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

runtime/bin/socket.cc

 // 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.
 
 #include "bin/io_buffer.h"
 #include "bin/socket.h"
 #include "bin/dartutils.h"
 #include "bin/thread.h"
 #include "bin/utils.h"
 
@@ skipping 202 matching lines @@
   intptr_t total_bytes_written = 0;
   intptr_t bytes_written = 0;
   Dart_TypedData_Type type;
   uint8_t* buffer = NULL;
   intptr_t len;
   result = Dart_TypedDataAcquireData(buffer_obj, &type,
                                      reinterpret_cast<void**>(&buffer), &len);
   if (!Dart_IsError(result)) {
     buffer += offset;
     bytes_written = Socket::Write(socket, buffer, length);
-    if (bytes_written > 0) total_bytes_written = bytes_written;
-    Dart_TypedDataReleaseData(buffer_obj);
+    if (bytes_written >= 0) {
+      total_bytes_written = bytes_written;
+      Dart_TypedDataReleaseData(buffer_obj);
+    } else {
+      // Extract OSError before we release data, as it may override the error.
+      OSError os_error;
+      Dart_TypedDataReleaseData(buffer_obj);
+      Dart_SetReturnValue(args, DartUtils::NewDartOSError(&os_error));
+    }
   } else {
     // Send data in chunks of maximum 16KB.
     const intptr_t max_chunk_length =
         dart::Utils::Minimum(length, static_cast<intptr_t>(16 * KB));
     buffer = new uint8_t[max_chunk_length];
     do {
       intptr_t chunk_length =
           dart::Utils::Minimum(max_chunk_length, length - total_bytes_written);
       result = Dart_ListGetAsBytes(buffer_obj,
                                    offset + total_bytes_written,
                                    buffer,
                                    chunk_length);
       if (Dart_IsError(result)) {
         delete[] buffer;
         Dart_PropagateError(result);
       }
       bytes_written =
           Socket::Write(socket, reinterpret_cast<void*>(buffer), chunk_length);
-      if (bytes_written > 0) total_bytes_written += bytes_written;
+      if (bytes_written >= 0) {
+        total_bytes_written += bytes_written;
+      } else {
+        Dart_SetReturnValue(args, DartUtils::NewDartOSError());
+      }
     } while (bytes_written > 0 && total_bytes_written < length);
     delete[] buffer;
   }
   if (bytes_written >= 0) {
     Dart_SetReturnValue(args, Dart_NewInteger(total_bytes_written));
-  } else {
-    Dart_SetReturnValue(args, DartUtils::NewDartOSError());
   }
   Dart_ExitScope();
 }
 
 
 void FUNCTION_NAME(Socket_GetPort)(Dart_NativeArguments args) {
   Dart_EnterScope();
   Dart_Handle socket_obj = Dart_GetNativeArgument(args, 0);
   intptr_t socket = 0;
   Dart_Handle err = Socket::GetSocketIdNativeField(socket_obj, &socket);
@@ skipping 357 matching lines @@
   return Dart_SetNativeInstanceField(socket, kSocketIdNativeField, id);
 }
 
 
 Dart_Handle Socket::GetSocketIdNativeField(Dart_Handle socket, intptr_t* id) {
   return Dart_GetNativeInstanceField(socket, kSocketIdNativeField, id);
 }
 
 }  // namespace bin
 }  // namespace dart