Prevent keyboards from being recognized as a stylus

We are getting reports of keyboards and other peripherals being
misconfigured as a stylus, because they report support for stylus
buttons.

To eliminate some of these misconfigurations, prevent anything detected
as a alphabetical keyboard from being categorized as a stylus.

Bug: 293996865
Test: None
Change-Id: I3f071d2ac6a2b70abc1130b4d5df1509452bb63b
(cherry picked from commit 3c28b94505b5c6edaeb7e0df3ace7cf3f8125887)

2 files changed, 19 insertions, 0 deletions

diff --git a/services/inputflinger/reader/EventHub.cpp b/services/inputflinger/reader/EventHub.cpp
index 4d0e13ed2f..44e80a732c 100644
--- a/services/inputflinger/reader/EventHub.cpp
+++ b/services/inputflinger/reader/EventHub.cpp
@@ -2403,6 +2403,7 @@ void EventHub::openDeviceLocked(const std::string& devicePath) {
 
         // See if this device has any stylus buttons that we would want to fuse with touch data.
         if (!device->classes.any(InputDeviceClass::TOUCH | InputDeviceClass::TOUCH_MT) &&
+            !device->classes.any(InputDeviceClass::ALPHAKEY) &&
             std::any_of(STYLUS_BUTTON_KEYCODES.begin(), STYLUS_BUTTON_KEYCODES.end(),
                         [&](int32_t keycode) { return device->hasKeycodeLocked(keycode); })) {
             device->classes |= InputDeviceClass::EXTERNAL_STYLUS;
diff --git a/services/inputflinger/tests/InputReader_test.cpp b/services/inputflinger/tests/InputReader_test.cpp
index d1c3f7d156..dd93e93a86 100644
--- a/services/inputflinger/tests/InputReader_test.cpp
+++ b/services/inputflinger/tests/InputReader_test.cpp
@@ -1476,6 +1476,24 @@ TEST_F(InputReaderIntegrationTest, ExternalStylusesButtons) {
             AllOf(UP, WithKeyCode(AKEYCODE_STYLUS_BUTTON_TERTIARY))));
 }
 
+TEST_F(InputReaderIntegrationTest, KeyboardWithStylusButtons) {
+    std::unique_ptr<UinputKeyboard> keyboard =
+            createUinputDevice<UinputKeyboard>("KeyboardWithStylusButtons", /*productId=*/99,
+                                               std::initializer_list<int>{KEY_Q, KEY_W, KEY_E,
+                                                                          KEY_R, KEY_T, KEY_Y,
+                                                                          BTN_STYLUS, BTN_STYLUS2,
+                                                                          BTN_STYLUS3});
+    ASSERT_NO_FATAL_FAILURE(mFakePolicy->assertInputDevicesChanged());
+
+    const auto device = findDeviceByName(keyboard->getName());
+    ASSERT_TRUE(device.has_value());
+
+    // An alphabetical keyboard that reports stylus buttons should not be recognized as a stylus.
+    ASSERT_EQ(AINPUT_SOURCE_KEYBOARD, device->getSources())
+            << "Unexpected source " << inputEventSourceToString(device->getSources()).c_str();
+    ASSERT_EQ(AINPUT_KEYBOARD_TYPE_ALPHABETIC, device->getKeyboardType());
+}
+
 /**
  * The Steam controller sends BTN_GEAR_DOWN and BTN_GEAR_UP for the two "paddle" buttons
  * on the back. In this test, we make sure that BTN_GEAR_DOWN / BTN_WHEEL and BTN_GEAR_UP