Error reporting on File in dart:io

runtime/bin/file.cc

Index: runtime/bin/file.cc
diff --git a/runtime/bin/file.cc b/runtime/bin/file.cc
index 093ff4d4655fa7d49f9f64d5a08a1ac85e838c2c..ea50e4f86ed5059a3b06e666f542417a71c7502d 100644
--- a/runtime/bin/file.cc
+++ b/runtime/bin/file.cc
@@ -72,8 +72,14 @@ void FUNCTION_NAME(File_Open)(Dart_NativeArguments args) {
   // files. Directories can be opened for reading using the posix
   // 'open' call.
   File* file = NULL;
-  if (((file_mode & File::kWrite) != 0) || File::Exists(filename)) {
-    file = File::Open(filename, file_mode);
+  OSError os_error;
+  file = File::Open(filename, file_mode, &os_error);
+  if (file == NULL) {
+    Dart_Handle os_error_handle = Dart_GetNativeArgument(args, 2);
+    DartUtils::SetIntegerInstanceField(
+        os_error_handle, "errorCode", os_error.errno_);
+    DartUtils::SetStringInstanceField(
+        os_error_handle, "message", os_error.strerror_);
   }
   Dart_SetReturnValue(args, Dart_NewInteger(reinterpret_cast<intptr_t>(file)));
   Dart_ExitScope();
@@ -413,9 +419,18 @@ static CObject* FileCreateRequest(const CObjectArray& request) {
   return CObject::False();
 }
 
+static CObject* MakeOsError(OSError os_error) {
+  CObject* error_message =
+      new CObjectString(CObject::NewString(os_error.strerror_));
+  CObjectArray* result = new CObjectArray(CObject::NewArray(2));
+  result->SetAt(0, new CObjectInt32(CObject::NewInt32(os_error.errno_)));
+  result->SetAt(1, error_message);
+  return result;
+}
 
 static CObject* FileOpenRequest(const CObjectArray& request) {
   File* file = NULL;
+  OSError os_error;
   if (request.Length() == 3 &&
       request[1]->IsString() &&
       request[2]->IsInt32()) {
@@ -424,12 +439,14 @@ static CObject* FileOpenRequest(const CObjectArray& request) {
     File::DartFileOpenMode dart_file_mode =
         static_cast<File::DartFileOpenMode>(mode.Value());
     File::FileOpenMode file_mode = File::DartModeToFileMode(dart_file_mode);
-    if (((file_mode & File::kWrite) != 0) || File::Exists(filename.CString())) {
-      file = File::Open(filename.CString(), file_mode);
-    }
+    file = File::Open(filename.CString(), file_mode, &os_error);
+  }
+  if (file != NULL) {
+    return new CObjectIntptr(
+        CObject::NewIntptr(reinterpret_cast<intptr_t>(file)));
+  } else {
+    return MakeOsError(os_error);
   }
-  return new CObjectIntptr(
-      CObject::NewIntptr(reinterpret_cast<intptr_t>(file)));
 }