Increase leniency of precondition check for MotionEvent::split

The severity of a specific precondition check was unintentionally
promoted from WARNING to FATAL in the following refactor:
I6230b6aa0696dcfc275a5a14ab4af3d4b7bd0b45

Here, we demote it back to a non-fatal check.

Bug: 328852741
Bug: 329107108
Test: atest inputflinger_tests
Change-Id: If2cb22d528d5e68c1e035a3e4291dae7fc32bb34

2 files changed, 16 insertions, 1 deletions

diff --git a/libs/input/Input.cpp b/libs/input/Input.cpp
index ff9d9a94c9..61a964ece9 100644
--- a/libs/input/Input.cpp
+++ b/libs/input/Input.cpp
@@ -1034,7 +1034,8 @@ std::tuple<int32_t, std::vector<PointerProperties>, std::vector<PointerCoords>>
                         (splitPointerProperties.size() * (historySize + 1)));
 
     if (CC_UNLIKELY(splitPointerProperties.size() != splitCount)) {
-        LOG(FATAL) << "Cannot split MotionEvent: Requested splitting " << splitCount
+        // TODO(b/329107108): Promote this to a fatal check once bugs in the caller are resolved.
+        LOG(ERROR) << "Cannot split MotionEvent: Requested splitting " << splitCount
                    << " pointers from the original event, but the original event only contained "
                    << splitPointerProperties.size() << " of those pointers.";
     }
diff --git a/services/inputflinger/dispatcher/InputDispatcher.cpp b/services/inputflinger/dispatcher/InputDispatcher.cpp
index 73bbed6c68..3c83affcbe 100644
--- a/services/inputflinger/dispatcher/InputDispatcher.cpp
+++ b/services/inputflinger/dispatcher/InputDispatcher.cpp
@@ -4285,6 +4285,20 @@ std::unique_ptr<MotionEntry> InputDispatcher::splitMotionEvent(
             MotionEvent::split(originalMotionEntry.action, originalMotionEntry.flags,
                                /*historySize=*/0, originalMotionEntry.pointerProperties,
                                originalMotionEntry.pointerCoords, pointerIds);
+    if (pointerIds.count() != pointerCoords.size()) {
+        // TODO(b/329107108): Determine why some IDs in pointerIds were not in originalMotionEntry.
+        // This is bad.  We are missing some of the pointers that we expected to deliver.
+        // Most likely this indicates that we received an ACTION_MOVE events that has
+        // different pointer ids than we expected based on the previous ACTION_DOWN
+        // or ACTION_POINTER_DOWN events that caused us to decide to split the pointers
+        // in this way.
+        ALOGW("Dropping split motion event because the pointer count is %d but "
+              "we expected there to be %zu pointers.  This probably means we received "
+              "a broken sequence of pointer ids from the input device: %s",
+              pointerCoords.size(), pointerIds.count(),
+              originalMotionEntry.getDescription().c_str());
+        return nullptr;
+    }
 
     // TODO(b/327503168): Move this check inside MotionEvent::split once all callers handle it
     //   correctly.