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------------------------------------------------------------------------------

--                                                                          --

--                         GNAT COMPILER COMPONENTS                         --

--                                                                          --

--                      G N A T . L O C K _ F I L E S                       --

--                                                                          --

--                                 B o d y                                  --

--                                                                          --

--          Copyright (C) 1998-2009, Free Software Foundation, Inc.         --

--                                                                          --

-- 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.      --

--                                                                          --

------------------------------------------------------------------------------

with System;

package body GNAT.Lock_Files is

   Dir_Separator : Character;

   pragma Import (C, Dir_Separator, "__gnat_dir_separator");

   ---------------

   -- Lock_File --

   ---------------

   procedure Lock_File

     (Directory      : Path_Name;

      Lock_File_Name : Path_Name;

      Wait           : Duration := 1.0;

      Retries        : Natural  := Natural'Last)

   is

      Dir  : aliased String := Directory & ASCII.NUL;

      File : aliased String := Lock_File_Name & ASCII.NUL;

      function Try_Lock (Dir, File : System.Address) return Integer;

      pragma Import (C, Try_Lock, "__gnat_try_lock");

   begin

      --  If a directory separator was provided, just remove the one we have

      --  added above.

      if Directory (Directory'Last) = Dir_Separator

        or else Directory (Directory'Last) = '/'

      then

         Dir (Dir'Last - 1) := ASCII.NUL;

      end if;

      --  Try to lock the file Retries times

      for I in 0 .. Retries loop

         if Try_Lock (Dir'Address, File'Address) = 1 then

            return;

         end if;

         exit when I = Retries;

         delay Wait;

      end loop;

      raise Lock_Error;

   end Lock_File;

   ---------------

   -- Lock_File --

   ---------------

   procedure Lock_File

     (Lock_File_Name : Path_Name;

      Wait           : Duration := 1.0;

      Retries        : Natural  := Natural'Last)

   is

   begin

      for J in reverse Lock_File_Name'Range loop

         if Lock_File_Name (J) = Dir_Separator

           or else Lock_File_Name (J) = '/'

         then

            Lock_File

              (Lock_File_Name (Lock_File_Name'First .. J - 1),

               Lock_File_Name (J + 1 .. Lock_File_Name'Last),

               Wait,

               Retries);

            return;

         end if;

      end loop;

      Lock_File (".", Lock_File_Name, Wait, Retries);

   end Lock_File;

   -----------------

   -- Unlock_File --

   -----------------

   procedure Unlock_File (Lock_File_Name : Path_Name) is

      S : aliased String := Lock_File_Name & ASCII.NUL;

      procedure unlink (A : System.Address);

      pragma Import (C, unlink, "unlink");

   begin

      unlink (S'Address);

   end Unlock_File;

   -----------------

   -- Unlock_File --

   -----------------

   procedure Unlock_File (Directory : Path_Name; Lock_File_Name : Path_Name) is

   begin

      if Directory (Directory'Last) = Dir_Separator

        or else Directory (Directory'Last) = '/'

      then

         Unlock_File (Directory & Lock_File_Name);

      else

         Unlock_File (Directory & Dir_Separator & Lock_File_Name);

      end if;

   end Unlock_File;

end GNAT.Lock_Files;