Extend dart:io error handling to all socket functions

runtime/bin/utils_win.cc

 // Copyright (c) 2012, 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 <errno.h>
 
 #include "bin/utils.h"
 
+static void FormatMessageIntoBuffer(DWORD code,
+                                    char* buffer,
+                                    int buffer_length) {
+  DWORD message_size =
+      FormatMessage(FORMAT_MESSAGE_FROM_SYSTEM | FORMAT_MESSAGE_IGNORE_INSERTS,
+                    NULL,
+                    code,
+                    MAKELANGID(LANG_NEUTRAL, SUBLANG_DEFAULT),
+                    buffer,
+                    buffer_length,
+                    NULL);
+  if (message_size == 0) {
+    if (GetLastError() != ERROR_INSUFFICIENT_BUFFER) {
+      fprintf(stderr, "FormatMessage failed %d\n", GetLastError());
+    }
+    snprintf(buffer, buffer_length, "OS Error %d", code);
+  }
+  buffer[buffer_length - 1] = '\0';
+}
+
+
 OSError::OSError() : sub_system_(kSystem), code_(0), message_(NULL) {
   set_code(GetLastError());
 
   static const int kMaxMessageLength = 256;
   char message[kMaxMessageLength];
-  DWORD message_size =
-      FormatMessage(FORMAT_MESSAGE_FROM_SYSTEM | FORMAT_MESSAGE_IGNORE_INSERTS,
-                    NULL,
-                    code_,
-                    MAKELANGID(LANG_NEUTRAL, SUBLANG_DEFAULT),
-                    message,
-                    kMaxMessageLength,
-                    NULL);
-  if (message_size == 0) {
-    if (GetLastError() != ERROR_INSUFFICIENT_BUFFER) {
-      fprintf(stderr, "FormatMessage failed %d\n", GetLastError());
-    }
-    snprintf(message, kMaxMessageLength, "OS Error %d", code_);
-  }
-  message[kMaxMessageLength - 1] = '\0';
-
+  FormatMessageIntoBuffer(code_, message, kMaxMessageLength);
   SetMessage(message);
 }
+
+void OSError::SetCodeAndMessage(SubSystem sub_system, int code) {
+  set_sub_system(sub_system);
+  set_code(code);
+
+  static const int kMaxMessageLength = 256;
+  char message[kMaxMessageLength];
+  FormatMessageIntoBuffer(code_, message, kMaxMessageLength);
+  SetMessage(message);
+}