Add POLICY_FLAG_PASS_TO_USER to complete the gesture

Before an input event is processed by the dispatcher, the policy has the
chance to intercept it. The policy sets POLICY_FLAG_PASS_TO_USER if it
wants the event to be processed by the dispatcher, and does not set this
flag if it wants the event to get dropped.

If the device becomes non-interactive, the policy would stop sending
this flag. This could happen in the middle of the gesture.

To account for this, check whether there's an active stream inside the
dispatcher, and finish the gesture if so.

This allows the policy implementation to remain simple. If we wanted the
policy to be consistent (either the whole gesture is sent to the app, or
the whole gesture isn't), it would complicate the policy implementation
and require it to keep state.

Dispatcher already keeps the state, so we fix this in the dispatcher.

Bug: 267614813
Test: atest inputflinger_tests:InputDispatcherTest#TwoPointerCancel
Change-Id: I8d162c658f4f53a76d32d5e5a1de8ac3722e277d

2 files changed, 204 insertions, 0 deletions

diff --git a/services/inputflinger/dispatcher/InputDispatcher.cpp b/services/inputflinger/dispatcher/InputDispatcher.cpp
index 079b80dad6..d14a781473 100644
--- a/services/inputflinger/dispatcher/InputDispatcher.cpp
+++ b/services/inputflinger/dispatcher/InputDispatcher.cpp
@@ -4185,6 +4185,17 @@ void InputDispatcher::notifyMotion(const NotifyMotionArgs* args) {
     bool needWake = false;
     { // acquire lock
         mLock.lock();
+        if (!(policyFlags & POLICY_FLAG_PASS_TO_USER)) {
+            // Set the flag anyway if we already have an ongoing gesture. That would allow us to
+            // complete the processing of the current stroke.
+            const auto touchStateIt = mTouchStatesByDisplay.find(args->displayId);
+            if (touchStateIt != mTouchStatesByDisplay.end()) {
+                const TouchState& touchState = touchStateIt->second;
+                if (touchState.deviceId == args->deviceId && touchState.isDown()) {
+                    policyFlags |= POLICY_FLAG_PASS_TO_USER;
+                }
+            }
+        }
 
         if (shouldSendMotionToInputFilterLocked(args)) {
             ui::Transform displayTransform;
diff --git a/services/inputflinger/tests/InputDispatcher_test.cpp b/services/inputflinger/tests/InputDispatcher_test.cpp
index b1b6e058e4..f8d425639b 100644
--- a/services/inputflinger/tests/InputDispatcher_test.cpp
+++ b/services/inputflinger/tests/InputDispatcher_test.cpp
@@ -1567,6 +1567,113 @@ private:
     std::vector<PointerBuilder> mPointers;
 };
 
+class MotionArgsBuilder {
+public:
+    MotionArgsBuilder(int32_t action, int32_t source) {
+        mAction = action;
+        mSource = source;
+        mEventTime = systemTime(SYSTEM_TIME_MONOTONIC);
+        mDownTime = mEventTime;
+    }
+
+    MotionArgsBuilder& deviceId(int32_t deviceId) {
+        mDeviceId = deviceId;
+        return *this;
+    }
+
+    MotionArgsBuilder& downTime(nsecs_t downTime) {
+        mDownTime = downTime;
+        return *this;
+    }
+
+    MotionArgsBuilder& eventTime(nsecs_t eventTime) {
+        mEventTime = eventTime;
+        return *this;
+    }
+
+    MotionArgsBuilder& displayId(int32_t displayId) {
+        mDisplayId = displayId;
+        return *this;
+    }
+
+    MotionArgsBuilder& policyFlags(int32_t policyFlags) {
+        mPolicyFlags = policyFlags;
+        return *this;
+    }
+
+    MotionArgsBuilder& actionButton(int32_t actionButton) {
+        mActionButton = actionButton;
+        return *this;
+    }
+
+    MotionArgsBuilder& buttonState(int32_t buttonState) {
+        mButtonState = buttonState;
+        return *this;
+    }
+
+    MotionArgsBuilder& rawXCursorPosition(float rawXCursorPosition) {
+        mRawXCursorPosition = rawXCursorPosition;
+        return *this;
+    }
+
+    MotionArgsBuilder& rawYCursorPosition(float rawYCursorPosition) {
+        mRawYCursorPosition = rawYCursorPosition;
+        return *this;
+    }
+
+    MotionArgsBuilder& pointer(PointerBuilder pointer) {
+        mPointers.push_back(pointer);
+        return *this;
+    }
+
+    MotionArgsBuilder& addFlag(uint32_t flags) {
+        mFlags |= flags;
+        return *this;
+    }
+
+    NotifyMotionArgs build() {
+        std::vector<PointerProperties> pointerProperties;
+        std::vector<PointerCoords> pointerCoords;
+        for (const PointerBuilder& pointer : mPointers) {
+            pointerProperties.push_back(pointer.buildProperties());
+            pointerCoords.push_back(pointer.buildCoords());
+        }
+
+        // Set mouse cursor position for the most common cases to avoid boilerplate.
+        if (mSource == AINPUT_SOURCE_MOUSE &&
+            !MotionEvent::isValidCursorPosition(mRawXCursorPosition, mRawYCursorPosition) &&
+            mPointers.size() == 1) {
+            mRawXCursorPosition = pointerCoords[0].getX();
+            mRawYCursorPosition = pointerCoords[0].getY();
+        }
+
+        NotifyMotionArgs args(InputEvent::nextId(), mEventTime, /*readTime=*/mEventTime, mDeviceId,
+                              mSource, mDisplayId, mPolicyFlags, mAction, mActionButton, mFlags,
+                              AMETA_NONE, mButtonState, MotionClassification::NONE, /*edgeFlags=*/0,
+                              mPointers.size(), pointerProperties.data(), pointerCoords.data(),
+                              /*xPrecision=*/0, /*yPrecision=*/0, mRawXCursorPosition,
+                              mRawYCursorPosition, mDownTime, /*videoFrames=*/{});
+
+        return args;
+    }
+
+private:
+    int32_t mAction;
+    int32_t mDeviceId = DEVICE_ID;
+    int32_t mSource;
+    nsecs_t mDownTime;
+    nsecs_t mEventTime;
+    int32_t mDisplayId{ADISPLAY_ID_DEFAULT};
+    int32_t mPolicyFlags = DEFAULT_POLICY_FLAGS;
+    int32_t mActionButton{0};
+    int32_t mButtonState{0};
+    int32_t mFlags{0};
+    float mRawXCursorPosition{AMOTION_EVENT_INVALID_CURSOR_POSITION};
+    float mRawYCursorPosition{AMOTION_EVENT_INVALID_CURSOR_POSITION};
+
+    std::vector<PointerBuilder> mPointers;
+};
+
 static InputEventInjectionResult injectMotionEvent(
         const std::unique_ptr<InputDispatcher>& dispatcher, const MotionEvent& event,
         std::chrono::milliseconds injectionTimeout = INJECT_EVENT_TIMEOUT,
@@ -2055,6 +2162,92 @@ TEST_F(InputDispatcherTest, WallpaperWindowWhenSlippery) {
 }
 
 /**
+ * The policy typically sets POLICY_FLAG_PASS_TO_USER to the events. But when the display is not
+ * interactive, it might stop sending this flag.
+ * In this test, we check that if the policy stops sending this flag mid-gesture, we still ensure
+ * to have a consistent input stream.
+ *
+ * Test procedure:
+ * DOWN -> POINTER_DOWN -> (stop sending POLICY_FLAG_PASS_TO_USER) -> CANCEL.
+ * DOWN (new gesture).
+ *
+ * In the bad implementation, we could potentially drop the CANCEL event, and get an inconsistent
+ * state in the dispatcher. This would cause the final DOWN event to not be delivered to the app.
+ *
+ * We technically just need a single window here, but we are using two windows (spy on top and a
+ * regular window below) to emulate the actual situation where it happens on the device.
+ */
+TEST_F(InputDispatcherTest, TwoPointerCancelInconsistentPolicy) {
+    std::shared_ptr<FakeApplicationHandle> application = std::make_shared<FakeApplicationHandle>();
+    sp<FakeWindowHandle> spyWindow =
+            sp<FakeWindowHandle>::make(application, mDispatcher, "Spy", ADISPLAY_ID_DEFAULT);
+    spyWindow->setFrame(Rect(0, 0, 200, 200));
+    spyWindow->setTrustedOverlay(true);
+    spyWindow->setSpy(true);
+
+    sp<FakeWindowHandle> window =
+            sp<FakeWindowHandle>::make(application, mDispatcher, "Window", ADISPLAY_ID_DEFAULT);
+    window->setFrame(Rect(0, 0, 200, 200));
+
+    mDispatcher->setInputWindows({{ADISPLAY_ID_DEFAULT, {spyWindow, window}}});
+    const int32_t touchDeviceId = 4;
+    NotifyMotionArgs args;
+
+    // Two pointers down
+    mDispatcher->notifyMotion(&(
+            args = MotionArgsBuilder(AMOTION_EVENT_ACTION_DOWN, AINPUT_SOURCE_TOUCHSCREEN)
+                           .deviceId(touchDeviceId)
+                           .policyFlags(DEFAULT_POLICY_FLAGS)
+                           .pointer(PointerBuilder(0, AMOTION_EVENT_TOOL_TYPE_FINGER).x(100).y(100))
+                           .build()));
+
+    mDispatcher->notifyMotion(&(
+            args = MotionArgsBuilder(POINTER_1_DOWN, AINPUT_SOURCE_TOUCHSCREEN)
+                           .deviceId(touchDeviceId)
+                           .policyFlags(DEFAULT_POLICY_FLAGS)
+                           .pointer(PointerBuilder(0, AMOTION_EVENT_TOOL_TYPE_FINGER).x(100).y(100))
+                           .pointer(PointerBuilder(1, AMOTION_EVENT_TOOL_TYPE_FINGER).x(120).y(120))
+                           .build()));
+    spyWindow->consumeMotionEvent(WithMotionAction(AMOTION_EVENT_ACTION_DOWN));
+    spyWindow->consumeMotionEvent(WithMotionAction(POINTER_1_DOWN));
+    window->consumeMotionEvent(WithMotionAction(AMOTION_EVENT_ACTION_DOWN));
+    window->consumeMotionEvent(WithMotionAction(POINTER_1_DOWN));
+
+    // Cancel the current gesture. Send the cancel without the default policy flags.
+    mDispatcher->notifyMotion(&(
+            args = MotionArgsBuilder(AMOTION_EVENT_ACTION_CANCEL, AINPUT_SOURCE_TOUCHSCREEN)
+                           .deviceId(touchDeviceId)
+                           .policyFlags(0)
+                           .pointer(PointerBuilder(0, AMOTION_EVENT_TOOL_TYPE_FINGER).x(100).y(100))
+                           .pointer(PointerBuilder(1, AMOTION_EVENT_TOOL_TYPE_FINGER).x(120).y(120))
+                           .build()));
+    spyWindow->consumeMotionEvent(WithMotionAction(AMOTION_EVENT_ACTION_CANCEL));
+    window->consumeMotionEvent(WithMotionAction(AMOTION_EVENT_ACTION_CANCEL));
+
+    // We don't need to reset the device to reproduce the issue, but the reset event typically
+    // follows, so we keep it here to model the actual listener behaviour more closely.
+    NotifyDeviceResetArgs resetArgs;
+    resetArgs.id = 1; // arbitrary id
+    resetArgs.eventTime = systemTime(SYSTEM_TIME_MONOTONIC);
+    resetArgs.deviceId = touchDeviceId;
+    mDispatcher->notifyDeviceReset(&resetArgs);
+
+    // Start new gesture
+    mDispatcher->notifyMotion(&(
+            args = MotionArgsBuilder(AMOTION_EVENT_ACTION_DOWN, AINPUT_SOURCE_TOUCHSCREEN)
+                           .deviceId(touchDeviceId)
+                           .policyFlags(DEFAULT_POLICY_FLAGS)
+                           .pointer(PointerBuilder(0, AMOTION_EVENT_TOOL_TYPE_FINGER).x(100).y(100))
+                           .build()));
+    spyWindow->consumeMotionEvent(WithMotionAction(AMOTION_EVENT_ACTION_DOWN));
+    window->consumeMotionEvent(WithMotionAction(AMOTION_EVENT_ACTION_DOWN));
+
+    // No more events
+    spyWindow->assertNoEvents();
+    window->assertNoEvents();
+}
+
+/**
  * Two windows: a window on the left and a window on the right.
  * Mouse is hovered from the right window into the left window.
  * Next, we tap on the left window, where the cursor was last seen.