Custom exception hook in reverse C interop (JetBrains#2946)

backend.native/compiler/ir/backend.native/src/org/jetbrains/kotlin/backend/konan/CAdapterGenerator.kt

@@ -432,6 +432,7 @@ private class ExportedElement(val kind: ElementKind,
         val isStringReturned = owner.isMappedToString(cfunction[0].second)
         // TODO: do we really need that in every function?
         builder.append("  Kotlin_initRuntimeIfNeeded();\n")
+        builder.append("   try {\n")
         if (isObjectReturned || isStringReturned) {
             builder.append("  KObjHolder result_holder;\n")
             args += "result_holder.slot()"
@@ -455,6 +456,8 @@ private class ExportedElement(val kind: ElementKind,
                     "result", cfunction[0].second, Direction.KOTLIN_TO_C, builder)
             builder.append("  return $result;\n")
         }
+        builder.append("   } catch (ExceptionObjHolder& e) { TerminateWithUnhandledException(e.obj()); } \n")
+
         builder.append("}\n")
 
         return builder.toString()
@@ -885,6 +888,7 @@ internal class CAdapterGenerator(val context: Context) : DeclarationDescriptorVi
         |
         |#define RUNTIME_NOTHROW __attribute__((nothrow))
         |#define RUNTIME_USED __attribute__((used))
+        |#define RUNTIME_NORETURN __attribute__((noreturn))
         |
         |extern "C" {
         |void UpdateHeapRef(KObjHeader**, const KObjHeader*) RUNTIME_NOTHROW;
@@ -897,6 +901,7 @@ internal class CAdapterGenerator(val context: Context) : DeclarationDescriptorVi
         |void EnterFrame(KObjHeader** start, int parameters, int count) RUNTIME_NOTHROW;
         |void LeaveFrame(KObjHeader** start, int parameters, int count) RUNTIME_NOTHROW;
         |void Kotlin_initRuntimeIfNeeded();
+        |void TerminateWithUnhandledException(KObjHeader*) RUNTIME_NORETURN;
         |
         |KObjHeader* CreateStringFromCString(const char*, KObjHeader**);
         |char* CreateCStringFromString(const KObjHeader*);
@@ -930,6 +935,20 @@ internal class CAdapterGenerator(val context: Context) : DeclarationDescriptorVi
         |
         |  KObjHeader** frame() { return reinterpret_cast<KObjHeader**>(&frame_); }
         |};
+        |
+        |class ExceptionObjHolder {
+        | public:
+        |  explicit ExceptionObjHolder(const KObjHeader* obj): obj_(nullptr) {
+        |    ::UpdateHeapRef(&obj_, obj);
+        |  }
+        |  ~ExceptionObjHolder() {
+        |    UpdateHeapRef(&obj_, nullptr);
+        |  }
+        |  KObjHeader* obj() { return obj_; }
+        | private:
+        |  KObjHeader* obj_;
+        |};
+        |
         |static void DisposeStablePointerImpl(${prefix}_KNativePtr ptr) {
         |  DisposeStablePointer(ptr);
         |}

backend.native/tests/build.gradle

@@ -3297,7 +3297,8 @@ task produce_dynamic(type: DynamicKonanTest) {
                 "object = 42\n" +
                 "singleton = I am single\n" +
                 "mutable = foo\n" +
-                "topLevel = 777 3\n"
+                "topLevel = 777 3\n" +
+                "Error handler: kotlin.Error: Expected error\n"
 }
 
 task library_mismatch(type: RunStandaloneKonanTest) {

backend.native/tests/produce_dynamic/simple/hello.kt

@@ -6,6 +6,7 @@
 import kotlinx.cinterop.*
 
 import kotlin.native.CName
+import kotlin.native.concurrent.freeze
 
 // Top level functions.
 fun hello() {
@@ -96,3 +97,17 @@ fun useInlineClasses(ic1: IC1, ic2: IC2, ic3: IC3) {
     assert(ic2.value == "bar")
     assert(ic3.value is Base)
 }
+
+fun setCErrorHandler(callback: CPointer<CFunction<(CPointer<ByteVar>) -> Unit>>?) {
+    setUnhandledExceptionHook({
+        throwable: Throwable ->
+        memScoped {
+            callback!!(throwable.toString().cstr.ptr)
+        }
+        kotlin.system.exitProcess(0)
+    }.freeze())
+}
+
+fun throwException() {
+    throw Error("Expected error")
+}

backend.native/tests/produce_dynamic/simple/main.c

@@ -5,6 +5,10 @@
 #define T_(x) testlib_kref_ ## x
 #define CAST(T, v) testlib_kref_ ## T { .pinned = v }
 
+void errorHandler(const char* str) {
+  printf("Error handler: %s\n", str);
+}
+
 int main(void) {
     T_(Singleton) singleton = __ kotlin.root.Singleton._instance();
     T_(Base) base = __ kotlin.root.Base.Base();
@@ -61,6 +65,9 @@ int main(void) {
     __ DisposeStablePointer(enum1.pinned);
     __ DisposeStablePointer(object1.pinned);
 
+    __ kotlin.root.setCErrorHandler(&errorHandler);
+    __ kotlin.root.throwException();
+
     return 0;
 }
 

runtime/src/main/cpp/Memory.h

@@ -569,7 +569,6 @@ class ExceptionObjHolder {
    ObjHeader* obj_;
 };
 
-
 class KRefSharedHolder {
  public:
   inline ObjHeader** slotToInit() {