Incomplete body reading

[CorefLava]

Hi, recently some trouble pushed me to look into function ngx_http_dyups_read_body and find these codes:

    cl = r->request_body->bufs;
    buf = cl->buf;

    if (cl->next == NULL) {

        return buf;

    } else {

        next = cl->next->buf;
        len = (buf->last - buf->pos) + (next->last - next->pos);

        body = ngx_create_temp_buf(r->pool, len);
        if (body == NULL) {
            return NULL;
        }

        body->last = ngx_cpymem(body->last, buf->pos, buf->last - buf->pos);
        body->last = ngx_cpymem(body->last, next->pos, next->last - next->pos);
    }

In the code above, dyups may only read the first two parts of buf chain, and the peril is, may cause body data incomplete, comparing with ngx_http_variable_request_body in ngx_http_variables.c:

    len = buf->last - buf->pos;
    cl = cl->next;

    for ( /* void */ ; cl; cl = cl->next) {
        buf = cl->buf;
        len += buf->last - buf->pos;
    }

    p = ngx_pnalloc(r->pool, len);
    if (p == NULL) {
        return NGX_ERROR;
    }

    v->data = p;
    cl = r->request_body->bufs;

    for ( /* void */ ; cl; cl = cl->next) {
        buf = cl->buf;
        p = ngx_cpymem(p, buf->pos, buf->last - buf->pos);
    }

Imo, if body reading ceases at some coincidence place, dyups syncing may succeed and cause unexpected problems.

So ist a bug? Or else why its safe?