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 <[email protected]> --- winsup/cygwin/fhandler/termios.cc | 6 +++++- winsup/cygwin/mm/cygheap.cc | 2 ++ winsup/cygwin/pinfo.cc | 4 +++- 3 files changed, 10 insertions(+), 2 deletions(-) diff --git a/winsup/cygwin/fhandler/termios.cc b/winsup/cygwin/fhandler/termios.cc index fe4dfd13e..f94e20ff6 100644 --- a/winsup/cygwin/fhandler/termios.cc +++ b/winsup/cygwin/fhandler/termios.cc @@ -737,7 +737,11 @@ fhandler_termios::ioctl (int cmd, void *varg) } myself->ctty = -1; - myself->set_ctty (this, 0); + if (!myself->set_ctty (this, 0)) + { + set_errno (EPERM); + return -1; + } return 0; } diff --git a/winsup/cygwin/mm/cygheap.cc b/winsup/cygwin/mm/cygheap.cc index a305570df..72861d8d7 100644 --- a/winsup/cygwin/mm/cygheap.cc +++ b/winsup/cygwin/mm/cygheap.cc @@ -127,6 +127,8 @@ void init_cygheap::close_ctty () { debug_printf ("closing cygheap->ctty %p", cygheap->ctty); + if (cygheap->ctty->tc ()->getsid () == pid) + cygheap->ctty->tc ()->setsid (0); /* Release CTTY ownership */ cygheap->ctty->close_with_arch (); cygheap->ctty = NULL; } 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. */ + else if (fh && (ctty <= 0 || ctty == tc.ntty) && !(flags & O_NOCTTY)) { ctty = tc.ntty; if (cygheap->ctty != fh->archetype) -- 2.39.0
