This is xnu-8019. See this file in:
/*
 * Copyright (c) 2019-2019 Apple Inc. All rights reserved.
 *
 * @APPLE_OSREFERENCE_LICENSE_HEADER_START@
 *
 * This file contains Original Code and/or Modifications of Original Code
 * as defined in and that are subject to the Apple Public Source License
 * Version 2.0 (the 'License'). You may not use this file except in
 * compliance with the License. The rights granted to you under the License
 * may not be used to create, or enable the creation or redistribution of,
 * unlawful or unlicensed copies of an Apple operating system, or to
 * circumvent, violate, or enable the circumvention or violation of, any
 * terms of an Apple operating system software license agreement.
 *
 * Please obtain a copy of the License at
 * http://www.opensource.apple.com/apsl/ and read it before using this file.
 *
 * The Original Code and all software distributed under the License are
 * distributed on an 'AS IS' basis, WITHOUT WARRANTY OF ANY KIND, EITHER
 * EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES,
 * INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE, QUIET ENJOYMENT OR NON-INFRINGEMENT.
 * Please see the License for the specific language governing rights and
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 *
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 */

#ifndef _IOKIT_OSACTION_H
#define _IOKIT_OSACTION_H

#include <DriverKit/OSObject.iig>

typedef void (^OSActionCancelHandler)(void);
typedef void (^OSActionAbortedHandler)(void);
struct OSActionWaitToken;
class OSString;

/*!
 * @class OSAction
 *
 * @abstract
 * OSAction is an object that represents a callback to be be invoked.
 *
 * @discussion
 * The callback is specified as a method and object pair.
 * State associated with the callback may be allocated and stored for the creator of the object.
 * Methods to allocate an OSAction instance are generated for each method defined in a class with
 * a TYPE attribute. The generated methods are named CreateAction{name of method with type attribute}
 * and have the following declaration:
 *
 * kern_return_t CreateActionNameOfMethod(size_t referenceSize, OSAction **action);
 *
 * referenceSize refers to the size of additional state structure available to the creator of the OSAction
 * with GetReference. If successful, the generated method returns kIOReturnSuccess and a created OSAction
 * through the 'action' parameter with a +1 retain count to be released by the caller. See IOReturn.h for
 * error codes.
 */

class NATIVE KERNEL OSAction : public OSObject
{
public:

#if DRIVERKIT_PRIVATE
    /*!
     * @brief       Create an instance of OSAction.
	 * @discussion  Methods to allocate an OSAction instance are generated for each method defined in a class with
     *              a TYPE attribute, so there should not be any need to directly call OSAction::Create().
     * @param       target OSObject to receive the callback. This object will be retained until the OSAction is
     *              canceled or freed.
     * @param       targetmsgid Generated message ID for the target method.
     * @param       msgid Generated message ID for the method invoked by the receiver of the OSAction
     *              to generate the callback.
     * @param       referenceSize Size of additional state structure available to the creator of the OSAction
     *              with GetReference.
     * @param       action Created OSAction with +1 retain count to be released by the caller.
     * @return      kIOReturnSuccess on success. See IOReturn.h for error codes.
     */
	static kern_return_t
	Create(
		OSObject      * target,
		uint64_t        targetmsgid,
		uint64_t        msgid,
		size_t          referenceSize,
		OSAction     ** action) LOCAL;

     static kern_return_t
     CreateWithTypeName(
          OSObject      * target,
          uint64_t        targetmsgid,
          uint64_t        msgid,
          size_t          referenceSize,
          OSString      * typeName,
          OSAction     ** action) LOCAL;
#endif

	virtual void
	free() override;

    /*!
     * @brief       Return a pointer to any state allocated by the OSAction creator.
     * @discussion  Reference data is allocated with zero initialized content. It may be set and retrieved later
     *              with this method.
     * @return      A pointer to storage for the owner. It will be NULL if referenceSize was zero, and NULL
     *              when called in a process other than the owner that is receiving the OSAction as a parameter.
     */
	void *
	GetReference() LOCALONLY;

    /*!
     * @brief       Cancel all callbacks from the action.
     * @discussion  After cancellation, the action can only be freed. It cannot be reactivated.
     * @param       handler Handler block to be invoked after any callbacks have completed.
     * @return      kIOReturnSuccess on success. See IOReturn.h for error codes.
     */
	kern_return_t
	Cancel(OSActionCancelHandler handler) LOCALONLY;

    /*!
     * @brief       Install a handler to be invoked when no other processes reference the action.
     * @discussion  When all tasks other than the creator release their references to the action,
     *              invoke the handler in the owner. A task exiting will always remove its references.
     * @param       handler Handler block to be invoked on no more references.
     * @return      kIOReturnSuccess on success. See IOReturn.h for error codes.
     */
	kern_return_t
	SetAbortedHandler(OSActionAbortedHandler handler) LOCALONLY;

    /*!
     * @brief       Mark this OSAction to be waited for later with Wait().
     * @discussion  This call should be made before any possible invocation of the action.
     *              An OSAction instance only supports one waiter and WillWait() will return an error if already called.
     * @param       token Opaque value to be passed to a later call to Wait() and EndWait().
     * @return      kIOReturnSuccess on success. See IOReturn.h for error codes.
     */
	kern_return_t
	WillWait(OSActionWaitToken ** token) LOCALONLY;

    /*!
     * @brief       Discard the OSActionWaitToken for the action.
     * @discussion  Free any resources needed to wait for the action allocated by WillWait().
     *              There should be no outstanding invocations of the action when EndWait is called,
     *              if necessary the action should be canceled before calling EndWait().
     * @param       token Opaque value to be passed from an earlier call to WillWait().
     * @return      kIOReturnSuccess on success. kIOReturnAborted if aborted or canceled.
					kIOReturnTimeout if the deadline was passed. See IOReturn.h for error codes.
     */
	kern_return_t
	EndWait(
		OSActionWaitToken * token) LOCALONLY;

    /*!
     * @brief       Wait for the action to be invoked.
     * @discussion  The current thread is blocked until the action invocation has completed, the action canceled
					or aborted, or the deadline passed.
     * @param       token Opaque value to be passed from an earlier call to WillWait().
     * @param       options Pass one of the kIOTimerClock* options to specify the timebase for the
     *              deadline, or zero for no timeout.
     * @param       deadline Pass the time the wait should timeout, or zero for no timeout.
     * @return      kIOReturnSuccess on success. kIOReturnAborted if aborted or canceled.
					kIOReturnTimeout if the deadline was passed. See IOReturn.h for error codes.
     */
	kern_return_t
	Wait(
		OSActionWaitToken * token,
		uint64_t options,
		uint64_t deadline) LOCALONLY;

	virtual void
	Aborted(void) LOCAL;
};

#endif /* ! _IOKIT_OSACTION_H */