Как получить имя программы, с которой ассоциировано то или иное расширение

uses

{$IFDEF WIN32}
  Registry; {We will get it from the registry}
{$ELSE}
  IniFiles; {We will get it from the win.ini file}
{$ENDIF}

{$IFNDEF WIN32}
const

  MAX_PATH = 144;
{$ENDIF}

function
 GetProgramAssociation(Ext: string
): string
;
var

{$IFDEF WIN32}
  reg: TRegistry;
  s: string
;
{$ELSE}
  WinIni: TIniFile;
  WinIniFileName: array
[0..MAX_PATH] of
 char;
  s: string
;
{$ENDIF}
begin

{$IFDEF WIN32}
  s := '';
  reg := TRegistry.Create;
  reg.RootKey := HKEY_CLASSES_ROOT;
  if
 reg.OpenKey('.' + ext + 'shellopencommand',
    false
) <> false
 then

  begin

    {The open command has been found}
    s := reg.ReadString('');
    reg.CloseKey;
  end

  else

  begin

    {perhaps thier is a system file pointer}
    if
 reg.OpenKey('.' + ext,
      false
) <> false
 then

    begin

      s := reg.ReadString('');
      reg.CloseKey;
      if
 s <> '' then

      begin

        {A system file pointer was found}
        if
 reg.OpenKey(s + 'shellopencommand',
          false
) <> false
 then

          {The open command has been found}
          s := reg.ReadString('');
        reg.CloseKey;
      end
;
    end
;
  end
;
  {Delete any command line, quotes and spaces}
  if
 Pos('%', s) > 0 then

    Delete(s, Pos('%', s), length(s));
  if
 ((length(s) > 0) and

    (s[1] = '"')) then

    Delete(s, 1, 1);
  if
 ((length(s) > 0) and

    (s[length(s)] = '"')) then

    Delete(s, Length(s), 1);
  while
 ((length(s) > 0) and

    ((s[length(s)] = #32) or

    (s[length(s)] = '"'))) do

    Delete(s, Length(s), 1);
{$ELSE}
  GetWindowsDirectory(WinIniFileName, sizeof(WinIniFileName));
  StrCat(WinIniFileName, 'win.ini');
  WinIni := TIniFile.Create(WinIniFileName);
  s := WinIni.ReadString('Extensions',
    ext,
    '');
  WinIni.Free;
  {Delete any command line}
  if
 Pos(' ^', s) > 0 then

    Delete(s, Pos(' ^', s), length(s));
{$ENDIF}
  result := s;
end
;

procedure
 TForm1.Button1Click(Sender: TObject);
begin

  ShowMessage(GetProgramAssociation('gif'));
end
;

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