Make YubiKeyDeviceListener resettable

Yubico.Core/src/Yubico/Core/Devices/DeviceEventArgs.cs

@@ -0,0 +1,72 @@
+// Copyright 2024 Yubico AB
+//
+// Licensed under the Apache License, Version 2.0 (the "License").
+// You may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS, 
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+using System;
+
+namespace Yubico.Core.Devices
+{
+    /// <summary>
+    /// Defines the contract for device-related event arguments in a generic context.
+    /// This interface allows for type-safe access to device information in event handling
+    /// scenarios, supporting device types that implement the <see cref="IDevice"/> interface.
+    /// It enables specific device type information to be preserved and accessed in event handlers.
+    /// </summary>
+    /// <remarks>
+    /// While this interface does not inherit from <see cref="System.EventArgs"/>, it retains the "Args" suffix
+    /// in its name. This naming convention is deliberately chosen to maintain consistency with standard
+    /// event argument naming patterns in C#, particularly for improved readability when used in delegate
+    /// and event handler signatures. The familiar "Args" suffix clearly indicates the interface's role
+    /// in event-related contexts, despite not directly extending <see cref="System.EventArgs"/>.
+    /// </remarks>
+    /// <typeparam name="TDevice">The specific type of <see cref="IDevice"/> this event argument represents.
+    /// This type parameter is covariant, allowing for more specific device types to be used
+    /// where a more general device type is expected.</typeparam>
+    #pragma warning disable CA1711 // Identifiers should not have incorrect suffix
+    public interface IDeviceEventArgs<out TDevice> where TDevice : IDevice
+    #pragma warning restore CA1711 // Identifiers should not have incorrect suffix
+    {
+        /// <summary>
+        /// Gets the specific type of <see cref="IDevice"/> that originated the event.
+        /// This property will always be populated, regardless of whether this is an arrival event or a removal event.
+        /// If the device was removed, not all members will be available on the object. An exception will be thrown if
+        /// you try to use the device in a way that requires it to be present.
+        /// </summary>
+        /// <remarks>
+        /// This property provides access to the specific <c>TDevice</c> instance associated with the current event.
+        /// </remarks>
+        /// <value>
+        /// An instance of <c>TDevice</c> that triggered this event.
+        /// </value>
+        TDevice Device { get; }
+    }
+
+    /// <summary>
+    /// Event arguments given whenever a device is added or removed from the system, providing strongly-typed access to the device that triggered the event.
+    /// </summary>
+    /// <typeparam name="TDevice">The type of device associated with this event, which must implement <see cref="IDevice"/>.</typeparam>
+    public abstract class DeviceEventArgs<TDevice> : EventArgs, IDeviceEventArgs<TDevice>
+        where TDevice : IDevice
+    {
+        /// <inheritdoc />
+        public TDevice Device { get; }
+
+        /// <summary>
+        /// Constructs a new instance of the <see cref="DeviceEventArgs{TDevice}"/> class.
+        /// </summary>
+        protected DeviceEventArgs(TDevice device)
+        {
+            Device = device;
+        }
+    }
+}

Yubico.Core/src/Yubico/Core/Devices/Hid/HidDeviceEventArgs.cs

@@ -12,34 +12,22 @@
 // See the License for the specific language governing permissions and
 // limitations under the License.
 
-using System;
-
 namespace Yubico.Core.Devices.Hid
 {
     /// <summary>
     /// Event arguments given whenever a HID device is added or removed from the system.
     /// </summary>
-    public class HidDeviceEventArgs : EventArgs
+    public class HidDeviceEventArgs : DeviceEventArgs<IHidDevice>
     {
-        /// <summary>
-        /// The HID device that originated the event.
-        /// </summary>
-        /// <remarks>
-        /// This property will always be populated, regardless of whether this is an arrival event or a removal event.
-        /// If the device was removed, not all members will be available on the object. An exception will be thrown if
-        /// you try to use the device in a way that requires it to be present.
-        /// </remarks>
-        public IHidDevice? Device { get; set; }
 
         /// <summary>
         /// Constructs a new instance of the <see cref="HidDeviceEventArgs"/> class.
         /// </summary>
         /// <param name="device">
         /// The HID device that is originating this event.
         /// </param>
-        public HidDeviceEventArgs(IHidDevice? device)
+        public HidDeviceEventArgs(IHidDevice device) : base(device)
         {
-            Device = device;
         }
     }
 }

Yubico.Core/src/Yubico/Core/Devices/Hid/HidDeviceListener.cs

@@ -86,7 +86,7 @@ protected void OnArrived(IHidDevice device)
         /// <param name="device">
         /// The device instance that originates this event.
         /// </param>
-        protected void OnRemoved(IHidDevice? device)
+        protected void OnRemoved(IHidDevice device)
         {
             _log.LogInformation("HID {Device} removed.", device);
             Removed?.Invoke(this, new HidDeviceEventArgs(device));

Yubico.Core/src/Yubico/Core/Devices/Hid/MacOSHidDeviceListener.cs

@@ -139,6 +139,6 @@ private void ArrivedCallback(IntPtr context, int result, IntPtr sender, IntPtr d
             OnArrived(new MacOSHidDevice(MacOSHidDevice.GetEntryId(device)));
 
         private void RemovedCallback(IntPtr context, int result, IntPtr sender, IntPtr device) =>
-            OnRemoved(null);
+            OnRemoved(NullDevice.Instance);
     }
 }

Yubico.Core/src/Yubico/Core/Devices/Hid/NullDevice.cs

@@ -0,0 +1,38 @@
+// Copyright 2024 Yubico AB
+// 
+// Licensed under the Apache License, Version 2.0 (the "License").
+// You may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+// 
+//     http://www.apache.org/licenses/LICENSE-2.0
+// 
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+using System;
+
+namespace Yubico.Core.Devices.Hid
+{
+    public class NullDevice : IHidDevice
+    {
+        public string Path => string.Empty;
+        public string? ParentDeviceId => default;
+        public DateTime LastAccessed => default;
+        public short VendorId => default;
+        public short ProductId => default;
+        public short Usage => default;
+        public HidUsagePage UsagePage => default;
+        public IHidConnection ConnectToFeatureReports() => throw new NotImplementedException();
+        public IHidConnection ConnectToIOReports() => throw new NotImplementedException();
+
+        /// <summary>
+        /// Creates a default <see cref="IHidDevice"/> with all it's properties set to its default values, indicating a null device.
+        /// This might be used in cases where the <see cref="IHidDevice"/> otherwise would be null.
+        /// </summary>
+        internal static IHidDevice Instance => new NullDevice();
+        private NullDevice() { }
+    }
+}

Yubico.Core/src/Yubico/Core/Devices/Hid/WindowsHidDeviceListener.cs

@@ -128,7 +128,7 @@ private static int OnEventReceived(IntPtr hNotify, IntPtr context, CM_NOTIFY_ACT
             }
             else if (action == CM_NOTIFY_ACTION.DEVICEINTERFACEREMOVAL)
             {
-                thisObj?.OnRemoved(null);
+                thisObj?.OnRemoved(NullDevice.Instance);
             }
 
             return 0;

Yubico.Core/src/Yubico/Core/Devices/SmartCard/SmartCardDeviceEventArgs.cs

@@ -12,34 +12,21 @@
 // See the License for the specific language governing permissions and
 // limitations under the License.
 
-using System;
-
 namespace Yubico.Core.Devices.SmartCard
 {
     /// <summary>
     /// Event arguments given whenever a smart card device is added or removed from the system.
     /// </summary>
-    public class SmartCardDeviceEventArgs : EventArgs
+    public class SmartCardDeviceEventArgs : DeviceEventArgs<ISmartCardDevice>
     {
-        /// <summary>
-        /// The smart card device that originated the event.
-        /// </summary>
-        /// <remarks>
-        /// This property will always be populated, regardless of whether this is an arrival event or a removal event.
-        /// If the device was removed, not all members will be available on the object. An exception will be thrown if
-        /// you try to use the device in a way that requires it to be present.
-        /// </remarks>
-        public ISmartCardDevice Device { get; set; }
-
         /// <summary>
         /// Constructs a new instance of the <see cref="SmartCardDeviceEventArgs"/> class.
         /// </summary>
         /// <param name="device">
         /// The smart card device that is originating this event.
         /// </param>
-        public SmartCardDeviceEventArgs(ISmartCardDevice device)
+        public SmartCardDeviceEventArgs(ISmartCardDevice device) : base(device)
         {
-            Device = device;
         }
     }
 }

Yubico.Core/tests/Yubico/Core/Devices/Hid/HidTranslatorTests.cs

@@ -146,7 +146,10 @@ public void TestSpecializedKeyboardSupportsModhexString(KeyboardLayout layout)
 #if Windows
 #pragma warning disable CA1825
         [Theory]
+#pragma warning disable CA1825 // Avoid zero-length array allocations
+        // The compiler mistakenly thinks that this somehow involves a zero-length array.
         [MemberData(nameof(GetTestData))]
+#pragma warning restore CA1825 // Avoid zero-length array allocations
         public void GetChar_GivenHidCode_ReturnsCorrectChar(KeyboardLayout layout, (char, byte)[] testData)
         {
             var hid = HidCodeTranslator.GetInstance(layout);

Yubico.YubiKey/src/Yubico/YubiKey/YubiKeyDevice.Static.cs

@@ -54,6 +54,11 @@ public partial class YubiKeyDevice
         /// <see cref="IYubiKeyDevice"/> using their serial number. If they cannot be matched,
         /// each connection will be returned as a separate <see cref="IYubiKeyDevice"/>.
         /// </para>
+        /// <para>
+        /// If your application no longer needs to watch for insertion or removal notifications,
+        /// you can call <see cref="YubiKeyDeviceListener.StopListening"/> to release resources
+        /// and avoid the logging and other actions from the listeners.
+        /// </para>
         /// </remarks>
         /// <param name="transport">
         /// Argument controls which devices are searched for. Values <see cref="Transport.None"/>