CheckHeader Reads and validates a header previously written with writeHeader(DataOutput, String, int).

CheckHeaderNoMagic Like checkHeader(DataInput, String, int, int) except this version assumes the first int has already been read and validated from the input.

FooterLength Computes the length of a codec footer.

WriteFooter Writes a codec footer, which records both a checksum algorithm ID and a checksum.

WriteHeader Writes a codec header, which records both a string to identify the file and a version number.