[PATCH] Cygwin: pty: Fix screen distortion after less for native apps again.

[Takashi Yano]

- Commit c4b060e3fe3bed05b3a69ccbcc20993ad85e163d seems to be not
  enough. Fixed again.
---
 winsup/cygwin/fhandler_tty.cc | 19 ++++++++++++++-----
 1 file changed, 14 insertions(+), 5 deletions(-)

diff --git a/winsup/cygwin/fhandler_tty.cc b/winsup/cygwin/fhandler_tty.cc
index bcc7648f3..742fa7e33 100644
--- a/winsup/cygwin/fhandler_tty.cc
+++ b/winsup/cygwin/fhandler_tty.cc
@@ -1394,10 +1394,6 @@ fhandler_pty_slave::push_to_pcon_screenbuffer (const char *ptr, size_t len,
 	    nlen = p0 - buf;
 	}
     }
-  if (!nlen) /* Nothing to be synchronized */
-    goto cleanup;
-  if (get_ttyp ()->switch_to_pcon_out && !is_echo)
-    goto cleanup;
   /* Remove ESC sequence which returns results to console
      input buffer. Without this, cursor position report
      is put into the input buffer as a garbage. */
@@ -1413,6 +1409,10 @@ fhandler_pty_slave::push_to_pcon_screenbuffer (const char *ptr, size_t len,
       memmove (p0, p0+4, nlen - (p0+4 - buf));
       nlen -= 4;
     }
+  if (!nlen) /* Nothing to be synchronized */
+    goto cleanup;
+  if (get_ttyp ()->switch_to_pcon_out && !is_echo)
+    goto cleanup;
 
   /* If the ESC sequence ESC[?3h or ESC[?3l which clears console screen
      buffer is pushed, set need_redraw_screen to trigger redraw screen. */
@@ -1504,6 +1504,15 @@ fhandler_pty_slave::write (const void *ptr, size_t len)
 
   reset_switch_to_pcon ();
 
+  bool screen_alternated_orig = get_ttyp ()->screen_alternated;
+  /* Push slave output to pseudo console screen buffer */
+  if (get_pseudo_console () && !screen_alternated_orig)
+    {
+      acquire_output_mutex (INFINITE);
+      push_to_pcon_screenbuffer ((char *)ptr, len, false);
+      release_output_mutex ();
+    }
+
   bool output_to_pcon =
     get_ttyp ()->switch_to_pcon_out && !get_ttyp ()->screen_alternated;
 
@@ -1564,7 +1573,7 @@ fhandler_pty_slave::write (const void *ptr, size_t len)
   restore_reattach_pcon ();
 
   /* Push slave output to pseudo console screen buffer */
-  if (get_pseudo_console ())
+  if (get_pseudo_console () && screen_alternated_orig)
     {
       acquire_output_mutex (INFINITE);
       push_to_pcon_screenbuffer ((char *)ptr, len, false);
-- 
2.26.2