Make File.readSync return only the bytes read

runtime/bin/file.cc

-// Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
+// Copyright (c) 2013, the Dart project authors.  Please see the AUTHORS file

[Ivan Posva, 2013/02/27 18:18:56]

No need to update.

 // 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/file.h"
 
 #include "bin/builtin.h"
 #include "bin/dartutils.h"
 #include "bin/io_buffer.h"
 #include "bin/thread.h"
 #include "bin/utils.h"
@@ skipping 161 matching lines @@
   if (DartUtils::GetInt64Value(length_object, &length)) {
     uint8_t* buffer = NULL;
     Dart_Handle external_array = IOBuffer::Allocate(length, &buffer);
     int64_t bytes_read = file->Read(reinterpret_cast<void*>(buffer), length);
     if (bytes_read < 0) {
       Dart_Handle err = DartUtils::NewDartOSError();
       if (Dart_IsError(err)) Dart_PropagateError(err);
       Dart_SetReturnValue(args, err);
     } else {
       if (bytes_read < length) {
-        // TODO(ager): cache the 'length' string if this becomes a bottle neck.
-        Dart_SetField(external_array,

[Mads Ager (google), 2013/02/27 15:02:36]

I should have been beaten with a stick for doing this in the first place. ;-)

-                      DartUtils::NewString("length"),
-                      Dart_NewInteger(bytes_read));
+        const int kNumArgs = 3;
+        Dart_Handle dart_args[kNumArgs];
+        dart_args[0] = external_array;
+        dart_args[1] = Dart_NewInteger(0);
+        dart_args[2] = Dart_NewInteger(bytes_read);
+        // TODO(sgjesse): Cache the _makeUint8ListView function somewhere.
+        Dart_Handle io_lib =
+            Dart_LookupLibrary(DartUtils::NewString("dart:io"));
+        if (Dart_IsError(io_lib)) Dart_PropagateError(io_lib);
+        Dart_Handle array_view =
+            Dart_Invoke(io_lib,
+                        DartUtils::NewString("_makeUint8ListView"),
+                        kNumArgs,
+                        dart_args);
+        if (Dart_IsError(array_view)) Dart_PropagateError(array_view);
+        Dart_SetReturnValue(args, array_view);
+      } else {
+        Dart_SetReturnValue(args, external_array);
       }
-      Dart_SetReturnValue(args, external_array);
     }
   } else {
     OSError os_error(-1, "Invalid argument", OSError::kUnknown);
     Dart_Handle err = DartUtils::NewDartOSError(&os_error);
     if (Dart_IsError(err)) Dart_PropagateError(err);
     Dart_SetReturnValue(args, err);
   }
   Dart_ExitScope();
 }
 
@@ skipping 777 matching lines @@
   Dart_EnterScope();
   Dart_SetReturnValue(args, Dart_Null());
   Dart_Port service_port = File::GetServicePort();
   if (service_port != ILLEGAL_PORT) {
     // Return a send port for the service port.
     Dart_Handle send_port = Dart_NewSendPort(service_port);
     Dart_SetReturnValue(args, send_port);
   }
   Dart_ExitScope();
 }