Checking If File Is In Use

IsFileInUse will return true if the file is locked for exclusive access. It would fail if the file doesn't exist at all. 
 

function IsFileInUse(fName : string) : boolean;
var
    HFileRes : HFILE;
begin
    Result := false;
    if not FileExists(fName) then exit;
    HFileRes :=
      CreateFile(pchar(fName),
                 GENERIC_READ or GENERIC_WRITE,
                 0, nil, OPEN_EXISTING,
                 FILE_ATTRIBUTE_NORMAL,
                 0) ;
    Result := (HFileRes = INVALID_HANDLE_VALUE) ;
    if not Result then
    CloseHandle
end;