Re: [PATCH v2 2/3] Cygwin: pty: Discard pcon input buffer when discard_input is called.

Hi Takashi,

On 6/13/2026 7:09 AM, Takashi Yano wrote:
> Previously, the process on pty could not be a child of non-cygwin
> process. So, it is not necessary to flush pcon input buffer even
            ^^^^ replace "So" with "In that case"

> when discard_input() is called. However, now, the child process
> of non-cygwin app on pseudo console is running on pty. So,
> discard_input() should affect to the pcon input buffer as well.
> 
> This prevents the probelm:
                     ^^^^^^^
>    1) Run 'sleep 10' in cmd.exe
>    2) Enter 'ps\n' while sleeping
>    3) Press Ctrl-C
>    4) 'ps' will be executed after terminating 'sleep' by Ctrl-C.
> 
> Signed-off-by: Takashi Yano <[email protected]>
> Reviwed-by:
> ---
>   winsup/cygwin/fhandler/pty.cc | 11 ++++++++++-
>   1 file changed, 10 insertions(+), 1 deletion(-)
> 
> diff --git a/winsup/cygwin/fhandler/pty.cc b/winsup/cygwin/fhandler/pty.cc
> index d625ff9df..b3a8d57cc 100644
> --- a/winsup/cygwin/fhandler/pty.cc
> +++ b/winsup/cygwin/fhandler/pty.cc
> @@ -583,6 +583,14 @@ fhandler_pty_master::discard_input ()
>     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);
> +  else
> +    {
> +      DWORD target_pid = get_ttyp ()->nat_pipe_owner_pid;
> +      DWORD resume_pid =
> +	fhandler_pty_common::attach_console_temporarily (target_pid);
> +      FlushConsoleInputBuffer (h_pcon_in_dupped);
> +      fhandler_pty_common::resume_from_temporarily_attach (resume_pid);
> +    }
>     get_ttyp ()->discard_input = true;
>     ReleaseMutex (input_mutex);
>   }
> @@ -2585,7 +2593,8 @@ fhandler_pty_master::write (const void *ptr, size_t len)
>         for (size_t i = 0, j = 0; i < len; i++)
>   	{
>   	  process_sig_state r = process_sigs (buf[i], get_ttyp (), this);
> -	  if (r != done_with_debugger)
> +	  if (r != done_with_debugger &&
> +	      (r != signalled || (ti.c_lflag & NOFLSH) || buf[i] == '\003'))
>   	    {
>   	      char c = buf[i];
>   	      /* Workaround for pseudo console in Windows 11 */

Other than the minor commentary changes, this LGTM.

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