[newlib-cygwin] Cygwin: pty: Discard input in from_master_nat pipe on signal as well.

[Takashi Yano <tyan0@sourceware.org>]

https://sourceware.org/git/gitweb.cgi?p=newlib-cygwin.git;h=c4704c7c204e377859f657a3b06c112133adff09

commit c4704c7c204e377859f657a3b06c112133adff09
Author: Takashi Yano <takashi.yano@nifty.ne.jp>
Date:   Sun Feb 13 02:16:32 2022 +0900

    Cygwin: pty: Discard input in from_master_nat pipe on signal as well.
    
    - Currently, pty discards input only in from_master pipe on signal.
      Due to this, if pty is started without pseudo console support and
      start a non-cygwin process from cmd.exe, type adhead input is not
      discarded on signals such as Ctrl-C. This patch fixes the issue.

Diff:
---
 winsup/cygwin/fhandler_tty.cc | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/winsup/cygwin/fhandler_tty.cc b/winsup/cygwin/fhandler_tty.cc
index 7e733e49a..8c9a10c23 100644
--- a/winsup/cygwin/fhandler_tty.cc
+++ b/winsup/cygwin/fhandler_tty.cc
@@ -438,6 +438,9 @@ fhandler_pty_master::discard_input ()
   while (::bytes_available (bytes_in_pipe, from_master) && bytes_in_pipe)
     ReadFile (from_master, buf, sizeof(buf), &n, NULL);
   ResetEvent (input_available_event);
+  if (!get_ttyp ()->pcon_activated)
+    while (::bytes_available (bytes_in_pipe, from_master_nat) && bytes_in_pipe)
+      ReadFile (from_master_nat, buf, sizeof(buf), &n, NULL);
   get_ttyp ()->discard_input = true;
   ReleaseMutex (input_mutex);
 }