[PATCH] Cygwin: pty: Discard remnants of win32-input-mode

[Takashi Yano]

In Windoes 11, some remnants sequences of win32-input-mode used by
pseudo console occasionally sent to shell which start non-cygwin
apps. With this patch, the remnants sequneces just after closing
pseudo console will be discarded.

Signed-off-by: Takashi Yano <takashi.yano@nifty.ne.jp>
Reviewed-by:
---
 winsup/cygwin/fhandler/pty.cc      | 11 +++++++++++
 winsup/cygwin/local_includes/tty.h |  1 +
 winsup/cygwin/tty.cc               |  1 +
 3 files changed, 13 insertions(+)

diff --git a/winsup/cygwin/fhandler/pty.cc b/winsup/cygwin/fhandler/pty.cc
index b30cb0128..b90b2b609 100644
--- a/winsup/cygwin/fhandler/pty.cc
+++ b/winsup/cygwin/fhandler/pty.cc
@@ -2504,6 +2504,16 @@ fhandler_pty_master::write (const void *ptr, size_t len)
       return len;
     }
 
+  /* Remnants of win32-input-mode sequence in pcon_activated mode */
+  bool is_remnants_to_nat =
+    GetTickCount64 () - get_ttyp ()->pcon_close_time < 32
+    && len >= 3 && p[0] == '\033' && p[1] == '[' && p[len - 1] =='_';
+  if (is_remnants_to_nat) /* Discard */
+    {
+      ReleaseMutex (input_mutex);
+      return len;
+    }
+
   /* The code path reaches here when pseudo console is not activated
      or cygwin process is foreground even though pseudo console is
      activated. */
@@ -3947,6 +3957,7 @@ fhandler_pty_slave::close_pseudoconsole (tty *ttyp, DWORD force_switch_to)
 	  /* HeapFree() will be called in ClosePseudoConsole() */
 	  ClosePseudoConsole ((HPCON) hp);
 	  CloseHandle (ttyp->h_pcon_conhost_process);
+	  ttyp->pcon_close_time = GetTickCount64 ();
 	  ttyp->pcon_activated = false;
 	  ttyp->switch_to_nat_pipe = false;
 	  ttyp->nat_pipe_owner_pid = 0;
diff --git a/winsup/cygwin/local_includes/tty.h b/winsup/cygwin/local_includes/tty.h
index 9485e24c5..14b8f0278 100644
--- a/winsup/cygwin/local_includes/tty.h
+++ b/winsup/cygwin/local_includes/tty.h
@@ -141,6 +141,7 @@ private:
   xfer_dir pty_input_state;
   bool discard_input;
   bool stop_fwd_thread;
+  ULONGLONG pcon_close_time;
 
 public:
   HANDLE from_master_nat () const { return _from_master_nat; }
diff --git a/winsup/cygwin/tty.cc b/winsup/cygwin/tty.cc
index 0c49dc2bd..defd3ead5 100644
--- a/winsup/cygwin/tty.cc
+++ b/winsup/cygwin/tty.cc
@@ -255,6 +255,7 @@ tty::init ()
   last_sig = 0;
   discard_input = false;
   stop_fwd_thread = false;
+  pcon_close_time = 0;
 }
 
 HANDLE
-- 
2.51.0