Encoded length larger than max_encoding_length when source length is divisible by 254

[sandermirme]

When source data doesn't contain any zero bytes and the data length is divisible by 254 then cobs.rs encoded data will be larger that the maximum size returned by max_encoding_length method.

use cobs::encode;

const SIZE: usize = 254;

fn main() {
    let mut dest = [0u8; SIZE * 2];
    let src = [1u8; SIZE];

    let size = encode(&src, &mut dest);
    let maxsize = cobs::max_encoding_length(SIZE);

    println!("maxsize: {}", maxsize);
    println!("size: {}", size);
}

prints:

maxsize: 255
size: 256

[robamu]

I tried this with C code

#include <iostream>
#include <cstring>
#include "cobs.h"

static constexpr size_t SIZE = 254;

int main(int, char**) {
    uint8_t destination[SIZE * 2] = {};
    uint8_t src[SIZE];
    std::memset(src, 1, sizeof(src));
    size_t encodedLen =  cobsEncode(src, sizeof(src), destination);
    printf("Encoded length: %zu", encodedLen);
}

where the cobsEncode is the one from wikipedia. The encoded length is 255 here