gcc/ada/g-locfil.adb

   1 ------------------------------------------------------------------------------
   2 --                                                                          --
   3 --                         GNAT COMPILER COMPONENTS                         --
   4 --                                                                          --
   5 --                      G N A T . L O C K _ F I L E S                       --
   6 --                                                                          --
   7 --                                 B o d y                                  --
   8 --                                                                          --
   9 --                            $Revision: 1.1 $
  10 --                                                                          --
  11 --          Copyright (C) 1998-2001 Free Software Foundation, Inc.          --
  12 --                                                                          --
  13 -- GNAT is free software;  you can  redistribute it  and/or modify it under --
  14 -- terms of the  GNU General Public License as published  by the Free Soft- --
  15 -- ware  Foundation;  either version 2,  or (at your option) any later ver- --
  16 -- sion.  GNAT is distributed in the hope that it will be useful, but WITH- --
  17 -- OUT ANY WARRANTY;  without even the  implied warranty of MERCHANTABILITY --
  18 -- or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License --
  19 -- for  more details.  You should have  received  a copy of the GNU General --
  20 -- Public License  distributed with GNAT;  see file COPYING.  If not, write --
  21 -- to  the Free Software Foundation,  59 Temple Place - Suite 330,  Boston, --
  22 -- MA 02111-1307, USA.                                                      --
  23 --                                                                          --
  24 -- As a special exception,  if other files  instantiate  generics from this --
  25 -- unit, or you link  this unit with other files  to produce an executable, --
  26 -- this  unit  does not  by itself cause  the resulting  executable  to  be --
  27 -- covered  by the  GNU  General  Public  License.  This exception does not --
  28 -- however invalidate  any other reasons why  the executable file  might be --
  29 -- covered by the  GNU Public License.                                      --
  30 --                                                                          --
  31 -- Extensive contributions were provided by Ada Core Technologies Inc.   --
  32 --                                                                          --
  33 ------------------------------------------------------------------------------
  34
  35 with System;
  36
  37 package body GNAT.Lock_Files is
  38
  39    Dir_Separator : Character;
  40    pragma Import (C, Dir_Separator, "__gnat_dir_separator");
  41
  42    ---------------
  43    -- Lock_File --
  44    ---------------
  45
  46    procedure Lock_File
  47      (Directory      : String;
  48       Lock_File_Name : String;
  49       Wait           : Duration := 1.0;
  50       Retries        : Natural  := Natural'Last)
  51    is
  52       Dir  : aliased String := Directory & ASCII.NUL;
  53       File : aliased String := Lock_File_Name & ASCII.NUL;
  54
  55       function Try_Lock (Dir, File : System.Address) return Integer;
  56       pragma Import (C, Try_Lock, "__gnat_try_lock");
  57
  58    begin
  59       for I in 0 .. Retries loop
  60          if Try_Lock (Dir'Address, File'Address) = 1 then
  61             return;
  62          end if;
  63          exit when I = Retries;
  64          delay Wait;
  65       end loop;
  66       raise Lock_Error;
  67    end Lock_File;
  68
  69    ---------------
  70    -- Lock_File --
  71    ---------------
  72
  73    procedure Lock_File
  74      (Lock_File_Name : String;
  75       Wait           : Duration := 1.0;
  76       Retries        : Natural  := Natural'Last)
  77    is
  78    begin
  79       for J in reverse Lock_File_Name'Range loop
  80          if Lock_File_Name (J) = Dir_Separator then
  81             Lock_File
  82               (Lock_File_Name (Lock_File_Name'First .. J - 1),
  83                Lock_File_Name (J + 1 .. Lock_File_Name'Last),
  84                Wait,
  85                Retries);
  86             return;
  87          end if;
  88       end loop;
  89
  90       Lock_File (".", Lock_File_Name, Wait, Retries);
  91    end Lock_File;
  92
  93    -----------------
  94    -- Unlock_File --
  95    -----------------
  96
  97    procedure Unlock_File (Lock_File_Name : String) is
  98       S : aliased String := Lock_File_Name & ASCII.NUL;
  99
 100       procedure unlink (A : System.Address);
 101       pragma Import (C, unlink, "unlink");
 102
 103    begin
 104       unlink (S'Address);
 105    end Unlock_File;
 106
 107    -----------------
 108    -- Unlock_File --
 109    -----------------
 110
 111    procedure Unlock_File (Directory : String; Lock_File_Name : String) is
 112    begin
 113       Unlock_File (Directory & Dir_Separator & Lock_File_Name);
 114    end Unlock_File;
 115
 116 end GNAT.Lock_Files;