[PATCH] Cygwin: pinfo: Align CTTY behavior to the statement of POSIX.
Corinna Vinschen
corinna-cygwin@cygwin.com
Tue Dec 20 18:14:35 GMT 2022
Hi Takashi,
On Dec 20 21:41, Takashi Yano wrote:
> POSIX states "A terminal may be the controlling terminal for at most
> one session."
> https://pubs.opengroup.org/onlinepubs/9699919799/basedefs/V1_chap11.html
>
> However, in cygwin, multiple sessions could be associated with the
> same TTY. This patch aligns CTTY behavior to the statement of POSIX.
>
> Signed-off-by: Takashi Yano <takashi.yano@nifty.ne.jp>
> ---
> winsup/cygwin/fhandler/termios.cc | 6 +++++-
> winsup/cygwin/mm/cygheap.cc | 2 ++
> winsup/cygwin/pinfo.cc | 4 +++-
> 3 files changed, 10 insertions(+), 2 deletions(-)
Do you want to handle this as bug (3.4) or extension (3.5)?
> diff --git a/winsup/cygwin/pinfo.cc b/winsup/cygwin/pinfo.cc
> index e086ab9a8..749a4064c 100644
> --- a/winsup/cygwin/pinfo.cc
> +++ b/winsup/cygwin/pinfo.cc
> @@ -528,7 +528,9 @@ _pinfo::set_ctty (fhandler_termios *fh, int flags)
> {
> tty_min& tc = *fh->tc ();
> debug_printf ("old %s, ctty device number %y, tc.ntty device number %y flags & O_NOCTTY %y", __ctty (), ctty, tc.ntty, flags & O_NOCTTY);
> - if (fh && (ctty <= 0 || ctty == tc.ntty) && !(flags & O_NOCTTY))
> + if (tc.getsid () && tc.getsid () != pid)
> + ; /* Do not attach if another session already attached to the CTTY. */
I'm sure I'm missing something, but I'm a bit puzzled about the
tc.getsid () != pid
test here. If that's not the case, this process is the process group
leader and already has a controlling tty, isn't it?
Thanks,
Corinna
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