Deal with unhandled exceptions the same way in all Dart api functions.

runtime/vm/dart_api_impl.cc

Index: runtime/vm/dart_api_impl.cc
===================================================================
--- runtime/vm/dart_api_impl.cc	(revision 1328)
+++ runtime/vm/dart_api_impl.cc	(working copy)
@@ -27,43 +27,138 @@
 
 namespace dart {
 
-DART_EXPORT bool Dart_IsValid(const Dart_Handle& handle) {
+DART_EXPORT bool Dart_IsError(const Dart_Handle& handle) {
   ASSERT(Isolate::Current() != NULL);
   Zone zone;  // Setup a VM zone as we are creating some handles.
   HandleScope scope;  // Setup a VM handle scope.
+  const Object& obj = Object::Handle(Api::UnwrapHandle(handle));
+  return obj.IsApiError();
+}
 
-  // Make sure that the object isn't an ApiFailure.
+
+DART_EXPORT bool Dart_IsUnhandledException(Dart_Handle handle) {
+  Zone zone;  // Setup a VM zone as we are creating some handles.
+  HandleScope scope;  // Setup a VM handle scope.
   const Object& obj = Object::Handle(Api::UnwrapHandle(handle));
-  return !obj.IsApiFailure();
+  if (obj.IsApiError()) {
+    ApiError& failure = ApiError::Handle();
+    failure ^= obj.raw();

[Anton Muhin, 2011/11/09 12:34:03]

may you used const ApiError& = ApiError::Handle(obj.raw()) instead?

[turnidge, 2011/11/09 19:53:41]

Done.

[Anton Muhin, 2011/11/10 08:28:39]

Thanks.  There are ways more instance of the same pattern, if you like, I can go
over CL and tag them.

On 2011/11/09 19:53:41, turnidge wrote:

[turnidge, 2011/11/10 20:59:13]

To get this to work I need to use CheckedHandle.

Rather not fix all instances of this in this CL.  Follow-up?

+    const Object& data = Object::Handle(failure.data());
+    return data.IsUnhandledException();
+  }
+  return false;
 }
 
 
-DART_EXPORT void _Dart_ReportInvalidHandle(const char* file,
+DART_EXPORT Dart_Handle Dart_GetException(Dart_Handle handle) {
+  Zone zone;  // Setup a VM zone as we are creating some handles.
+  HandleScope scope;  // Setup a VM handle scope.
+  const Object& obj = Object::Handle(Api::UnwrapHandle(handle));
+  if (obj.IsApiError()) {
+    ApiError& failure = ApiError::Handle();
+    failure ^= obj.raw();
+    const Object& data = Object::Handle(failure.data());
+    if (data.IsUnhandledException()) {
+      const UnhandledException& unhandled = UnhandledException::Handle(
+          reinterpret_cast<RawUnhandledException*>(data.raw()));
+      const Object& exception = Object::Handle(unhandled.exception());
+      return Api::NewLocalHandle(exception);
+    } else {
+      return Api::Error("This error is not an unhandled exception error.");
+    }
+  } else {
+    return Api::Error("Can only get exceptions from error handles.");
+  }
+}
+
+
+DART_EXPORT Dart_Handle Dart_GetStacktrace(Dart_Handle handle) {
+  Zone zone;  // Setup a VM zone as we are creating some handles.
+  HandleScope scope;  // Setup a VM handle scope.
+  const Object& obj = Object::Handle(Api::UnwrapHandle(handle));
+  if (obj.IsApiError()) {
+    ApiError& failure = ApiError::Handle();
+    failure ^= obj.raw();
+    const Object& data = Object::Handle(failure.data());
+    if (data.IsUnhandledException()) {
+      const UnhandledException& unhandled = UnhandledException::Handle(
+          reinterpret_cast<RawUnhandledException*>(data.raw()));
+      const Object& stacktrace = Object::Handle(unhandled.stacktrace());
+      return Api::NewLocalHandle(stacktrace);
+    } else {
+      return Api::Error("This error is not an unhandled exception error.");
+    }
+  } else {
+    return Api::Error("Can only get stacktraces from error handles.");
+  }
+}
+
+
+DART_EXPORT void _Dart_ReportErrorHandle(const char* file,
                                            int line,
                                            const char* handle,
                                            const char* message) {
-  fprintf(stderr, "%s:%d: invalid handle: '%s':\n    '%s'\n",
+  fprintf(stderr, "%s:%d: error handle: '%s':\n    '%s'\n",
           file, line, handle, message);
   OS::Abort();
 }
 
 
+static const char* MakeUnhandledExceptionCString(
+    const UnhandledException& uhe) {
+  const Instance& exception = Instance::Handle(uhe.exception());
+  Object& strtmp = Object::Handle(DartLibraryCalls::ToString(exception));

[Anton Muhin, 2011/11/09 12:34:03]

this is a typical paranoia and DartLibraryCalls::ToString is not quite correct
in this regard, but technically .toString in Dart may return any kind of object
including null, so maybe you should have it differently: if
(!strtmp.IsUnhandledException() { ... } 

[turnidge, 2011/11/09 19:53:41]

Done.

+  const char* exc_str =
+      "<Received exception while converting exception to string>";
+  if (strtmp.IsString()) {
+    exc_str = strtmp.ToCString();
+  }
+
+  const Instance& stack = Instance::Handle(uhe.stacktrace());
+  strtmp = DartLibraryCalls::ToString(stack);
+  const char* stack_str =
+      "<Received exception while converting stacktrace to string>";
+  if (strtmp.IsString()) {
+    stack_str = strtmp.ToCString();
+  }
+
+  const char* format = "Unhandled exception:\n%s\n%s";
+  int len = strlen(exc_str) + strlen(stack_str) + strlen(format) - 2;

[Anton Muhin, 2011/11/09 12:34:03]

why - 2, to account for %s?  if yes, shouldn't it be -4 then?  and if still yes,
it might be more obvious to a reader if written as: - 2 * strlen("%s").

[Anton Muhin, 2011/11/09 12:34:03]

maybe add + 1 into len as well not to duplicate it below.

[turnidge, 2011/11/09 19:53:41]

Sorry, brain spasm there.  Reworked this to be more correct and clear.

+  char* buffer = reinterpret_cast<char*>(Api::Allocate(len + 1));
+  OS::SNPrint(buffer, (len + 1), format, exc_str, stack_str);
+  return buffer;
+}
+
+
 DART_EXPORT const char* Dart_GetError(const Dart_Handle& handle) {
   ASSERT(Isolate::Current() != NULL);
   Zone zone;  // Setup a VM zone as we are creating some handles.
   HandleScope scope;  // Setup a VM handle scope.
   const Object& obj = Object::Handle(Api::UnwrapHandle(handle));
-  if (!obj.IsApiFailure()) {
+  if (!obj.IsApiError()) {
     return "";
   }
-  ApiFailure& failure = ApiFailure::Handle();
+  ApiError& failure = ApiError::Handle();
   failure ^= obj.raw();
-  const String& message = String::Handle(failure.message());
-  const char* msg = message.ToCString();
-  intptr_t len = strlen(msg) + 1;
-  char* msg_copy = reinterpret_cast<char*>(Api::Allocate(len));
-  OS::SNPrint(msg_copy, len, "%s", msg);
-  return msg_copy;
+  const Object& data = Object::Handle(failure.data());
+  if (data.IsString()) {
+    // Simple error message.
+    String& message = String::Handle();
+    message ^= failure.data();
+    const char* msg = message.ToCString();
+    intptr_t len = strlen(msg) + 1;
+    char* msg_copy = reinterpret_cast<char*>(Api::Allocate(len));
+    OS::SNPrint(msg_copy, len, "%s", msg);

[Anton Muhin, 2011/11/09 12:34:03]

I see you're keeping old code, but strncpy (unless forbidden by a style guide)
appears to be a more direct way to copy a string :)

[turnidge, 2011/11/09 19:53:41]

Um, fixed.

+    return msg_copy;
+
+  } else if (data.IsUnhandledException()) {
+    UnhandledException& uhe = UnhandledException::Handle();
+    uhe ^= data.raw();
+    return MakeUnhandledExceptionCString(uhe);
+
+  } else {
+    return "<Internal error in Dart_GetError: malformed error handle>";
+  }
 }
 
 
@@ -141,7 +236,7 @@
   // may get deallocated when we return back from the Dart API call.
   const String& error = String::Handle(
       Isolate::Current()->object_store()->sticky_error());
-  const Object& obj = Object::Handle(ApiFailure::New(error));
+  const Object& obj = Object::Handle(ApiError::New(error));
   *handle = Api::NewLocalHandle(obj);
 }
 
@@ -172,22 +267,9 @@
 }
 
 
-static void ProcessUnhandledException(const UnhandledException& uhe) {
-  const Instance& exception = Instance::Handle(uhe.exception());
-  Instance& strtmp = Instance::Handle(DartLibraryCalls::ToString(exception));
-  const char* str = strtmp.ToCString();
-  fprintf(stderr, "%s\n", str);
-  const Instance& stack = Instance::Handle(uhe.stacktrace());
-  strtmp = DartLibraryCalls::ToString(stack);
-  str = strtmp.ToCString();
-  fprintf(stderr, "%s\n", str);
-  exit(255);
-}
-
-
-DART_EXPORT void Dart_HandleMessage(Dart_Port dest_port,
-                                    Dart_Port reply_port,
-                                    Dart_Message dart_message) {
+DART_EXPORT Dart_Handle Dart_HandleMessage(Dart_Port dest_port,
+                                           Dart_Port reply_port,
+                                           Dart_Message dart_message) {
   Zone zone;  // Setup a VM zone as we are creating some handles.
   HandleScope scope;  // Setup a VM handle scope.
   const Instance& msg = Instance::Handle(DeserializeMessage(dart_message));
@@ -211,14 +293,10 @@
   const Object& result = Object::Handle(
       DartEntry::InvokeStatic(function, arguments, kNoArgumentNames));
   if (result.IsUnhandledException()) {
-    UnhandledException& uhe = UnhandledException::Handle();
-    uhe ^= result.raw();
-    // TODO(turnidge): Instead of exiting here, just return the
-    // exception so that the embedder can choose how to handle this
-    // case.
-    ProcessUnhandledException(uhe);
+    return Api::ErrorFromException(result);
   }
   ASSERT(result.IsNull());
+  return Api::Success();
 }
 
 
@@ -448,7 +526,7 @@
     receiver ^= obj.raw();
     result = DartLibraryCalls::ToString(receiver);
     if (result.IsUnhandledException()) {
-      return Api::Error("An exception occurred when converting to string");
+      return Api::ErrorFromException(result);
     }
   } else {
     // This is a VM internal object. Call the C++ method of printing.
@@ -510,8 +588,10 @@
     b ^= result.raw();
     *value = b.value();
     return Api::Success();
+  } else if (result.IsUnhandledException()) {
+    return Api::ErrorFromException(result);
   } else {
-    return Api::Error("An exception occured when calling '=='");
+    return Api::Error("Expected boolean result from ==");
   }
 }
 
@@ -981,6 +1061,8 @@
             result = Api::Error("Length of List object is greater than the "
                                 "maximum value that 'len' parameter can hold");
           }
+        } else if (retval.IsUnhandledException()) {
+          result = Api::ErrorFromException(retval);
         } else {
           result = Api::Error("Length of List object is not an integer");
         }
@@ -1015,7 +1097,7 @@
                                       args,
                                       kNoArgumentNames);
     if (retval.IsUnhandledException()) {
-      *result = Api::Error("Unexpected exception in '[]'");
+      *result = Api::ErrorFromException(retval);
     } else {
       *result = Api::Success();
     }
@@ -1068,7 +1150,7 @@
       for (int i = 0; i < length; i++) {
         intobj = Integer::New(offset + i);
         element = GetListAt(isolate, instance, intobj, function, &result);
-        if (!Dart_IsValid(result)) {
+        if (Dart_IsError(result)) {
           return result;  // Error condition.
         }
         intobj ^= element.raw();
@@ -1111,7 +1193,7 @@
       Dart_Handle result;
       indexobj = Integer::New(index);
       element = GetListAt(isolate, instance, indexobj, function, &result);
-      if (!Dart_IsValid(result)) {
+      if (Dart_IsError(result)) {
         return result;  // Error condition.
       }
       return Api::NewLocalHandle(element);
@@ -1143,7 +1225,7 @@
                                       args,
                                       kNoArgumentNames);
     if (retval.IsUnhandledException()) {
-      *result = Api::Error("Unexpected exception in '[]='");
+      *result = Api::ErrorFromException(retval);
     } else {
       *result = Api::Success();
     }
@@ -1190,7 +1272,7 @@
         indexobj = Integer::New(offset + i);
         valueobj ^= Integer::New(native_array[i]);
         SetListAt(isolate, instance, indexobj, valueobj, function, &result);
-        if (!Dart_IsValid(result)) {
+        if (Dart_IsError(result)) {
           return result;  // Error condition.
         }
       }
@@ -1252,7 +1334,11 @@
     const Array& kNoArgumentNames = Array::Handle();
     const Instance& retval = Instance::Handle(
         DartEntry::InvokeStatic(function, args, kNoArgumentNames));
-    *result = Api::NewLocalHandle(retval);
+    if (retval.IsUnhandledException()) {
+      *result = Api::ErrorFromException(retval);
+    } else {
+      *result = Api::NewLocalHandle(retval);
+    }
   } else {
     SetupErrorResult(result);
   }
@@ -1276,7 +1362,11 @@
     const Array& kNoArgumentNames = Array::Handle();
     const Instance& retval = Instance::Handle(
         DartEntry::InvokeDynamic(receiver, function, args, kNoArgumentNames));
-    *result = Api::NewLocalHandle(retval);
+    if (retval.IsUnhandledException()) {
+      *result = Api::ErrorFromException(retval);
+    } else {
+      *result = Api::NewLocalHandle(retval);
+    }
   } else {
     SetupErrorResult(result);
   }
@@ -1299,7 +1389,11 @@
     const Array& kNoArgumentNames = Array::Handle();
     const Instance& retval = Instance::Handle(
         DartEntry::InvokeClosure(closure, args, kNoArgumentNames));
-    *result = Api::NewLocalHandle(retval);
+    if (retval.IsUnhandledException()) {
+      *result = Api::ErrorFromException(retval);
+    } else {
+      *result = Api::NewLocalHandle(retval);
+    }
   } else {
     SetupErrorResult(result);
   }
@@ -1463,42 +1557,6 @@
 }
 
 
-DART_EXPORT bool Dart_ExceptionOccurred(Dart_Handle result) {
-  Zone zone;  // Setup a VM zone as we are creating some handles.
-  HandleScope scope;  // Setup a VM handle scope.
-  const Object& retval  = Object::Handle(Api::UnwrapHandle(result));
-  return retval.IsUnhandledException();
-}
-
-
-DART_EXPORT Dart_Handle Dart_GetException(Dart_Handle result) {
-  Zone zone;  // Setup a VM zone as we are creating some handles.
-  HandleScope scope;  // Setup a VM handle scope.
-  const Object& retval = Object::Handle(Api::UnwrapHandle(result));
-  if (retval.IsUnhandledException()) {
-    const UnhandledException& unhandled = UnhandledException::Handle(
-        reinterpret_cast<RawUnhandledException*>(retval.raw()));
-    const Object& exception = Object::Handle(unhandled.exception());
-    return Api::NewLocalHandle(exception);
-  }
-  return Api::Error("Object is not an unhandled exception object");
-}
-
-
-DART_EXPORT Dart_Handle Dart_GetStacktrace(Dart_Handle unhandled_excp) {
-  Zone zone;  // Setup a VM zone as we are creating some handles.
-  HandleScope scope;  // Setup a VM handle scope.
-  const Object& retval = Object::Handle(Api::UnwrapHandle(unhandled_excp));
-  if (retval.IsUnhandledException()) {
-    const UnhandledException& unhandled = UnhandledException::Handle(
-        reinterpret_cast<RawUnhandledException*>(retval.raw()));
-    const Object& stacktrace = Object::Handle(unhandled.stacktrace());
-    return Api::NewLocalHandle(stacktrace);
-  }
-  return Api::Error("Object is not an unhandled exception object");
-}
-
-
 DART_EXPORT Dart_Handle Dart_ThrowException(Dart_Handle exception) {
   Isolate* isolate = Isolate::Current();
   ASSERT(isolate != NULL);
@@ -1695,7 +1753,7 @@
   Zone zone;  // Setup a VM zone as we are creating some handles.
   HandleScope scope;  // Setup a VM handle scope.
   Dart_Handle result = LookupStaticField(cls, name, kGetter);
-  if (!::Dart_IsValid(result)) {
+  if (::Dart_IsError(result)) {
     return result;
   }
   Object& retval = Object::Handle();
@@ -1710,25 +1768,20 @@
     func ^= obj.raw();
     GrowableArray<const Object*> args;
     InvokeStatic(func, args, &result);
-    if (::Dart_IsValid(result)) {
-      if (Dart_ExceptionOccurred(result)) {
-        return Api::Error(
-            "An exception occurred when getting the static field");
-      }
-    }
     return result;
   }
 }
 
 
 // TODO(iposva): The value parameter should be documented as being an instance.
+// TODO(turnidge): Is this skipping the setter?
 DART_EXPORT Dart_Handle Dart_SetStaticField(Dart_Handle cls,
                                             Dart_Handle name,
                                             Dart_Handle value) {
   Zone zone;  // Setup a VM zone as we are creating some handles.
   HandleScope scope;  // Setup a VM handle scope.
   Dart_Handle result = LookupStaticField(cls, name, kSetter);
-  if (!::Dart_IsValid(result)) {
+  if (::Dart_IsError(result)) {
     return result;
   }
   Field& fld = Field::Handle();
@@ -1755,19 +1808,13 @@
   Instance& object = Instance::Handle();
   object ^= param.raw();
   Dart_Handle result = LookupInstanceField(object, name, kGetter);
-  if (!::Dart_IsValid(result)) {
+  if (::Dart_IsError(result)) {
     return result;
   }
   Function& func = Function::Handle();
   func ^= Api::UnwrapHandle(result);
   GrowableArray<const Object*> arguments;
   InvokeDynamic(object, func, arguments, &result);
-  if (::Dart_IsValid(result)) {
-    if (Dart_ExceptionOccurred(result)) {
-      return Api::Error(
-          "An exception occurred when accessing the instance field");
-    }
-  }
   return result;
 }
 
@@ -1784,7 +1831,7 @@
   Instance& object = Instance::Handle();
   object ^= param.raw();
   Dart_Handle result = LookupInstanceField(object, name, kSetter);
-  if (!::Dart_IsValid(result)) {
+  if (::Dart_IsError(result)) {
     return result;
   }
   Function& func = Function::Handle();
@@ -1793,12 +1840,6 @@
   const Object& arg = Object::Handle(Api::UnwrapHandle(value));
   arguments.Add(&arg);
   InvokeDynamic(object, func, arguments, &result);
-  if (::Dart_IsValid(result)) {
-    if (Dart_ExceptionOccurred(result)) {
-      return Api::Error(
-          "An exception occurred when setting the instance field");
-    }
-  }
   return result;
 }
 
@@ -2034,7 +2075,7 @@
   OS::VSNPrint(buffer, (len + 1), format, args);
 
   const String& message = String::Handle(String::New(buffer));
-  const Object& obj = Object::Handle(ApiFailure::New(message));
+  const Object& obj = Object::Handle(ApiError::New(message));
   return Api::NewLocalHandle(obj);
 }
 
@@ -2048,6 +2089,22 @@
 }
 
 
+Dart_Handle Api::ErrorFromException(const Object& obj) {
+  Zone zone;  // Setup a VM zone as we are creating some handles.
+  HandleScope scope;  // Setup a VM handle scope.
+
+  ASSERT(obj.IsUnhandledException());
+  if (obj.IsUnhandledException()) {
+    UnhandledException& uhe = UnhandledException::Handle();
+    uhe ^= obj.raw();
+    const Object& error = Object::Handle(ApiError::New(uhe));
+    return Api::NewLocalHandle(error);
+  } else {
+    return Api::Error("Internal error: expected obj.IsUnhandledException().");
+  }
+}
+
+
 Dart_Handle Api::Null() {
   Isolate* isolate = Isolate::Current();
   ASSERT(isolate != NULL);