Handle load errors in deferred code

runtime/bin/dartutils.cc

 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 #include "bin/dartutils.h"
 
 #include "include/dart_api.h"
 #include "include/dart_native_api.h"
 
 #include "platform/assert.h"
@@ skipping 693 matching lines @@
   free(const_cast<uint8_t *>(buffer));
   if (Dart_IsError(result)) {
     Dart_PropagateError(result);
   }
 }
 
 
 // Callback function, gets called from asynchronous script and library
 // reading code when there is an i/o error.
 void FUNCTION_NAME(Builtin_AsyncLoadError)(Dart_NativeArguments args) {
-  // Dart_Handle script_uri = Dart_GetNativeArgument(args, 0);
-  Dart_Handle error = Dart_GetNativeArgument(args, 1);
-  Dart_Handle res = Dart_NewUnhandledExceptionError(error);
-  Dart_PropagateError(res);
+  //  Dart_Handle source_uri = Dart_GetNativeArgument(args, 0);
+  Dart_Handle library_uri = Dart_GetNativeArgument(args, 1);
+  Dart_Handle error = Dart_GetNativeArgument(args, 2);
+
+  Dart_Handle library = Dart_LookupLibrary(library_uri);
+  // If a library with the given uri exists, give it a chance to handle
+  // the error. If the load requests stems from a deferred library load,
+  // an IO error is not fatal.
+  if (!Dart_IsError(library)) {
+    ASSERT(Dart_IsLibrary(library));
+    Dart_Handle res = Dart_LibraryHandleError(library, error);
+    if (Dart_IsNull(res)) {
+      return;
+    }
+  }
+  // The error was not handled above. Propagate an unhandled exception.
+  error = Dart_NewUnhandledExceptionError(error);
+  Dart_PropagateError(error);
 }
 
 
 // Callback function that gets called from dartutils when the library
 // source has been read. Loads the library or part into the VM.
 void FUNCTION_NAME(Builtin_LoadLibrarySource)(Dart_NativeArguments args) {
   Dart_Handle tag_in = Dart_GetNativeArgument(args, 0);
   Dart_Handle resolved_script_uri = Dart_GetNativeArgument(args, 1);
   Dart_Handle library_uri = Dart_GetNativeArgument(args, 2);
   Dart_Handle sourceText = Dart_GetNativeArgument(args, 3);
 
   int64_t tag = DartUtils::GetIntegerValue(tag_in);
 
   Dart_Handle result;
   if (tag == Dart_kImportTag) {
     result = Dart_LoadLibrary(resolved_script_uri, sourceText);
   } else {
     ASSERT(tag == Dart_kSourceTag);
     Dart_Handle library = Dart_LookupLibrary(library_uri);
     DART_CHECK_VALID(library);
     result = Dart_LoadSource(library, resolved_script_uri, sourceText);
   }
-  if (Dart_IsError(result)) Dart_PropagateError(result);
+  if (Dart_IsError(result)) {
+    // TODO(hausner): If compilation/loading errors are supposed to
+    // be observable by the program, we need to mark the bad library
+    // with the error instead of propagating it.
+    Dart_PropagateError(result);
+  }
 }
 
 
 // Callback function that gets called from dartutils when there are
 // no more outstanding load requests.
 void FUNCTION_NAME(Builtin_DoneLoading)(Dart_NativeArguments args) {
   Dart_Handle res = Dart_FinalizeLoading(true);
   if (Dart_IsError(res)) {
+    // TODO(hausner): If compilation/loading errors are supposed to
+    // be observable by the program, we need to mark the bad library
+    // with the error instead of propagating it.
     Dart_PropagateError(res);
   }
 }
 
 
 Dart_Handle DartUtils::LoadSource(Dart_Handle library,
                                   Dart_Handle url,
                                   Dart_LibraryTag tag,
                                   const char* url_string) {
   bool is_http_scheme_url = DartUtils::IsHttpSchemeURL(url_string);
@@ skipping 401 matching lines @@
       new CObjectString(CObject::NewString(os_error->message()));
   CObjectArray* result = new CObjectArray(CObject::NewArray(3));
   result->SetAt(0, new CObjectInt32(CObject::NewInt32(kOSError)));
   result->SetAt(1, new CObjectInt32(CObject::NewInt32(os_error->code())));
   result->SetAt(2, error_message);
   return result;
 }
 
 }  // namespace bin
 }  // namespace dart