Function crypto_generichash_final 

pub fn crypto_generichash_final(
    state: GenericHashState,
    output: &mut [u8],
) -> Result<(), Error>

Finalizes the hash computation, copying the result into output. The length of output should match outlen from the call to crypto_generichash_init.

Equivalent to libsodium’s crypto_generichash_final

Errors

Returns an error if output is empty or longer than the maximum supported digest.