struct MetaBuffer<'a> {
    buffers: &'a [&'a [u8]]
}

impl <'a> MetaBuffer<'a> {
    fn slice<'b>(&self, mut start: usize, mut length: usize, slice_buffer: &'b mut Vec<&'a [u8]>) -> &'b [&[u8]] {

        let mut i = 0;
        for buffer in self.buffers {
            if buffer.len() <= start {
                start -= buffer.len();
                i += 1;
            } else {
                break;
            }
        }
        let to_take = (self.buffers[i].len() - start).min(length);
        slice_buffer.push(&self.buffers[i][start .. start + to_take]);
        length -= to_take;
        while length > 0 {
            i += 1;
            let to_take = self.buffers[i].len().min(length);
            slice_buffer.push(&self.buffers[i][..to_take]);
            length -= to_take;
        }
        &slice_buffer[..]
    }
}

pub fn main() {
    let a = [1,2,3];
    let b = [4,5];
    let c = [6,7,8];
    let buffers = [&a[..], &b[..], &c[..]];
    let meta_buffer = MetaBuffer { buffers: &buffers[..] };
    let mut result_buffer = vec![];
    let my_slice = meta_buffer.slice(2, 4, &mut result_buffer);
    println!("{:?}", my_slice);
}