// [012345......]
uint32_t tailsize = buf->size - buf->offset;
memcpy(newdata, buf->data + buf->offset, tailsize);
- memcpy(newdata + tailsize, buf->data, buf->used - buf->offset);
+ memcpy(newdata + tailsize, buf->data, buf->used - tailsize);
} else {
// Old situation:
// [....012345..]