Extract the correct os-error on Socket.write, and report correctly in IOSink.

sdk/lib/io/io_sink.dart

 // Copyright (c) 2013, 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.
 
 part of dart.io;
 
 /**
  * Helper class to wrap a [StreamConsumer<List<int>>] and provide
  * utility functions for writing to the StreamConsumer directly. The
  * [IOSink] buffers the input given by all [StringSink] methods and will delay
@@ skipping 44 matching lines @@
 }
 
 class _StreamSinkImpl<T> implements StreamSink<T> {
   final StreamConsumer<T> _target;
   Completer _doneCompleter = new Completer();
   Future _doneFuture;
   StreamController<T> _controllerInstance;
   Completer _controllerCompleter;
   bool _isClosed = false;
   bool _isBound = false;
+  bool _hasError = false;
 
   _StreamSinkImpl(StreamConsumer<T> this._target) {
     _doneFuture = _doneCompleter.future;
   }
 
   void add(T data) {
     _controller.add(data);
   }
 
   void addError(error) {
     _controller.addError(error);
   }
 
   Future addStream(Stream<T> stream) {
     if (_isBound) {
       throw new StateError("StreamSink is already bound to a stream");
     }
     _isBound = true;
+    if (_hasError) return done;
     // Wait for any sync operations to complete.
     Future targetAddStream() {
       return _target.addStream(stream)
           .whenComplete(() {
             _isBound = false;
           });
     }
     if (_controllerInstance == null) return targetAddStream();
     var future = _controllerCompleter.future;
     _controllerInstance.close();
@@ skipping 21 matching lines @@
               onError: (error) => _completeDone(error: error));
   }
 
   Future get done => _doneFuture;
 
   void _completeDone({value, error}) {
     if (_doneCompleter == null) return;
     if (error == null) {
       _doneCompleter.complete(value);
     } else {
+      _hasError = true;

[Bill Hesse, 2013/07/01 11:18:05]

Do you also want to set hasError in the case that _doneCompleter is null?

[Anders Johnsen, 2013/07/01 11:18:57]

No, it's just a guard to avoid us setting it twice (should not be possible,
except by bad API usage).

       _doneCompleter.completeError(error);
     }
     _doneCompleter = null;
   }
 
   StreamController<T> get _controller {
     if (_isBound) {
       throw new StateError("StreamSink is bound to a stream");
     }
     if (_isClosed) {
@@ skipping 84 matching lines @@
 
   void writeln([Object obj = ""]) {
     write(obj);
     write("\n");
   }
 
   void writeCharCode(int charCode) {
     write(new String.fromCharCode(charCode));
   }
 }