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------------------------------------------------------------------------------
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-- --
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-- GNAT COMPILER COMPONENTS --
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-- --
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-- G N A T . L O C K _ F I L E S --
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-- --
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-- S p e c --
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-- --
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-- Copyright (C) 1995-2008, AdaCore --
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-- --
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-- GNAT is free software; you can redistribute it and/or modify it under --
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-- terms of the GNU General Public License as published by the Free Soft- --
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-- ware Foundation; either version 2, or (at your option) any later ver- --
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-- sion. GNAT is distributed in the hope that it will be useful, but WITH- --
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-- OUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY --
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-- or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License --
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-- for more details. You should have received a copy of the GNU General --
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-- Public License distributed with GNAT; see file COPYING. If not, write --
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-- to the Free Software Foundation, 51 Franklin Street, Fifth Floor, --
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-- Boston, MA 02110-1301, USA. --
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-- --
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-- As a special exception, if other files instantiate generics from this --
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-- unit, or you link this unit with other files to produce an executable, --
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-- this unit does not by itself cause the resulting executable to be --
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-- covered by the GNU General Public License. This exception does not --
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-- however invalidate any other reasons why the executable file might be --
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-- covered by the GNU Public License. --
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-- --
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-- GNAT was originally developed by the GNAT team at New York University. --
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-- Extensive contributions were provided by Ada Core Technologies Inc. --
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-- --
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------------------------------------------------------------------------------
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-- This package contains the necessary routines for using files for the
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-- purpose of providing reliable system wide locking capability.
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package GNAT.Lock_Files is
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pragma Preelaborate;
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Lock_Error : exception;
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-- Exception raised if file cannot be locked
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subtype Path_Name is String;
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-- Pathname is used by all services provided in this unit to specified
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-- directory name and file name. On DOS based systems both directory
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-- separators are handled (i.e. slash and backslash).
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procedure Lock_File
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(Directory : Path_Name;
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Lock_File_Name : Path_Name;
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Wait : Duration := 1.0;
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Retries : Natural := Natural'Last);
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-- Create a lock file Lock_File_Name in directory Directory. If the file
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-- cannot be locked because someone already owns the lock, this procedure
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-- waits Wait seconds and retries at most Retries times. If the file
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-- still cannot be locked, Lock_Error is raised. The default is to try
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-- every second, almost forever (Natural'Last times). The full path of
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-- the file is constructed by concatenating Directory and Lock_File_Name.
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-- Directory can optionally terminate with a directory separator.
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procedure Lock_File
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(Lock_File_Name : Path_Name;
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Wait : Duration := 1.0;
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Retries : Natural := Natural'Last);
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-- See above. The full lock file path is given as one string
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procedure Unlock_File (Directory : Path_Name; Lock_File_Name : Path_Name);
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-- Unlock a file. Directory can optionally terminate with a directory
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-- separator.
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procedure Unlock_File (Lock_File_Name : Path_Name);
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-- Unlock a file whose full path is given in Lock_File_Name
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end GNAT.Lock_Files;
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