--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/gcc/ada/libgnat/g-stseme.adb	Fri Oct 27 22:46:09 2017 +0900
@@ -0,0 +1,48 @@
+------------------------------------------------------------------------------
+--                                                                          --
+--                         GNAT COMPILER COMPONENTS                         --
+--                                                                          --
+--                  GNAT.SOCKETS.THIN.SOCKET_ERROR_MESSAGE                  --
+--                                                                          --
+--                                 B o d y                                  --
+--                                                                          --
+--                     Copyright (C) 2007-2017, AdaCore                     --
+--                                                                          --
+-- GNAT is free software;  you can  redistribute it  and/or modify it under --
+-- terms of the  GNU General Public License as published  by the Free Soft- --
+-- ware  Foundation;  either version 3,  or (at your option) any later ver- --
+-- sion.  GNAT is distributed in the hope that it will be useful, but WITH- --
+-- OUT ANY WARRANTY;  without even the  implied warranty of MERCHANTABILITY --
+-- or FITNESS FOR A PARTICULAR PURPOSE.                                     --
+--                                                                          --
+-- As a special exception under Section 7 of GPL version 3, you are granted --
+-- additional permissions described in the GCC Runtime Library Exception,   --
+-- version 3.1, as published by the Free Software Foundation.               --
+--                                                                          --
+-- You should have received a copy of the GNU General Public License and    --
+-- a copy of the GCC Runtime Library Exception along with this program;     --
+-- see the files COPYING3 and COPYING.RUNTIME respectively.  If not, see    --
+-- <http://www.gnu.org/licenses/>.                                          --
+--                                                                          --
+-- GNAT was originally developed  by the GNAT team at  New York University. --
+-- Extensive contributions were provided by Ada Core Technologies Inc.      --
+--                                                                          --
+------------------------------------------------------------------------------
+
+--  This is the default implementation of this unit, using the standard C
+--  library's strerror(3) function. It is used on all platforms except Windows,
+--  since on that platform socket errno values are distinct from the system
+--  ones: there is a specific variant of this function in g-socthi-mingw.adb.
+
+separate (GNAT.Sockets.Thin)
+
+--------------------------
+-- Socket_Error_Message --
+--------------------------
+
+function Socket_Error_Message
+  (Errno : Integer) return String
+is
+begin
+   return Errno_Message (Errno, Default => "Unknown system error");
+end Socket_Error_Message;