Added synchronous socket implementation to dart:io.

runtime/bin/sync_socket.h

Index: runtime/bin/sync_socket.h
diff --git a/runtime/bin/sync_socket.h b/runtime/bin/sync_socket.h
new file mode 100644
index 0000000000000000000000000000000000000000..4a918365aa79548c4d769668485a86064e3f6627
--- /dev/null
+++ b/runtime/bin/sync_socket.h
@@ -0,0 +1,48 @@
+// Copyright (c) 2017, 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.
+
+#ifndef RUNTIME_BIN_SYNC_SOCKET_H_
+#define RUNTIME_BIN_SYNC_SOCKET_H_
+
+#if defined(DART_IO_DISABLED)
+#error "sync_socket.h can only be included on builds with IO enabled"
+#endif
+
+#include "bin/socket_base.h"
+#include "platform/globals.h"
+
+namespace dart {
+namespace bin {
+
+class SynchronousSocket {
+ public:
+  explicit SynchronousSocket(intptr_t fd);
+  ~SynchronousSocket() { ASSERT(fd_ == kClosedFd); }
+
+  intptr_t fd() const { return fd_; }
+  void SetClosedFd();
+
+  static bool Initialize();
+
+  static intptr_t CreateConnect(const RawAddr& addr);
+
+  static Dart_Handle SetSocketIdNativeField(Dart_Handle handle, intptr_t id);
+  static Dart_Handle GetSocketIdNativeField(Dart_Handle socket_obj,
+                                            SynchronousSocket** socket);
+
+  static void ShutdownRead(intptr_t fd);
+  static void ShutdownWrite(intptr_t fd);
+
+ private:
+  static const int kClosedFd = -1;
+
+  intptr_t fd_;
+
+  DISALLOW_COPY_AND_ASSIGN(SynchronousSocket);
+};
+
+}  // namespace bin
+}  // namespace dart
+
+#endif  // RUNTIME_BIN_SYNC_SOCKET_H_