libbpf: Add ring__consume

Add ring__consume to consume a single ringbuffer, analogous to
ring_buffer__consume.

Signed-off-by: Martin Kelly <martin.kelly@crowdstrike.com>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/bpf/20230925215045.2375758-14-martin.kelly@crowdstrike.com

src/ringbuf.c

@@ -371,6 +371,17 @@ int ring__map_fd(const struct ring *r)
 	return r->map_fd;
 }
 
+int ring__consume(struct ring *r)
+{
+	int64_t res;
+
+	res = ringbuf_process_ring(r);
+	if (res < 0)
+		return libbpf_err(res);
+
+	return res > INT_MAX ? INT_MAX : res;
+}
+
 static void user_ringbuf_unmap_ring(struct user_ring_buffer *rb)
 {
 	if (rb->consumer_pos) {