io: handle duplex corner cases.

Especially where we have just done a read and spin off a duplex to do a read
as well.
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>

ccan/io/io.c

@@ -100,6 +100,10 @@ int io_debug_io(int ret)
 	case 1: /* Done: get next plan. */
 		if (timeout_active(conn))
 			backend_del_timeout(conn);
+		/* In case they call io_duplex, clear our poll flags so
+		 * both sides don't seem to be both doing read or write
+		 * (See	assert(!mask || pfd->events != mask) in poll.c) */
+		conn->plan.pollflag = 0;
 		conn->plan.next(conn, conn->plan.next_arg);
 		break;
 	default:
@@ -443,13 +447,17 @@ void io_ready(struct io_conn *conn)
 	case 1: /* Done: get next plan. */
 		if (timeout_active(conn))
 			backend_del_timeout(conn);
+		/* In case they call io_duplex, clear our poll flags so
+		 * both sides don't seem to be both doing read or write
+		 * (See	assert(!mask || pfd->events != mask) in poll.c) */
+		conn->plan.pollflag = 0;
 		conn->plan = conn->plan.next(conn, conn->plan.next_arg);
 		backend_plan_changed(conn);
 	}
 	set_current(NULL);
 
-	/* If it closed, close duplex. */
-	if (!conn->plan.next && conn->duplex) {
+	/* If it closed, close duplex if not already */
+	if (!conn->plan.next && conn->duplex && conn->duplex->plan.next) {
 		set_current(conn->duplex);
 		conn->duplex->plan = io_close();
 		backend_plan_changed(conn->duplex);

ccan/io/poll.c

@@ -346,7 +346,11 @@ void *do_io_loop(struct io_conn **ready)
 						 * anything can change. */
 						if (doing_debug())
 							break;
-						if (!(events&(POLLIN|POLLOUT)))
+
+						/* If no events, or it closed
+						 * the duplex, continue. */
+						if (!(events&(POLLIN|POLLOUT))
+						    || !c->plan.next)
 							continue;
 					}
 				}

ccan/io/test/run-14-duplex-both-read-DEBUG.c

+#define DEBUG
+#define PORT "64014"
+#define main real_main
+int real_main(void);
+#include "run-14-duplex-both-read.c"
+#undef main
+static bool always_debug(struct io_conn *conn) { return true; }
+int main(void) { io_debug_conn = always_debug; return real_main(); }

ccan/io/test/run-14-duplex-both-read.c

+/* Check a bug where we have just completed a read, then set up a duplex
+ * which tries to do a read. */
+#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 "65014"
+#endif
+
+#define is_idle(conn) ((conn)->plan.io == NULL)
+
+struct data {
+	struct io_listener *l;
+	int state;
+	struct io_conn *c1, *c2;
+	char buf[4];
+	char wbuf[32];
+};
+
+static void finish_ok(struct io_conn *conn, struct data *d)
+{
+	d->state++;
+}
+
+static struct io_plan end(struct io_conn *conn, struct data *d)
+{
+	d->state++;
+
+	/* last one out closes. */
+	if (conn == d->c1 && is_idle(d->c2))
+		return io_close();
+
+	/* last one out closes. */
+	if (conn == d->c2 && is_idle(d->c1))
+		return io_close();
+
+	return io_idle();
+}
+
+static struct io_plan make_duplex(struct io_conn *conn, struct data *d)
+{
+	/* Have duplex read the rest of the buffer. */
+	d->c2 = io_duplex(conn, io_read(d->buf+1, sizeof(d->buf)-1, end, d));
+	ok1(d->c2);
+	io_set_finish(d->c2, finish_ok, d);
+
+	return io_write(d->wbuf, sizeof(d->wbuf), end, d);
+}
+
+static void init_conn(int fd, struct data *d)
+{
+	ok1(d->state == 0);
+	d->state++;
+
+	io_close_listener(d->l);
+
+	memset(d->wbuf, 7, sizeof(d->wbuf));
+
+	d->c1 = io_new_conn(fd, io_read(d->buf, 1, make_duplex, d));
+	io_set_finish(d->c1, finish_ok, d);
+}
+
+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 < strlen("hellothere"); i++) {
+			if (write(fd, "hellothere" + i, 1) != 1)
+				break;
+		}
+		for (i = 0; i < 32; i++) {
+			if (read(fd, buf+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();
+}