From b98453a3f57dd5b7ab875387fefd6f4a9d8b1e62 Mon Sep 17 00:00:00 2001
From: Alex Tyrer <alextyrer@unity3d.com>
Date: Mon, 30 Sep 2024 17:10:38 +0100
Subject: [PATCH 1/2] [Input System] MakeEscapedJsonString now null-checks
 inputs. Empty strings also now bypass an allocation.

This matches older behaviour on null-checking descriptor fields which is needed for certain device implementations.
---
 Assets/Tests/InputSystem/CoreTests_Devices.cs | 41 +++++++++++++++----
 Packages/com.unity.inputsystem/CHANGELOG.md   |  3 ++
 .../InputSystem/InputManager.cs               |  9 ++++
 3 files changed, 46 insertions(+), 7 deletions(-)

diff --git a/Assets/Tests/InputSystem/CoreTests_Devices.cs b/Assets/Tests/InputSystem/CoreTests_Devices.cs
index 62b5a9232f..3dd8c69193 100644
--- a/Assets/Tests/InputSystem/CoreTests_Devices.cs
+++ b/Assets/Tests/InputSystem/CoreTests_Devices.cs
@@ -4162,13 +4162,40 @@ public void Devices_RemovingAndReaddingDevice_DoesNotAllocateMemory()
         recorder.CollectFromAllThreads();
 #endif
 
-        // We expect a single allocation for each call to ReportNewInputDevice when there is one disconnected device
-        //
-        int numberOfRepeats = 2;
-        int numberOfDisconnectedDevices = 1;
-        int numberOfCallsToReportNewInputDevicePerRun = 2;
-        int expectedAllocations = numberOfRepeats * numberOfDisconnectedDevices * numberOfCallsToReportNewInputDevicePerRun;
-        Assert.AreEqual(expectedAllocations, recorder.sampleBlockCount);
+        // No allocations are expected.
+        Assert.AreEqual(0, recorder.sampleBlockCount);
+    }
+
+    // Regression test to cover having null descriptor fields for a device. Some non-desktop gamepad device types do this.
+    [Test]
+    [Category("Devices")]
+    public void Devices_RemovingAndReaddingDeviceWithNullDescriptorFields_DoesNotThrow()
+    {
+        // InputDeviceDescription.ToJson writes empty string fields and not null values, whereas reporting a device via an incomplete description string will fully omit the fields.
+        string description = @"{
+            ""type"": ""Gamepad"",
+            ""product"": ""TestProduct""
+        }";
+
+        var deviceId = runtime.ReportNewInputDevice(description);
+        InputSystem.Update();
+
+        // "Unplug" device.
+                var removeEvent1 = DeviceRemoveEvent.Create(deviceId);
+        InputSystem.QueueEvent(ref removeEvent1);
+        InputSystem.Update();
+
+        // "Plug" it back in.
+        deviceId = runtime.ReportNewInputDevice(description);
+        InputSystem.Update();
+
+        // Repeat that sequence.
+        var removeEvent2 = DeviceRemoveEvent.Create(deviceId);
+        InputSystem.QueueEvent(ref removeEvent2);
+        InputSystem.Update();
+
+        runtime.ReportNewInputDevice(description);
+        InputSystem.Update();
     }
 
     [Test]
diff --git a/Packages/com.unity.inputsystem/CHANGELOG.md b/Packages/com.unity.inputsystem/CHANGELOG.md
index d06a397cfb..4aa5bc38b7 100644
--- a/Packages/com.unity.inputsystem/CHANGELOG.md
+++ b/Packages/com.unity.inputsystem/CHANGELOG.md
@@ -10,6 +10,9 @@ however, it has to be formatted properly to pass verification tests.
 
 ## [Unreleased] - yyyy-mm-dd
 
+### Fixed
+- Fixed `NullReferenceException` from disconnecting and reconnecting a GXDKGamepad.
+
 ### Added
 - Added the display of the device flag `CanRunInBackground` in device debug view.
 - Added analytics for programmatic `InputAction` setup via `InputActionSetupExtensions` when exiting play-mode.
diff --git a/Packages/com.unity.inputsystem/InputSystem/InputManager.cs b/Packages/com.unity.inputsystem/InputSystem/InputManager.cs
index 989ec623cf..10e3c17fb8 100644
--- a/Packages/com.unity.inputsystem/InputSystem/InputManager.cs
+++ b/Packages/com.unity.inputsystem/InputSystem/InputManager.cs
@@ -2562,6 +2562,15 @@ private JsonParser.JsonString MakeEscapedJsonString(string theString)
             // To avoid a very costly escape-skipping character-by-character string comparison in JsonParser.Json.Equals() we
             // reconstruct an escaped string and make an escaped JsonParser.JsonString and use that for the comparison instead.
             //
+            if (string.IsNullOrEmpty(theString))
+            {
+                return new JsonParser.JsonString
+                {
+                    text = string.Empty,    // text should be an empty string and not null for consistency on property comparisons
+                    hasEscapes = false
+                };
+            }
+
             var builder = new StringBuilder();
             var length = theString.Length;
             var hasEscapes = false;

From 336bfd5364f72479276ba21980977806b1b75ec1 Mon Sep 17 00:00:00 2001
From: Alex Tyrer <alextyrer@unity3d.com>
Date: Tue, 1 Oct 2024 09:58:59 +0100
Subject: [PATCH 2/2] Fix formatting in CoreTests_Devices.cs (indentation)

---
 Assets/Tests/InputSystem/CoreTests_Devices.cs | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/Assets/Tests/InputSystem/CoreTests_Devices.cs b/Assets/Tests/InputSystem/CoreTests_Devices.cs
index 3dd8c69193..bc4ec5a82b 100644
--- a/Assets/Tests/InputSystem/CoreTests_Devices.cs
+++ b/Assets/Tests/InputSystem/CoreTests_Devices.cs
@@ -4181,7 +4181,7 @@ public void Devices_RemovingAndReaddingDeviceWithNullDescriptorFields_DoesNotThr
         InputSystem.Update();
 
         // "Unplug" device.
-                var removeEvent1 = DeviceRemoveEvent.Create(deviceId);
+        var removeEvent1 = DeviceRemoveEvent.Create(deviceId);
         InputSystem.QueueEvent(ref removeEvent1);
         InputSystem.Update();