Expose NativeWebView.ProcessTerminated when the web content process is gone

src/Avalonia.Controls.WebView.Core/Gtk/GtkWebViewAdapter.cs

@@ -14,7 +14,8 @@
 
 namespace Avalonia.Controls.Gtk;
 
-internal abstract class GtkWebViewAdapter : IWebViewAdapterWithFocus, IGtkWebViewPlatformHandle, IWebViewWithPrintWithOptions
+internal abstract class GtkWebViewAdapter : IWebViewAdapterWithFocus, IGtkWebViewPlatformHandle, IWebViewWithPrintWithOptions,
+    IWebViewAdapterWithProcessTermination
 {
     internal enum WebKitLoadEvent
     {
@@ -45,6 +46,9 @@ internal enum WebKitLoadEvent
     private static readonly unsafe IntPtr s_resourceLoadStartedCallback =
         new((delegate* unmanaged[Cdecl]<IntPtr, IntPtr, IntPtr, IntPtr, void>)&ResourceLoadStartedCallback);
 
+    private static readonly unsafe IntPtr s_processTerminatedCallback =
+        new((delegate* unmanaged[Cdecl]<IntPtr, int, IntPtr, void>)&ProcessTerminatedCallback);
+
     private readonly IntPtr _settings;
     private IntPtr _webViewHandle;
     private GtkSignal? _loadChangedSignal;
@@ -53,6 +57,7 @@ internal enum WebKitLoadEvent
     private GtkSignal? _focusOutSignal;
     private GtkSignal? _scriptMessageReceivedSignal;
     private GtkSignal? _resourceLoadStarted;
+    private GtkSignal? _processTerminatedSignal;
     private Uri _source = WebViewHelper.EmptyPage;
     private bool _hostFocusChange;
 
@@ -135,6 +140,7 @@ protected GtkWebViewAdapter(GtkWebViewEnvironmentRequestedEventArgs args)
         _focusInSignal = new GtkSignal(WebViewHandle, "focus-in-event", s_focusInCallback, this);
         _focusOutSignal = new GtkSignal(WebViewHandle, "focus-out-event", s_focusOutCallback, this);
         _resourceLoadStarted = new GtkSignal(WebViewHandle, "resource-load-started", s_resourceLoadStartedCallback, this);
+        _processTerminatedSignal = new GtkSignal(WebViewHandle, "web-process-terminated", s_processTerminatedCallback, this);
     }
 
     public IntPtr WebViewHandle => _webViewHandle;
@@ -185,6 +191,7 @@ public virtual Color DefaultBackground
     public event EventHandler<WebResourceRequestedEventArgs>? WebResourceRequested;
     public event EventHandler? GotFocus;
     public event EventHandler<IWebViewAdapterWithFocus.LostFocusDirection>? LostFocus;
+    public event EventHandler<WebViewProcessTerminatedEventArgs>? ProcessTerminated;
 
     /// <summary>
     /// The GTK toplevel holding the web view, or zero when the adapter has none.
@@ -611,6 +618,22 @@ private static void ScriptMessageReceivedCallback(IntPtr widget, IntPtr jsResult
         });
     }
 
+    [UnmanagedCallersOnly(CallConvs = [typeof(CallConvCdecl)])]
+    private static void ProcessTerminatedCallback(IntPtr webView, int reason, IntPtr data)
+    {
+        if (!GtkSignal.TryGetState<GtkWebViewAdapter>(data, out var adapter)
+            || adapter.ProcessTerminated is not { } handler)
+        {
+            return;
+        }
+
+        var reasonName = WebKitWebProcessTermination.GetReasonName(reason);
+        WebViewDispatcher.InvokeAsync(() =>
+        {
+            handler.Invoke(adapter, new WebViewProcessTerminatedEventArgs { Reason = reasonName });
+        });
+    }
+
     [UnmanagedCallersOnly(CallConvs = [typeof(CallConvCdecl)])]
     private static void ResourceLoadStartedCallback(IntPtr widget, IntPtr resource, IntPtr request, IntPtr data)
     {
@@ -696,6 +719,7 @@ protected virtual void DisposeSafe(bool disposing)
             Interlocked.Exchange(ref _focusOutSignal, null)?.Dispose();
             Interlocked.Exchange(ref _scriptMessageReceivedSignal, null)?.Dispose();
             Interlocked.Exchange(ref _resourceLoadStarted, null)?.Dispose();
+            Interlocked.Exchange(ref _processTerminatedSignal, null)?.Dispose();
         }
 
         var webView = Interlocked.Exchange(ref _webViewHandle, IntPtr.Zero);

src/Avalonia.Controls.WebView.Core/IWebViewAdapter.cs

@@ -100,6 +100,14 @@ public class WebViewNavigationEventArgs : EventArgs
     public Uri? Request { get; init; }
 }
 
+public sealed class WebViewProcessTerminatedEventArgs : EventArgs
+{
+    /// <summary>
+    /// Platform-specific detail about the web content process termination, or null if the platform doesn't provide one.
+    /// </summary>
+    public string? Reason { get; init; }
+}
+
 public sealed class WebViewNavigationCompletedEventArgs : WebViewNavigationEventArgs
 {
     public bool IsSuccess { get; init; } = true;
@@ -390,6 +398,21 @@ internal interface IWebViewAdapterWithInputRedirect : IWebViewAdapter
     event Action<RoutedEventArgs> Input;
 }
 
+internal interface IWebViewAdapterWithProcessTermination : IWebViewAdapter
+{
+    /// <summary>
+    ///     ProcessTerminated dispatches when the web content process backing the webview is gone,
+    ///     for example after a crash or when the operating system reclaims its memory.
+    ///     The event is not raised for recoverable conditions, such as process unresponsiveness,
+    ///     nor when only subframe processes exit and the top-level document survives.
+    /// </summary>
+    /// <remarks>
+    ///     Raised by the WebView2, WKWebView, WebKitGTK and WPE WebKit adapters.
+    ///     The headless, browser and Android adapters do not raise it.
+    /// </remarks>
+    event EventHandler<WebViewProcessTerminatedEventArgs>? ProcessTerminated;
+}
+
 internal interface IWebViewAdapterWithCommands
 {
     void Copy();

src/Avalonia.Controls.WebView.Core/Linux/WpeWebViewAdapter.cs

@@ -21,6 +21,7 @@ internal sealed unsafe class WpeWebViewAdapter
       IWebViewAdapterWithCookieManager,
       IWebViewAdapterWithVisibility,
       IWebViewAdapterWithGpuSurface,
+      IWebViewAdapterWithProcessTermination,
       ILinuxWpePlatformHandle
 {
     private IntPtr _webView;
@@ -35,6 +36,7 @@ internal sealed unsafe class WpeWebViewAdapter
 
     // Pin callback delegates to prevent GC
     private readonly GSignalCallback _loadChangedCallback;
+    private readonly GSignalCallback _processTerminatedCallback;
     private readonly GSignalDecidePolicyCallback _decidePolicyCallback;
     private readonly GSignalCreateCallback _createCallback;
     private readonly GSignalScriptMessageCallback _scriptMessageCallback;
@@ -45,6 +47,7 @@ private WpeWebViewAdapter()
     {
         // Pin callbacks as instance fields
         _loadChangedCallback = OnLoadChanged;
+        _processTerminatedCallback = OnProcessTerminated;
         _decidePolicyCallback = OnDecidePolicy;
         _createCallback = OnCreate;
         _scriptMessageCallback = OnScriptMessageReceived;
@@ -149,6 +152,7 @@ private void Initialize(LinuxWpeWebViewEnvironmentRequestedEventArgs args, Contr
         ConnectSignal(_webView, "load-failed", Marshal.GetFunctionPointerForDelegate(_loadFailedCallback), selfPtr);
         ConnectSignal(_webView, "decide-policy", Marshal.GetFunctionPointerForDelegate(_decidePolicyCallback), selfPtr);
         ConnectSignal(_webView, "create", Marshal.GetFunctionPointerForDelegate(_createCallback), selfPtr);
+        ConnectSignal(_webView, "web-process-terminated", Marshal.GetFunctionPointerForDelegate(_processTerminatedCallback), selfPtr);
 
         // 4. Register the message handler, connecting before registering so that no message can arrive unhandled.
         ConnectSignal(_userContentManager, $"script-message-received::{WebViewHelper.PostAvWebViewMessageName}",
@@ -228,6 +232,15 @@ private static int OnLoadFailed(IntPtr webView, int loadEvent, IntPtr failingUri
         return 0; // FALSE = don't suppress default handling
     }
 
+    private static void OnProcessTerminated(IntPtr webView, int reason, IntPtr userData)
+    {
+        var adapter = (WpeWebViewAdapter)GCHandle.FromIntPtr(userData).Target!;
+        adapter.ProcessTerminated?.Invoke(adapter, new WebViewProcessTerminatedEventArgs
+        {
+            Reason = WebKitWebProcessTermination.GetReasonName(reason)
+        });
+    }
+
     // WebKitPolicyDecisionType
     private const int WEBKIT_POLICY_DECISION_TYPE_NAVIGATION_ACTION = 0;
     private const int WEBKIT_POLICY_DECISION_TYPE_NEW_WINDOW_ACTION = 1;
@@ -724,6 +737,7 @@ private static void OnGetAllCookiesFinished(IntPtr sourceObject, IntPtr result,
     public event EventHandler<WebViewNewWindowRequestedEventArgs>? NewWindowRequested;
     public event EventHandler<WebMessageReceivedEventArgs>? WebMessageReceived;
     public event EventHandler<WebResourceRequestedEventArgs>? WebResourceRequested;
+    public event EventHandler<WebViewProcessTerminatedEventArgs>? ProcessTerminated;
 
     // --- Static info ---
 

src/Avalonia.Controls.WebView.Core/Macios/Interop/WebKit/WKNavigationDelegate.cs

@@ -13,23 +13,29 @@ internal unsafe class WKNavigationDelegate : NSManagedObjectBase
         s_willPresentNotification = &OnDidFinishNavigation;
     private static readonly delegate* unmanaged[Cdecl]<IntPtr, IntPtr, IntPtr, IntPtr, IntPtr, void>
         s_decidePolicyForNavigationAction = &OnDecidePolicyForNavigationAction;
+    private static readonly delegate* unmanaged[Cdecl]<IntPtr, IntPtr, IntPtr, void>
+        s_webContentProcessDidTerminate = &OnWebContentProcessDidTerminate;
 
     static WKNavigationDelegate()
     {
         var delegateClass = AllocateClassPair("ManagedWKNavigationDelegate");
 
         var willPresentNotificationSel = Libobjc.sel_getUid("webView:didFinishNavigation:");
         var didReceiveNotificationResponse = Libobjc.sel_getUid("webView:decidePolicyForNavigationAction:decisionHandler:");
+        var webContentProcessDidTerminateSel = Libobjc.sel_getUid("webViewWebContentProcessDidTerminate:");
 
         // All WKNavigationDelegate methods are optional.
         AddProtocol(delegateClass, "WKNavigationDelegate",
             new ProtocolMethod(willPresentNotificationSel, "v@:@@", false),
-            new ProtocolMethod(didReceiveNotificationResponse, "v@:@@@?", false));
+            new ProtocolMethod(didReceiveNotificationResponse, "v@:@@@?", false),
+            new ProtocolMethod(webContentProcessDidTerminateSel, "v@:@", false));
 
         AddMethod(delegateClass, willPresentNotificationSel, new IntPtr(s_willPresentNotification), "v@:@@");
 
         AddMethod(delegateClass, didReceiveNotificationResponse, new IntPtr(s_decidePolicyForNavigationAction), "v@:@@@");
 
+        AddMethod(delegateClass, webContentProcessDidTerminateSel, new IntPtr(s_webContentProcessDidTerminate), "v@:@");
+
         RegisterManagedMembers(delegateClass);
 
         Libobjc.objc_registerClassPair(delegateClass);
@@ -43,6 +49,7 @@ public WKNavigationDelegate() : base(s_class)
 
     public event EventHandler? DidFinishNavigation;
     public event EventHandler<DecidePolicyNavigationEventArgs>? DecidePolicyNavigation;
+    public event EventHandler? WebContentProcessDidTerminate;
 
     [UnmanagedCallersOnly(CallConvs = [typeof(CallConvCdecl)])]
     private static void OnDidFinishNavigation(IntPtr self, IntPtr sel, IntPtr webView, IntPtr navigation)
@@ -51,6 +58,13 @@ private static void OnDidFinishNavigation(IntPtr self, IntPtr sel, IntPtr webVie
         managed?.DidFinishNavigation?.Invoke(managed, EventArgs.Empty);
     }
 
+    [UnmanagedCallersOnly(CallConvs = [typeof(CallConvCdecl)])]
+    private static void OnWebContentProcessDidTerminate(IntPtr self, IntPtr sel, IntPtr webView)
+    {
+        var managed = ReadManagedSelf<WKNavigationDelegate>(self);
+        managed?.WebContentProcessDidTerminate?.Invoke(managed, EventArgs.Empty);
+    }
+
     private static readonly IntPtr s_actionRequest = Libobjc.sel_getUid("request");
     private static readonly IntPtr s_navigationType = Libobjc.sel_getUid("navigationType");
     private static readonly IntPtr s_targetFrame = Libobjc.sel_getUid("targetFrame");

src/Avalonia.Controls.WebView.Core/Macios/MaciosWebViewAdapter.cs

@@ -19,7 +19,8 @@ namespace Avalonia.Controls.Macios;
 [SupportedOSPlatform("macos")]
 [SupportedOSPlatform("ios")]
 internal class MaciosWebViewAdapter : IWebViewAdapterWithFocus, IWebViewAdapterWithInputRedirect,
-    IWebViewAdapterWithCookieManager, IWebViewAdapterWithCommands, IWebViewWithPrint, IAppleWKWebViewPlatformHandle
+    IWebViewAdapterWithCookieManager, IWebViewAdapterWithCommands, IWebViewAdapterWithProcessTermination,
+    IWebViewWithPrint, IAppleWKWebViewPlatformHandle
 {
     private readonly string _scriptHandlerMessageName;
     private readonly NSString _scriptHandlerMessageNameNative;
@@ -79,6 +80,7 @@ public MaciosWebViewAdapter(AppleWKWebViewEnvironmentRequestedEventArgs options)
         _navDelegate = new WKNavigationDelegate();
         _navDelegate.DidFinishNavigation += OnDelegateOnDidFinishNavigation;
         _navDelegate.DecidePolicyNavigation += OnDelegateOnDecidePolicyNavigation;
+        _navDelegate.WebContentProcessDidTerminate += OnDelegateOnWebContentProcessDidTerminate;
 
         _webView = new WKWebView(_config);
         // The view is released explicitly in ReleaseWebView, never by the wrapper.
@@ -177,6 +179,7 @@ public Color DefaultBackground
     public event EventHandler<WebResourceRequestedEventArgs>? WebResourceRequested;
     public event EventHandler? GotFocus;
     public event EventHandler<IWebViewAdapterWithFocus.LostFocusDirection>? LostFocus;
+    public event EventHandler<WebViewProcessTerminatedEventArgs>? ProcessTerminated;
     public event Action<RoutedEventArgs>? Input;
     public bool GoBack() => _webView.GoBack() != default;
     public bool GoForward() => _webView.GoForward() != default;
@@ -229,6 +232,7 @@ public void Dispose()
         _scriptHandler.DidReceiveScriptMessage -= OnScriptHandlerOnDidReceiveScriptMessage;
         _navDelegate.DidFinishNavigation -= OnDelegateOnDidFinishNavigation;
         _navDelegate.DecidePolicyNavigation -= OnDelegateOnDecidePolicyNavigation;
+        _navDelegate.WebContentProcessDidTerminate -= OnDelegateOnWebContentProcessDidTerminate;
         _webView.PerformKeyEquivalent -= WebViewOnPerformKeyEquivalent;
         _webView.BecomeFirstResponder -= OnWebViewOnBecomeFirstResponder;
         _webView.ResignFirstResponder -= OnWebViewOnResignFirstResponder;
@@ -327,6 +331,12 @@ private void OnDelegateOnDidFinishNavigation(object? sender, EventArgs args)
         NavigationCompleted?.Invoke(this, new WebViewNavigationCompletedEventArgs { Request = Uri.TryCreate(url!.AbsoluteString, UriKind.Absolute, out var uri) ? uri : null, IsSuccess = true });
     }
 
+    private void OnDelegateOnWebContentProcessDidTerminate(object? sender, EventArgs args)
+    {
+        // WKWebView doesn't report a termination reason.
+        ProcessTerminated?.Invoke(this, new WebViewProcessTerminatedEventArgs { Reason = null });
+    }
+
     private void OnWebViewOnResignFirstResponder(object? o, EventArgs eventArgs)
     {
         LostFocus?.Invoke(this, IWebViewAdapterWithFocus.LostFocusDirection.Unknown);

src/Avalonia.Controls.WebView.Core/WebKitWebProcessTermination.cs

@@ -0,0 +1,23 @@
+namespace Avalonia.Controls;
+
+/// <summary>
+/// Maps <c>WebKitWebProcessTerminationReason</c> values, shared by the WebKitGTK and WPE WebKit ports.
+/// </summary>
+internal static class WebKitWebProcessTermination
+{
+    // WebKitWebProcessTerminationReason
+    private enum Reason
+    {
+        Crashed = 0,
+        ExceededMemoryLimit = 1,
+        TerminatedByApi = 2
+    }
+
+    internal static string GetReasonName(int reason) => reason switch
+    {
+        (int)Reason.Crashed => "Crashed",
+        (int)Reason.ExceededMemoryLimit => "ExceededMemoryLimit",
+        (int)Reason.TerminatedByApi => "TerminatedByApi",
+        _ => $"Unknown({reason})"
+    };
+}

src/Avalonia.Controls.WebView.Core/Win/WebView2/Interop/ICoreWebView2.cs

@@ -45,7 +45,7 @@ internal partial interface ICoreWebView2
     void add_PermissionRequested([MarshalAs(UnmanagedType.Interface)] IntPtr eventHandler, out EventRegistrationToken token);
     void remove_PermissionRequested(EventRegistrationToken token);
 
-    void add_ProcessFailed([MarshalAs(UnmanagedType.Interface)] IntPtr eventHandler, out EventRegistrationToken token);
+    void add_ProcessFailed([MarshalAs(UnmanagedType.Interface)] ICoreWebView2ProcessFailedEventHandler eventHandler, out EventRegistrationToken token);
     void remove_ProcessFailed(EventRegistrationToken token);
 
     void AddScriptToExecuteOnDocumentCreated([MarshalAs(UnmanagedType.LPWStr)] string javaScript, [MarshalAs(UnmanagedType.Interface)] ICoreWebView2AddScriptToExecuteOnDocumentCreatedCompletedHandler handler);

src/Avalonia.Controls.WebView.Core/Win/WebView2/Interop/ICoreWebView2ProcessFailedEventHandler.cs

@@ -0,0 +1,32 @@
+using System.Runtime.InteropServices;
+using System.Runtime.InteropServices.Marshalling;
+
+namespace Avalonia.Controls.Win.WebView2.Interop;
+
+internal enum COREWEBVIEW2_PROCESS_FAILED_KIND
+{
+    COREWEBVIEW2_PROCESS_FAILED_KIND_BROWSER_PROCESS_EXITED,
+    COREWEBVIEW2_PROCESS_FAILED_KIND_RENDER_PROCESS_EXITED,
+    COREWEBVIEW2_PROCESS_FAILED_KIND_RENDER_PROCESS_UNRESPONSIVE,
+    COREWEBVIEW2_PROCESS_FAILED_KIND_FRAME_RENDER_PROCESS_EXITED,
+    COREWEBVIEW2_PROCESS_FAILED_KIND_UTILITY_PROCESS_EXITED,
+    COREWEBVIEW2_PROCESS_FAILED_KIND_SANDBOX_HELPER_PROCESS_EXITED,
+    COREWEBVIEW2_PROCESS_FAILED_KIND_GPU_PROCESS_EXITED,
+    COREWEBVIEW2_PROCESS_FAILED_KIND_PPAPI_PLUGIN_PROCESS_EXITED,
+    COREWEBVIEW2_PROCESS_FAILED_KIND_PPAPI_BROKER_PROCESS_EXITED,
+    COREWEBVIEW2_PROCESS_FAILED_KIND_UNKNOWN_PROCESS_EXITED
+}
+
+[GeneratedComInterface(Options = ComInterfaceOptions.ComObjectWrapper)]
+[Guid("8155A9A4-1474-4A86-8CAE-151B0FA6B8CA")]
+internal partial interface ICoreWebView2ProcessFailedEventArgs
+{
+    COREWEBVIEW2_PROCESS_FAILED_KIND GetProcessFailedKind();
+}
+
+[GeneratedComInterface(Options = ComInterfaceOptions.ManagedObjectWrapper)]
+[Guid("79E0AEA4-990B-42D9-AA1D-0FCC2E5BC7F1")]
+internal partial interface ICoreWebView2ProcessFailedEventHandler
+{
+    void Invoke([MarshalAs(UnmanagedType.Interface)] ICoreWebView2 sender, [MarshalAs(UnmanagedType.Interface)] ICoreWebView2ProcessFailedEventArgs args);
+}

src/Avalonia.Controls.WebView.Core/Win/WebView2/WebView2BaseAdapter.cs

@@ -17,7 +17,8 @@ namespace Avalonia.Controls.Win.WebView2;
 
 [SupportedOSPlatform("windows6.1")] // win7
 internal abstract partial class WebView2BaseAdapter(ICoreWebView2Controller controller)
-    : IWebViewAdapterWithCookieManager, IWebViewAdapterWithFocus, IWindowsWebView2PlatformHandle, IWebViewWithPrintWithOptions
+    : IWebViewAdapterWithCookieManager, IWebViewAdapterWithFocus, IWebViewAdapterWithProcessTermination,
+    IWindowsWebView2PlatformHandle, IWebViewWithPrintWithOptions
 {
     private EventHandler<WebResourceRequestedEventArgs>? _webResourceRequested;
     private Action? _subscriptions;
@@ -86,6 +87,7 @@ public event EventHandler<WebResourceRequestedEventArgs>? WebResourceRequested
 
     public event EventHandler? GotFocus;
     public event EventHandler<IWebViewAdapterWithFocus.LostFocusDirection>? LostFocus;
+    public event EventHandler<WebViewProcessTerminatedEventArgs>? ProcessTerminated;
 
     public Color DefaultBackground
     {
@@ -291,6 +293,7 @@ private static class HResult
     internal EventHandler<WebViewNewWindowRequestedEventArgs>? GetNewWindowRequested() => NewWindowRequested;
     internal EventHandler? GetGotFocus() => GotFocus;
     internal EventHandler<IWebViewAdapterWithFocus.LostFocusDirection>? GetLostFocus() => LostFocus;
+    internal EventHandler<WebViewProcessTerminatedEventArgs>? GetProcessTerminated() => ProcessTerminated;
 
     public async Task InitializeAsync(WindowsWebView2EnvironmentRequestedEventArgs environmentArgs)
     {
@@ -344,6 +347,7 @@ private Action AddHandlers(ICoreWebView2 webView)
         webView.add_WebMessageReceived(callbacks, out var webMessageReceivedToken);
         webView.add_WebResourceRequested(callbacks, out var webResourceRequestedToken);
         webView.add_NewWindowRequested(callbacks, out var newWindowRequestedToken);
+        webView.add_ProcessFailed(callbacks, out var processFailedToken);
         controller.add_MoveFocusRequested(callbacks, out var moveFocusRequestedToken);
         controller.add_GotFocus(callbacks, out var gotFocusToken);
         RegisterCallbacks(callbacks);
@@ -355,6 +359,7 @@ private Action AddHandlers(ICoreWebView2 webView)
             webView.remove_WebMessageReceived(webMessageReceivedToken);
             webView.remove_WebResourceRequested(webResourceRequestedToken);
             webView.remove_NewWindowRequested(newWindowRequestedToken);
+            webView.remove_ProcessFailed(processFailedToken);
             controller.remove_MoveFocusRequested(moveFocusRequestedToken);
             controller.remove_GotFocus(gotFocusToken);
             UnregisterCallbacks();