Re: [PATCH v2 4/5] Cygwin: pty: Prevent pty from changing code page of parent console.

[Corinna Vinschen <corinna-cygwin@cygwin.com>]

Hi Takashi,

On Jan 18 20:24, Takashi Yano via Cygwin-patches wrote:
> @@ -59,6 +59,46 @@ struct pipe_reply {
>    DWORD error;
>  };
>  
> +extern HANDLE attach_mutex; /* Defined in fhandler_console.cc */
> +
> +static DWORD
> +get_console_process_id (DWORD pid, bool match)
> +{
> +  DWORD list1;
> +  DWORD num, num_req;
> +  num = 1;
> +  num_req = GetConsoleProcessList (&list1, num);
> +  DWORD *list;
> +  if (num_req == 1)
> +    list = &list1;
> +  else
> +    while (true)
> +      {
> +	list = (DWORD *)
> +	  HeapAlloc (GetProcessHeap (), 0, num_req * sizeof (DWORD));
> +	num = num_req;
> +	num_req = GetConsoleProcessList (list, num);
> +	if (num_req > num)
> +	  HeapFree (GetProcessHeap (), 0, list);
> +	else
> +	  break;
> +      }
> +  num = num_req;
> +
> +  DWORD res = 0;
> +  /* Last one is the oldest. */
> +  /* https://github.com/microsoft/terminal/issues/95 */
> +  for (int i = (int) num - 1; i >= 0; i--)
> +    if ((match && list[i] == pid) || (!match && list[i] != pid))
> +      {
> +	res = list[i];
> +	break;
> +      }
> +  if (num > 1)
> +    HeapFree (GetProcessHeap (), 0, list);
> +  return res;
> +}

Sorry if I'm slow, but I was just mulling over this code snippet again,
and I was wondering if we couldn't do without the HeapAlloc loop.
Assuming you use a tmp_pathbuf here, you'd have space for 16384
processes per console.  Shouldn't that be more than enough?  I.e.

static DWORD
get_console_process_id (DWORD pid, bool match)
{
  tmp_pathbuf tp;
  DWORD *list = (DWORD *) tp.w_get ();
  const DWORD num = NT_MAX_PATH * sizeof (WCHAR) / sizeof (DWORD);
  DWORD res = 0;

  num = GetConsoleProcessList (&list, num);

  /* Last one is the oldest. */
  /* https://github.com/microsoft/terminal/issues/95 */
  for (int i = (int) num - 1; i >= 0; i--)
    if ((match && list[i] == pid) || (!match && list[i] != pid))
      {
	res = list[i];
	break;
      }
  return res;
}


What do you think?

Corinna