igfile_size the <a href="#file_datastream">LibRaw_file_datastream</a>
      will be used and the <a href="#bigfile_datastream">LibRaw_bigfile_datastream</a>
      otherwise.</p>
    <p>The function returns an integer number in accordance with the <a href="API-notes.html#errors">return
        code convention</a>: positive if any system call has returned an error,
      negative (from the <a href="API-datastruct.html#LibRaw_errors">LibRaw
        error list</a>) if there has been an error situation within Li