From 970854886ac7827cb4c8f6f8700edfc6accff6d9 Mon Sep 17 00:00:00 2001 From: Jonathan Peppers Date: Thu, 27 Jan 2022 10:22:15 -0600 Subject: [PATCH] [Mono.Android] Marshal exceptions in RegisterNativeMembers() (#6672) MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Context: https://github.com/dotnet/maui/issues/4262 Context: https://github.com/xamarin/xamarin-android/pull/6675 If you run the `maui-blazor` template in a Release build: dotnet build -t:Run -c Release it crashes at runtime: D monodroid-assembly: typemap: type with token 33555274 (0x200034a) in module {C7B4CC8F-7A03-4A3F-A34A-DC66EDC548B9} (Mono.Android) corresponds to Java type 'android/runtime/JavaProxyThrowable' … F DEBUG : backtrace: F DEBUG : #00 pc 000000000065d8fc /apex/com.android.art/lib64/libart.so (void art::StackVisitor::WalkStack<(art::StackVisitor::CountTransitions)0>(bool)+156) (BuildId: 7fbaf2a1a3317bd634b00eb90e32291e) F DEBUG : #01 pc 000000000069b25d /apex/com.android.art/lib64/libart.so (art::Thread::GetCurrentMethod(unsigned int*, bool, bool) const+157) (BuildId: 7fbaf2a1a3317bd634b00eb90e32291e) F DEBUG : #02 pc 0000000000430fed /apex/com.android.art/lib64/libart.so (art::JNI::FindClass(_JNIEnv*, char const*)+765) (BuildId: 7fbaf2a1a3317bd634b00eb90e32291e) F DEBUG : #03 pc 0000000000047e5a /data/app/~~0Qm6D1S0sO3f1lwfakN0PA==/com.companyname.mauiapp2-08UokVCH5k_PlbZEH_hhkA==/split_config.x86_64.apk!libmono-android.release.so (offset 0x11e000) (java_interop_jnienv_find_class+26) (BuildId: 3d04f8b946590175e97b89aee2e3b19ceed4b524) F DEBUG : #04 pc 00000000000128ac The crash can be avoided by disabling the linker: dotnet build -t:Run -c Release -p:AndroidLinkMode=None # -or- dotnet build -t:Run -c Release -p:PublishTrimmed=false However, let us return to the crash: *why* is it crashing? This isn't a "good debugging experience"; we have no useful context. Lots of investigation later -- all hail printf debugging -- and we found that the cause of the crash was an unhandled exception: 1. `Mono.Android.dll` has it's Java Callable Wrappers generated from the *unlinked* assembly, into `mono.android.jar` and `mono.android.dex` files. The Java Callable Wrapper for `Android.Runtime.InputStreamAdapter` thus includes *all* `Read()` method overloads. 2. When the app is built in Release configuration, linking is enabled, and *some* of the `InputStreamAdapter.Read()` methods are removed by the linker, along with the `Java.IO.InputStream.Read()` methods that were overridden. 3. At runtime, we perform [Java Type Registration][0] for the `Android.Runtime.InputStreamAdapter` type, which eventually calls `AndroidTypeManager.RegisterNativeMembers()`, which eventually attempts to *effectively* do: Delegate.CreateDelegate ( typeof(Func), typeof(InputStreamAdapter), "GetReadHandler"); 4. Because of (2), `Java.IO.InputStream.GetReadHandler()` *does not exist*, and thus `Delegate.CreateDelegate()` throws an `ArgumentException`. So far, so reasonable, but… 5. `AndroidTypeManager.RegisterNativeMembers()` didn't catch any exceptions, nor did any other method between the original Java `Runtime.register()` invocation and `AndroidTypeManager.RegisterNativeMembers()`. The result is that a C# exception was "in flight", and Mono then proceeded to *tear down the stack frame* as it unwound the callstack looking for `catch` handlers. At this point, the process is toast: the runtime stack is FUBAR. This is also why the `backtrace:` is "rooted" in `JNIEnv::FindClass()`: `JNIEnv::FindClass()` invokes Java static constructors before returning, which is how the static constructor in the Java Callable Wrapper for `InputStreamAdapter` called `Runtime.register()` in the first place. All of this makes for a miserable debugging experience. Fixing the "original" linker issue will be done in xamarin/xamarin-android#6675. This hasn't been an issue in "Classic" Xamarin.Android, presumably because the classic linker isn't as good as the net6 linker. What we want to do *here* is improve this debugging experience, by "wrapping" `AndroidTypeManager.RegisterNativeMembers()` in a `try`/`catch` block, which can then *marshal the thrown exception* back to Java. This *prevents* Mono from unwinding the callstack past a JNI boundary, and avoids the annoying-to-debug app crash. After this change, we get a much friendlier unhandled exception crash: I MonoDroid: Android.Runtime.JavaProxyThrowable: Exception_WasThrown, Android.Runtime.JavaProxyThrowable I MonoDroid: I MonoDroid: --- End of managed Android.Runtime.JavaProxyThrowable stack trace --- I MonoDroid: android.runtime.JavaProxyThrowable: System.ArgumentException: Arg_DlgtTargMeth I MonoDroid: at System.Delegate.CreateDelegate(Type , Type , String , Boolean , Boolean ) I MonoDroid: at System.Delegate.CreateDelegate(Type , Type , String ) I MonoDroid: at Android.Runtime.AndroidTypeManager.RegisterNativeMembers(JniType , Type , String ) I MonoDroid: --- End of stack trace from previous location --- I MonoDroid: at Java.Interop.JniEnvironment.StaticMethods.CallStaticObjectMethod(JniObjectReference , JniMethodInfo , JniArgumentValue* ) I MonoDroid: at Android.Runtime.JNIEnv.CallStaticObjectMethod(IntPtr , IntPtr , JValue* ) I MonoDroid: at Android.Runtime.JNIEnv.CallStaticObjectMethod(IntPtr , IntPtr , JValue[] ) I MonoDroid: at Android.Runtime.JNIEnv.FindClass(String ) I MonoDroid: at Android.Runtime.JNIEnv.AllocObject(String ) I MonoDroid: at Android.Runtime.JNIEnv.StartCreateInstance(String , String , JValue* ) I MonoDroid: at Android.Runtime.JNIEnv.StartCreateInstance(String , String , JValue[] ) I MonoDroid: at Android.Runtime.InputStreamAdapter..ctor(Stream ) I MonoDroid: at Android.Runtime.InputStreamAdapter.ToLocalJniHandle(Stream ) I MonoDroid: at Android.Webkit.WebResourceResponse..ctor(String , String , Int32 , String , IDictionary`2 , Stream ) I MonoDroid: at Microsoft.AspNetCore.Components.WebView.Maui.WebKitWebViewClient.ShouldInterceptRequest(WebView view, IWebResourceRequest request) I MonoDroid: at Android.Webkit.WebViewClient.n_ShouldInterceptRequest_Landroid_webkit_WebView_Landroid_webkit_WebResourceRequest_(IntPtr , IntPtr , IntPtr , IntPtr ) I MonoDroid: at crc64d693e2d9159537db.WebKitWebViewClient.n_shouldInterceptRequest(Native Method) I MonoDroid: at crc64d693e2d9159537db.WebKitWebViewClient.shouldInterceptRequest(WebKitWebViewClient.java:39) I MonoDroid: at Rr.a(chromium-TrichromeWebViewGoogle.apk-stable-410410686:16) I MonoDroid: at org.chromium.android_webview.AwContentsBackgroundThreadClient.shouldInterceptRequestFromNative(chromium-TrichromeWebViewGoogle.apk-stable-410410686:2) I MonoDroid: I MonoDroid: --- End of managed Android.Runtime.JavaProxyThrowable stack trace --- I MonoDroid: android.runtime.JavaProxyThrowable: System.ArgumentException: Arg_DlgtTargMeth I MonoDroid: at System.Delegate.CreateDelegate(Type , Type , String , Boolean , Boolean ) I MonoDroid: at System.Delegate.CreateDelegate(Type , Type , String ) I MonoDroid: at Android.Runtime.AndroidTypeManager.RegisterNativeMembers(JniType , Type , String ) I MonoDroid: --- End of stack trace from previous location --- I MonoDroid: at Java.Interop.JniEnvironment.StaticMethods.CallStaticObjectMethod(JniObjectReference , JniMethodInfo , JniArgumentValue* ) I MonoDroid: at Android.Runtime.JNIEnv.CallStaticObjectMethod(IntPtr , IntPtr , JValue* ) I MonoDroid: at Android.Runtime.JNIEnv.CallStaticObjectMethod(IntPtr , IntPtr , JValue[] ) I MonoDroid: at Android.Runtime.JNIEnv.FindClass(String ) I MonoDroid: at Android.Runtime.JNIEnv.AllocObject(String ) I MonoDroid: at Android.Runtime.JNIEnv.StartCreateInstance(String , String , JValue* ) I MonoDroid: at Android.Runtime.JNIEnv.StartCreateInstance(String , String , JValue[] ) I MonoDroid: at Android.Runtime.InputStreamAdapter..ctor(Stream ) I MonoDroid: at Android.Runtime.InputStreamAdapter.ToLocalJniHandle(Stream ) I MonoDroid: at Android.Webkit.WebResourceResponse..ctor(String , String , Int32 , String , IDictionary`2 , Stream ) I MonoDroid: at Microsoft.AspNetCore.Components.WebView.Maui.WebKitWebViewClient.ShouldInterceptRequest(WebView view, IWebResourceRequest request) I MonoDroid: at Android.Webkit.WebViewClient.n_ShouldInterceptRequest_Landroid_webkit_WebView_Landroid_webkit_WebResourceRequest_(IntPtr , IntPtr , IntPtr , IntPtr ) I MonoDroid: at crc64d693e2d9159537db.WebKitWebViewClient.n_shouldInterceptRequest(Native Method) I MonoDroid: at crc64d693e2d9159537db.WebKitWebViewClient.shouldInterceptRequest(WebKitWebViewClient.java:39) I MonoDroid: at Rr.a(chromium-TrichromeWebViewGoogle.apk-stable-410410686:16) I MonoDroid: at org.chromium.android_webview.AwContentsBackgroundThreadClient.shouldInterceptRequestFromNative(chromium-TrichromeWebViewGoogle.apk-stable-410410686:2) This is much easier to reason about, and will save us time in the future. [0]: https://github.com/xamarin/xamarin-android/wiki/Blueprint#java-type-registration --- .../Android.Runtime/AndroidRuntime.cs | 92 ++++++++++--------- 1 file changed, 48 insertions(+), 44 deletions(-) diff --git a/src/Mono.Android/Android.Runtime/AndroidRuntime.cs b/src/Mono.Android/Android.Runtime/AndroidRuntime.cs index e57ec864cbb..7269bd08b37 100644 --- a/src/Mono.Android/Android.Runtime/AndroidRuntime.cs +++ b/src/Mono.Android/Android.Runtime/AndroidRuntime.cs @@ -378,57 +378,61 @@ static bool CallRegisterMethodByIndex (JniNativeMethodRegistrationArguments argu public override void RegisterNativeMembers (JniType nativeClass, Type type, string? methods) { - if (FastRegisterNativeMembers (nativeClass, type, methods)) - return; + try { + if (FastRegisterNativeMembers (nativeClass, type, methods)) + return; - if (string.IsNullOrEmpty (methods)) { - if (jniAddNativeMethodRegistrationAttributePresent) - base.RegisterNativeMembers (nativeClass, type, methods); - return; - } + if (string.IsNullOrEmpty (methods)) { + if (jniAddNativeMethodRegistrationAttributePresent) + base.RegisterNativeMembers (nativeClass, type, methods); + return; + } - string[] members = methods!.Split ('\n'); - if (members.Length < 2) { - if (jniAddNativeMethodRegistrationAttributePresent) - base.RegisterNativeMembers (nativeClass, type, methods); - return; - } + string[] members = methods!.Split ('\n'); + if (members.Length < 2) { + if (jniAddNativeMethodRegistrationAttributePresent) + base.RegisterNativeMembers (nativeClass, type, methods); + return; + } - JniNativeMethodRegistration[] natives = new JniNativeMethodRegistration [members.Length-1]; - for (int i = 0; i < members.Length; ++i) { - string method = members [i]; - if (string.IsNullOrEmpty (method)) - continue; - string[] toks = members [i].Split (new[]{':'}, 4); - Delegate callback; - if (toks [2] == "__export__") { - var mname = toks [0].Substring (2); - MethodInfo? minfo = null; - foreach (var mi in type.GetMethods (BindingFlags.Public | BindingFlags.NonPublic | BindingFlags.Instance | BindingFlags.Static)) - if (mi.Name == mname && JavaNativeTypeManager.GetJniSignature (mi) == toks [1]) { - minfo = mi; - break; + JniNativeMethodRegistration[] natives = new JniNativeMethodRegistration [members.Length-1]; + for (int i = 0; i < members.Length; ++i) { + string method = members [i]; + if (string.IsNullOrEmpty (method)) + continue; + string[] toks = members [i].Split (new[]{':'}, 4); + Delegate callback; + if (toks [2] == "__export__") { + var mname = toks [0].Substring (2); + MethodInfo? minfo = null; + foreach (var mi in type.GetMethods (BindingFlags.Public | BindingFlags.NonPublic | BindingFlags.Instance | BindingFlags.Static)) + if (mi.Name == mname && JavaNativeTypeManager.GetJniSignature (mi) == toks [1]) { + minfo = mi; + break; + } + + if (minfo == null) + throw new InvalidOperationException (String.Format ("Specified managed method '{0}' was not found. Signature: {1}", mname, toks [1])); + callback = CreateDynamicCallback (minfo); + } else { + Type callbackDeclaringType = type; + if (toks.Length == 4) { + callbackDeclaringType = Type.GetType (toks [3], throwOnError: true)!; } - - if (minfo == null) - throw new InvalidOperationException (String.Format ("Specified managed method '{0}' was not found. Signature: {1}", mname, toks [1])); - callback = CreateDynamicCallback (minfo); - } else { - Type callbackDeclaringType = type; - if (toks.Length == 4) { - callbackDeclaringType = Type.GetType (toks [3], throwOnError: true)!; - } - while (callbackDeclaringType.ContainsGenericParameters) { - callbackDeclaringType = callbackDeclaringType.BaseType!; + while (callbackDeclaringType.ContainsGenericParameters) { + callbackDeclaringType = callbackDeclaringType.BaseType!; + } + GetCallbackHandler connector = (GetCallbackHandler) Delegate.CreateDelegate (typeof (GetCallbackHandler), + callbackDeclaringType, toks [2]); + callback = connector (); } - GetCallbackHandler connector = (GetCallbackHandler) Delegate.CreateDelegate (typeof (GetCallbackHandler), - callbackDeclaringType, toks [2]); - callback = connector (); + natives [i] = new JniNativeMethodRegistration (toks [0], toks [1], callback); } - natives [i] = new JniNativeMethodRegistration (toks [0], toks [1], callback); - } - JniEnvironment.Types.RegisterNatives (nativeClass.PeerReference, natives, natives.Length); + JniEnvironment.Types.RegisterNatives (nativeClass.PeerReference, natives, natives.Length); + } catch (Exception e) { + JniEnvironment.Runtime.RaisePendingException (e); + } } }