This is xnu-8019. See this file in:
/*
 * Copyright (c) 2011-2014 Apple Inc. All rights reserved.
 *
 * @APPLE_APACHE_LICENSE_HEADER_START@
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 *
 * @APPLE_APACHE_LICENSE_HEADER_END@
 */

#if KERNEL

#ifndef __OS_OBJECT__
#define __OS_OBJECT__

#ifdef __APPLE__
#include <Availability.h>
#endif
#include <os/base.h>

/*!
 * @header
 *
 * @preprocinfo
 * By default, libSystem objects such as GCD and XPC objects are declared as
 * Objective-C types when building with an Objective-C compiler. This allows
 * them to participate in ARC, in RR management by the Blocks runtime and in
 * leaks checking by the static analyzer, and enables them to be added to Cocoa
 * collections.
 *
 * NOTE: this requires explicit cancellation of dispatch sources and xpc
 *       connections whose handler blocks capture the source/connection object,
 *       resp. ensuring that such captures do not form retain cycles (e.g. by
 *       declaring the source as __weak).
 *
 * To opt-out of this default behavior, add -DOS_OBJECT_USE_OBJC=0 to your
 * compiler flags.
 *
 * This mode requires a platform with the modern Objective-C runtime, the
 * Objective-C GC compiler option to be disabled, and at least a Mac OS X 10.8
 * or iOS 6.0 deployment target.
 */

#ifndef OS_OBJECT_HAVE_OBJC_SUPPORT
#if defined(__OBJC__) && defined(__OBJC2__) && !defined(__OBJC_GC__) && ( \
	__MAC_OS_X_VERSION_MIN_REQUIRED >= __MAC_10_8 || \
	__IPHONE_OS_VERSION_MIN_REQUIRED >= __IPHONE_6_0)
#define OS_OBJECT_HAVE_OBJC_SUPPORT 1
#else
#define OS_OBJECT_HAVE_OBJC_SUPPORT 0
#endif
#endif

#if OS_OBJECT_HAVE_OBJC_SUPPORT
#ifndef OS_OBJECT_USE_OBJC
#define OS_OBJECT_USE_OBJC 1
#endif
#elif defined(OS_OBJECT_USE_OBJC) && OS_OBJECT_USE_OBJC
/* Unsupported platform for OS_OBJECT_USE_OBJC=1 */
#undef OS_OBJECT_USE_OBJC
#define OS_OBJECT_USE_OBJC 0
#else
#define OS_OBJECT_USE_OBJC 0
#endif

#if OS_OBJECT_USE_OBJC
#import <objc/NSObject.h>
#if defined(__has_attribute)
#if __has_attribute(objc_independent_class)
#define OS_OBJC_INDEPENDENT_CLASS __attribute__((objc_independent_class))
#endif
#endif // __has_attribute(objc_independent_class)
#ifndef OS_OBJC_INDEPENDENT_CLASS
#define OS_OBJC_INDEPENDENT_CLASS
#endif
#define OS_OBJECT_CLASS(name) OS_##name
#define OS_OBJECT_DECL_IMPL(name, ...) \
	        @protocol OS_OBJECT_CLASS(name) __VA_ARGS__ \
	        @end \
	        typedef NSObject<OS_OBJECT_CLASS(name)> \
	                        * OS_OBJC_INDEPENDENT_CLASS name##_t
#define OS_OBJECT_DECL(name, ...) \
	        OS_OBJECT_DECL_IMPL(name, <NSObject>)
#define OS_OBJECT_DECL_SUBCLASS(name, super) \
	        OS_OBJECT_DECL_IMPL(name, <OS_OBJECT_CLASS(super)>)
#if defined(__has_attribute)
#if __has_attribute(ns_returns_retained)
#define OS_OBJECT_RETURNS_RETAINED __attribute__((__ns_returns_retained__))
#else
#define OS_OBJECT_RETURNS_RETAINED
#endif
#if __has_attribute(ns_consumed)
#define OS_OBJECT_CONSUMED __attribute__((__ns_consumed__))
#else
#define OS_OBJECT_CONSUMED
#endif
#else
#define OS_OBJECT_RETURNS_RETAINED
#define OS_OBJECT_CONSUMED
#endif
#if defined(__has_feature)
#if __has_feature(objc_arc)
#define OS_OBJECT_BRIDGE __bridge
#define OS_WARN_RESULT_NEEDS_RELEASE
#else
#define OS_OBJECT_BRIDGE
#define OS_WARN_RESULT_NEEDS_RELEASE OS_WARN_RESULT
#endif
#else
#define OS_OBJECT_BRIDGE
#define OS_WARN_RESULT_NEEDS_RELEASE OS_WARN_RESULT
#endif
#ifndef OS_OBJECT_USE_OBJC_RETAIN_RELEASE
#if defined(__clang_analyzer__)
#define OS_OBJECT_USE_OBJC_RETAIN_RELEASE 1
#elif defined(__has_feature)
#if __has_feature(objc_arc)
#define OS_OBJECT_USE_OBJC_RETAIN_RELEASE 1
#else
#define OS_OBJECT_USE_OBJC_RETAIN_RELEASE 0
#endif
#else
#define OS_OBJECT_USE_OBJC_RETAIN_RELEASE 0
#endif
#endif
#else
/*! @parseOnly */
#define OS_OBJECT_RETURNS_RETAINED
/*! @parseOnly */
#define OS_OBJECT_CONSUMED
/*! @parseOnly */
#define OS_OBJECT_BRIDGE
/*! @parseOnly */
#define OS_WARN_RESULT_NEEDS_RELEASE OS_WARN_RESULT
#define OS_OBJECT_USE_OBJC_RETAIN_RELEASE 0
#endif

#define OS_OBJECT_GLOBAL_OBJECT(type, object) ((OS_OBJECT_BRIDGE type)&(object))

__BEGIN_DECLS

/*!
 * @function os_retain
 *
 * @abstract
 * Increment the reference count of an os_object.
 *
 * @discussion
 * On a platform with the modern Objective-C runtime this is exactly equivalent
 * to sending the object the -[retain] message.
 *
 * @param object
 * The object to retain.
 *
 * @result
 * The retained object.
 */
    __OSX_AVAILABLE_STARTING(__MAC_10_12, __IPHONE_10_0)
OS_EXPORT
void*
os_retain(void *object);
#if OS_OBJECT_USE_OBJC
#undef os_retain
#define os_retain(object) [object retain]
#endif

/*!
 * @function os_release
 *
 * @abstract
 * Decrement the reference count of a os_object.
 *
 * @discussion
 * On a platform with the modern Objective-C runtime this is exactly equivalent
 * to sending the object the -[release] message.
 *
 * @param object
 * The object to release.
 */
__OSX_AVAILABLE_STARTING(__MAC_10_12, __IPHONE_10_0)
OS_EXPORT
void
os_release(void *object);
#if OS_OBJECT_USE_OBJC
#undef os_release
#define os_release(object) [object release]
#endif

#define fastpath(x) ((typeof(x))__builtin_expect((long)(x), ~0l))
#define slowpath(x) ((typeof(x))__builtin_expect((long)(x), 0l))

__END_DECLS

#endif /* OS_OBJECT file guard */

#else /* KERNEL */

/* This should use the libdispatch header */
#include_next <os/object.h>

#endif /* KERNEL */