From ab3f910a76568d8a0c234aee0227c65705729da8 Mon Sep 17 00:00:00 2001
From: Mathias Dobler <81033366+huesla@users.noreply.github.com>
Date: Mon, 18 Mar 2024 06:54:29 +0100
Subject: [PATCH] Do not pass static zero IntPtr to epoll wait. Dispose driver
 in tests in all cases. (#2291)

---
 src/System.Device.Gpio.Tests/GpioControllerTestBase.cs    | 8 ++++----
 src/System.Device.Gpio/Interop/UnmanagedArray.cs          | 5 +----
 .../System/Device/Gpio/Drivers/SysFsDriver.cs             | 8 +++++---
 3 files changed, 10 insertions(+), 11 deletions(-)

diff --git a/src/System.Device.Gpio.Tests/GpioControllerTestBase.cs b/src/System.Device.Gpio.Tests/GpioControllerTestBase.cs
index 8be336df11..c2fd94c396 100644
--- a/src/System.Device.Gpio.Tests/GpioControllerTestBase.cs
+++ b/src/System.Device.Gpio.Tests/GpioControllerTestBase.cs
@@ -28,7 +28,7 @@ protected GpioControllerTestBase(ITestOutputHelper testOutputHelper)
     [InlineData(false)]
     public void PinValueStaysSameAfterDispose(bool closeAsHigh)
     {
-        var driver = GetTestDriver();
+        using var driver = GetTestDriver();
         if (driver is SysFsDriver)
         {
             // This check fails on the SysFsDriver, because it always sets the value to 0 when the pin is opened (but on close, the value does stay high)
@@ -181,7 +181,7 @@ public void ThrowsIfWritingClosedPin()
     [Trait("SkipOnTestRun", "Windows_NT")] // Currently, the Windows Driver is defaulting to InputPullDown, and it seems this cannot be changed
     public void OpenPinDefaultsModeToLastMode(PinMode modeToTest)
     {
-        var driver = GetTestDriver();
+        using var driver = GetTestDriver();
         if (driver is SysFsDriver)
         {
             // See issue #1581. There seems to be a library-version issue or some other random cause for this test to act differently on different hardware.
@@ -230,7 +230,7 @@ void Callback(object sender, PinValueChangedEventArgs pinValueChangedEventArgs)
     [Fact]
     public void AddCallbackFallingEdgeNotDetectedTest()
     {
-        var driver = GetTestDriver();
+        using var driver = GetTestDriver();
         if (driver is SysFsDriver)
         {
             // This test is unreliable (flaky) with SysFs.
@@ -317,7 +317,7 @@ void Callback(object sender, PinValueChangedEventArgs e)
     [Fact]
     public void AddCallbackRemoveAllCallbackTest()
     {
-        GpioDriver testDriver = GetTestDriver();
+        using GpioDriver testDriver = GetTestDriver();
         // Skipping the test for now when using the SysFsDriver or the RaspberryPi3Driver given that this test is flaky for those drivers.
         // Issue tracking this problem is https://github.com/dotnet/iot/issues/629
         if (testDriver is SysFsDriver || testDriver is RaspberryPi3Driver)
diff --git a/src/System.Device.Gpio/Interop/UnmanagedArray.cs b/src/System.Device.Gpio/Interop/UnmanagedArray.cs
index df2b4c4295..b96dac7856 100644
--- a/src/System.Device.Gpio/Interop/UnmanagedArray.cs
+++ b/src/System.Device.Gpio/Interop/UnmanagedArray.cs
@@ -10,8 +10,6 @@ internal sealed class UnmanagedArray<T> : SafeHandle
     private readonly int _arrayLength;
     private readonly int _typeSize;
 
-    public static readonly UnmanagedArray<T> Empty = new(0);
-
     public UnmanagedArray(int arrayLength)
         : base(IntPtr.Zero, true)
     {
@@ -21,7 +19,7 @@ public UnmanagedArray(int arrayLength)
         }
 
         _arrayLength = arrayLength;
-        _typeSize = Marshal.SizeOf(typeof(T));
+        _typeSize = Marshal.SizeOf<T>();
         SetHandle(Marshal.AllocHGlobal(_typeSize * arrayLength));
     }
 
@@ -58,4 +56,3 @@ public static implicit operator IntPtr(UnmanagedArray<T> unmanagedArray)
         return !unmanagedArray.IsInvalid ? unmanagedArray.handle : throw new InvalidOperationException("Invalid handle");
     }
 }
-
diff --git a/src/System.Device.Gpio/System/Device/Gpio/Drivers/SysFsDriver.cs b/src/System.Device.Gpio/System/Device/Gpio/Drivers/SysFsDriver.cs
index a2877d5c6c..5bf0d062d7 100644
--- a/src/System.Device.Gpio/System/Device/Gpio/Drivers/SysFsDriver.cs
+++ b/src/System.Device.Gpio/System/Device/Gpio/Drivers/SysFsDriver.cs
@@ -456,7 +456,8 @@ private void AddPinToPoll(int pinNumber, ref int valueFileDescriptor, ref int po
         }
 
         // Ignore first time because it will always return the current state.
-        while (Interop.epoll_wait(pollFileDescriptor, UnmanagedArray<epoll_event>.Empty, 1, 0) == -1)
+        using var eventBuffer = new UnmanagedArray<epoll_event>(1);
+        while (Interop.epoll_wait(pollFileDescriptor, eventBuffer, 1, 0) == -1)
         {
             var errorCode = Marshal.GetLastWin32Error();
             if (errorCode != ERROR_CODE_EINTR)
@@ -467,14 +468,15 @@ private void AddPinToPoll(int pinNumber, ref int valueFileDescriptor, ref int po
         }
     }
 
-    private unsafe bool WasEventDetected(int pollFileDescriptor, int valueFileDescriptor, out int pinNumber, CancellationToken cancellationToken)
+    private bool WasEventDetected(int pollFileDescriptor, int valueFileDescriptor, out int pinNumber, CancellationToken cancellationToken)
     {
         pinNumber = -1;
 
+        using var eventBuffer = new UnmanagedArray<epoll_event>(1);
+
         while (!cancellationToken.IsCancellationRequested)
         {
             // Wait until something happens
-            using var eventBuffer = new UnmanagedArray<epoll_event>(1);
             int waitResult = Interop.epoll_wait(pollFileDescriptor, eventBuffer, 1, PollingTimeout);
             if (waitResult == -1)
             {