Function sbuf_trim

freebsd/kern/subr_sbuf.c:771–790

* Trim whitespace characters from end of an sbuf. */

 * Trim whitespace characters from end of an sbuf.
 */
int
sbuf_trim(struct sbuf *s)
{

	assert_sbuf_integrity(s);
	assert_sbuf_state(s, 0);
	KASSERT(s->s_drain_func == NULL,
	    ("%s makes no sense on sbuf %p with drain", __func__, s));

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

	while (s->s_len > 0 && isspace(s->s_buf[s->s_len-1])) {
		--s->s_len;
		if (SBUF_ISSECTION(s))
			s->s_sect_len--;
	}

	return (0);
}

/*
 * Check if an sbuf has an error.