Add virtual Face HAL

Fixes: 230514750
Test: atest VtsHalBiometricsFaceTargetTest
Test: atest VtsHalBiometricsFingerprintTargetTest
Test: atest android.hardware.biometrics.face.FakeFaceEngineTest
Test: atest android.hardware.biometrics.face.FakeFingerprintEngineTest
Test: See README.md
Test: Verified that face and fingerprint get reset upon authenticating.

Change-Id: I57c1a61bec960e3be28736e6050be662ef412d8c
diff --git a/biometrics/face/aidl/default/FakeFaceEngine.h b/biometrics/face/aidl/default/FakeFaceEngine.h
new file mode 100644
index 0000000..edb54ce
--- /dev/null
+++ b/biometrics/face/aidl/default/FakeFaceEngine.h
@@ -0,0 +1,65 @@
+/*
+ * Copyright (C) 2022 The Android Open Source Project
+ *
+ * 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.
+ */
+
+#pragma once
+
+#include <aidl/android/hardware/biometrics/common/SensorStrength.h>
+#include <aidl/android/hardware/biometrics/face/BnSession.h>
+#include <aidl/android/hardware/biometrics/face/FaceSensorType.h>
+#include <aidl/android/hardware/biometrics/face/ISessionCallback.h>
+
+#include <random>
+
+#include <future>
+#include <vector>
+
+namespace aidl::android::hardware::biometrics::face {
+
+namespace face = aidl::android::hardware::biometrics::face;
+namespace common = aidl::android::hardware::biometrics::common;
+namespace keymaster = aidl::android::hardware::keymaster;
+
+using aidl::android::hardware::common::NativeHandle;
+// A fake engine that is backed by system properties instead of hardware.
+class FakeFaceEngine {
+  public:
+    FakeFaceEngine() : mRandom(std::mt19937::default_seed) {}
+
+    static face::FaceSensorType GetSensorType();
+    static common::SensorStrength GetSensorStrength();
+    void generateChallengeImpl(ISessionCallback* cb);
+    void revokeChallengeImpl(ISessionCallback* cb, int64_t challenge);
+    void getEnrollmentConfigImpl(ISessionCallback* cb,
+                                 std::vector<EnrollmentStageConfig>* return_val);
+    void enrollImpl(ISessionCallback* cb, const keymaster::HardwareAuthToken& hat,
+                    EnrollmentType enrollmentType, const std::vector<Feature>& features,
+                    const std::future<void>& cancel);
+    void authenticateImpl(ISessionCallback* cb, int64_t operationId,
+                          const std::future<void>& cancel);
+    void detectInteractionImpl(ISessionCallback* cb, const std::future<void>& cancel);
+    void enumerateEnrollmentsImpl(ISessionCallback* cb);
+    void removeEnrollmentsImpl(ISessionCallback* cb, const std::vector<int32_t>& enrollmentIds);
+    void getFeaturesImpl(ISessionCallback* cb);
+    void setFeatureImpl(ISessionCallback* cb, const keymaster::HardwareAuthToken& hat,
+                        Feature feature, bool enabled);
+    void getAuthenticatorIdImpl(ISessionCallback* cb);
+    void invalidateAuthenticatorIdImpl(ISessionCallback* cb);
+    void resetLockoutImpl(ISessionCallback* cb, const keymaster::HardwareAuthToken& /*hat*/);
+
+    std::mt19937 mRandom;
+};
+
+}  // namespace aidl::android::hardware::biometrics::face
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