Remove a cr before each lf
delcr
delcr removes a CR at the end of each line of input, if a CR is present. It also removes a CR at the end of a partial final line.
The pipeline
addcr | delcr
prints an exact copy of its input.
Some vendors ship dos2unix or dos2bsd tools similar to delcr. Those tools often blow up on long lines and nulls. delcr has no trouble with long lines and nulls.