io: io_close_other()

And add test for that which also tests duplex case.
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>

ccan/io/io.c

@@ -435,6 +435,10 @@ void io_wake_(struct io_conn *conn, struct io_plan plan)
 
 void io_ready(struct io_conn *conn)
 {
+	/* Beware io_close_other! */
+	if (!conn->plan.next)
+		return;
+
 	set_current(conn);
 	switch (conn->plan.io(conn->fd.fd, &conn->plan)) {
 	case -1: /* Failure means a new plan: close up. */
@@ -474,6 +478,12 @@ struct io_plan io_close_cb(struct io_conn *conn, void *arg)
 	return io_close();
 }
 
+void io_close_other(struct io_conn *conn)
+{
+	conn->plan = io_close_();
+	backend_plan_changed(conn);
+}
+
 /* Exit the loop, returning this (non-NULL) arg. */
 struct io_plan io_break_(void *ret, struct io_plan plan)
 {

ccan/io/io.h

@@ -495,6 +495,24 @@ struct io_plan io_close_(void);
  */
 struct io_plan io_close_cb(struct io_conn *, void *unused);
 
+/**
+ * io_close_other - close different connection next time around the I/O loop.
+ * @conn: the connection to close.
+ *
+ * This is used to force a different connection to close: no more I/O will
+ * happen on @conn, even if it's pending.
+ *
+ * It's a bug to use this on the current connection!
+ *
+ * Example:
+ * static void stop_connection(struct io_conn *conn)
+ * {
+ *	printf("forcing stop on connection\n");
+ *	io_close_other(conn);
+ * }
+ */
+void io_close_other(struct io_conn *conn);
+
 /**
  * io_loop - process fds until all closed on io_break.
  *

ccan/io/test/run-16-duplex-test.c

+/* Tests when the last connection is a duplex, and poll.c moves it over
+ * deleted fd. */
+#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>
+
+#ifndef PORT
+#define PORT "65016"
+#endif
+
+struct data {
+	struct io_listener *l;
+	struct io_conn *writer;
+	int state;
+	char buf[4];
+	char wbuf[32];
+};
+
+static void finish_ok(struct io_conn *conn, struct data *d)
+{
+	d->state++;
+}
+
+static struct io_plan write_done(struct io_conn *conn, struct data *d)
+{
+	d->state++;
+	return io_idle();
+}
+
+static struct io_plan read_done(struct io_conn *conn, struct data *d)
+{
+	d->state++;
+	io_close_other(d->writer);
+	return io_close();
+}
+
+static void init_conn(int fd, struct data *d)
+{
+	struct io_conn *conn;
+
+	ok1(d->state == 0);
+	d->state++;
+
+	memset(d->wbuf, 7, sizeof(d->wbuf));
+
+	conn = io_new_conn(fd, io_read(d->buf, sizeof(d->buf), read_done, d));
+	io_set_finish(conn, finish_ok, d);
+	d->writer = io_duplex(conn, io_write(d->wbuf, sizeof(d->wbuf), write_done, d));
+	ok1(d->writer);
+	io_set_finish(d->writer, finish_ok, d);
+
+	io_close_listener(d->l);
+}
+
+static int make_listen_fd(const char *port, struct addrinfo **info)
+{
+	int fd, on = 1;
+	struct addrinfo *addrinfo, hints;
+
+	memset(&hints, 0, sizeof(hints));
+	hints.ai_family = AF_UNSPEC;
+	hints.ai_socktype = SOCK_STREAM;
+	hints.ai_flags = AI_PASSIVE;
+	hints.ai_protocol = 0;
+
+	if (getaddrinfo(NULL, port, &hints, &addrinfo) != 0)
+		return -1;
+
+	fd = socket(addrinfo->ai_family, addrinfo->ai_socktype,
+		    addrinfo->ai_protocol);
+	if (fd < 0)
+		return -1;
+
+	setsockopt(fd, SOL_SOCKET, SO_REUSEADDR, &on, sizeof(on));
+	if (bind(fd, addrinfo->ai_addr, addrinfo->ai_addrlen) != 0) {
+		close(fd);
+		return -1;
+	}
+	if (listen(fd, 1) != 0) {
+		close(fd);
+		return -1;
+	}
+	*info = addrinfo;
+	return fd;
+}
+
+int main(void)
+{
+	struct data *d = malloc(sizeof(*d));
+	struct addrinfo *addrinfo;
+	int fd, status;
+
+	/* This is how many tests you plan to run */
+	plan_tests(10);
+	d->state = 0;
+	fd = make_listen_fd(PORT, &addrinfo);
+	ok1(fd >= 0);
+	d->l = io_new_listener(fd, init_conn, d);
+	ok1(d->l);
+	fflush(stdout);
+	if (!fork()) {
+		int i;
+		char buf[32];
+
+		io_close_listener(d->l);
+		free(d);
+		fd = socket(addrinfo->ai_family, addrinfo->ai_socktype,
+			    addrinfo->ai_protocol);
+		if (fd < 0)
+			exit(1);
+		if (connect(fd, addrinfo->ai_addr, addrinfo->ai_addrlen) != 0)
+			exit(2);
+		signal(SIGPIPE, SIG_IGN);
+		for (i = 0; i < 32; i++) {
+			if (read(fd, buf+i, 1) != 1)
+				break;
+		}
+		for (i = 0; i < strlen("hellothere"); i++) {
+			if (write(fd, "hellothere" + i, 1) != 1)
+				break;
+		}
+		close(fd);
+		freeaddrinfo(addrinfo);
+		exit(0);
+	}
+	freeaddrinfo(addrinfo);
+	ok1(io_loop() == NULL);
+	ok1(d->state == 5);
+	ok1(memcmp(d->buf, "hellothere", sizeof(d->buf)) == 0);
+	free(d);
+
+	ok1(wait(&status));
+	ok1(WIFEXITED(status));
+	ok1(WEXITSTATUS(status) == 0);
+
+	/* This exits depending on whether all tests passed */
+	return exit_status();
+}