X-Git-Url: http://git.ozlabs.org/?p=ccan;a=blobdiff_plain;f=ccan%2Fio%2Fio.c;h=7ebd5a202d7899f356ed1963eb3c6f463ee986e2;hp=e2dd44430b79d0f3a0977a92861cb72a86f56df6;hb=a5881c0deb210f56c2095366ae6cdabd5230d68d;hpb=e40f5c50a7a930fc98974936b7366b498ebf984c

diff --git a/ccan/io/io.c b/ccan/io/io.c
index e2dd4443..7ebd5a20 100644
--- a/ccan/io/io.c
+++ b/ccan/io/io.c
@@ -8,170 +8,114 @@
 #include <errno.h>
 #include <stdlib.h>
 #include <assert.h>
-#include <poll.h>
 #include <unistd.h>
 #include <fcntl.h>
+#include <ccan/container_of/container_of.h>
 
 void *io_loop_return;
 
-struct io_alloc io_alloc = {
-	malloc, realloc, free
-};
+struct io_plan io_conn_freed;
 
-#ifdef DEBUG
-/* Set to skip the next plan. */
-bool io_plan_nodebug;
-/* The current connection to apply plan to. */
-struct io_conn *current;
-/* User-defined function to select which connection(s) to debug. */
-bool (*io_debug_conn)(struct io_conn *conn);
-/* Set when we wake up an connection we are debugging. */
-bool io_debug_wakeup;
-
-struct io_plan io_debug(struct io_plan plan)
+struct io_listener *io_new_listener_(const tal_t *ctx, int fd,
+				     struct io_plan *(*init)(struct io_conn *,
+							     void *),
+				     void *arg)
 {
-	struct io_conn *ready = NULL;
-
-	if (io_plan_nodebug) {
-		io_plan_nodebug = false;
-		return plan;
-	}
+	struct io_listener *l = tal(ctx, struct io_listener);
+	if (!l)
+		return NULL;
 
-	if (!current || !doing_debug_on(current)) {
-		if (!io_debug_wakeup)
-			return plan;
-	}
+	l->fd.listener = true;
+	l->fd.fd = fd;
+	l->init = init;
+	l->arg = arg;
+	l->ctx = ctx;
+	if (!add_listener(l))
+		return tal_free(l);
+	return l;
+}
 
-	io_debug_wakeup = false;
-	current->plan = plan;
-	backend_plan_changed(current);
-
-	/* Call back into the loop immediately. */
-	io_loop_return = do_io_loop(&ready);
-
-	if (ready) {
-		set_current(ready);
-		if (!ready->plan.next) {
-			/* Call finish function immediately. */
-			if (ready->finish) {
-				errno = ready->plan.u1.s;
-				ready->finish(ready, ready->finish_arg);
-				ready->finish = NULL;
-			}
-			backend_del_conn(ready);
-		} else {
-			/* Calls back in itself, via io_debug_io(). */
-			if (ready->plan.io(ready->fd.fd, &ready->plan) != 2)
-				abort();
-		}
-		set_current(NULL);
-	}
+void io_close_listener(struct io_listener *l)
+{
+	tal_free(l);
+}
 
-	/* Return a do-nothing plan, so backend_plan_changed in
-	 * io_ready doesn't do anything (it's already been called). */
-	return io_idle_();
+static struct io_plan *io_never_called(struct io_conn *conn, void *arg)
+{
+	abort();
 }
 
-int io_debug_io(int ret)
+/* Returns false if conn was freed. */
+static bool next_plan(struct io_conn *conn, struct io_plan *plan)
 {
-	/* Cache it for debugging; current changes. */
-	struct io_conn *conn = current;
-	int saved_errno = errno;
+	struct io_plan *(*next)(struct io_conn *, void *arg);
 
-	if (!doing_debug_on(conn))
-		return ret;
+	next = plan->next;
 
-	/* These will all go linearly through the io_debug() path above. */
-	switch (ret) {
-	case -1:
-		/* This will call io_debug above. */
-		errno = saved_errno;
-		io_close();
-		break;
-	case 0: /* Keep going with plan. */
-		io_debug(conn->plan);
-		break;
-	case 1: /* Done: get next plan. */
-		if (timeout_active(conn))
-			backend_del_timeout(conn);
-		conn->plan.next(conn, conn->plan.next_arg);
-		break;
-	default:
-		abort();
-	}
+	plan->status = IO_UNSET;
+	plan->io = NULL;
+	plan->next = io_never_called;
 
-	/* Normally-invalid value, used for sanity check. */
-	return 2;
-}
+	plan = next(conn, plan->next_arg);
 
-static void debug_io_wake(struct io_conn *conn)
-{
-	/* We want linear if we wake a debugged connection, too. */
-	if (io_debug_conn && io_debug_conn(conn))
-		io_debug_wakeup = true;
-}
+	if (plan == &io_conn_freed)
+		return false;
 
-/* Counterpart to io_plan_no_debug(), called in macros in io.h */
-static void io_plan_debug_again(void)
-{
-	io_plan_nodebug = false;
-}
-#else
-static void debug_io_wake(struct io_conn *conn)
-{
-}
-static void io_plan_debug_again(void)
-{
+	assert(plan == &conn->plan[plan->dir]);
+	assert(conn->plan[IO_IN].status != IO_UNSET
+	       || conn->plan[IO_OUT].status != IO_UNSET);
+
+	backend_new_plan(conn);
+	return true;
 }
-#endif
 
-struct io_listener *io_new_listener_(int fd,
-				     void (*init)(int fd, void *arg),
-				     void *arg)
+bool io_fd_block(int fd, bool block)
 {
-	struct io_listener *l = io_alloc.alloc(sizeof(*l));
+	int flags = fcntl(fd, F_GETFL);
 
-	if (!l)
-		return NULL;
+	if (flags == -1)
+		return false;
 
-	l->fd.listener = true;
-	l->fd.fd = fd;
-	l->init = init;
-	l->arg = arg;
-	if (!add_listener(l)) {
-		io_alloc.free(l);
-		return NULL;
-	}
-	return l;
-}
+	if (block)
+		flags &= ~O_NONBLOCK;
+	else
+		flags |= O_NONBLOCK;
 
-void io_close_listener(struct io_listener *l)
-{
-	close(l->fd.fd);
-	del_listener(l);
-	io_alloc.free(l);
+	return fcntl(fd, F_SETFL, flags) != -1;
 }
 
-struct io_conn *io_new_conn_(int fd, struct io_plan plan)
+struct io_conn *io_new_conn_(const tal_t *ctx, int fd,
+			     struct io_plan *(*init)(struct io_conn *, void *),
+			     void *arg)
 {
-	struct io_conn *conn = io_alloc.alloc(sizeof(*conn));
-
-	io_plan_debug_again();
+	struct io_conn *conn = tal(ctx, struct io_conn);
 
 	if (!conn)
 		return NULL;
 
 	conn->fd.listener = false;
 	conn->fd.fd = fd;
-	conn->plan = plan;
 	conn->finish = NULL;
 	conn->finish_arg = NULL;
-	conn->duplex = NULL;
-	conn->timeout = NULL;
-	if (!add_conn(conn)) {
-		io_alloc.free(conn);
+
+	if (!add_conn(conn))
+		return tal_free(conn);
+
+	/* Keep our I/O async. */
+	io_fd_block(fd, false);
+
+	/* So we can get back from plan -> conn later */
+	conn->plan[IO_OUT].dir = IO_OUT;
+	conn->plan[IO_IN].dir = IO_IN;
+
+	/* We start with out doing nothing, and in doing our init. */
+	conn->plan[IO_OUT].status = IO_UNSET;
+
+	conn->plan[IO_IN].next = init;
+	conn->plan[IO_IN].next_arg = arg;
+	if (!next_plan(conn, &conn->plan[IO_IN]))
 		return NULL;
-	}
+
 	return conn;
 }
 
@@ -183,172 +127,177 @@ void io_set_finish_(struct io_conn *conn,
 	conn->finish_arg = arg;
 }
 
-struct io_conn *io_duplex_(struct io_conn *old, struct io_plan plan)
+struct io_plan_arg *io_plan_arg(struct io_conn *conn, enum io_direction dir)
 {
-	struct io_conn *conn;
+	assert(conn->plan[dir].status == IO_UNSET);
 
-	io_plan_debug_again();
+	conn->plan[dir].status = IO_POLLING_NOTSTARTED;
+	return &conn->plan[dir].arg;
+}
 
-	assert(!old->duplex);
+static struct io_plan *set_always(struct io_conn *conn,
+				  enum io_direction dir,
+				  struct io_plan *(*next)(struct io_conn *,
+							  void *),
+				  void *arg)
+{
+	struct io_plan *plan = &conn->plan[dir];
 
-	conn = io_alloc.alloc(sizeof(*conn));
-	if (!conn)
+	plan->status = IO_ALWAYS;
+	/* Only happens on OOM, and only with non-default tal_backend. */
+	if (!backend_new_always(plan))
 		return NULL;
-
-	conn->fd.listener = false;
-	conn->fd.fd = old->fd.fd;
-	conn->plan = plan;
-	conn->duplex = old;
-	conn->finish = NULL;
-	conn->finish_arg = NULL;
-	conn->timeout = NULL;
-	if (!add_duplex(conn)) {
-		io_alloc.free(conn);
-		return NULL;
-	}
-	old->duplex = conn;
-	return conn;
+	return io_set_plan(conn, dir, NULL, next, arg);
 }
 
-bool io_timeout_(struct io_conn *conn, struct timespec ts,
-		 struct io_plan (*cb)(struct io_conn *, void *), void *arg)
+static struct io_plan *io_always_dir(struct io_conn *conn,
+				     enum io_direction dir,
+				     struct io_plan *(*next)(struct io_conn *,
+							     void *),
+				     void *arg)
 {
-	assert(cb);
+	return set_always(conn, dir, next, arg);
+}
 
-	if (!conn->timeout) {
-		conn->timeout = io_alloc.alloc(sizeof(*conn->timeout));
-		if (!conn->timeout)
-			return false;
-	} else
-		assert(!timeout_active(conn));
+struct io_plan *io_always_(struct io_conn *conn,
+			   struct io_plan *(*next)(struct io_conn *, void *),
+			   void *arg)
+{
+	return io_always_dir(conn, IO_IN, next, arg);
+}
 
-	conn->timeout->next = cb;
-	conn->timeout->next_arg = arg;
-	backend_add_timeout(conn, ts);
-	return true;
+struct io_plan *io_out_always_(struct io_conn *conn,
+			       struct io_plan *(*next)(struct io_conn *,
+						       void *),
+			       void *arg)
+{
+	return io_always_dir(conn, IO_OUT, next, arg);
 }
 
-/* Returns true if we're finished. */
-static int do_write(int fd, struct io_plan *plan)
+static int do_write(int fd, struct io_plan_arg *arg)
 {
-	ssize_t ret = write(fd, plan->u1.cp, plan->u2.s);
+	ssize_t ret = write(fd, arg->u1.cp, arg->u2.s);
 	if (ret < 0)
-		return io_debug_io(-1);
+		return -1;
 
-	plan->u1.cp += ret;
-	plan->u2.s -= ret;
-	return io_debug_io(plan->u2.s == 0);
+	arg->u1.cp += ret;
+	arg->u2.s -= ret;
+	return arg->u2.s == 0;
 }
 
 /* Queue some data to be written. */
-struct io_plan io_write_(const void *data, size_t len,
-			 struct io_plan (*cb)(struct io_conn *, void *),
-			 void *arg)
+struct io_plan *io_write_(struct io_conn *conn, const void *data, size_t len,
+			  struct io_plan *(*next)(struct io_conn *, void *),
+			  void *next_arg)
 {
-	struct io_plan plan;
+	struct io_plan_arg *arg = io_plan_arg(conn, IO_OUT);
 
-	assert(cb);
-	plan.u1.const_vp = data;
-	plan.u2.s = len;
-	plan.io = do_write;
-	plan.next = cb;
-	plan.next_arg = arg;
-	plan.pollflag = POLLOUT;
+	if (len == 0)
+		return set_always(conn, IO_OUT, next, next_arg);
 
-	return plan;
+	arg->u1.const_vp = data;
+	arg->u2.s = len;
+
+	return io_set_plan(conn, IO_OUT, do_write, next, next_arg);
 }
 
-static int do_read(int fd, struct io_plan *plan)
+static int do_read(int fd, struct io_plan_arg *arg)
 {
-	ssize_t ret = read(fd, plan->u1.cp, plan->u2.s);
-	if (ret <= 0)
-		return io_debug_io(-1);
+	ssize_t ret = read(fd, arg->u1.cp, arg->u2.s);
+	if (ret <= 0) {
+		/* Errno isn't set if we hit EOF, so set it to distinct value */
+		if (ret == 0)
+			errno = 0;
+		return -1;
+	}
 
-	plan->u1.cp += ret;
-	plan->u2.s -= ret;
-	return io_debug_io(plan->u2.s == 0);
+	arg->u1.cp += ret;
+	arg->u2.s -= ret;
+	return arg->u2.s == 0;
 }
 
 /* Queue a request to read into a buffer. */
-struct io_plan io_read_(void *data, size_t len,
-			struct io_plan (*cb)(struct io_conn *, void *),
-			void *arg)
+struct io_plan *io_read_(struct io_conn *conn,
+			 void *data, size_t len,
+			 struct io_plan *(*next)(struct io_conn *, void *),
+			 void *next_arg)
 {
-	struct io_plan plan;
+	struct io_plan_arg *arg = io_plan_arg(conn, IO_IN);
 
-	assert(cb);
-	plan.u1.cp = data;
-	plan.u2.s = len;
-	plan.io = do_read;
-	plan.next = cb;
-	plan.next_arg = arg;
-	plan.pollflag = POLLIN;
+	if (len == 0)
+		return set_always(conn, IO_IN, next, next_arg);
 
-	return plan;
+	arg->u1.cp = data;
+	arg->u2.s = len;
+
+	return io_set_plan(conn, IO_IN, do_read, next, next_arg);
 }
 
-static int do_read_partial(int fd, struct io_plan *plan)
+static int do_read_partial(int fd, struct io_plan_arg *arg)
 {
-	ssize_t ret = read(fd, plan->u1.cp, *(size_t *)plan->u2.vp);
-	if (ret <= 0)
-		return io_debug_io(-1);
+	ssize_t ret = read(fd, arg->u1.cp, *(size_t *)arg->u2.vp);
+	if (ret <= 0) {
+		/* Errno isn't set if we hit EOF, so set it to distinct value */
+		if (ret == 0)
+			errno = 0;
+		return -1;
+	}
 
-	*(size_t *)plan->u2.vp = ret;
-	return io_debug_io(1);
+	*(size_t *)arg->u2.vp = ret;
+	return 1;
 }
 
 /* Queue a partial request to read into a buffer. */
-struct io_plan io_read_partial_(void *data, size_t *len,
-				struct io_plan (*cb)(struct io_conn *, void *),
-				void *arg)
+struct io_plan *io_read_partial_(struct io_conn *conn,
+				 void *data, size_t maxlen, size_t *len,
+				 struct io_plan *(*next)(struct io_conn *,
+							 void *),
+				 void *next_arg)
 {
-	struct io_plan plan;
+	struct io_plan_arg *arg = io_plan_arg(conn, IO_IN);
 
-	assert(cb);
-	plan.u1.cp = data;
-	plan.u2.vp = len;
-	plan.io = do_read_partial;
-	plan.next = cb;
-	plan.next_arg = arg;
-	plan.pollflag = POLLIN;
+	if (maxlen == 0)
+		return set_always(conn, IO_IN, next, next_arg);
 
-	return plan;
+	arg->u1.cp = data;
+	/* We store the max len in here temporarily. */
+	*len = maxlen;
+	arg->u2.vp = len;
+
+	return io_set_plan(conn, IO_IN, do_read_partial, next, next_arg);
 }
 
-static int do_write_partial(int fd, struct io_plan *plan)
+static int do_write_partial(int fd, struct io_plan_arg *arg)
 {
-	ssize_t ret = write(fd, plan->u1.cp, *(size_t *)plan->u2.vp);
+	ssize_t ret = write(fd, arg->u1.cp, *(size_t *)arg->u2.vp);
 	if (ret < 0)
-		return io_debug_io(-1);
+		return -1;
 
-	*(size_t *)plan->u2.vp = ret;
-	return io_debug_io(1);
+	*(size_t *)arg->u2.vp = ret;
+	return 1;
 }
 
 /* Queue a partial write request. */
-struct io_plan io_write_partial_(const void *data, size_t *len,
-				 struct io_plan (*cb)(struct io_conn*, void *),
-				 void *arg)
+struct io_plan *io_write_partial_(struct io_conn *conn,
+				  const void *data, size_t maxlen, size_t *len,
+				  struct io_plan *(*next)(struct io_conn *,
+							  void*),
+				  void *next_arg)
 {
-	struct io_plan plan;
+	struct io_plan_arg *arg = io_plan_arg(conn, IO_OUT);
 
-	assert(cb);
-	plan.u1.const_vp = data;
-	plan.u2.vp = len;
-	plan.io = do_write_partial;
-	plan.next = cb;
-	plan.next_arg = arg;
-	plan.pollflag = POLLOUT;
+	if (maxlen == 0)
+		return set_always(conn, IO_OUT, next, next_arg);
 
-	return plan;
-}
+	arg->u1.const_vp = data;
+	/* We store the max len in here temporarily. */
+	*len = maxlen;
+	arg->u2.vp = len;
 
-static int already_connected(int fd, struct io_plan *plan)
-{
-	return io_debug_io(1);
+	return io_set_plan(conn, IO_OUT, do_write_partial, next, next_arg);
 }
 
-static int do_connect(int fd, struct io_plan *plan)
+static int do_connect(int fd, struct io_plan_arg *arg)
 {
 	int err, ret;
 	socklen_t len = sizeof(err);
@@ -359,124 +308,249 @@ static int do_connect(int fd, struct io_plan *plan)
 		return -1;
 
 	if (err == 0) {
-		/* Restore blocking if it was initially. */
-		fcntl(fd, F_SETFD, plan->u1.s);
 		return 1;
-	}
-	return 0;
+	} else if (err == EINPROGRESS)
+		return 0;
+
+	errno = err;
+	return -1;
 }
 
-struct io_plan io_connect_(int fd, const struct addrinfo *addr,
-			   struct io_plan (*cb)(struct io_conn*, void *),
-			   void *arg)
+struct io_plan *io_connect_(struct io_conn *conn, const struct addrinfo *addr,
+			    struct io_plan *(*next)(struct io_conn *, void *),
+			    void *next_arg)
 {
-	struct io_plan plan;
+	int fd = io_conn_fd(conn);
 
-	assert(cb);
+	/* We don't actually need the arg, but we need it polling. */
+	io_plan_arg(conn, IO_OUT);
 
-	plan.next = cb;
-	plan.next_arg = arg;
-
-	/* Save old flags, set nonblock if not already. */
-	plan.u1.s = fcntl(fd, F_GETFD);
-	fcntl(fd, F_SETFD, plan.u1.s | O_NONBLOCK);
+	/* Note that io_new_conn() will make fd O_NONBLOCK */
 
 	/* Immediate connect can happen. */
-	if (connect(fd, addr->ai_addr, addr->ai_addrlen) == 0) {
-		/* Dummy will be called immediately. */
-		plan.pollflag = POLLOUT;
-		plan.io = already_connected;
-	} else {
-		if (errno != EINPROGRESS)
-			return io_close_();
-
-		plan.pollflag = POLLIN;
-		plan.io = do_connect;
-	}
-	return plan;
+	if (connect(fd, addr->ai_addr, addr->ai_addrlen) == 0)
+		return set_always(conn, IO_OUT, next, next_arg);
+
+	if (errno != EINPROGRESS)
+		return io_close(conn);
+
+	return io_set_plan(conn, IO_OUT, do_connect, next, next_arg);
 }
 
-struct io_plan io_idle_(void)
+static struct io_plan *io_wait_dir(struct io_conn *conn,
+				   const void *wait,
+				   enum io_direction dir,
+				   struct io_plan *(*next)(struct io_conn *,
+							   void *),
+				   void *next_arg)
 {
-	struct io_plan plan;
+	struct io_plan_arg *arg = io_plan_arg(conn, dir);
+	arg->u1.const_vp = wait;
 
-	plan.pollflag = 0;
-	plan.io = NULL;
-	/* Never called (overridden by io_wake), but NULL means closing */
-	plan.next = (void *)io_idle_;
+	conn->plan[dir].status = IO_WAITING;
 
-	return plan;
+	return io_set_plan(conn, dir, NULL, next, next_arg);
 }
 
-void io_wake_(struct io_conn *conn, struct io_plan plan)
-
+struct io_plan *io_wait_(struct io_conn *conn,
+			 const void *wait,
+			 struct io_plan *(*next)(struct io_conn *, void *),
+			 void *next_arg)
 {
-	io_plan_debug_again();
+	return io_wait_dir(conn, wait, IO_IN, next, next_arg);
+}
 
-	/* It might be closing, but we haven't called its finish() yet. */
-	if (!conn->plan.next)
-		return;
-	/* It was idle, right? */
-	assert(!conn->plan.io);
-	conn->plan = plan;
-	backend_plan_changed(conn);
+struct io_plan *io_out_wait_(struct io_conn *conn,
+			     const void *wait,
+			     struct io_plan *(*next)(struct io_conn *, void *),
+			     void *next_arg)
+{
+	return io_wait_dir(conn, wait, IO_OUT, next, next_arg);
+}
 
-	debug_io_wake(conn);
+void io_wake(const void *wait)
+{
+	backend_wake(wait);
 }
 
-void io_ready(struct io_conn *conn)
+/* Returns false if this should not be touched (eg. freed). */
+static bool do_plan(struct io_conn *conn, struct io_plan *plan,
+		    bool idle_on_epipe)
 {
-	set_current(conn);
-	switch (conn->plan.io(conn->fd.fd, &conn->plan)) {
-	case -1: /* Failure means a new plan: close up. */
-		conn->plan = io_close();
-		backend_plan_changed(conn);
-		break;
-	case 0: /* Keep going with plan. */
-		break;
-	case 1: /* Done: get next plan. */
-		if (timeout_active(conn))
-			backend_del_timeout(conn);
-		conn->plan = conn->plan.next(conn, conn->plan.next_arg);
-		backend_plan_changed(conn);
+	/* We shouldn't have polled for this event if this wasn't true! */
+	assert(plan->status == IO_POLLING_NOTSTARTED
+	       || plan->status == IO_POLLING_STARTED);
+
+	switch (plan->io(conn->fd.fd, &plan->arg)) {
+	case -1:
+		if (errno == EPIPE && idle_on_epipe) {
+			plan->status = IO_UNSET;
+			backend_new_plan(conn);
+			return false;
+		}
+		io_close(conn);
+		return false;
+	case 0:
+		plan->status = IO_POLLING_STARTED;
+		return true;
+	case 1:
+		return next_plan(conn, plan);
+	default:
+		/* IO should only return -1, 0 or 1 */
+		abort();
 	}
-	set_current(NULL);
 }
 
-/* Close the connection, we're done. */
-struct io_plan io_close_(void)
+void io_ready(struct io_conn *conn, int pollflags)
 {
-	struct io_plan plan;
+	if (pollflags & POLLIN)
+		if (!do_plan(conn, &conn->plan[IO_IN], false))
+			return;
+
+	if (pollflags & POLLOUT)
+		/* If we're writing to a closed pipe, we need to wait for
+		 * read to fail if we're duplex: we want to drain it! */
+		do_plan(conn, &conn->plan[IO_OUT],
+			conn->plan[IO_IN].status == IO_POLLING_NOTSTARTED
+			|| conn->plan[IO_IN].status == IO_POLLING_STARTED);
+}
 
-	plan.pollflag = 0;
-	/* This means we're closing. */
-	plan.next = NULL;
-	plan.u1.s = errno;
+void io_do_always(struct io_plan *plan)
+{
+	struct io_conn *conn;
 
-	return plan;
+	assert(plan->status == IO_ALWAYS);
+	conn = container_of(plan, struct io_conn, plan[plan->dir]);
+
+	next_plan(conn, plan);
 }
 
-struct io_plan io_close_cb(struct io_conn *conn, void *arg)
+void io_do_wakeup(struct io_conn *conn, enum io_direction dir)
 {
-	return io_close();
+	struct io_plan *plan = &conn->plan[dir];
+
+	assert(plan->status == IO_WAITING);
+
+	set_always(conn, dir, plan->next, plan->next_arg);
 }
 
-/* Exit the loop, returning this (non-NULL) arg. */
-struct io_plan io_break_(void *ret, struct io_plan plan)
+/* Close the connection, we're done. */
+struct io_plan *io_close(struct io_conn *conn)
+{
+	tal_free(conn);
+	return &io_conn_freed;
+}
+
+struct io_plan *io_close_cb(struct io_conn *conn, void *next_arg)
+{
+	return io_close(conn);
+}
+
+struct io_plan *io_close_taken_fd(struct io_conn *conn)
 {
-	io_plan_debug_again();
+	io_fd_block(conn->fd.fd, true);
 
+	cleanup_conn_without_close(conn);
+	return io_close(conn);
+}
+
+/* Exit the loop, returning this (non-NULL) arg. */
+void io_break(const void *ret)
+{
 	assert(ret);
-	io_loop_return = ret;
+	io_loop_return = (void *)ret;
+}
+
+struct io_plan *io_never(struct io_conn *conn, void *unused)
+{
+	return io_always(conn, io_never_called, NULL);
+}
+
+int io_conn_fd(const struct io_conn *conn)
+{
+	return conn->fd.fd;
+}
+
+struct io_plan *io_duplex(struct io_conn *conn,
+			  struct io_plan *in_plan, struct io_plan *out_plan)
+{
+	assert(conn == container_of(in_plan, struct io_conn, plan[IO_IN]));
+	/* in_plan must be conn->plan[IO_IN], out_plan must be [IO_OUT] */
+	assert(out_plan == in_plan + 1);
+	return in_plan;
+}
+
+struct io_plan *io_halfclose(struct io_conn *conn)
+{
+	/* Both unset?  OK. */
+	if (conn->plan[IO_IN].status == IO_UNSET
+	    && conn->plan[IO_OUT].status == IO_UNSET)
+		return io_close(conn);
+
+	/* We leave this unset then. */
+	if (conn->plan[IO_IN].status == IO_UNSET)
+		return &conn->plan[IO_IN];
+	else
+		return &conn->plan[IO_OUT];
+}
+
+struct io_plan *io_set_plan(struct io_conn *conn, enum io_direction dir,
+			    int (*io)(int fd, struct io_plan_arg *arg),
+			    struct io_plan *(*next)(struct io_conn *, void *),
+			    void *next_arg)
+{
+	struct io_plan *plan = &conn->plan[dir];
+
+	plan->io = io;
+	plan->next = next;
+	plan->next_arg = next_arg;
+	assert(next != NULL);
 
 	return plan;
 }
 
-void io_set_alloc(void *(*allocfn)(size_t size),
-		  void *(*reallocfn)(void *ptr, size_t size),
-		  void (*freefn)(void *ptr))
+bool io_plan_in_started(const struct io_conn *conn)
+{
+	return conn->plan[IO_IN].status == IO_POLLING_STARTED;
+}
+
+bool io_plan_out_started(const struct io_conn *conn)
+{
+	return conn->plan[IO_OUT].status == IO_POLLING_STARTED;
+}
+
+bool io_flush_sync(struct io_conn *conn)
 {
-	io_alloc.alloc = allocfn;
-	io_alloc.realloc = reallocfn;
-	io_alloc.free = freefn;
+	struct io_plan *plan = &conn->plan[IO_OUT];
+	bool ok;
+
+	/* Not writing?  Nothing to do. */
+	if (plan->status != IO_POLLING_STARTED
+	    && plan->status != IO_POLLING_NOTSTARTED)
+		return true;
+
+	/* Synchronous please. */
+	io_fd_block(io_conn_fd(conn), true);
+
+again:
+	switch (plan->io(conn->fd.fd, &plan->arg)) {
+	case -1:
+		ok = false;
+		break;
+	/* Incomplete, try again. */
+	case 0:
+		plan->status = IO_POLLING_STARTED;
+		goto again;
+	case 1:
+		ok = true;
+		/* In case they come back. */
+		set_always(conn, IO_OUT, plan->next, plan->next_arg);
+		break;
+	default:
+		/* IO should only return -1, 0 or 1 */
+		abort();
+	}
+
+	io_fd_block(io_conn_fd(conn), false);
+	return ok;
 }