How do I create a SecretVec which length is unknown? about secrets

[sandevins]

Nevermind, I found the error. It was a dumb problem due to copying.

The libsodium call should be like this.

Ok(SecretVec::<u8>::new(plaintext.len() + MAC_LEN, |s| {
        if -1 == unsafe {
            sodium::crypto_secretbox_easy(
                s.as_mut_ptr(),
                plaintext.borrow().as_ptr(),
                plaintext.len() as _,
                nonce.as_ptr(),
                key.borrow().as_ptr(),
            )
        } {
            panic!("failed");
        }
    }))

The MAC len has to be added to the length.