--- /dev/null
+#include <ccan/io/io.h>
+/* Include the C files directly. */
+#include <ccan/io/poll.c>
+#include <ccan/io/io.c>
+#include <ccan/tap/tap.h>
+#include <sys/wait.h>
+#include <stdio.h>
+
+#define NUM 100
+#define NUM_ITERS 1000
+
+struct buffer {
+ int iters;
+ struct io_conn *reader, *writer;
+ char buf[32];
+};
+
+static struct io_op *poke_writer(struct io_conn *conn, struct buffer *buf);
+static struct io_op *poke_reader(struct io_conn *conn, struct buffer *buf);
+
+static struct io_op *do_read(struct io_conn *conn, struct buffer *buf)
+{
+ assert(conn == buf->reader);
+
+ return io_read(&buf->buf, sizeof(buf->buf),
+ io_next(conn, poke_writer, buf));
+}
+
+static struct io_op *do_write(struct io_conn *conn, struct buffer *buf)
+{
+ assert(conn == buf->writer);
+
+ return io_write(&buf->buf, sizeof(buf->buf),
+ io_next(conn, poke_reader, buf));
+}
+
+static struct io_op *poke_writer(struct io_conn *conn, struct buffer *buf)
+{
+ assert(conn == buf->reader);
+
+ if (buf->iters == NUM_ITERS)
+ return io_close(conn, NULL);
+
+ /* You write. */
+ io_wake(buf->writer, do_write, buf);
+
+ /* I'll wait until you wake me. */
+ return io_idle(conn);
+}
+
+static struct io_op *poke_reader(struct io_conn *conn, struct buffer *buf)
+{
+ assert(conn == buf->writer);
+ /* You read. */
+ io_wake(buf->reader, do_read, buf);
+
+ if (++buf->iters == NUM_ITERS)
+ return io_close(conn, NULL);
+
+ /* I'll wait until you tell me to write. */
+ return io_idle(conn);
+}
+
+static struct io_op *reader(struct io_conn *conn, struct buffer *buf)
+{
+ assert(conn == buf->reader);
+
+ /* Wait for writer to tell us to read. */
+ return io_idle(conn);
+}
+
+static struct buffer buf[NUM];
+
+int main(void)
+{
+ unsigned int i;
+ int fds[2], last_read, last_write;
+
+ plan_tests(5 + NUM);
+
+ ok1(pipe(fds) == 0);
+ last_read = fds[0];
+ last_write = fds[1];
+
+ for (i = 1; i < NUM; i++) {
+ if (pipe(fds) < 0)
+ break;
+ memset(buf[i].buf, i, sizeof(buf[i].buf));
+ sprintf(buf[i].buf, "%i-%i", i, i);
+
+ buf[i].reader = io_new_conn(last_read, reader, NULL, &buf[i]);
+ if (!buf[i].reader)
+ break;
+ buf[i].writer = io_new_conn(fds[1], do_write, NULL, &buf[i]);
+ if (!buf[i].writer)
+ break;
+ last_read = fds[0];
+ }
+ if (!ok1(i == NUM))
+ exit(exit_status());
+
+ /* Last one completes the cirle. */
+ i = 0;
+ sprintf(buf[i].buf, "%i-%i", i, i);
+ buf[i].reader = io_new_conn(last_read, reader, NULL, &buf[i]);
+ ok1(buf[i].reader);
+ buf[i].writer = io_new_conn(last_write, do_write, NULL, &buf[i]);
+ ok1(buf[i].writer);
+
+ /* They should eventually exit */
+ ok1(io_loop() == NULL);
+
+ for (i = 0; i < NUM; i++) {
+ char b[sizeof(buf[0].buf)];
+ memset(b, i, sizeof(b));
+ sprintf(b, "%i-%i", i, i);
+ ok1(memcmp(b, buf[(i + NUM_ITERS) % NUM].buf, sizeof(b)) == 0);
+ }
+
+ /* This exits depending on whether all tests passed */
+ return exit_status();
+}