propagate font zoom via SIGWINCH

[Thomas Wolff]

xterm 368 and mintty 3.5.1 implement a new feature to support 
notification of terminal scaling via font zooming also if the terminal 
text dimensions (rows/columns) stay unchanged, using ioctl(TIOCSWINSZ), 
raising SIGWINCH.
This does not work in cygwin currently. The attached patch fixes that.
Thomas
-------------- next part --------------
From b9795ed6ec3979f68173e54d01e681271eea4a9a Mon Sep 17 00:00:00 2001
From: Thomas Wolff <mined@users.noreply.github.com>
Date: Sat, 3 Jul 2021 00:00:00 +0200
Subject: [PATCH] tty/pty: support TIOCSWINSZ pixel-size-only change
 notification

---
 winsup/cygwin/fhandler_tty.cc | 10 ++++++++--
 1 file changed, 8 insertions(+), 2 deletions(-)

diff --git a/winsup/cygwin/fhandler_tty.cc b/winsup/cygwin/fhandler_tty.cc
index 1ed41d3b2..f2ac26892 100644
--- a/winsup/cygwin/fhandler_tty.cc
+++ b/winsup/cygwin/fhandler_tty.cc
@@ -1687,7 +1687,10 @@ fhandler_pty_slave::ioctl (unsigned int cmd, void *arg)
       break;
     case TIOCSWINSZ:
       if (get_ttyp ()->winsize.ws_row != ((struct winsize *) arg)->ws_row
-	  || get_ttyp ()->winsize.ws_col != ((struct winsize *) arg)->ws_col)
+	  || get_ttyp ()->winsize.ws_col != ((struct winsize *) arg)->ws_col
+	  || get_ttyp ()->winsize.ws_ypixel != ((struct winsize *) arg)->ws_ypixel
+	  || get_ttyp ()->winsize.ws_xpixel != ((struct winsize *) arg)->ws_xpixel
+	 )
 	{
 	  if (get_ttyp ()->pcon_activated && get_ttyp ()->pcon_pid)
 	    resize_pseudo_console ((struct winsize *) arg);
@@ -2279,7 +2282,10 @@ fhandler_pty_master::ioctl (unsigned int cmd, void *arg)
       break;
     case TIOCSWINSZ:
       if (get_ttyp ()->winsize.ws_row != ((struct winsize *) arg)->ws_row
-	  || get_ttyp ()->winsize.ws_col != ((struct winsize *) arg)->ws_col)
+	  || get_ttyp ()->winsize.ws_col != ((struct winsize *) arg)->ws_col
+	  || get_ttyp ()->winsize.ws_ypixel != ((struct winsize *) arg)->ws_ypixel
+	  || get_ttyp ()->winsize.ws_xpixel != ((struct winsize *) arg)->ws_xpixel
+	 )
 	{
 	  if (get_ttyp ()->pcon_activated && get_ttyp ()->pcon_pid)
 	    resize_pseudo_console ((struct winsize *) arg);
-- 
2.32.0