Pass the stdout file descriptor from the client as well as stdin and use

them for control clients directly instead of passing everything via the
client.

client.c

@@ -402,6 +402,8 @@ client_main(struct event_base *base, int argc, char **argv, int flags, int feat)
 	} else if (client_exitreason != CLIENT_EXIT_NONE)
 		fprintf(stderr, "%s\n", client_exit_message());
 	setblocking(STDIN_FILENO, 1);
+	setblocking(STDOUT_FILENO, 1);
+	setblocking(STDERR_FILENO, 1);
 	return (client_exitval);
 }
 
@@ -429,6 +431,9 @@ client_send_identify(const char *ttynam, const char *cwd, int feat)
 	if ((fd = dup(STDIN_FILENO)) == -1)
 		fatal("dup failed");
 	proc_send(client_peer, MSG_IDENTIFY_STDIN, fd, NULL, 0);
+	if ((fd = dup(STDOUT_FILENO)) == -1)
+		fatal("dup failed");
+	proc_send(client_peer, MSG_IDENTIFY_STDOUT, fd, NULL, 0);
 
 	pid = getpid();
 	proc_send(client_peer, MSG_IDENTIFY_CLIENTPID, -1, &pid, sizeof pid);

control.c

@@ -23,10 +23,11 @@
 #include <stdlib.h>
 #include <string.h>
 #include <time.h>
+#include <unistd.h>
 
 #include "tmux.h"
 
-/* Control offsets. */
+/* Control client offset. */
 struct control_offset {
 	u_int				pane;
 
@@ -34,13 +35,16 @@ struct control_offset {
 	int				flags;
 #define CONTROL_OFFSET_OFF 0x1
 
-	RB_ENTRY(control_offset)		entry;
+	RB_ENTRY(control_offset)	entry;
 };
 RB_HEAD(control_offsets, control_offset);
 
-/* Control state. */
+/* Control client state. */
 struct control_state {
-	struct control_offsets	offsets;
+	struct control_offsets	 offsets;
+
+	struct bufferevent	*read_event;
+	struct bufferevent	*write_event;
 };
 
 /* Compare client offsets. */
@@ -146,18 +150,24 @@ control_set_pane_off(struct client *c, struct window_pane *wp)
 void
 control_write(struct client *c, const char *fmt, ...)
 {
-	va_list	ap;
+	struct control_state	*cs = c->control_state;
+	va_list			 ap;
+	char			*s;
 
 	va_start(ap, fmt);
-	file_vprint(c, fmt, ap);
-	file_print(c, "\n");
+	xvasprintf(&s, fmt, ap);
 	va_end(ap);
+
+	bufferevent_write(cs->write_event, s, strlen(s));
+	bufferevent_write(cs->write_event, "\n", 1);
+	free(s);
 }
 
 /* Write output from a pane. */
 void
 control_write_output(struct client *c, struct window_pane *wp)
 {
+	struct control_state	*cs = c->control_state;
 	struct control_offset	*co;
 	struct evbuffer		*message;
 	u_char			*new_data;
@@ -165,11 +175,6 @@ control_write_output(struct client *c, struct window_pane *wp)
 
 	if (c->flags & CLIENT_CONTROL_NOOUTPUT)
 		return;
-
-	/*
-	 * Only write input if the window pane is linked to a window belonging
-	 * to the client's session.
-	 */
 	if (winlink_find_by_window(&c->session->windows, wp->window) == NULL)
 		return;
 
@@ -193,15 +198,15 @@ control_write_output(struct client *c, struct window_pane *wp)
 		else
 			evbuffer_add_printf(message, "%c", new_data[i]);
 	}
-	evbuffer_add(message, "", 1);
+	evbuffer_add(message, "\n", 1);
 
-	control_write(c, "%s", EVBUFFER_DATA(message));
+	bufferevent_write_buffer(cs->write_event, message);
 	evbuffer_free(message);
 
 	window_pane_update_used_data(wp, &co->offset, new_size, 1);
 }
 
-/* Control error callback. */
+/* Control client error callback. */
 static enum cmd_retval
 control_error(struct cmdq_item *item, void *data)
 {
@@ -216,18 +221,27 @@ control_error(struct cmdq_item *item, void *data)
 	return (CMD_RETURN_NORMAL);
 }
 
-/* Control input callback. Read lines and fire commands. */
+/* Control client error callback. */
 static void
-control_callback(__unused struct client *c, __unused const char *path,
-    int read_error, int closed, struct evbuffer *buffer, __unused void *data)
+control_error_callback(__unused struct bufferevent *bufev,
+    __unused short what, void *data)
 {
+	struct client	*c = data;
+
+	c->flags |= CLIENT_EXIT;
+}
+
+/* Control client input callback. Read lines and fire commands. */
+static void
+control_read_callback(__unused struct bufferevent *bufev, void *data)
+{
+	struct client		*c = data;
+	struct control_state	*cs = c->control_state;
+	struct evbuffer		*buffer = cs->read_event->input;
 	char			*line, *error;
 	struct cmdq_state	*state;
 	enum cmd_parse_status	 status;
 
-	if (closed || read_error != 0)
-		c->flags |= CLIENT_EXIT;
-
 	for (;;) {
 		line = evbuffer_readln(buffer, NULL, EVBUFFER_EOL_LF);
 		if (line == NULL)
@@ -255,13 +269,30 @@ control_start(struct client *c)
 {
 	struct control_state	*cs;
 
+	if (c->flags & CLIENT_CONTROLCONTROL) {
+		close(c->out_fd);
+		c->out_fd = -1;
+	} else
+		setblocking(c->out_fd, 0);
+	setblocking(c->fd, 0);
+
 	cs = c->control_state = xcalloc(1, sizeof *cs);
 	RB_INIT(&cs->offsets);
 
-	file_read(c, "-", control_callback, c);
+	cs->read_event = bufferevent_new(c->fd, control_read_callback, NULL,
+	    control_error_callback, c);
+	bufferevent_enable(cs->read_event, EV_READ);
 
 	if (c->flags & CLIENT_CONTROLCONTROL)
-		file_print(c, "\033P1000p");
+		cs->write_event = cs->read_event;
+	else {
+		cs->write_event = bufferevent_new(c->out_fd, NULL, NULL,
+		    control_error_callback, c);
+	}
+	bufferevent_enable(cs->write_event, EV_WRITE);
+
+	if (c->flags & CLIENT_CONTROLCONTROL)
+		control_write(c, "\033P1000p");
 }
 
 /* Stop control mode. */
@@ -270,6 +301,10 @@ control_stop(struct client *c)
 {
 	struct control_state	*cs = c->control_state;
 
+	if (~c->flags & CLIENT_CONTROLCONTROL)
+		bufferevent_free(cs->write_event);
+	bufferevent_free(cs->read_event);
+
 	control_free_offsets(c);
 	free(cs);
 }

file.c

@@ -242,7 +242,9 @@ file_write(struct client *c, const char *path, int flags, const void *bdata,
 		cf->path = xstrdup("-");
 
 		fd = STDOUT_FILENO;
-		if (c == NULL || c->flags & CLIENT_ATTACHED) {
+		if (c == NULL ||
+		    (c->flags & CLIENT_ATTACHED) ||
+		    (c->flags & CLIENT_CONTROL)) {
 			cf->error = EBADF;
 			goto done;
 		}
@@ -311,7 +313,9 @@ file_read(struct client *c, const char *path, client_file_cb cb, void *cbdata)
 		cf->path = xstrdup("-");
 
 		fd = STDIN_FILENO;
-		if (c == NULL || c->flags & CLIENT_ATTACHED) {
+		if (c == NULL ||
+		    (c->flags & CLIENT_ATTACHED) ||
+		    (c->flags & CLIENT_CONTROL)) {
 			cf->error = EBADF;
 			goto done;
 		}

server-client.c

@@ -223,7 +223,7 @@ server_client_create(int fd)
 	c->environ = environ_create();
 
 	c->fd = -1;
-	c->cwd = NULL;
+	c->out_fd = -1;
 
 	c->queue = cmdq_new();
 	RB_INIT(&c->windows);
@@ -338,6 +338,8 @@ server_client_lost(struct client *c)
 	proc_remove_peer(c->peer);
 	c->peer = NULL;
 
+	if (c->out_fd != -1)
+		close(c->out_fd);
 	if (c->fd != -1) {
 		close(c->fd);
 		c->fd = -1;
@@ -1573,10 +1575,9 @@ server_client_check_pane_buffer(struct window_pane *wp)
 out:
 	/*
 	 * If there is data remaining, and there are no clients able to consume
-	 * it, do not read any more. This is true when 1) there are attached
-	 * clients 2) all the clients are control clients 3) all of them have
-	 * either the OFF flag set, or are otherwise not able to accept any
-	 * more data for this pane.
+	 * it, do not read any more. This is true when there are attached
+	 * clients, all of which are control clients which are not able to
+	 * accept any more data.
 	 */
 	if (off)
 		bufferevent_disable(wp->event, EV_READ);
@@ -1969,6 +1970,7 @@ server_client_dispatch(struct imsg *imsg, void *arg)
 	case MSG_IDENTIFY_TTYNAME:
 	case MSG_IDENTIFY_CWD:
 	case MSG_IDENTIFY_STDIN:
+	case MSG_IDENTIFY_STDOUT:
 	case MSG_IDENTIFY_ENVIRON:
 	case MSG_IDENTIFY_CLIENTPID:
 	case MSG_IDENTIFY_DONE:
@@ -2179,6 +2181,12 @@ server_client_dispatch_identify(struct client *c, struct imsg *imsg)
 		c->fd = imsg->fd;
 		log_debug("client %p IDENTIFY_STDIN %d", c, imsg->fd);
 		break;
+	case MSG_IDENTIFY_STDOUT:
+		if (datalen != 0)
+			fatalx("bad MSG_IDENTIFY_STDOUT size");
+		c->out_fd = imsg->fd;
+		log_debug("client %p IDENTIFY_STDOUT %d", c, imsg->fd);
+		break;
 	case MSG_IDENTIFY_ENVIRON:
 		if (datalen == 0 || data[datalen - 1] != '\0')
 			fatalx("bad MSG_IDENTIFY_ENVIRON string");
@@ -2207,11 +2215,9 @@ server_client_dispatch_identify(struct client *c, struct imsg *imsg)
 	c->name = name;
 	log_debug("client %p name is %s", c, c->name);
 
-	if (c->flags & CLIENT_CONTROL) {
-		close(c->fd);
-		c->fd = -1;
+	 if (c->flags & CLIENT_CONTROL)
 		control_start(c);
-	} else if (c->fd != -1) {
+	else if (c->fd != -1) {
 		if (tty_init(&c->tty, c) != 0) {
 			close(c->fd);
 			c->fd = -1;
@@ -2219,6 +2225,8 @@ server_client_dispatch_identify(struct client *c, struct imsg *imsg)
 			tty_resize(&c->tty);
 			c->flags |= CLIENT_TERMINAL;
 		}
+		close(c->out_fd);
+		c->out_fd = -1;
 	}
 
 	/*
@@ -2335,7 +2343,8 @@ void
 server_client_set_flags(struct client *c, const char *flags)
 {
 	char	*s, *copy, *next;
-	int	 flag, not;
+	uint64_t flag;
+	int	 not;
 
 	s = copy = xstrdup (flags);
 	while ((next = strsep(&s, ",")) != NULL) {

tmux.h

@@ -498,6 +498,7 @@ enum msgtype {
 	MSG_IDENTIFY_CLIENTPID,
 	MSG_IDENTIFY_CWD,
 	MSG_IDENTIFY_FEATURES,
+	MSG_IDENTIFY_STDOUT,
 
 	MSG_COMMAND = 200,
 	MSG_DETACH,
@@ -967,6 +968,7 @@ struct window_pane {
 
 	int		 fd;
 	struct bufferevent *event;
+
 	struct window_pane_offset offset;
 	size_t		 base_offset;
 
@@ -1581,6 +1583,7 @@ struct client {
 
 	pid_t		 pid;
 	int		 fd;
+	int		 out_fd;
 	struct event	 event;
 	int		 retval;