[newlib-cygwin] Cygwin: pty: Close pseudo console only if the process is the owner.

[Takashi Yano]

https://sourceware.org/git/gitweb.cgi?p=newlib-cygwin.git;h=45cfcfbd71a02608db543c2e57371881aad4c0b1

commit 45cfcfbd71a02608db543c2e57371881aad4c0b1
Author: Takashi Yano <takashi.yano@nifty.ne.jp>
Date:   Sat Apr 9 12:59:54 2022 +0900

    Cygwin: pty: Close pseudo console only if the process is the owner.
    
    - Currently, close_pseudoconsole() is called unconditionally from
      fhandler_termios::process_sigs() on Ctrl-C. This causes deadlock
      if Ctrl-C is pressed while setup_pseudoconsole() is called. With
      this patch, close_pseudoconsole() is called only if the master
      process is the owner of the nat-pipe to avoid the deadlock.

Diff:
---
 winsup/cygwin/fhandler_tty.cc | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/winsup/cygwin/fhandler_tty.cc b/winsup/cygwin/fhandler_tty.cc
index 4cb5f1411..c02dfb8ed 100644
--- a/winsup/cygwin/fhandler_tty.cc
+++ b/winsup/cygwin/fhandler_tty.cc
@@ -4152,7 +4152,8 @@ void
 fhandler_pty_slave::release_ownership_of_nat_pipe (tty *ttyp,
 						   fhandler_termios *fh)
 {
-  if (fh->get_major () == DEV_PTYM_MAJOR)
+  if (fh->get_major () == DEV_PTYM_MAJOR
+      && nat_pipe_owner_self (ttyp->nat_pipe_owner_pid))
     {
       fhandler_pty_master *ptym = (fhandler_pty_master *) fh;
       WaitForSingleObject (ptym->pipe_sw_mutex, INFINITE);