Function sbuf_copyin

freebsd/kern/subr_sbuf.c:554–588

* Append a string from userland to an sbuf. */

 * Append a string from userland to an sbuf.
 */
int
sbuf_copyin(struct sbuf *s, const void *uaddr, size_t len)
{
	size_t done;

	assert_sbuf_integrity(s);
	assert_sbuf_state(s, 0);
	KASSERT(s->s_drain_func == NULL,
	    ("Nonsensical copyin to sbuf %p with a drain", s));

	if (s->s_error != 0)
		return (-1);

	if (len == 0)
		len = SBUF_FREESPACE(s);	/* XXX return 0? */
	if (len > SBUF_FREESPACE(s)) {
		sbuf_extend(s, len);
		if (SBUF_FREESPACE(s) < len)
			len = SBUF_FREESPACE(s);
	}
	switch (copyinstr(uaddr, s->s_buf + s->s_len, len + 1, &done)) {
	case ENAMETOOLONG:
		s->s_error = ENOMEM;
		/* fall through */
	case 0:
		s->s_len += done - 1;
		if (SBUF_ISSECTION(s))
			s->s_sect_len += done - 1;
		break;
	default:
		return (-1);	/* XXX */
	}

	return (done);
}
#endif

/*