Extend dart:io error handling to all socket functions

runtime/bin/utils_win.cc

Index: runtime/bin/utils_win.cc
diff --git a/runtime/bin/utils_win.cc b/runtime/bin/utils_win.cc
index a3813f4b437b274d207b376e97904799ea8ff2fa..0dba5b5f7af60d343302de0ca3c8961c561d5fef 100644
--- a/runtime/bin/utils_win.cc
+++ b/runtime/bin/utils_win.cc
@@ -6,26 +6,42 @@
 
 #include "bin/utils.h"
 
-OSError::OSError() : sub_system_(kSystem), code_(0), message_(NULL) {
-  set_code(GetLastError());
-
-  static const int kMaxMessageLength = 256;
-  char message[kMaxMessageLength];
+static void FormatMessageIntoBuffer(DWORD code,
+                                    char* buffer,
+                                    int buffer_length) {
   DWORD message_size =
       FormatMessage(FORMAT_MESSAGE_FROM_SYSTEM | FORMAT_MESSAGE_IGNORE_INSERTS,
                     NULL,
-                    code_,
+                    code,
                     MAKELANGID(LANG_NEUTRAL, SUBLANG_DEFAULT),
-                    message,
-                    kMaxMessageLength,
+                    buffer,
+                    buffer_length,
                     NULL);
   if (message_size == 0) {
     if (GetLastError() != ERROR_INSUFFICIENT_BUFFER) {
       fprintf(stderr, "FormatMessage failed %d\n", GetLastError());
     }
-    snprintf(message, kMaxMessageLength, "OS Error %d", code_);
+    snprintf(buffer, buffer_length, "OS Error %d", code);
   }
-  message[kMaxMessageLength - 1] = '\0';
+  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];
+  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);
 }