fn pad(buf: &[u8], len: usize) -> Result<Vec<u8>, Error>Expand description
Creates a new vector with bytes in buf, left-padded with zeros so
that the result is exactly len big.
§Errors
Returns an crate::Error::Default, if the input buffer buf is
longer than the targeted len.
§Examples
let input = vec![1, 2, 3];
let output = pad(&input, 4)?;
assert_eq!(output, vec![0, 1, 2, 3]);