fn window_ending(file: &mut File, end: u64, take: u64) -> Result<Window>Expand description
Read up to take bytes ending at end, and the byte before the window as
well.
That one byte is what says whether the window starts on a row. A window beginning exactly at a row’s first byte holds that whole row; one beginning anywhere else holds a fragment of the row before it, and the two are indistinguishable from inside the window.