The following function will return True if a file is read only.
function IsReadOnly(const FileName: string): Boolean;
var
sr: TSearchRec;
begin
(* Assume not read only *)
Result := False;
if FindFirst(FileName, faAnyFile, sr) = 0 then
begin
Result := (sr.Attr and faReadOnly) <> 0;
FindClose(sr);
end;
end;