--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/gcc/ada/libgnat/g-locfil.ads	Fri Oct 27 22:46:09 2017 +0900
@@ -0,0 +1,72 @@
+------------------------------------------------------------------------------
+--                                                                          --
+--                         GNAT COMPILER COMPONENTS                         --
+--                                                                          --
+--                      G N A T . L O C K _ F I L E S                       --
+--                                                                          --
+--                                 S p e c                                  --
+--                                                                          --
+--                     Copyright (C) 1995-2017, 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 package contains the necessary routines for using files for the
+--  purpose of providing reliable system wide locking capability.
+
+package GNAT.Lock_Files is
+   pragma Preelaborate;
+
+   Lock_Error : exception;
+   --  Exception raised if file cannot be locked
+
+   subtype Path_Name is String;
+   --  Pathname is used by all services provided in this unit to specify
+   --  directory name and file name. On DOS based systems both directory
+   --  separators are handled (i.e. slash and backslash).
+
+   procedure Lock_File
+     (Directory      : Path_Name;
+      Lock_File_Name : Path_Name;
+      Wait           : Duration := 1.0;
+      Retries        : Natural  := Natural'Last);
+   --  Create a lock file Lock_File_Name in directory Directory. If the file
+   --  cannot be locked because someone already owns the lock, this procedure
+   --  waits Wait seconds and retries at most Retries times. If the file
+   --  still cannot be locked, Lock_Error is raised. The default is to try
+   --  every second, almost forever (Natural'Last times). The full path of
+   --  the file is constructed by concatenating Directory and Lock_File_Name.
+   --  Directory can optionally terminate with a directory separator.
+
+   procedure Lock_File
+     (Lock_File_Name : Path_Name;
+      Wait           : Duration := 1.0;
+      Retries        : Natural  := Natural'Last);
+   --  See above. The full lock file path is given as one string
+
+   procedure Unlock_File (Directory : Path_Name; Lock_File_Name : Path_Name);
+   --  Unlock a file. Directory can optionally terminate with a directory
+   --  separator.
+
+   procedure Unlock_File (Lock_File_Name : Path_Name);
+   --  Unlock a file whose full path is given in Lock_File_Name
+
+end GNAT.Lock_Files;