ccan/io: keep more io_plan details internal.

To write a normal helper you only need access to the args, so only
expose that.

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

ccan/io/backend.h

@@ -22,6 +22,39 @@ struct io_listener {
 	void *arg;
 };
 
+enum io_plan_status {
+	/* As before calling next function. */
+	IO_UNSET,
+	/* Normal. */
+	IO_POLLING,
+	/* Waiting for io_wake */
+	IO_WAITING,
+	/* Always do this. */
+	IO_ALWAYS,
+	/* Closing (both plans will be the same). */
+	IO_CLOSING
+};
+
+/**
+ * struct io_plan - one half of I/O to do
+ * @status: the status of this plan.
+ * @io: function to call when fd becomes read/writable, returns 0 to be
+ *      called again, 1 if it's finished, and -1 on error (fd will be closed)
+ * @next: the next function which is called if io returns 1.
+ * @next_arg: the argument to @next
+ * @u1, @u2: scratch space for @io.
+ */
+struct io_plan {
+	enum io_plan_status status;
+
+	int (*io)(int fd, struct io_plan_arg *arg);
+
+	struct io_plan *(*next)(struct io_conn *, void *next_arg);
+	void *next_arg;
+
+	struct io_plan_arg arg;
+};
+
 /* One connection per client. */
 struct io_conn {
 	struct fd fd;

ccan/io/io.c

@@ -104,106 +104,101 @@ void io_set_finish_(struct io_conn *conn,
 	conn->finish_arg = arg;
 }
 
-struct io_plan *io_get_plan(struct io_conn *conn, enum io_direction dir)
+struct io_plan_arg *io_plan_arg(struct io_conn *conn, enum io_direction dir)
 {
 	assert(conn->plan[dir].status == IO_UNSET);
 
 	conn->plan[dir].status = IO_POLLING;
-	return &conn->plan[dir];
+	return &conn->plan[dir].arg;
 }
 
 static struct io_plan *set_always(struct io_conn *conn,
-				  struct io_plan *plan,
+				  enum io_direction dir,
 				  struct io_plan *(*next)(struct io_conn *,
 							  void *),
 				  void *arg)
 {
+	struct io_plan *plan = &conn->plan[dir];
+
 	plan->status = IO_ALWAYS;
 	backend_new_always(conn);
-	return io_set_plan(conn, plan, NULL, next, arg);
+	return io_set_plan(conn, dir, NULL, next, arg);
 }
 
 struct io_plan *io_always_(struct io_conn *conn,
 			   struct io_plan *(*next)(struct io_conn *, void *),
 			   void *arg)
 {
-	struct io_plan *plan;
-
 	/* If we're duplex, we want this on the current plan.  Otherwise,
 	 * doesn't matter. */
 	if (conn->plan[IO_IN].status == IO_UNSET)
-		plan = io_get_plan(conn, IO_IN);
+		return set_always(conn, IO_IN, next, arg);
 	else
-		plan = io_get_plan(conn, IO_OUT);
-
-	assert(next);
-	return set_always(conn, plan, next, arg);
+		return set_always(conn, IO_OUT, next, arg);
 }
 
-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 -1;
 
-	plan->u1.cp += ret;
-	plan->u2.s -= ret;
-	return 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_(struct io_conn *conn, const void *data, size_t len,
 			  struct io_plan *(*next)(struct io_conn *, void *),
-			  void *arg)
+			  void *next_arg)
 {
-	struct io_plan *plan = io_get_plan(conn, IO_OUT);
+	struct io_plan_arg *arg = io_plan_arg(conn, IO_OUT);
 
 	if (len == 0)
-		return set_always(conn, plan, next, arg);
+		return set_always(conn, IO_OUT, next, next_arg);
 
-	plan->u1.const_vp = data;
-	plan->u2.s = len;
+	arg->u1.const_vp = data;
+	arg->u2.s = len;
 
-	return io_set_plan(conn, plan, do_write, next, arg);
+	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);
+	ssize_t ret = read(fd, arg->u1.cp, arg->u2.s);
 	if (ret <= 0)
 		return -1;
 
-	plan->u1.cp += ret;
-	plan->u2.s -= ret;
-	return 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_(struct io_conn *conn,
 			 void *data, size_t len,
 			 struct io_plan *(*next)(struct io_conn *, void *),
-			 void *arg)
+			 void *next_arg)
 {
-	struct io_plan *plan = io_get_plan(conn, IO_IN);
-
-	assert(next);
+	struct io_plan_arg *arg = io_plan_arg(conn, IO_IN);
 
 	if (len == 0)
-		return set_always(conn, plan, next, arg);
+		return set_always(conn, IO_IN, next, next_arg);
 
-	plan->u1.cp = data;
-	plan->u2.s = len;
+	arg->u1.cp = data;
+	arg->u2.s = len;
 
-	return io_set_plan(conn, plan, do_read, next, arg);
+	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);
+	ssize_t ret = read(fd, arg->u1.cp, *(size_t *)arg->u2.vp);
 	if (ret <= 0)
 		return -1;
 
-	*(size_t *)plan->u2.vp = ret;
+	*(size_t *)arg->u2.vp = ret;
 	return 1;
 }
 
@@ -212,28 +207,28 @@ 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 *arg)
+				 void *next_arg)
 {
-	struct io_plan *plan = io_get_plan(conn, IO_IN);
+	struct io_plan_arg *arg = io_plan_arg(conn, IO_IN);
 
 	if (maxlen == 0)
-		return set_always(conn, plan, next, arg);
+		return set_always(conn, IO_IN, next, next_arg);
 
-	plan->u1.cp = data;
+	arg->u1.cp = data;
 	/* We store the max len in here temporarily. */
 	*len = maxlen;
-	plan->u2.vp = len;
+	arg->u2.vp = len;
 
-	return io_set_plan(conn, plan, do_read_partial, next, arg);
+	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 -1;
 
-	*(size_t *)plan->u2.vp = ret;
+	*(size_t *)arg->u2.vp = ret;
 	return 1;
 }
 
@@ -242,22 +237,22 @@ 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 *arg)
+				  void *next_arg)
 {
-	struct io_plan *plan = io_get_plan(conn, IO_OUT);
+	struct io_plan_arg *arg = io_plan_arg(conn, IO_OUT);
 
 	if (maxlen == 0)
-		return set_always(conn, plan, next, arg);
+		return set_always(conn, IO_OUT, next, next_arg);
 
-	plan->u1.const_vp = data;
+	arg->u1.const_vp = data;
 	/* We store the max len in here temporarily. */
 	*len = maxlen;
-	plan->u2.vp = len;
+	arg->u2.vp = len;
 
-	return io_set_plan(conn, plan, do_write_partial, next, arg);
+	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);
@@ -269,7 +264,7 @@ static int do_connect(int fd, struct io_plan *plan)
 
 	if (err == 0) {
 		/* Restore blocking if it was initially. */
-		fcntl(fd, F_SETFL, plan->u1.s);
+		fcntl(fd, F_SETFL, arg->u1.s);
 		return 1;
 	} else if (err == EINPROGRESS)
 		return 0;
@@ -280,45 +275,46 @@ static int do_connect(int fd, struct io_plan *plan)
 
 struct io_plan *io_connect_(struct io_conn *conn, const struct addrinfo *addr,
 			    struct io_plan *(*next)(struct io_conn *, void *),
-			    void *arg)
+			    void *next_arg)
 {
-	struct io_plan *plan = io_get_plan(conn, IO_IN);
+	struct io_plan_arg *arg = io_plan_arg(conn, IO_IN);
 	int fd = io_conn_fd(conn);
 
-	assert(next);
-
 	/* Save old flags, set nonblock if not already. */
-	plan->u1.s = fcntl(fd, F_GETFL);
-	fcntl(fd, F_SETFL, plan->u1.s | O_NONBLOCK);
+	arg->u1.s = fcntl(fd, F_GETFL);
+	fcntl(fd, F_SETFL, arg->u1.s | O_NONBLOCK);
 
 	/* Immediate connect can happen. */
 	if (connect(fd, addr->ai_addr, addr->ai_addrlen) == 0)
-		return set_always(conn, plan, next, arg);
+		return set_always(conn, IO_IN, next, next_arg);
 
 	if (errno != EINPROGRESS)
 		return io_close(conn);
 
-	return io_set_plan(conn, plan, do_connect, next, arg);
+	return io_set_plan(conn, IO_IN, do_connect, next, next_arg);
 }
 
 struct io_plan *io_wait_(struct io_conn *conn,
 			 const void *wait,
 			 struct io_plan *(*next)(struct io_conn *, void *),
-			 void *arg)
+			 void *next_arg)
 {
-	struct io_plan *plan;
+	enum io_direction dir;
+	struct io_plan_arg *arg;
 
 	/* If we're duplex, we want this on the current plan.  Otherwise,
 	 * doesn't matter. */
 	if (conn->plan[IO_IN].status == IO_UNSET)
-		plan = io_get_plan(conn, IO_IN);
+		dir = IO_IN;
 	else
-		plan = io_get_plan(conn, IO_OUT);
+		dir = IO_OUT;
+
+	arg = io_plan_arg(conn, dir);
+	arg->u1.const_vp = wait;
 
-	plan->status = IO_WAITING;
-	plan->u1.const_vp = wait;
+	conn->plan[dir].status = IO_WAITING;
 
-	return io_set_plan(conn, plan, NULL, next, arg);
+	return io_set_plan(conn, dir, NULL, next, next_arg);
 }
 
 void io_wake(const void *wait)
@@ -335,7 +331,7 @@ static int do_plan(struct io_conn *conn, struct io_plan *plan)
 	/* We shouldn't have polled for this event if this wasn't true! */
 	assert(plan->status == IO_POLLING);
 
-	switch (plan->io(conn->fd.fd, plan)) {
+	switch (plan->io(conn->fd.fd, &plan->arg)) {
 	case -1:
 		io_close(conn);
 		return -1;
@@ -382,13 +378,13 @@ struct io_plan *io_close(struct io_conn *conn)
 		return &conn->plan[IO_IN];
 
 	conn->plan[IO_IN].status = conn->plan[IO_OUT].status = IO_CLOSING;
-	conn->plan[IO_IN].u1.s = errno;
+	conn->plan[IO_IN].arg.u1.s = errno;
 	backend_new_closing(conn);
 
-	return io_set_plan(conn, &conn->plan[IO_IN], NULL, NULL, NULL);
+	return io_set_plan(conn, IO_IN, NULL, NULL, NULL);
 }
 
-struct io_plan *io_close_cb(struct io_conn *conn, void *arg)
+struct io_plan *io_close_cb(struct io_conn *conn, void *next_arg)
 {
 	return io_close(conn);
 }
@@ -415,6 +411,8 @@ void io_duplex_prepare(struct io_conn *conn)
 	assert(conn->plan[IO_IN].status == IO_UNSET);
 	assert(conn->plan[IO_OUT].status == IO_UNSET);
 
+	/* We can't sync debug until we've set both: io_wait() and io_always
+	 * can't handle it. */
 	conn->debug_saved = conn->debug;
 	conn->debug = false;
 }
@@ -431,20 +429,20 @@ struct io_plan *io_duplex_(struct io_plan *in_plan, struct io_plan *out_plan)
 	conn->debug = conn->debug_saved;
 
 	/* Now set the plans again, to invoke sync debug. */
-	io_set_plan(conn,
-		    out_plan, out_plan->io, out_plan->next, out_plan->next_arg);
-	io_set_plan(conn,
-		    in_plan, in_plan->io, in_plan->next, in_plan->next_arg);
+	io_set_plan(conn, IO_OUT,
+		    out_plan->io, out_plan->next, out_plan->next_arg);
+	io_set_plan(conn, IO_IN,
+		    in_plan->io, in_plan->next, in_plan->next_arg);
 
 	return out_plan + 1;
 }
 
-struct io_plan *io_set_plan(struct io_conn *conn, struct io_plan *plan,
-			    int (*io)(int fd, struct io_plan *plan),
+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 *other;
+	struct io_plan *plan = &conn->plan[dir];
 
 	plan->io = io;
 	plan->next = next;
@@ -468,11 +466,7 @@ struct io_plan *io_set_plan(struct io_conn *conn, struct io_plan *plan,
 		abort();
 	case IO_ALWAYS:
 		/* If other one is ALWAYS, leave in list! */
-		if (plan == &conn->plan[IO_IN])
-			other = &conn->plan[IO_OUT];
-		else
-			other = &conn->plan[IO_IN];
-		if (other->status != IO_ALWAYS)
+		if (conn->plan[!dir].status != IO_ALWAYS)
 			remove_from_always(conn);
 		next_plan(conn, plan);
 		break;

ccan/io/io_plan.h

@@ -4,9 +4,9 @@
 struct io_conn;
 
 /**
- * union io_plan_arg - scratch space for struct io_plan read/write fns.
+ * union io_plan_union - type for struct io_plan read/write fns.
  */
-union io_plan_arg {
+union io_plan_union {
 	char *cp;
 	void *vp;
 	const void *const_vp;
@@ -14,17 +14,11 @@ union io_plan_arg {
 	char c[sizeof(size_t)];
 };
 
-enum io_plan_status {
-	/* As before calling next function. */
-	IO_UNSET,
-	/* Normal. */
-	IO_POLLING,
-	/* Waiting for io_wake */
-	IO_WAITING,
-	/* Always do this. */
-	IO_ALWAYS,
-	/* Closing (both plans will be the same). */
-	IO_CLOSING
+/**
+ * struct io_plan_arg - scratch space for struct io_plan read/write fns.
+ */
+struct io_plan_arg {
+	union io_plan_union u1, u2;
 };
 
 enum io_direction {
@@ -33,58 +27,38 @@ enum io_direction {
 };
 
 /**
- * struct io_plan - one half of I/O to do
- * @status: the status of this plan.
- * @io: function to call when fd becomes read/writable, returns 0 to be
- *      called again, 1 if it's finished, and -1 on error (fd will be closed)
- * @next: the next function which is called if io returns 1.
- * @next_arg: the argument to @next
- * @u1, @u2: scratch space for @io.
- */
-struct io_plan {
-	enum io_plan_status status;
-
-	int (*io)(int fd, struct io_plan *plan);
-
-	struct io_plan *(*next)(struct io_conn *, void *arg);
-	void *next_arg;
-
-	union io_plan_arg u1, u2;
-};
-
-/**
- * io_get_plan - get a conn's io_plan for a given direction.
+ * io_plan_arg - get a conn's io_plan_arg for a given direction.
  * @conn: the connection.
  * @dir: IO_IN or IO_OUT.
  *
- * This is how an io helper gets a plan to store into; you must call
- * io_done_plan() when you've initialized it.
+ * This is how an io helper gets scratch space to store into; you must call
+ * io_set_plan() when you've initialized it.
  *
  * Example:
  * // Simple helper to read a single char.
- * static int do_readchar(int fd, struct io_plan *plan)
+ * static int do_readchar(int fd, struct io_plan_arg *arg)
  * {
- *	return read(fd, plan->u1.cp, 1) <= 0 ? -1 : 1;
+ *	return read(fd, arg->u1.cp, 1) <= 0 ? -1 : 1;
  * }
  *
  * struct io_plan *io_read_char_(struct io_conn *conn, char *in,
  *				 struct io_plan *(*next)(struct io_conn*,void*),
  *				 void *arg)
  * {
- *	struct io_plan *plan = io_get_plan(conn, IO_IN);
+ *	struct io_plan_arg *arg = io_get_plan_arg(conn, IO_IN);
  *
  *	// Store information we need in the plan unions u1 and u2.
- *	plan->u1.cp = in;
+ *	arg->u1.cp = in;
  *
- *	return io_set_plan(conn, plan, do_readchar, next, arg);
+ *	return io_set_plan(conn, IO_IN, do_readchar, next, arg);
  * }
  */
-struct io_plan *io_get_plan(struct io_conn *conn, enum io_direction dir);
+struct io_plan_arg *io_plan_arg(struct io_conn *conn, enum io_direction dir);
 
 /**
  * io_set_plan - set a conn's io_plan.
  * @conn: the connection.
- * @plan: the plan
+ * @dir: IO_IN or IO_OUT.
  * @io: the IO function to call when the fd is ready.
  * @next: the next callback when @io returns 1.
  * @next_arg: the argument to @next.
@@ -93,10 +67,10 @@ struct io_plan *io_get_plan(struct io_conn *conn, enum io_direction dir);
  * so it's important that this be the last thing in your function!
  *
  * See also:
- *	io_get_plan()
+ *	io_get_plan_arg()
  */
-struct io_plan *io_set_plan(struct io_conn *conn, struct io_plan *plan,
-			    int (*io)(int fd, struct io_plan *plan),
+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);
 #endif /* CCAN_IO_PLAN_H */

ccan/io/poll.c

@@ -151,11 +151,11 @@ void backend_wake(const void *wait)
 
 		c = (void *)fds[i];
 		if (c->plan[IO_IN].status == IO_WAITING
-		    && c->plan[IO_IN].u1.const_vp == wait)
+		    && c->plan[IO_IN].arg.u1.const_vp == wait)
 			io_do_wakeup(c, &c->plan[IO_IN]);
 
 		if (c->plan[IO_OUT].status == IO_WAITING
-		    && c->plan[IO_OUT].u1.const_vp == wait)
+		    && c->plan[IO_OUT].arg.u1.const_vp == wait)
 			io_do_wakeup(c, &c->plan[IO_OUT]);
 	}
 }
@@ -170,7 +170,7 @@ static void del_conn(struct io_conn *conn)
 	del_fd(&conn->fd);
 	if (conn->finish) {
 		/* Saved by io_close */
-		errno = conn->plan[IO_IN].u1.s;
+		errno = conn->plan[IO_IN].arg.u1.s;
 		conn->finish(conn, conn->finish_arg);
 	}
 	tal_free(conn);

ccan/io/test/run-17-homemade-io.c

@@ -25,19 +25,19 @@ static void finish_ok(struct io_conn *conn, struct packet *pkt)
 	io_break(pkt);
 }
 
-static int do_read_packet(int fd, struct io_plan *plan)
+static int do_read_packet(int fd, struct io_plan_arg *arg)
 {
-	struct packet *pkt = plan->u1.vp;
+	struct packet *pkt = arg->u1.vp;
 	char *dest;
 	ssize_t ret;
 	size_t off, totlen;
 
 	/* Reading len? */
-	if (plan->u2.s < sizeof(size_t)) {
+	if (arg->u2.s < sizeof(size_t)) {
 		ok1(pkt->state == 1);
 		pkt->state++;
 		dest = (char *)&pkt->len;
-		off = plan->u2.s;
+		off = arg->u2.s;
 		totlen = sizeof(pkt->len);
 	} else {
 		ok1(pkt->state == 2);
@@ -48,7 +48,7 @@ static int do_read_packet(int fd, struct io_plan *plan)
 			goto fail;
 		else {
 			dest = pkt->contents;
-			off = plan->u2.s - sizeof(pkt->len);
+			off = arg->u2.s - sizeof(pkt->len);
 			totlen = pkt->len;
 		}
 	}
@@ -57,11 +57,11 @@ static int do_read_packet(int fd, struct io_plan *plan)
 	if (ret <= 0)
 		goto fail;
 
-	plan->u2.s += ret;
+	arg->u2.s += ret;
 
 	/* Finished? */
-	return plan->u2.s >= sizeof(pkt->len)
-		&& plan->u2.s == pkt->len + sizeof(pkt->len);
+	return arg->u2.s >= sizeof(pkt->len)
+		&& arg->u2.s == pkt->len + sizeof(pkt->len);
 
 fail:
 	free(pkt->contents);
@@ -70,17 +70,17 @@ fail:
 
 static struct io_plan *io_read_packet(struct io_conn *conn,
 				      struct packet *pkt,
-				      struct io_plan *(*cb)(struct io_conn *, void *),
-				      void *arg)
+				      struct io_plan *(*cb)(struct io_conn *,
+							    void *),
+				      void *cb_arg)
 {
-	struct io_plan *plan = io_get_plan(conn, IO_IN);
+	struct io_plan_arg *arg = io_plan_arg(conn, IO_IN);
 
-	assert(cb);
 	pkt->contents = NULL;
-	plan->u1.vp = pkt;
-	plan->u2.s = 0;
+	arg->u1.vp = pkt;
+	arg->u2.s = 0;
 
-	return io_set_plan(conn, plan, do_read_packet, cb, arg);
+	return io_set_plan(conn, IO_IN, do_read_packet, cb, cb_arg);
 }
 
 static struct io_plan *init_conn(struct io_conn *conn, struct packet *pkt)