1/*
2 * Copyright (C) 2014 The Android Open Source Project
3 *
4 * Licensed under the Apache License, Version 2.0 (the "License");
5 * you may not use this file except in compliance with the License.
6 * You may obtain a copy of the License at
7 *
8 *      http://www.apache.org/licenses/LICENSE-2.0
9 *
10 * Unless required by applicable law or agreed to in writing, software
11 * distributed under the License is distributed on an "AS IS" BASIS,
12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13 * See the License for the specific language governing permissions and
14 * limitations under the License.
15 */
16
17package android.hardware.camera2.legacy;
18
19import android.hardware.ICameraService;
20import android.hardware.Camera;
21import android.hardware.Camera.CameraInfo;
22import android.hardware.camera2.CameraAccessException;
23import android.hardware.camera2.CameraCharacteristics;
24import android.hardware.camera2.CaptureRequest;
25import android.hardware.camera2.ICameraDeviceCallbacks;
26import android.hardware.camera2.ICameraDeviceUser;
27import android.hardware.camera2.impl.CameraMetadataNative;
28import android.hardware.camera2.impl.CaptureResultExtras;
29import android.hardware.camera2.params.OutputConfiguration;
30import android.hardware.camera2.utils.SubmitInfo;
31import android.os.ConditionVariable;
32import android.os.IBinder;
33import android.os.Looper;
34import android.os.Handler;
35import android.os.HandlerThread;
36import android.os.Message;
37import android.os.RemoteException;
38import android.os.ServiceSpecificException;
39import android.util.Log;
40import android.util.SparseArray;
41import android.view.Surface;
42
43import java.util.ArrayList;
44import java.util.List;
45
46import static android.system.OsConstants.EACCES;
47import static android.system.OsConstants.ENODEV;
48
49/**
50 * Compatibility implementation of the Camera2 API binder interface.
51 *
52 * <p>
53 * This is intended to be called from the same process as client
54 * {@link android.hardware.camera2.CameraDevice}, and wraps a
55 * {@link android.hardware.camera2.legacy.LegacyCameraDevice} that emulates Camera2 service using
56 * the Camera1 API.
57 * </p>
58 *
59 * <p>
60 * Keep up to date with ICameraDeviceUser.aidl.
61 * </p>
62 */
63@SuppressWarnings("deprecation")
64public class CameraDeviceUserShim implements ICameraDeviceUser {
65    private static final String TAG = "CameraDeviceUserShim";
66
67    private static final boolean DEBUG = false;
68    private static final int OPEN_CAMERA_TIMEOUT_MS = 5000; // 5 sec (same as api1 cts timeout)
69
70    private final LegacyCameraDevice mLegacyDevice;
71
72    private final Object mConfigureLock = new Object();
73    private int mSurfaceIdCounter;
74    private boolean mConfiguring;
75    private final SparseArray<Surface> mSurfaces;
76    private final CameraCharacteristics mCameraCharacteristics;
77    private final CameraLooper mCameraInit;
78    private final CameraCallbackThread mCameraCallbacks;
79
80
81    protected CameraDeviceUserShim(int cameraId, LegacyCameraDevice legacyCamera,
82            CameraCharacteristics characteristics, CameraLooper cameraInit,
83            CameraCallbackThread cameraCallbacks) {
84        mLegacyDevice = legacyCamera;
85        mConfiguring = false;
86        mSurfaces = new SparseArray<Surface>();
87        mCameraCharacteristics = characteristics;
88        mCameraInit = cameraInit;
89        mCameraCallbacks = cameraCallbacks;
90
91        mSurfaceIdCounter = 0;
92    }
93
94    private static int translateErrorsFromCamera1(int errorCode) {
95        if (errorCode == -EACCES) {
96            return ICameraService.ERROR_PERMISSION_DENIED;
97        }
98
99        return errorCode;
100    }
101
102    /**
103     * Create a separate looper/thread for the camera to run on; open the camera.
104     *
105     * <p>Since the camera automatically latches on to the current thread's looper,
106     * it's important that we have our own thread with our own looper to guarantee
107     * that the camera callbacks get correctly posted to our own thread.</p>
108     */
109    private static class CameraLooper implements Runnable, AutoCloseable {
110        private final int mCameraId;
111        private Looper mLooper;
112        private volatile int mInitErrors;
113        private final Camera mCamera = Camera.openUninitialized();
114        private final ConditionVariable mStartDone = new ConditionVariable();
115        private final Thread mThread;
116
117        /**
118         * Spin up a new thread, immediately open the camera in the background.
119         *
120         * <p>Use {@link #waitForOpen} to block until the camera is finished opening.</p>
121         *
122         * @param cameraId numeric camera Id
123         *
124         * @see #waitForOpen
125         */
126        public CameraLooper(int cameraId) {
127            mCameraId = cameraId;
128
129            mThread = new Thread(this);
130            mThread.start();
131        }
132
133        public Camera getCamera() {
134            return mCamera;
135        }
136
137        @Override
138        public void run() {
139            // Set up a looper to be used by camera.
140            Looper.prepare();
141
142            // Save the looper so that we can terminate this thread
143            // after we are done with it.
144            mLooper = Looper.myLooper();
145            mInitErrors = mCamera.cameraInitUnspecified(mCameraId);
146            mStartDone.open();
147            Looper.loop();  // Blocks forever until #close is called.
148        }
149
150        /**
151         * Quit the looper safely; then join until the thread shuts down.
152         */
153        @Override
154        public void close() {
155            if (mLooper == null) {
156                return;
157            }
158
159            mLooper.quitSafely();
160            try {
161                mThread.join();
162            } catch (InterruptedException e) {
163                throw new AssertionError(e);
164            }
165
166            mLooper = null;
167        }
168
169        /**
170         * Block until the camera opens; then return its initialization error code (if any).
171         *
172         * @param timeoutMs timeout in milliseconds
173         *
174         * @return int error code
175         *
176         * @throws ServiceSpecificException if the camera open times out with ({@code CAMERA_ERROR})
177         */
178        public int waitForOpen(int timeoutMs) {
179            // Block until the camera is open asynchronously
180            if (!mStartDone.block(timeoutMs)) {
181                Log.e(TAG, "waitForOpen - Camera failed to open after timeout of "
182                        + OPEN_CAMERA_TIMEOUT_MS + " ms");
183                try {
184                    mCamera.release();
185                } catch (RuntimeException e) {
186                    Log.e(TAG, "connectBinderShim - Failed to release camera after timeout ", e);
187                }
188
189                throw new ServiceSpecificException(ICameraService.ERROR_INVALID_OPERATION);
190            }
191
192            return mInitErrors;
193        }
194    }
195
196    /**
197     * A thread to process callbacks to send back to the camera client.
198     *
199     * <p>This effectively emulates one-way binder semantics when in the same process as the
200     * callee.</p>
201     */
202    private static class CameraCallbackThread implements ICameraDeviceCallbacks {
203        private static final int CAMERA_ERROR = 0;
204        private static final int CAMERA_IDLE = 1;
205        private static final int CAPTURE_STARTED = 2;
206        private static final int RESULT_RECEIVED = 3;
207        private static final int PREPARED = 4;
208        private static final int REPEATING_REQUEST_ERROR = 5;
209
210        private final HandlerThread mHandlerThread;
211        private Handler mHandler;
212
213        private final ICameraDeviceCallbacks mCallbacks;
214
215        public CameraCallbackThread(ICameraDeviceCallbacks callbacks) {
216            mCallbacks = callbacks;
217
218            mHandlerThread = new HandlerThread("LegacyCameraCallback");
219            mHandlerThread.start();
220        }
221
222        public void close() {
223            mHandlerThread.quitSafely();
224        }
225
226        @Override
227        public void onDeviceError(final int errorCode, final CaptureResultExtras resultExtras) {
228            Message msg = getHandler().obtainMessage(CAMERA_ERROR,
229                /*arg1*/ errorCode, /*arg2*/ 0,
230                /*obj*/ resultExtras);
231            getHandler().sendMessage(msg);
232        }
233
234        @Override
235        public void onDeviceIdle() {
236            Message msg = getHandler().obtainMessage(CAMERA_IDLE);
237            getHandler().sendMessage(msg);
238        }
239
240        @Override
241        public void onCaptureStarted(final CaptureResultExtras resultExtras, final long timestamp) {
242            Message msg = getHandler().obtainMessage(CAPTURE_STARTED,
243                    /*arg1*/ (int) (timestamp & 0xFFFFFFFFL),
244                    /*arg2*/ (int) ( (timestamp >> 32) & 0xFFFFFFFFL),
245                    /*obj*/ resultExtras);
246            getHandler().sendMessage(msg);
247        }
248
249        @Override
250        public void onResultReceived(final CameraMetadataNative result,
251                final CaptureResultExtras resultExtras) {
252            Object[] resultArray = new Object[] { result, resultExtras };
253            Message msg = getHandler().obtainMessage(RESULT_RECEIVED,
254                    /*obj*/ resultArray);
255            getHandler().sendMessage(msg);
256        }
257
258        @Override
259        public void onPrepared(int streamId) {
260            Message msg = getHandler().obtainMessage(PREPARED,
261                    /*arg1*/ streamId, /*arg2*/ 0);
262            getHandler().sendMessage(msg);
263        }
264
265
266        @Override
267        public void onRepeatingRequestError(long lastFrameNumber) {
268            Message msg = getHandler().obtainMessage(REPEATING_REQUEST_ERROR,
269                    /*arg1*/ (int) (lastFrameNumber & 0xFFFFFFFFL),
270                    /*arg2*/ (int) ( (lastFrameNumber >> 32) & 0xFFFFFFFFL));
271            getHandler().sendMessage(msg);
272        }
273
274        @Override
275        public IBinder asBinder() {
276            // This is solely intended to be used for in-process binding.
277            return null;
278        }
279
280        private Handler getHandler() {
281            if (mHandler == null) {
282                mHandler = new CallbackHandler(mHandlerThread.getLooper());
283            }
284            return mHandler;
285        }
286
287        private class CallbackHandler extends Handler {
288            public CallbackHandler(Looper l) {
289                super(l);
290            }
291
292            @Override
293            public void handleMessage(Message msg) {
294                try {
295                    switch (msg.what) {
296                        case CAMERA_ERROR: {
297                            int errorCode = msg.arg1;
298                            CaptureResultExtras resultExtras = (CaptureResultExtras) msg.obj;
299                            mCallbacks.onDeviceError(errorCode, resultExtras);
300                            break;
301                        }
302                        case CAMERA_IDLE:
303                            mCallbacks.onDeviceIdle();
304                            break;
305                        case CAPTURE_STARTED: {
306                            long timestamp = msg.arg2 & 0xFFFFFFFFL;
307                            timestamp = (timestamp << 32) | (msg.arg1 & 0xFFFFFFFFL);
308                            CaptureResultExtras resultExtras = (CaptureResultExtras) msg.obj;
309                            mCallbacks.onCaptureStarted(resultExtras, timestamp);
310                            break;
311                        }
312                        case RESULT_RECEIVED: {
313                            Object[] resultArray = (Object[]) msg.obj;
314                            CameraMetadataNative result = (CameraMetadataNative) resultArray[0];
315                            CaptureResultExtras resultExtras = (CaptureResultExtras) resultArray[1];
316                            mCallbacks.onResultReceived(result, resultExtras);
317                            break;
318                        }
319                        case PREPARED: {
320                            int streamId = msg.arg1;
321                            mCallbacks.onPrepared(streamId);
322                            break;
323                        }
324                        case REPEATING_REQUEST_ERROR: {
325                            long lastFrameNumber = msg.arg2 & 0xFFFFFFFFL;
326                            lastFrameNumber = (lastFrameNumber << 32) | (msg.arg1 & 0xFFFFFFFFL);
327                            mCallbacks.onRepeatingRequestError(lastFrameNumber);
328                            break;
329                        }
330                        default:
331                            throw new IllegalArgumentException(
332                                "Unknown callback message " + msg.what);
333                    }
334                } catch (RemoteException e) {
335                    throw new IllegalStateException(
336                        "Received remote exception during camera callback " + msg.what, e);
337                }
338            }
339        }
340    }
341
342    public static CameraDeviceUserShim connectBinderShim(ICameraDeviceCallbacks callbacks,
343                                                         int cameraId) {
344        if (DEBUG) {
345            Log.d(TAG, "Opening shim Camera device");
346        }
347
348        /*
349         * Put the camera open on a separate thread with its own looper; otherwise
350         * if the main thread is used then the callbacks might never get delivered
351         * (e.g. in CTS which run its own default looper only after tests)
352         */
353
354        CameraLooper init = new CameraLooper(cameraId);
355
356        CameraCallbackThread threadCallbacks = new CameraCallbackThread(callbacks);
357
358        // TODO: Make this async instead of blocking
359        int initErrors = init.waitForOpen(OPEN_CAMERA_TIMEOUT_MS);
360        Camera legacyCamera = init.getCamera();
361
362        // Check errors old HAL initialization
363        LegacyExceptionUtils.throwOnServiceError(initErrors);
364
365        // Disable shutter sounds (this will work unconditionally) for api2 clients
366        legacyCamera.disableShutterSound();
367
368        CameraInfo info = new CameraInfo();
369        Camera.getCameraInfo(cameraId, info);
370
371        Camera.Parameters legacyParameters = null;
372        try {
373            legacyParameters = legacyCamera.getParameters();
374        } catch (RuntimeException e) {
375            throw new ServiceSpecificException(ICameraService.ERROR_INVALID_OPERATION,
376                    "Unable to get initial parameters: " + e.getMessage());
377        }
378
379        CameraCharacteristics characteristics =
380                LegacyMetadataMapper.createCharacteristics(legacyParameters, info);
381        LegacyCameraDevice device = new LegacyCameraDevice(
382                cameraId, legacyCamera, characteristics, threadCallbacks);
383        return new CameraDeviceUserShim(cameraId, device, characteristics, init, threadCallbacks);
384    }
385
386    @Override
387    public void disconnect() {
388        if (DEBUG) {
389            Log.d(TAG, "disconnect called.");
390        }
391
392        if (mLegacyDevice.isClosed()) {
393            Log.w(TAG, "Cannot disconnect, device has already been closed.");
394        }
395
396        try {
397            mLegacyDevice.close();
398        } finally {
399            mCameraInit.close();
400            mCameraCallbacks.close();
401        }
402    }
403
404    @Override
405    public SubmitInfo submitRequest(CaptureRequest request, boolean streaming) {
406        if (DEBUG) {
407            Log.d(TAG, "submitRequest called.");
408        }
409        if (mLegacyDevice.isClosed()) {
410            String err = "Cannot submit request, device has been closed.";
411            Log.e(TAG, err);
412            throw new ServiceSpecificException(ICameraService.ERROR_DISCONNECTED, err);
413        }
414
415        synchronized(mConfigureLock) {
416            if (mConfiguring) {
417                String err = "Cannot submit request, configuration change in progress.";
418                Log.e(TAG, err);
419                throw new ServiceSpecificException(ICameraService.ERROR_INVALID_OPERATION, err);
420            }
421        }
422        return mLegacyDevice.submitRequest(request, streaming);
423    }
424
425    @Override
426    public SubmitInfo submitRequestList(CaptureRequest[] request, boolean streaming) {
427        if (DEBUG) {
428            Log.d(TAG, "submitRequestList called.");
429        }
430        if (mLegacyDevice.isClosed()) {
431            String err = "Cannot submit request list, device has been closed.";
432            Log.e(TAG, err);
433            throw new ServiceSpecificException(ICameraService.ERROR_DISCONNECTED, err);
434        }
435
436        synchronized(mConfigureLock) {
437            if (mConfiguring) {
438                String err = "Cannot submit request, configuration change in progress.";
439                Log.e(TAG, err);
440                throw new ServiceSpecificException(ICameraService.ERROR_INVALID_OPERATION, err);
441            }
442        }
443        return mLegacyDevice.submitRequestList(request, streaming);
444    }
445
446    @Override
447    public long cancelRequest(int requestId) {
448        if (DEBUG) {
449            Log.d(TAG, "cancelRequest called.");
450        }
451        if (mLegacyDevice.isClosed()) {
452            String err = "Cannot cancel request, device has been closed.";
453            Log.e(TAG, err);
454            throw new ServiceSpecificException(ICameraService.ERROR_DISCONNECTED, err);
455        }
456
457        synchronized(mConfigureLock) {
458            if (mConfiguring) {
459                String err = "Cannot cancel request, configuration change in progress.";
460                Log.e(TAG, err);
461                throw new ServiceSpecificException(ICameraService.ERROR_INVALID_OPERATION, err);
462            }
463        }
464        return mLegacyDevice.cancelRequest(requestId);
465    }
466
467    @Override
468    public void beginConfigure() {
469        if (DEBUG) {
470            Log.d(TAG, "beginConfigure called.");
471        }
472        if (mLegacyDevice.isClosed()) {
473            String err = "Cannot begin configure, device has been closed.";
474            Log.e(TAG, err);
475            throw new ServiceSpecificException(ICameraService.ERROR_DISCONNECTED, err);
476        }
477
478        synchronized(mConfigureLock) {
479            if (mConfiguring) {
480                String err = "Cannot begin configure, configuration change already in progress.";
481                Log.e(TAG, err);
482                throw new ServiceSpecificException(ICameraService.ERROR_INVALID_OPERATION, err);
483            }
484            mConfiguring = true;
485        }
486    }
487
488    @Override
489    public void endConfigure(boolean isConstrainedHighSpeed) {
490        if (DEBUG) {
491            Log.d(TAG, "endConfigure called.");
492        }
493        if (mLegacyDevice.isClosed()) {
494            String err = "Cannot end configure, device has been closed.";
495            Log.e(TAG, err);
496            throw new ServiceSpecificException(ICameraService.ERROR_DISCONNECTED, err);
497        }
498
499        SparseArray<Surface> surfaces = null;
500        synchronized(mConfigureLock) {
501            if (!mConfiguring) {
502                String err = "Cannot end configure, no configuration change in progress.";
503                Log.e(TAG, err);
504                throw new ServiceSpecificException(ICameraService.ERROR_INVALID_OPERATION, err);
505            }
506            if (mSurfaces != null) {
507                surfaces = mSurfaces.clone();
508            }
509            mConfiguring = false;
510        }
511        mLegacyDevice.configureOutputs(surfaces);
512    }
513
514    @Override
515    public void deleteStream(int streamId) {
516        if (DEBUG) {
517            Log.d(TAG, "deleteStream called.");
518        }
519        if (mLegacyDevice.isClosed()) {
520            String err = "Cannot delete stream, device has been closed.";
521            Log.e(TAG, err);
522            throw new ServiceSpecificException(ICameraService.ERROR_DISCONNECTED, err);
523        }
524
525        synchronized(mConfigureLock) {
526            if (!mConfiguring) {
527                String err = "Cannot delete stream, no configuration change in progress.";
528                Log.e(TAG, err);
529                throw new ServiceSpecificException(ICameraService.ERROR_INVALID_OPERATION, err);
530            }
531            int index = mSurfaces.indexOfKey(streamId);
532            if (index < 0) {
533                String err = "Cannot delete stream, stream id " + streamId + " doesn't exist.";
534                Log.e(TAG, err);
535                throw new ServiceSpecificException(ICameraService.ERROR_ILLEGAL_ARGUMENT, err);
536            }
537            mSurfaces.removeAt(index);
538        }
539    }
540
541    @Override
542    public int createStream(OutputConfiguration outputConfiguration) {
543        if (DEBUG) {
544            Log.d(TAG, "createStream called.");
545        }
546        if (mLegacyDevice.isClosed()) {
547            String err = "Cannot create stream, device has been closed.";
548            Log.e(TAG, err);
549            throw new ServiceSpecificException(ICameraService.ERROR_DISCONNECTED, err);
550        }
551
552        synchronized(mConfigureLock) {
553            if (!mConfiguring) {
554                String err = "Cannot create stream, beginConfigure hasn't been called yet.";
555                Log.e(TAG, err);
556                throw new ServiceSpecificException(ICameraService.ERROR_INVALID_OPERATION, err);
557            }
558            if (outputConfiguration.getRotation() != OutputConfiguration.ROTATION_0) {
559                String err = "Cannot create stream, stream rotation is not supported.";
560                Log.e(TAG, err);
561                throw new ServiceSpecificException(ICameraService.ERROR_ILLEGAL_ARGUMENT, err);
562            }
563            int id = ++mSurfaceIdCounter;
564            mSurfaces.put(id, outputConfiguration.getSurface());
565            return id;
566        }
567    }
568
569    @Override
570    public int createInputStream(int width, int height, int format) {
571        String err = "Creating input stream is not supported on legacy devices";
572        Log.e(TAG, err);
573        throw new ServiceSpecificException(ICameraService.ERROR_INVALID_OPERATION, err);
574    }
575
576    @Override
577    public Surface getInputSurface() {
578        String err = "Getting input surface is not supported on legacy devices";
579        Log.e(TAG, err);
580        throw new ServiceSpecificException(ICameraService.ERROR_INVALID_OPERATION, err);
581    }
582
583    @Override
584    public CameraMetadataNative createDefaultRequest(int templateId) {
585        if (DEBUG) {
586            Log.d(TAG, "createDefaultRequest called.");
587        }
588        if (mLegacyDevice.isClosed()) {
589            String err = "Cannot create default request, device has been closed.";
590            Log.e(TAG, err);
591            throw new ServiceSpecificException(ICameraService.ERROR_DISCONNECTED, err);
592        }
593
594        CameraMetadataNative template;
595        try {
596            template =
597                    LegacyMetadataMapper.createRequestTemplate(mCameraCharacteristics, templateId);
598        } catch (IllegalArgumentException e) {
599            String err = "createDefaultRequest - invalid templateId specified";
600            Log.e(TAG, err);
601            throw new ServiceSpecificException(ICameraService.ERROR_ILLEGAL_ARGUMENT, err);
602        }
603
604        return template;
605    }
606
607    @Override
608    public CameraMetadataNative getCameraInfo() {
609        if (DEBUG) {
610            Log.d(TAG, "getCameraInfo called.");
611        }
612        // TODO: implement getCameraInfo.
613        Log.e(TAG, "getCameraInfo unimplemented.");
614        return null;
615    }
616
617    @Override
618    public void waitUntilIdle() throws RemoteException {
619        if (DEBUG) {
620            Log.d(TAG, "waitUntilIdle called.");
621        }
622        if (mLegacyDevice.isClosed()) {
623            String err = "Cannot wait until idle, device has been closed.";
624            Log.e(TAG, err);
625            throw new ServiceSpecificException(ICameraService.ERROR_DISCONNECTED, err);
626        }
627
628        synchronized(mConfigureLock) {
629            if (mConfiguring) {
630                String err = "Cannot wait until idle, configuration change in progress.";
631                Log.e(TAG, err);
632                throw new ServiceSpecificException(ICameraService.ERROR_INVALID_OPERATION, err);
633            }
634        }
635        mLegacyDevice.waitUntilIdle();
636    }
637
638    @Override
639    public long flush() {
640        if (DEBUG) {
641            Log.d(TAG, "flush called.");
642        }
643        if (mLegacyDevice.isClosed()) {
644            String err = "Cannot flush, device has been closed.";
645            Log.e(TAG, err);
646            throw new ServiceSpecificException(ICameraService.ERROR_DISCONNECTED, err);
647        }
648
649        synchronized(mConfigureLock) {
650            if (mConfiguring) {
651                String err = "Cannot flush, configuration change in progress.";
652                Log.e(TAG, err);
653                throw new ServiceSpecificException(ICameraService.ERROR_INVALID_OPERATION, err);
654            }
655        }
656        return mLegacyDevice.flush();
657    }
658
659    public void prepare(int streamId) {
660        if (DEBUG) {
661            Log.d(TAG, "prepare called.");
662        }
663        if (mLegacyDevice.isClosed()) {
664            String err = "Cannot prepare stream, device has been closed.";
665            Log.e(TAG, err);
666            throw new ServiceSpecificException(ICameraService.ERROR_DISCONNECTED, err);
667        }
668
669        // LEGACY doesn't support actual prepare, just signal success right away
670        mCameraCallbacks.onPrepared(streamId);
671    }
672
673    public void prepare2(int maxCount, int streamId) {
674        // We don't support this in LEGACY mode.
675        prepare(streamId);
676    }
677
678    public void tearDown(int streamId) {
679        if (DEBUG) {
680            Log.d(TAG, "tearDown called.");
681        }
682        if (mLegacyDevice.isClosed()) {
683            String err = "Cannot tear down stream, device has been closed.";
684            Log.e(TAG, err);
685            throw new ServiceSpecificException(ICameraService.ERROR_DISCONNECTED, err);
686        }
687
688        // LEGACY doesn't support actual teardown, so just a no-op
689    }
690
691    @Override
692    public IBinder asBinder() {
693        // This is solely intended to be used for in-process binding.
694        return null;
695    }
696}
697