[UIKit] Fix GCHandle memory leak in NetworkReachability.SetNotification. Fixes #12962.

src/SystemConfiguration/NetworkReachability.cs

@@ -523,12 +523,18 @@ public StatusCode SetNotification (Notification? callback)
 				unsafe {
 					rv = SCNetworkReachabilitySetCallback (Handle, &Callback, &ctx) != 0;
 				}
+				if (!rv) {
+					gch.Free ();
+					return StatusCodeError.SCError ();
+				}
 			} else {
 				if (callback is null) {
 					this.notification = null;
 					unsafe {
 						rv = SCNetworkReachabilitySetCallback (Handle, null, null) != 0;
 					}
+					if (gch.IsAllocated)
+						gch.Free ();
 					if (!rv)
 						return StatusCodeError.SCError ();
 
@@ -678,5 +684,12 @@ public bool SetDispatchQueue (DispatchQueue? queue)
 			GC.KeepAlive (queue);
 			return result;
 		}
+
+		protected override void Dispose (bool disposing)
+		{
+			if (gch.IsAllocated)
+				gch.Free ();
+			base.Dispose (disposing);
+		}
 	}
 }

tests/cecil-tests/Documentation.KnownFailures.txt

@@ -16350,6 +16350,7 @@ M:StoreKit.SKStoreProductViewController.LoadProduct(StoreKit.StoreProductParamet
 M:StoreKit.SKStoreProductViewController.LoadProductAsync(Foundation.NSDictionary,StoreKit.SKAdImpression)
 M:StoreKit.SKStoreProductViewController.LoadProductAsync(StoreKit.StoreProductParameters,StoreKit.SKAdImpression)
 M:StoreKit.SKStoreProductViewController.remove_Finished(System.EventHandler)
+M:SystemConfiguration.NetworkReachability.Dispose(System.Boolean)
 M:ThreadNetwork.THClient.CheckPreferredNetworkAsync(Foundation.NSData)
 M:ThreadNetwork.THClient.DeleteCredentialsForBorderAgentAsync(Foundation.NSData)
 M:ThreadNetwork.THClient.IsPreferredNetworkAvailableAsync

tests/monotouch-test/SystemConfiguration/NetworkReachabilityTest.cs

@@ -12,6 +12,8 @@
 #endif
 using SystemConfiguration;
 using System.Net;
+using System.Threading;
+using System.Threading.Tasks;
 
 namespace MonoTouchFixtures.SystemConfiguration {
 
@@ -142,5 +144,114 @@ public void Schedule ()
 			Assert.IsTrue (defaultRouteReachability.Schedule (CFRunLoop.Main, CFRunLoop.ModeDefault), "Schedule");
 			Assert.IsTrue (defaultRouteReachability.Unschedule (CFRunLoop.Main, CFRunLoop.ModeDefault), "Unschedule");
 		}
+
+		[Test]
+		public void SetNotification ()
+		{
+			var ip = new IPAddress (0);
+			using var reachability = new NetworkReachability (ip);
+
+			// Test setting a notification
+			var statusCode = reachability.SetNotification ((flags) => {
+			});
+			Assert.AreEqual (StatusCode.OK, statusCode, "SetNotification should succeed");
+
+			// Test clearing the notification (this should free the GCHandle)
+			statusCode = reachability.SetNotification (null);
+			Assert.AreEqual (StatusCode.OK, statusCode, "SetNotification(null) should succeed");
+
+			// Test setting notification again after clearing
+			statusCode = reachability.SetNotification ((flags) => {
+			});
+			Assert.AreEqual (StatusCode.OK, statusCode, "SetNotification should succeed again");
+
+			// Test that disposing also works (should free the GCHandle in Dispose)
+		}
+
+		[Test]
+		public void SetNotification_GCHandleFreed ()
+		{
+			// Create weak references to track GC collection
+			var weakRefs = new WeakReference [10];
+
+			// Create NetworkReachability instances on a background thread
+			var thread = new Thread (() => {
+				for (int i = 0; i < 10; i++) {
+					var ip = new IPAddress (0);
+					var reachability = new NetworkReachability (ip);
+
+					// Set a notification to allocate the GCHandle
+					reachability.SetNotification ((flags) => {
+					});
+
+					// Store weak reference to track if object is collected
+					weakRefs [i] = new WeakReference (reachability);
+
+					// Dispose to ensure GCHandle is freed
+					reachability.Dispose ();
+				}
+			});
+
+			thread.Start ();
+			thread.Join ();
+
+			// Force garbage collection
+			GC.Collect ();
+			GC.WaitForPendingFinalizers ();
+			GC.Collect ();
+
+			// Assert that at least one NetworkReachability instance has been collected
+			var collectedCount = 0;
+			for (int i = 0; i < weakRefs.Length; i++) {
+				if (!weakRefs [i].IsAlive) {
+					collectedCount++;
+				}
+			}
+
+			Assert.IsTrue (collectedCount > 0, $"Expected at least one NetworkReachability instance to be collected, but {collectedCount} were collected");
+		}
+
+		[Test]
+		public void SetNotification_GCHandleFreedWithNull ()
+		{
+			// Create weak references to track GC collection
+			var weakRefs = new WeakReference [10];
+
+			// Create NetworkReachability instances on a background thread
+			var thread = new Thread (() => {
+				for (int i = 0; i < 10; i++) {
+					var ip = new IPAddress (0);
+					var reachability = new NetworkReachability (ip);
+
+					// Set a notification to allocate the GCHandle
+					reachability.SetNotification ((flags) => {
+					});
+
+					// Clear notification to free the GCHandle
+					reachability.SetNotification (null);
+
+					// Store weak reference to track if object is collected
+					weakRefs [i] = new WeakReference (reachability);
+				}
+			});
+
+			thread.Start ();
+			thread.Join ();
+
+			// Force garbage collection
+			GC.Collect ();
+			GC.WaitForPendingFinalizers ();
+			GC.Collect ();
+
+			// Assert that at least one NetworkReachability instance has been collected
+			var collectedCount = 0;
+			for (int i = 0; i < weakRefs.Length; i++) {
+				if (!weakRefs [i].IsAlive) {
+					collectedCount++;
+				}
+			}
+
+			Assert.IsTrue (collectedCount > 0, $"Expected at least one NetworkReachability instance to be collected, but {collectedCount} were collected");
+		}
 	}
 }