io: io_time_override to insert fake times.

Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>

ccan/io/io.h

@@ -649,6 +649,16 @@ void *io_loop(struct timers *timers, struct timer **expired);
  */
 int io_conn_fd(const struct io_conn *conn);
 
+/**
+ * io_time_override - override the normal call for time.
+ * @nowfn: the function to call.
+ *
+ * io usually uses time_now() internally, but this forces it
+ * to use your function (eg. for debugging).  Returns the old
+ * one.
+ */
+struct timeabs (*io_time_override(struct timeabs (*now)(void)))(void);
+
 /**
  * io_set_debug - set synchronous mode on a connection.
  * @conn: the connection.

ccan/io/poll.c

@@ -16,6 +16,14 @@ static struct pollfd *pollfds = NULL;
 static struct fd **fds = NULL;
 static LIST_HEAD(closing);
 static LIST_HEAD(always);
+static struct timeabs (*nowfn)(void) = time_now;
+
+struct timeabs (*io_time_override(struct timeabs (*now)(void)))(void)
+{
+	struct timeabs (*old)(void) = nowfn;
+	nowfn = now;
+	return old;
+}
 
 static bool add_fd(struct fd *fd, short events)
 {
@@ -256,7 +264,7 @@ void *io_loop(struct timers *timers, struct timer **expired)
 		if (timers) {
 			struct timeabs now, first;
 
-			now = time_now();
+			now = nowfn();
 
 			/* Call functions for expired timers. */
 			*expired = timers_expire(timers, now);

ccan/io/test/run-20-io_time_override.c

@@ -0,0 +1,92 @@
+#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 PORT "65020"
+
+static struct io_plan *init_conn(struct io_conn *conn, void *unused)
+{
+	return io_close(conn);
+}
+
+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;
+}
+
+static struct timeabs fake_time;
+
+static struct timeabs get_fake_time(void)
+{
+	return fake_time;
+}
+
+int main(void)
+{
+	struct io_listener *l;
+	int fd;
+	struct timers timers;
+	struct timer timer, *expired;
+	struct addrinfo *addrinfo;
+
+	/* This is how many tests you plan to run */
+	plan_tests(7);
+
+	fake_time = time_now();
+
+	timers_init(&timers, fake_time);
+	timer_init(&timer);
+	timer_add(&timers, &timer,
+		  timeabs_add(fake_time, time_from_sec(1000)));
+
+	fd = make_listen_fd(PORT, &addrinfo);
+	freeaddrinfo(addrinfo);
+	ok1(fd >= 0);
+	l = io_new_listener(NULL, fd, init_conn, NULL);
+	ok1(l);
+
+	fake_time.ts.tv_sec += 1000;
+	ok1(io_time_override(get_fake_time) == time_now);
+	ok1(io_loop(&timers, &expired) == NULL);
+
+	ok1(expired == &timer);
+	ok1(!timers_expire(&timers, fake_time));
+	ok1(io_time_override(time_now) == get_fake_time);
+	io_close_listener(l);
+
+	timers_cleanup(&timers);
+
+	/* This exits depending on whether all tests passed */
+	return exit_status();
+}