From 0449a29ac0c04c8dd0895b6dbd16f9b1945b1d57 Mon Sep 17 00:00:00 2001
From: Takashi Yano <takashi.yano@nifty.ne.jp>
Date: Wed, 15 Dec 2021 12:25:58 +0900
Subject: [PATCH] Cygwin: pty: Fix input switching failure.

- This patch fixes the failure of input switching between io_handle
  and io_handle_nat. This very rarely happens, however, input is
  wrongly switched to io_handle_nat even though the non-cygwin app
  is in the background.
---
 winsup/cygwin/fhandler_tty.cc | 3 +++
 winsup/cygwin/tty.cc          | 3 ++-
 2 files changed, 5 insertions(+), 1 deletion(-)

diff --git a/winsup/cygwin/fhandler_tty.cc b/winsup/cygwin/fhandler_tty.cc
index ee687d9ad..c8ad53cb7 100644
--- a/winsup/cygwin/fhandler_tty.cc
+++ b/winsup/cygwin/fhandler_tty.cc
@@ -1056,6 +1056,7 @@ fhandler_pty_slave::set_switch_to_pcon (void)
       isHybrid = true;
       setup_locale ();
       myself->exec_dwProcessId = myself->dwProcessId;
+      myself->process_state |= PID_NEW_PG; /* Marker for pcon_fg */
       bool nopcon = (disable_pcon || !term_has_pcon_cap (NULL));
       WaitForSingleObject (pcon_mutex, INFINITE);
       bool pcon_enabled = setup_pseudoconsole (nopcon);
@@ -1168,6 +1169,7 @@ fhandler_pty_slave::reset_switch_to_pcon (void)
 		    }
 		}
 	      myself->exec_dwProcessId = 0;
+	      myself->process_state &= ~PID_NEW_PG;
 	      isHybrid = false;
 	    }
 	}
@@ -2272,6 +2274,7 @@ fhandler_pty_master::write (const void *ptr, size_t len)
 	      _pinfo *p = pids[i];
 	      if (p->ctty == get_ttyp ()->ntty
 		  && p->pgid == get_ttyp ()->getpgid ()
+		  && (p->process_state & PID_NOTCYGWIN)
 		  && (p->process_state & PID_NEW_PG))
 		{
 		  wpid = p->dwProcessId;
diff --git a/winsup/cygwin/tty.cc b/winsup/cygwin/tty.cc
index 2566f4c45..11ad3ec51 100644
--- a/winsup/cygwin/tty.cc
+++ b/winsup/cygwin/tty.cc
@@ -392,7 +392,8 @@ tty::pcon_fg (pid_t pgid)
   for (unsigned i = 0; i < pids.npids; i++)
     {
       _pinfo *p = pids[i];
-      if (p->ctty == ntty && p->pgid == pgid && p->exec_dwProcessId)
+      if (p->ctty == ntty && p->pgid == pgid
+	  && (p->process_state & (PID_NOTCYGWIN | PID_NEW_PG)))
 	return true;
     }
   if (pgid > MAX_PID)