io_read_buf_alloc
void io_read_buf_alloc(struct ibuf *, void **, size_t *);
io_read_buf_alloc(b, (void **)&ent->data, &ent->datasz);
io_read_buf_alloc(b, (void **)&data, &dsz);
io_read_buf_alloc(b, (void **)&p->spki, &p->spkisz);