File : agpl-safe_file.adb
------------------------------------------------------------------------------
-- ADAGIO - ADALID - AENEA. --
-- --
-- Copyright (C) 2003 --
-- A. Mosteo. --
-- --
-- Authors: A. Mosteo. (adagio@mosteo.com) --
-- --
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-- them to the above email. --
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-- This program is free software; you can redistribute it and/or modify --
-- it under the terms of the GNU General Public License as published by --
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-- your option) any later version. --
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-- This program is distributed in the hope that it will be useful, but --
-- WITHOUT ANY WARRANTY; without even the implied warranty of --
-- MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU --
-- General Public License for more details. --
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-- You should have received a copy of the GNU General Public License --
-- along with this library; if not, write to the Free Software Foundation, --
-- Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA. --
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-- You are not allowed to use any part of this code to develop a program --
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------------------------------------------------------------------------------
-- $Id: agpl-safe_file.adb,v 1.3 2004/01/21 21:05:25 Jano Exp $
-- Facilities for saving/loading from a file in a way that it doesn't
-- overwrite the previous version.
-- When opening for writing, a temporary is used. After completion, the
-- original file is removed and the temporary renamed.
-- When opening for reading, regular filename is tried. If missing, a check
-- for a temporary is made, and if it exists, it is renamed to the regular
-- name and opened. If neither regular and temporary exists, error.
with Ada.Streams.Stream_IO;
use Ada.Streams.Stream_IO;
with Gnat.Os_lib;
use Gnat;
package body Agpl.Safe_file is
------------------------------------------------------------------------
-- Exists_for_reading --
------------------------------------------------------------------------
function Exists_for_reading (Name : in String) return Boolean is
begin
return Os_lib.Is_regular_file (Name) or else
Os_lib.Is_regular_file (Name & ".tmp");
end Exists_for_reading;
------------------------------------------------------------------------
-- Get_Real_Name --
------------------------------------------------------------------------
-- Gets the real name found (i.e. the supplied or the backup one
function Get_Real_Name (Name : in String) return String is
begin
if Os_Lib.Is_Regular_File (Name) then
return Name;
elsif Os_Lib.Is_Regular_File (Name & ".tmp") then
return Name & ".tmp";
else
raise File_Not_Found;
end if;
end Get_Real_Name;
------------------------------------------------------------------------
-- Open --
------------------------------------------------------------------------
-- Accepts In_file and Out_file
procedure Open (
File : in out Stream_IO.File_type;
Mode : in Stream_IO.File_mode;
Name : in String := "";
Form : in String := "")
is
Success : Boolean;
begin
case Mode is
when In_file =>
if Os_lib.Is_regular_file (Name & ".tmp") and
not Os_lib.Is_regular_file (Name)
then
Os_lib.Rename_file (Name & ".tmp", Name, Success);
if not Success then
raise Storage_error;
end if;
end if;
Stream_io.Open (File, Mode, Name, Form);
when Out_file =>
Stream_io.Create (File, Mode, Name & ".tmp", Form);
when Append_file =>
raise Unimplemented;
end case;
end Open;
------------------------------------------------------------------------
-- Close --
------------------------------------------------------------------------
procedure Close (File : in out Stream_IO.File_type) is
Filename : String := Stream_IO.Name (File);
Success : Boolean;
begin
case Mode (File) is
when In_file =>
Stream_IO.Close (File);
when Out_file =>
Stream_IO.Close (File);
-- Delete previous, if exists:
if Os_lib.Is_regular_file (
Filename (Filename'First .. Filename'Last - 4))
then
Os_lib.Delete_file (
Filename (Filename'First .. Filename'Last - 4), Success);
if not Success then
raise Storage_error;
end if;
end if;
-- Rename file:
Os_lib.Rename_file (
Filename,
Filename (Filename'First .. Filename'Last - 4),
Success);
if not Success then
raise Storage_error;
end if;
when Append_file =>
raise Unimplemented;
end case;
end Close;
end Agpl.Safe_file;