From b68b3a6e19eb57c9f1c8b70b624f103254f4964a Mon Sep 17 00:00:00 2001
From: Ori Bernstein <ori@eigenstate.org>
Date: Sat, 26 Jun 2021 17:29:27 +0000
Subject: [PATCH] vt, ssh: don't send interrupts on window resize

When resizing windows, vt would signal ssh by updating
the window size and sending an interrupt. Ssh reacted
by forwarding both the winch and an interrupt.

This change adds a WINCH generation counter so that
ssh can differentiate between resizes and interrupts.
If an interrupt comes in, and the WINCH generation
changes, then the interrupt is taken as signalling a
WINCH.
---
 sys/src/cmd/ssh.c     | 43 ++++++++++++++++++++++++++++---------------
 sys/src/cmd/vt/main.c |  2 ++
 2 files changed, 30 insertions(+), 15 deletions(-)

diff --git a/sys/src/cmd/ssh.c b/sys/src/cmd/ssh.c
index 00733bdd7..e9021a53b 100644
--- a/sys/src/cmd/ssh.c
+++ b/sys/src/cmd/ssh.c
@@ -1090,13 +1090,22 @@ static struct {
 	int	ypixels;
 	int	lines;
 	int	cols;
+	int	gen;
 } tty;
 
-void
+int
 getdim(void)
 {
 	char *s;
+	int g;
 
+	if(s = getenv("WINCH")){
+		g = atoi(s);
+		if(tty.gen == g)
+			return 0;
+		tty.gen = g;
+		free(s);
+	}
 	if(s = getenv("XPIXELS")){
 		tty.xpixels = atoi(s);
 		free(s);
@@ -1113,6 +1122,7 @@ getdim(void)
 		tty.cols = atoi(s);
 		free(s);
 	}
+	return 1;
 }
 
 void
@@ -1175,6 +1185,7 @@ main(int argc, char *argv[])
 	fmtinstall('[', encodefmt);
 	fmtinstall('k', kfmt);
 
+	tty.gen = -1;
 	tty.term = getenv("TERM");
 	if(tty.term == nil)
 		tty.term = "";
@@ -1403,20 +1414,22 @@ Mux:
 			intr = 1;
 		if(intr){
 			if(!raw) break;
-			getdim();
-			sendpkt("busbuuuu", MSG_CHANNEL_REQUEST,
-				send.chan,
-				"window-change", 13,
-				0,
-				tty.cols,
-				tty.lines,
-				tty.xpixels,
-				tty.ypixels);
-			sendpkt("busbs", MSG_CHANNEL_REQUEST,
-				send.chan,
-				"signal", 6,
-				0,
-				"INT", 3);
+			if(getdim()){
+				sendpkt("busbuuuu", MSG_CHANNEL_REQUEST,
+					send.chan,
+					"window-change", 13,
+					0,
+					tty.cols,
+					tty.lines,
+					tty.xpixels,
+					tty.ypixels);
+			}else{
+				sendpkt("busbs", MSG_CHANNEL_REQUEST,
+					send.chan,
+					"signal", 6,
+					0,
+					"INT", 3);
+			}
 			intr = 0;
 			continue;
 		}
diff --git a/sys/src/cmd/vt/main.c b/sys/src/cmd/vt/main.c
index 0622bb9ed..f1ed35b2b 100644
--- a/sys/src/cmd/vt/main.c
+++ b/sys/src/cmd/vt/main.c
@@ -61,6 +61,7 @@ int	backc;
 int	nbacklines;
 int	xmax, ymax;
 int	blocked;
+int	winchgen;
 int	resize_flag = 1;
 int	pagemode;
 int	olines;
@@ -867,6 +868,7 @@ putenvint(char *name, int x)
 void
 exportsize(void)
 {
+	putenvint("WINCH", ++winchgen);
 	putenvint("XPIXELS", (xmax+1)*ftsize.x);
 	putenvint("YPIXELS", (ymax+1)*ftsize.y);
 	putenvint("LINES", ymax+1);