Add error handling.

Signed-off-by: Jon Seymour <jon@wildducktheories.com>
Make everything.

Signed-off-by: Jon Seymour <jon@wildducktheories.com>
(Partially) tolerate data records that are longer than the header, but report them on stderr.

Signed-off-by: Jon Seymour <jon@wildducktheories.com>