FIX: Avoid potential for NullReferenceException in FireStateChangeNotifications (ISXB-724). (#1927)

* FIX: Avoid potential for NullReferenceException in FireStateChangeNotifications (ISXB-724).

* Fix changelog since issue isn't public (and add a minor string fix while I'm here).

* Formatting fix.

* Hopefully appease integration tests.

* Improve wording of changelog.

Author: graham-huws

Packages/com.unity.inputsystem/CHANGELOG.md

@@ -9,9 +9,12 @@ Due to package verification, the latest version below is the unpublished version
 however, it has to be formatted properly to pass verification tests.
 
 ## [Unreleased] - yyyy-mm-dd
-- Fixed Composite binding isn't triggered after ResetDevice() called during Action handler [ISXB-746](https://issuetracker.unity3d.com/product/unity/issues/guid/ISXB-746)
-- Fixed resource designation for "d_InputControl" icon to address CI failure
-- Fixed Composite binding isn't triggered after disabling action while there are in progress [ISXB-505](https://issuetracker.unity3d.com/product/unity/issues/guid/ISXB-505)
+
+### Fixed
+- Avoid potential crashes from `NullReferenceException` in `FireStateChangeNotifications`.
+- Fixed an issue where a composite binding would not be consecutively triggered after ResetDevice() has been called from the associated action handler [ISXB-746](https://issuetracker.unity3d.com/product/unity/issues/guid/ISXB-746).
+- Fixed resource designation for "d_InputControl" icon to address CI failure.
+- Fixed an issue where a composite binding would not be consecutively triggered after disabling actions while there are action modifiers in progress [ISXB-505](https://issuetracker.unity3d.com/product/unity/issues/guid/ISXB-505).
 
 ## [1.8.2] - 2024-04-29
 

Packages/com.unity.inputsystem/InputSystem/Devices/Gamepad.cs

@@ -86,7 +86,7 @@ public struct GamepadState : IInputStateTypeInfo
         internal const string ButtonSouthShortDisplayName = "Cross";
         internal const string ButtonNorthShortDisplayName = "Triangle";
         internal const string ButtonWestShortDisplayName = "Square";
-        internal const string ButtonEastShortDisplayName = "East";
+        internal const string ButtonEastShortDisplayName = "Circle";
         #elif UNITY_SWITCH
         internal const string ButtonSouthShortDisplayName = "B";
         internal const string ButtonNorthShortDisplayName = "X";

Packages/com.unity.inputsystem/InputSystem/InputManagerStateMonitors.cs

@@ -349,14 +349,28 @@ private unsafe bool ProcessStateChangeMonitors(int deviceIndex, void* newStateFr
 
         internal unsafe void FireStateChangeNotifications(int deviceIndex, double internalTime, InputEvent* eventPtr)
         {
-            Debug.Assert(m_StateChangeMonitors != null);
-            Debug.Assert(m_StateChangeMonitors.Length > deviceIndex);
+            if (m_StateChangeMonitors == null)
+            {
+                Debug.Assert(false, "m_StateChangeMonitors is null - has AddStateChangeMonitor been called?");
+                return;
+            }
+            if (m_StateChangeMonitors.Length <= deviceIndex)
+            {
+                Debug.Assert(false, $"deviceIndex {deviceIndex} passed to FireStateChangeNotifications is out of bounds (current length {m_StateChangeMonitors.Length}).");
+                return;
+            }
 
             // NOTE: This method must be safe for mutating the state change monitor arrays from *within*
             //       NotifyControlStateChanged()! This includes all monitors for the device being wiped
             //       completely or arbitrary additions and removals having occurred.
 
             ref var signals = ref m_StateChangeMonitors[deviceIndex].signalled;
+            if (signals.AnyBitIsSet() && m_StateChangeMonitors[deviceIndex].listeners == null)
+            {
+                Debug.Assert(false, $"A state change for device {deviceIndex} has been set, but list of listeners is null.");
+                return;
+            }
+
             ref var listeners = ref m_StateChangeMonitors[deviceIndex].listeners;
             var time = internalTime - InputRuntime.s_CurrentTimeOffsetToRealtimeSinceStartup;
 

Packages/com.unity.inputsystem/InputSystem/Utilities/DynamicBitfield.cs

@@ -51,6 +51,16 @@ public void ClearBit(int bitIndex)
             array[bitIndex / 64] &= ~(1UL << (bitIndex % 64));
         }
 
+        public bool AnyBitIsSet()
+        {
+            for (var i = 0; i < array.length; ++i)
+            {
+                if (array[i] != 0)
+                    return true;
+            }
+            return false;
+        }
+
         private static int BitCountToULongCount(int bitCount)
         {
             return (bitCount + 63) / 64;