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
 * limitations under the License.
 *
 * @APPLE_OSREFERENCE_LICENSE_HEADER_END@
 */

#ifndef _IOKIT_UIOSERVICEDISPATCHSOURCE_H
#define _IOKIT_UIOSERVICEDISPATCHSOURCE_H

#include <DriverKit/IODispatchQueue.iig>
#include <DriverKit/OSAction.iig>
#include <DriverKit/IOService.iig>


typedef void (^IOServiceNotificationBlock)(uint64_t type, IOService * service, uint64_t options);

enum {
	kIOServiceNotificationTypeTerminated = 0x00000000,
	kIOServiceNotificationTypeMatched    = 0x00000001,
	kIOServiceNotificationTypeLast       = kIOServiceNotificationTypeMatched,
	kIOServiceNotificationTypeNone       = 0xFFFFFFFF,
};

class NATIVE KERNEL IOServiceNotificationDispatchSource : public IODispatchSource
{
public:

    /*!
     * @brief       Create an IOServiceNotificationDispatchSource for IOService matching and termination events.
     * @param       matching An IOService matching dictionary.
     * @param       options None defined, pass zero.
     * @param       queue IODispatchQueue the source is attached to. Note that the ServiceNotificationReady
     *              handler is invoked on the queue set for the target method
     *              of the OSAction, not this queue.
     * @param       source Created source 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(
		OSDictionary	  *	matching,
		uint64_t            options,
	    IODispatchQueue   * queue,
		IOServiceNotificationDispatchSource ** notification) LOCAL;

	virtual bool
	init() override;

	virtual void
	free() override;

    /*!
     * @brief       Control the enable state of the notification.
     * @param       enable Pass true to enable the source or false to disable.
     * @param       handler Optional block to be executed after the interrupt has been disabled and any pending
     *              interrupt handlers completed.
     * @return      kIOReturnSuccess on success. See IOReturn.h for error codes.
     */
	virtual kern_return_t
	SetEnableWithCompletion(
		bool enable,
		IODispatchSourceCancelHandler handler) override LOCAL;

    /*!
     * @brief       Cancel all callbacks from the event source.
     * @discussion  After cancellation, the source 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.
     */
	virtual kern_return_t
	Cancel(IODispatchSourceCancelHandler handler) override LOCAL;

    /*!
     * @brief       Set the handler block to run when the notification has become ready.
     * @param       action OSAction instance specifying the callback method. The OSAction object will be retained
     *              until SetHandler is called again or the event source is cancelled.
     *              The ServiceNotificationReady handler is invoked on the queue set for the target method of the
     *              OSAction.
     * @return      kIOReturnSuccess on success. See IOReturn.h for error codes.
     */
	virtual kern_return_t
	SetHandler(
	OSAction * action TYPE(ServiceNotificationReady));

    /*!
     * @brief       Invoke a block for each notification available in response to ServiceNotificationReady.
     * @discussion  The IOService object passed to the notification is only retained for the duration of the block.
     *              It should be retained by the block code if used beyond the invocation.
     * @param       block to be invoked with each notification
     * @return      kIOReturnSuccess on success. See IOReturn.h for error codes.
     */
	kern_return_t
	DeliverNotifications(IOServiceNotificationBlock block) LOCALONLY;

private:
	virtual kern_return_t
	CheckForWork(bool synchronous) override LOCAL;

	virtual void
	ServiceNotificationReady(
		OSAction  * action TARGET) LOCAL = 0;

	virtual kern_return_t
	CopyNextNotification(
		uint64_t   * type,
		IOService ** service,
		uint64_t   * options);
};

#endif /* ! _IOKIT_UIOSERVICEDISPATCHSOURCE_H */