Implement support for exception marshaling.

Xamarin.iOS.sln

@@ -11,6 +11,10 @@ Project("{2150E333-8FDC-42A3-9474-1A3956D46DE8}") = "Tests", "Tests", "{2BFA13F8
 EndProject
 Project("{FAE04EC0-301F-11D3-BF4B-00C04F79EFBC}") = "introspection-ios", "tests\introspection\iOS\introspection-ios.csproj", "{208744BD-504E-47D7-9A98-1CF02454A6DA}"
 EndProject
+Project("{FAE04EC0-301F-11D3-BF4B-00C04F79EFBC}") = "libmonotouch", "runtime\libmonotouch.csproj", "{8A5B637C-E4FF-4145-B887-9347020100F4}"
+EndProject
+Project("{FAE04EC0-301F-11D3-BF4B-00C04F79EFBC}") = "xamios", "src\xamios.csproj", "{E1F334C3-8F77-46C9-A28B-A8E9BAEA9FE5}"
+EndProject
 Global
 	GlobalSection(SolutionConfigurationPlatforms) = preSolution
 		Debug|Any CPU = Debug|Any CPU
@@ -168,6 +172,74 @@ Global
 		{208744BD-504E-47D7-9A98-1CF02454A6DA}.Release|iPhone.Build.0 = Release|iPhone
 		{208744BD-504E-47D7-9A98-1CF02454A6DA}.DebugStaticRegistrar|iPhone.ActiveCfg = DebugStaticRegistrar|iPhone
 		{208744BD-504E-47D7-9A98-1CF02454A6DA}.DebugStaticRegistrar|iPhone.Build.0 = DebugStaticRegistrar|iPhone
+		{8A5B637C-E4FF-4145-B887-9347020100F4}.Debug|Any CPU.ActiveCfg = Debug|Any CPU
+		{8A5B637C-E4FF-4145-B887-9347020100F4}.Debug|Any CPU.Build.0 = Debug|Any CPU
+		{8A5B637C-E4FF-4145-B887-9347020100F4}.Release|Any CPU.ActiveCfg = Release|Any CPU
+		{8A5B637C-E4FF-4145-B887-9347020100F4}.Release|Any CPU.Build.0 = Release|Any CPU
+		{8A5B637C-E4FF-4145-B887-9347020100F4}.net_2_0_Debug|Any CPU.ActiveCfg = Debug|Any CPU
+		{8A5B637C-E4FF-4145-B887-9347020100F4}.net_2_0_Debug|Any CPU.Build.0 = Debug|Any CPU
+		{8A5B637C-E4FF-4145-B887-9347020100F4}.net_2_0_Release|Any CPU.ActiveCfg = Debug|Any CPU
+		{8A5B637C-E4FF-4145-B887-9347020100F4}.net_2_0_Release|Any CPU.Build.0 = Debug|Any CPU
+		{8A5B637C-E4FF-4145-B887-9347020100F4}.net_3_5_Debug|Any CPU.ActiveCfg = Debug|Any CPU
+		{8A5B637C-E4FF-4145-B887-9347020100F4}.net_3_5_Debug|Any CPU.Build.0 = Debug|Any CPU
+		{8A5B637C-E4FF-4145-B887-9347020100F4}.net_3_5_Release|Any CPU.ActiveCfg = Debug|Any CPU
+		{8A5B637C-E4FF-4145-B887-9347020100F4}.net_3_5_Release|Any CPU.Build.0 = Debug|Any CPU
+		{8A5B637C-E4FF-4145-B887-9347020100F4}.net_4_0_Debug|Any CPU.ActiveCfg = Debug|Any CPU
+		{8A5B637C-E4FF-4145-B887-9347020100F4}.net_4_0_Debug|Any CPU.Build.0 = Debug|Any CPU
+		{8A5B637C-E4FF-4145-B887-9347020100F4}.net_4_0_Release|Any CPU.ActiveCfg = Debug|Any CPU
+		{8A5B637C-E4FF-4145-B887-9347020100F4}.net_4_0_Release|Any CPU.Build.0 = Debug|Any CPU
+		{8A5B637C-E4FF-4145-B887-9347020100F4}.silverlight_Debug|Any CPU.ActiveCfg = Debug|Any CPU
+		{8A5B637C-E4FF-4145-B887-9347020100F4}.silverlight_Debug|Any CPU.Build.0 = Debug|Any CPU
+		{8A5B637C-E4FF-4145-B887-9347020100F4}.silverlight_Release|Any CPU.ActiveCfg = Debug|Any CPU
+		{8A5B637C-E4FF-4145-B887-9347020100F4}.silverlight_Release|Any CPU.Build.0 = Debug|Any CPU
+		{8A5B637C-E4FF-4145-B887-9347020100F4}.winphone_Debug|Any CPU.ActiveCfg = Debug|Any CPU
+		{8A5B637C-E4FF-4145-B887-9347020100F4}.winphone_Debug|Any CPU.Build.0 = Debug|Any CPU
+		{8A5B637C-E4FF-4145-B887-9347020100F4}.winphone_Release|Any CPU.ActiveCfg = Debug|Any CPU
+		{8A5B637C-E4FF-4145-B887-9347020100F4}.winphone_Release|Any CPU.Build.0 = Debug|Any CPU
+		{8A5B637C-E4FF-4145-B887-9347020100F4}.Debug|iPhoneSimulator.ActiveCfg = Debug|Any CPU
+		{8A5B637C-E4FF-4145-B887-9347020100F4}.Debug|iPhoneSimulator.Build.0 = Debug|Any CPU
+		{8A5B637C-E4FF-4145-B887-9347020100F4}.Release|iPhoneSimulator.ActiveCfg = Release|Any CPU
+		{8A5B637C-E4FF-4145-B887-9347020100F4}.Release|iPhoneSimulator.Build.0 = Release|Any CPU
+		{8A5B637C-E4FF-4145-B887-9347020100F4}.Debug|iPhone.ActiveCfg = Debug|Any CPU
+		{8A5B637C-E4FF-4145-B887-9347020100F4}.Debug|iPhone.Build.0 = Debug|Any CPU
+		{8A5B637C-E4FF-4145-B887-9347020100F4}.Release|iPhone.ActiveCfg = Release|Any CPU
+		{8A5B637C-E4FF-4145-B887-9347020100F4}.Release|iPhone.Build.0 = Release|Any CPU
+		{8A5B637C-E4FF-4145-B887-9347020100F4}.DebugStaticRegistrar|iPhone.ActiveCfg = Debug|Any CPU
+		{8A5B637C-E4FF-4145-B887-9347020100F4}.DebugStaticRegistrar|iPhone.Build.0 = Debug|Any CPU
+		{E1F334C3-8F77-46C9-A28B-A8E9BAEA9FE5}.Debug|Any CPU.ActiveCfg = Debug|Any CPU
+		{E1F334C3-8F77-46C9-A28B-A8E9BAEA9FE5}.Debug|Any CPU.Build.0 = Debug|Any CPU
+		{E1F334C3-8F77-46C9-A28B-A8E9BAEA9FE5}.Release|Any CPU.ActiveCfg = Release|Any CPU
+		{E1F334C3-8F77-46C9-A28B-A8E9BAEA9FE5}.Release|Any CPU.Build.0 = Release|Any CPU
+		{E1F334C3-8F77-46C9-A28B-A8E9BAEA9FE5}.net_2_0_Debug|Any CPU.ActiveCfg = Debug|Any CPU
+		{E1F334C3-8F77-46C9-A28B-A8E9BAEA9FE5}.net_2_0_Debug|Any CPU.Build.0 = Debug|Any CPU
+		{E1F334C3-8F77-46C9-A28B-A8E9BAEA9FE5}.net_2_0_Release|Any CPU.ActiveCfg = Debug|Any CPU
+		{E1F334C3-8F77-46C9-A28B-A8E9BAEA9FE5}.net_2_0_Release|Any CPU.Build.0 = Debug|Any CPU
+		{E1F334C3-8F77-46C9-A28B-A8E9BAEA9FE5}.net_3_5_Debug|Any CPU.ActiveCfg = Debug|Any CPU
+		{E1F334C3-8F77-46C9-A28B-A8E9BAEA9FE5}.net_3_5_Debug|Any CPU.Build.0 = Debug|Any CPU
+		{E1F334C3-8F77-46C9-A28B-A8E9BAEA9FE5}.net_3_5_Release|Any CPU.ActiveCfg = Debug|Any CPU
+		{E1F334C3-8F77-46C9-A28B-A8E9BAEA9FE5}.net_3_5_Release|Any CPU.Build.0 = Debug|Any CPU
+		{E1F334C3-8F77-46C9-A28B-A8E9BAEA9FE5}.net_4_0_Debug|Any CPU.ActiveCfg = Debug|Any CPU
+		{E1F334C3-8F77-46C9-A28B-A8E9BAEA9FE5}.net_4_0_Debug|Any CPU.Build.0 = Debug|Any CPU
+		{E1F334C3-8F77-46C9-A28B-A8E9BAEA9FE5}.net_4_0_Release|Any CPU.ActiveCfg = Debug|Any CPU
+		{E1F334C3-8F77-46C9-A28B-A8E9BAEA9FE5}.net_4_0_Release|Any CPU.Build.0 = Debug|Any CPU
+		{E1F334C3-8F77-46C9-A28B-A8E9BAEA9FE5}.silverlight_Debug|Any CPU.ActiveCfg = Debug|Any CPU
+		{E1F334C3-8F77-46C9-A28B-A8E9BAEA9FE5}.silverlight_Debug|Any CPU.Build.0 = Debug|Any CPU
+		{E1F334C3-8F77-46C9-A28B-A8E9BAEA9FE5}.silverlight_Release|Any CPU.ActiveCfg = Debug|Any CPU
+		{E1F334C3-8F77-46C9-A28B-A8E9BAEA9FE5}.silverlight_Release|Any CPU.Build.0 = Debug|Any CPU
+		{E1F334C3-8F77-46C9-A28B-A8E9BAEA9FE5}.winphone_Debug|Any CPU.ActiveCfg = Debug|Any CPU
+		{E1F334C3-8F77-46C9-A28B-A8E9BAEA9FE5}.winphone_Debug|Any CPU.Build.0 = Debug|Any CPU
+		{E1F334C3-8F77-46C9-A28B-A8E9BAEA9FE5}.winphone_Release|Any CPU.ActiveCfg = Debug|Any CPU
+		{E1F334C3-8F77-46C9-A28B-A8E9BAEA9FE5}.winphone_Release|Any CPU.Build.0 = Debug|Any CPU
+		{E1F334C3-8F77-46C9-A28B-A8E9BAEA9FE5}.Debug|iPhoneSimulator.ActiveCfg = Debug|Any CPU
+		{E1F334C3-8F77-46C9-A28B-A8E9BAEA9FE5}.Debug|iPhoneSimulator.Build.0 = Debug|Any CPU
+		{E1F334C3-8F77-46C9-A28B-A8E9BAEA9FE5}.Release|iPhoneSimulator.ActiveCfg = Release|Any CPU
+		{E1F334C3-8F77-46C9-A28B-A8E9BAEA9FE5}.Release|iPhoneSimulator.Build.0 = Release|Any CPU
+		{E1F334C3-8F77-46C9-A28B-A8E9BAEA9FE5}.Debug|iPhone.ActiveCfg = Debug|Any CPU
+		{E1F334C3-8F77-46C9-A28B-A8E9BAEA9FE5}.Debug|iPhone.Build.0 = Debug|Any CPU
+		{E1F334C3-8F77-46C9-A28B-A8E9BAEA9FE5}.Release|iPhone.ActiveCfg = Release|Any CPU
+		{E1F334C3-8F77-46C9-A28B-A8E9BAEA9FE5}.Release|iPhone.Build.0 = Release|Any CPU
+		{E1F334C3-8F77-46C9-A28B-A8E9BAEA9FE5}.DebugStaticRegistrar|iPhone.ActiveCfg = Debug|Any CPU
+		{E1F334C3-8F77-46C9-A28B-A8E9BAEA9FE5}.DebugStaticRegistrar|iPhone.Build.0 = Debug|Any CPU
 	EndGlobalSection
 	GlobalSection(NestedProjects) = preSolution
 		{208744BD-504E-47D7-9A98-1CF02454A6DA} = {2BFA13F8-B568-48BF-9A70-9D43F718C523}

runtime/EXCEPTIONS.md

@@ -0,0 +1,127 @@
+History
+====================
+
+Historically we've attempted to convert Objective-C exceptions to managed exceptions
+by adding a handler to be notified of uncaught Objective-C exceptions [1], but that one
+major problem: it did not handle *caught* Objective-C exceptions, where the exception
+handler would just abort.
+
+This is common in iOS apps, where the main runloop adds an Objective-C @try/@catch
+handler that just aborts, preventing us from being notified of the Objectice-C exception.
+
+This approach also has another problem: the Objective-C exception handling mechanism
+could unwind through managed code, which would result in all kinds of inexplicable
+behavior (if there was an Objective-C exception handler that _didn't_ abort the app):
+
+    try {
+        doSomethingThatCausesAnObjectiveCException ();
+    } finally {
+        Console.WriteLine ("Done!");
+    }
+
+If there happened to be an Objective-C exception handler in a stack frame further
+up, the Console.WriteLine would never be executed.
+
+Another frequent problem would occur in an IDE debugger if it tried to evaluate
+every property for an object. If there were properties not supported on the
+executing platform, it would throw an Objective-C exception (selector not found)
+that would terminate the app.
+
+The reverse problem also existed: throwing a managed exception that the native-to-managed
+boundary didn't catch, would make the mono runtime unwind through native frames,
+causing a similar set of inexplicable behavior:
+
+    [obj selectorThatManagedCodeHasOverriddenAndThrowAManagedException];
+    NSLog (@"done!");
+
+The NSLog statement would never be executed.
+
+[1] By using [NSSetUncaughtExceptionHandler](https://developer.apple.com/library/mac/documentation/Cocoa/Reference/Foundation/Miscellaneous/Foundation_Functions/#//apple_ref/c/func/NSSetUncaughtExceptionHandler).
+
+Exception marshaling
+====================
+
+There are two parts to exception marshaling: Objective-C exceptions
+and managed exceptions.
+
+In both cases we offer a managed event the app can subscribe to to
+be notified, and then the app can choose what to do:
+
+1. Convert the managed/Objective-C exception to its counterpart
+   (i.e. managed exceptions are converted to an Objective-C exception,
+   and Objective-C exceptions are converted to a managed exception).
+
+2. Abort.
+
+3. Rethrow the original exception (this is not available when
+   using the Coop GC, which is the only option on watchOS).
+
+Managed exception marshaling
+----------------------------
+
+This is the simplest case, we just make sure to catch any managed
+exceptions that reaches native code. There are a few sources:
+
+1. When we call mono_runtime_invoke in our trampolines.
+
+   In this case mono_runtime_invoke will catch any exceptions
+   and return them to us (without unwinding anything else).
+
+2. When managed code gives a delegate to native code, and 
+   native code calls that delegate.
+
+   This is still a TODO, we need to use this new API to be
+   notified when the mono runtime detects this case:
+   https://github.com/mono/mono/pull/2948
+
+Objective-C exception marshaling
+--------------------------------
+
+This is more complicated, because there must be an Objective-C
+exception handler on the managed-to-native boundary frame, 
+catching the Objective-C exception.
+
+We have two approaches for this:
+
+1. Custom wrappers of the objc_msgSend functions with an
+   Objective-C exception handler. These have to be written
+   in assembly code, since it's not possible to do it in C.
+   At runtime we inject a dllmap into the process, which
+   redirects any P/invoke to the objc_msgSend functions to
+   these custom wrappers.
+
+   Since we can't write assembly code for bitcode targets
+   (watchOS), another approach is still required though.
+
+   This is the used for iOS/tvOS/watchOS simulator builds
+   (both 32-bit and 64-bit) and Mac/64 bits. It does not
+   work on Mac/32 bits because that platform does not use
+   0-cost exceptions like the other platforms (it uses
+   setjmp/longjmp instead, and would require a very
+   different implementation in assembly code).
+
+   The assembly code for these wrappers is in the 
+   trampolines-[arch]-objc_msgSend* files.
+
+   The documentation about 0-cost exceptions is scarce,
+   but here are a few documents which were helpful:
+
+	https://developer.apple.com/library/mac/documentation/Cocoa/Conceptual/Exceptions/Articles/Exceptions64Bit.html  
+	https://sourceware.org/binutils/docs/as/CFI-directives.html  
+	http://mentorembedded.github.io/cxx-abi/abi-eh.html  
+	http://llvm.org/docs/ExceptionHandling.html  
+	http://www.opensource.apple.com/source/llvmCore/llvmCore-3425.0.33/docs/ExceptionHandling.rst  
+	http://stackoverflow.com/a/7535848  
+	http://www.darlinghq.org/for-developers/exception-handling-on-os-x  
+
+    The wrappers themselves were first created by writing
+    something similar in C, and then telling clang to
+    dump the corresponding assembly code (by passing
+    `--save-temps -fverbose-asm` to clang).
+
+2. At build time generate custom wrappers of every P/Invoke
+   to the objc_msgSend functions, and modify the P/Invoke to
+   call these generated wrappers.
+
+   This is used for iOS/tvOS/watchOS device builds, and
+   Mac/32 bits.

runtime/Makefile

@@ -20,8 +20,8 @@ SHIPPED_HEADERS +=         \
 	xamarin/runtime.h      \
 
 SHARED_SOURCES += mono-runtime.m bindings.m bindings-generated.m shared.m runtime.m trampolines.m trampolines-invoke.m xamarin-support.m nsstring-localization.m trampolines-varargs.m
-SHARED_I386_SOURCES += trampolines-i386.m trampolines-i386-asm.s
-SHARED_X86_64_SOURCES += trampolines-x86_64.m trampolines-x86_64-asm.s
+SHARED_I386_SOURCES += trampolines-i386.m trampolines-i386-asm.s trampolines-i386-objc_msgSend.s trampolines-i386-objc_msgSendSuper.s trampolines-i386-objc_msgSend_stret.s trampolines-i386-objc_msgSendSuper_stret.s
+SHARED_X86_64_SOURCES += trampolines-x86_64.m trampolines-x86_64-asm.s trampolines-x86_64-objc_msgSend.s trampolines-x86_64-objc_msgSendSuper.s trampolines-x86_64-objc_msgSend_stret.s trampolines-x86_64-objc_msgSendSuper_stret.s
 SHARED_HEADERS += shared.h product.h delegates.h runtime-internal.h $(SHARED_INC) $(SHIPPED_HEADERS) trampolines-internal.h slinked-list.h
 
 SHARED_FILES = $(SHARED_SOURCES) $(SHARED_HEADERS) $(SHARED_I386_SOURCES) $(SHARED_X86_64_SOURCES)

runtime/delegates.t4

@@ -19,6 +19,14 @@
 			"NSException *", "IntPtr", "exc"
 		) { WrappedManagedFunction = "ThrowNSException" },
 
+		new XDelegate ("int", "int", "xamarin_create_ns_exception",
+			"NSException *", "IntPtr", "exc"
+		) { WrappedManagedFunction = "CreateNSException" },
+
+		new XDelegate ("NSException *", "IntPtr", "xamarin_unwrap_ns_exception",
+			"int", "int", "exc_handle"
+		) { WrappedManagedFunction = "UnwrapNSException" },
+
 		new XDelegate ("MonoObject *", "IntPtr", "xamarin_get_block_wrapper_creator",
 			"MonoObject *", "IntPtr", "method",
 			"int", "int", "parameter"
@@ -147,6 +155,14 @@
 		new XDelegate ("char *", "IntPtr", "xamarin_lookup_managed_type_name",
 			"Class", "IntPtr", "klass"
 		) { WrappedManagedFunction = "LookupManagedTypeName" },
+
+		new XDelegate ("MarshalManagedExceptionMode", "MarshalManagedExceptionMode", "xamarin_on_marshal_managed_exception",
+			"int", "int", "exception"
+		) { WrappedManagedFunction = "OnMarshalManagedException" },
+
+		new XDelegate ("MarshalObjectiveCExceptionMode", "MarshalObjectiveCExceptionMode", "xamarin_on_marshal_objectivec_exception",
+			"id", "IntPtr", "exception"
+		) { WrappedManagedFunction = "OnMarshalObjectiveCException" },
 	};
 	delegates.CalculateLengths ();
 #><#+

runtime/exports.t4

@@ -218,6 +218,14 @@
 
 		#endregion
 
+		#region metadata/object-internals.h
+
+		new Export (true, "void", "mono_set_pending_exception",
+			"MonoException *", "exc"
+		),
+
+		#endregion
+
 		#region metadata/assembly.h
 
 		new Export ("void", "mono_set_assemblies_path",
@@ -288,6 +296,14 @@
 			"MonoMethod *", "method"
 		),
 
+		new Export ("void", "mono_dllmap_insert",
+			"MonoImage *", "assembly",
+			"const char *", "dll",
+			"const char *", "func",
+			"const char *", "tdll",
+			"const char *", "tfunc"
+		),
+
 		#endregion
 
 		#region metadata/appdomain.h

runtime/libmonotouch.csproj

@@ -83,5 +83,19 @@
     <None Include="trampolines-i386.m" />
     <None Include="trampolines-varargs.h" />
     <None Include="trampolines-varargs.m" />
+    <None Include="trampolines-x86_64-objc_msgSendSuper.s" />
+    <None Include="trampolines-x86_64-objc_msgSend.s" />
+    <None Include="trampolines-x86_64-objc_msgSend-post.inc" />
+    <None Include="trampolines-x86_64-objc_msgSend-copyframe.inc" />
+    <None Include="trampolines-x86_64-objc_msgSend-pre.inc" />
+    <None Include="trampolines-x86_64-objc_msgSend_stret.s" />
+    <None Include="trampolines-x86_64-objc_msgSendSuper_stret.s" />
+    <None Include="trampolines-i386-objc_msgSend.s" />
+    <None Include="trampolines-i386-objc_msgSendSuper.s" />
+    <None Include="trampolines-i386-objc_msgSend_stret.s" />
+    <None Include="trampolines-i386-objc_msgSendSuper_stret.s" />
+    <None Include="trampolines-i386-objc_msgSend-copyframe.inc" />
+    <None Include="trampolines-i386-objc_msgSend-post.inc" />
+    <None Include="trampolines-i386-objc_msgSend-pre.inc" />
   </ItemGroup>
 </Project>

runtime/runtime-internal.h

@@ -26,4 +26,19 @@
 
 void *xamarin_marshal_return_value (MonoType *mtype, const char *type, MonoObject *retval, bool retain, MonoMethod *method);
 
+/*
+ * XamarinGCHandle
+ *
+ * This is an ObjC type that ties the lifetime of a GCHandle to the lifetime of itself.
+ * It stores a GCHandle, and frees the GCHandle in dealloc.
+ */
+@interface XamarinGCHandle : NSObject {
+@public
+	int handle;
+}
++(XamarinGCHandle *) createWithHandle: (int) handle;
+-(void) dealloc;
+-(int) getHandle;
+@end
+
 #endif /* __RUNTIME_INTERNAL_H__ */