if defined(__GNUC__)
#define	__IDSTRING(name,string)	__asm__(".ident\t\"" string "\"")
#else
/*
 * The following definition might not work well if used in header files,
 * but it should be better than nothing.  If you want a "do nothing"
 * version, then it should generate some harmless declaration, such as:
 *    #define	__IDSTRING(name,string)	struct __hack
 */
#define	__IDSTRING(name,string)	static const char name[] __unused = string
#endif

/*
 * Embed the rcs id of a source file in the resulting library.  Note that in
 * more recent ELF binutils, we use .ident allowing the ID to be stripped.
 * Usage:
 *	__FBSDID("$FreeBSD$");
 */
#ifndef	__FBSDID
#if !defined(STRIP_FBSDID)
#define	__FBSDID(s)	__IDSTRING(__CONCAT(__rcsid_,__LINE__),s)
#else
#define	__FBSDID(s)	struct __hack
#endif
#endif

#ifndef	__RCSID
#ifndef	NO__RCSID
#define	__RCSID(s)	__IDSTRING(__CONCAT(__rcsid_,__LINE__),s)
#else
#define	__RCSID(s)	struct __hack
#endif
#endif

#ifndef	__RCSID_SOURCE
#ifndef	NO__RCSID_SOURCE
#define	__RCSID_SOURCE(s)	__IDSTRING(__CONCAT(__rcsid_source_,__LINE__),s)
#else
#define	__RCSID_SOURCE(s)	struct __hack
#endif
#endif

#ifndef	__SCCSID
#ifndef	NO__SCCSID
#define	__SCCSID(s)	__IDSTRING(__CONCAT(__sccsid_,__LINE__),s)
#else
#define	__SCCSID(s)	struct __hack
#endif
#endif

#ifndef	__COPYRIGHT
#ifndef	NO__COPYRIGHT
#define	__COPYRIGHT(s)	__IDSTRING(__CONCAT(__copyright_,__LINE__),s)
#else
#define	__COPYRIGHT(s)	struct __hack
#endif
#endif

#ifndef	__DECONST
#define	__DECONST(type, var)	((type)(__uintptr_t)(const void *)(var))
#endif

#ifndef	__DEVOLATILE
#define	__DEVOLATILE(type, var)	((type)(__uintptr_t)(volatile void *)(var))
#endif

#ifndef	__DEQUALIFY
#define	__DEQUALIFY(type, var)	((type)(__uintptr_t)(const volatile void *)(var))
#endif

/*-
 * The following definitions are an extension of the behavior originally
 * implemented in <sys/_posix.h>, but with a different level of granularity.
 * POSIX.1 requires that the macros we test be defined before any standard
 * header file is included.
 *
 * Here's a quick run-down of the versions:
 *  defined(_POSIX_SOURCE)		1003.1-1988
 *  _POSIX_C_SOURCE == 1		1003.1-1990
 *  _POSIX_C_SOURCE == 2		1003.2-1992 C Language Binding Option
 *  _POSIX_C_SOURCE == 199309		1003.1b-1993
 *  _POSIX_C_SOURCE == 199506		1003.1c-1995, 1003.1i-1995,
 *					and the omnibus ISO/IEC 9945-1: 1996
 *  _POSIX_C_SOURCE == 200112		1003.1-2001
 *  _POSIX_C_SOURCE == 200809		1003.1-2008
 *
 * In addition, the X/Open Portability Guide, which is now the Single UNIX
 * Specification, defines a feature-test macro which indicates the version of
 * that specification, and which subsumes _POSIX_C_SOURCE.
 *
 * Our macros begin with two underscores to avoid namespace screwage.
 */

/* Deal with IEEE Std. 1003.1-1990, in which _POSIX_C_SOURCE == 1. */
#if defined(_POSIX_C_SOURCE) && _POSIX_C_SOURCE == 1
#undef _POSIX_C_SOURCE		/* Probably illegal, but beyond caring now. */
#define	_POSIX_C_SOURCE		199009
#endif

/* Deal with IEEE Std. 1003.2-1992, in which _POSIX_C_SOURCE == 2. */
#if defined(_POSIX_C_SOURCE) && _POSIX_C_SOURCE == 2
#undef _POSIX_C_SOURCE
#define	_POSIX_C_SOURCE		199209
#endif

/* Deal with various X/Open Portability Guides and Single UNIX Spec. */
#ifdef _XOPEN_SOURCE
#if _XOPEN_SOURCE - 0 >= 700
#define	__XSI_VISIBLE		700
#undef _POSIX_C_SOURCE
#define	_POSIX_C_SOURCE		200809
#elif _XOPEN_SOURCE - 0 >= 600
#define	__XSI_VISIBLE		600
#undef _POSIX_C_SOURCE
#define	_POSIX_C_SOURCE		200112
#elif _XOPEN_SOURCE - 0 >= 500
#define	__XSI_VISIBLE		500
#undef _POSIX_C_SOURCE
#define	_POSIX_C_SOURCE		199506
#endif
#endif

/*
 * Deal with all versions of POSIX.  The ordering relative to the tests above is
 * important.
 */
#if defined(_POSIX_SOURCE) && !defined(_POSIX_C_SOURCE)
#define	_POSIX_C_SOURCE		198808
#endif
#ifdef _POSIX_C_SOURCE
#if _POSIX_C_SOURCE >= 200809
#define	__POSIX_VISIBLE		200809
#define	__ISO_C_VISIBLE		1999
#elif _POSIX_C_SOURCE >= 200112
#define	__POSIX_VISIBLE		200112
#define	__ISO_C_VISIBLE		1999
#elif _POSIX_C_SOURCE >= 199506
#define	__POSIX_VISIBLE		199506
#define	__ISO_C_VISIBLE		1990
#elif _POSIX_C_SOURCE >= 199309
#define	__POSIX_VISIBLE		199309
#define	__ISO_C_VISIBLE		1990
#elif _POSIX_C_SOURCE >= 199209
#define	__POSIX_VISIBLE		199209
#define	__ISO_C_VISIBLE		1990
#elif _POSIX_C_SOURCE >= 199009
#define	__POSIX_VISIBLE		199009
#define	__ISO_C_VISIBLE		1990
#else
#define	__POSIX_VISIBLE		198808
#define	__ISO_C_VISIBLE		0
#endif /* _POSIX_C_SOURCE */
#else
/*-
 * Deal with _ANSI_SOURCE:
 * If it is defined, and no other compilation environment is explicitly
 * requested, then define our internal feature-test macros to zero.  This
 * makes no difference to the preprocessor (undefined symbols in preprocessing
 * expressions are defined to have value zero), but makes it more convenient for
 * a test program to print out the values.
 *
 * If a program mistakenly defines _ANSI_SOURCE and some other macro such as
 * _POSIX_C_SOURCE, we will assume that it wants the broader compilation
 * environment (and in fact we will never get here).
 */
#if defined(_ANSI_SOURCE)	/* Hide almost everything. */
#define	__POSIX_VISIBLE		0
#define	__XSI_VISIBLE		0
#define	__BSD_VISIBLE		0
#define	__ISO_C_VISIBLE		1990
#define	__EXT1_VISIBLE		0
#elif defined(_C99_SOURCE)	/* Localism to specify strict C99 env. */
#define	__POSIX_VISIBLE		0
#define	__XSI_VISIBLE		0
#define	__BSD_VISIBLE		0
#define	__ISO_C_VISIBLE		1999
#define	__EXT1_VISIBLE		0
#elif defined(_C11_SOURCE)	/* Localism to specify strict C11 env. */
#define	__POSIX_VISIBLE		0
#define	__XSI_VISIBLE		0
#define	__BSD_VISIBLE		0
#define	__ISO_C_VISIBLE		2011
#define	__EXT1_VISIBLE		0
#else				/* Default environment: show everything. */
#define	__POSIX_VISIBLE		200809
#define	__XSI_VISIBLE		700
#define	__BSD_VISIBLE		1
#define	__ISO_C_VISIBLE		2011
#define	__EXT1_VISIBLE		1
#endif
#endif

/* User override __EXT1_VISIBLE */
#if defined(__STDC_WANT_LIB_EXT1__)
#undef	__EXT1_VISIBLE
#if __STDC_WANT_LIB_EXT1__
#define	__EXT1_VISIBLE		1
#else
#define	__EXT1_VISIBLE		0
#endif
#endif /* __STDC_WANT_LIB_EXT1__ */

#if defined(__powerpc64__) && (!defined(_CALL_ELF) || _CALL_ELF == 1)
#define	__NO_TLS 1
#endif

/*
 * Old versions of GCC use non-standard ARM arch symbols; acle-compat.h
 * translates them to __ARM_ARCH and the modern feature symbols defined by ARM.
 */
#if defined(__arm__) && !defined(__ARM_ARCH)
#include <machine/acle-compat.h>
#endif

/*
 * Nullability qualifiers: currently only supported by Clang.
 */
#if !(defined(__clang__) && __has_feature(nullability))
#define	_Nonnull
#define	_Nullable
#define	_Null_unspecified
#define	__NULLABILITY_PRAGMA_PUSH
#define	__NULLABILITY_PRAGMA_POP
#else
#define	__NULLABILITY_PRAGMA_PUSH _Pragma("clang diagnostic push")	\
	_Pragma("clang diagnostic ignored \"-Wnullability-completeness\"")
#define	__NULLABILITY_PRAGMA_POP _Pragma("clang diagnostic pop")
#endif

/*
 * Type Safety Checking
 *
 * Clang provides additional attributes to enable checking type safety
 * properties that cannot be enforced by the C type system. 
 */

#if __has_attribute(__argument_with_type_tag__) && \
    __has_attribute(__type_tag_for_datatype__)
#define	__arg_type_tag(arg_kind, arg_idx, type_tag_idx) \
	    __attribute__((__argument_with_type_tag__(arg_kind, arg_idx, type_tag_idx)))
#define	__datatype_type_tag(kind, type) \
	    __attribute__((__type_tag_for_datatype__(kind, type)))
#else
#define	__arg_type_tag(arg_kind, arg_idx, type_tag_idx)
#define	__datatype_type_tag(kind, type)
#endif

/*
 * Lock annotations.
 *
 * Clang provides support for doing basic thread-safety tests at
 * compile-time, by marking which locks will/should be held when
 * entering/leaving a functions.
 *
 * Furthermore, it is also possible to annotate variables and structure
 * members to enforce that they are only accessed when certain locks are
 * held.
 */

#if __has_extension(c_thread_safety_attributes)
#define	__lock_annotate(x)	__attribute__((x))
#else
#define	__lock_annotate(x)
#endif

/* Structure implements a lock. */
#define	__lockable		__lock_annotate(lockable)

/* Function acquires an exclusive or shared lock. */
#define	__locks_exclusive(...) \
	__lock_annotate(exclusive_lock_function(__VA_ARGS__))
#define	__locks_shared(...) \
	__lock_annotate(shared_lock_function(__VA_ARGS__))

/* Function attempts to acquire an exclusive or shared lock. */
#define	__trylocks_exclusive(...) \
	__lock_annotate(exclusive_trylock_function(__VA_ARGS__))
#define	__trylocks_shared(...) \
	__lock_annotate(shared_trylock_function(__VA_ARGS__))

/* Function releases a lock. */
#define	__unlocks(...)		__lock_annotate(unlock_function(__VA_ARGS__))

/* Function asserts that an exclusive or shared lock is held. */
#define	__asserts_exclusive(...) \
	__lock_annotate(assert_exclusive_lock(__VA_ARGS__))
#define	__asserts_shared(...) \
	__lock_annotate(assert_shared_lock(__VA_ARGS__))

/* Function requires that an exclusive or shared lock is or is not held. */
#define	__requires_exclusive(...) \
	__lock_annotate(exclusive_locks_required(__VA_ARGS__))
#define	__requires_shared(...) \
	__lock_annotate(shared_locks_required(__VA_ARGS__))
#define	__requires_unlocked(...) \
	__lock_annotate(locks_excluded(__VA_ARGS__))

/* Function should not be analyzed. */
#define	__no_lock_analysis	__lock_annotate(no_thread_safety_analysis)

/*
 * Function or variable should not be sanitized, i.e. by AddressSanitizer.
 * GCC has the nosanitize attribute, but as a function attribute only, and
 * warns on use as a variable attribute.
 */
#if __has_attribute(no_sanitize) && defined(__clang__)
#define __nosanitizeaddress	__attribute__((no_sanitize("address")))
#define __nosanitizethread	__attribute__((no_sanitize("thread")))
#else
#define __nosanitizeaddress
#define __nosanitizethread
#endif

/* Guard variables and structure members by lock. */
#define	__guarded_by(x)		__lock_annotate(guarded_by(x))
#define	__pt_guarded_by(x)	__lock_annotate(pt_guarded_by(x))

/* Alignment builtins for better type checking and improved code generation. */
/* Provide fallback versions for other compilers (GCC/Clang < 10): */
#if !__has_builtin(__builtin_is_aligned)
#define __builtin_is_aligned(x, align)	\
	(((__uintptr_t)x & ((align) - 1)) == 0)
#endif
#if !__has_builtin(__builtin_align_up)
#define __builtin_align_up(x, align)	\
	((__typeof__(x))(((__uintptr_t)(x)+((align)-1))&(~((align)-1))))
#endif
#if !__has_builtin(__builtin_align_down)
#define __builtin_align_down(x, align)	\
	((__typeof__(x))((x)&(~((align)-1))))
#endif

#define __align_up(x, y) __builtin_align_up(x, y)
#define __align_down(x, y) __builtin_align_down(x, y)
#define __is_aligned(x, y) __builtin_is_aligned(x, y)

#endif /* !_SYS_CDEFS_H_ */