use os.posix_spawn when available (i.e, 3.8) about ptyprocess HOT 4 OPEN

fd & tty should be non-inheritable already (by default), so there would be no race and the os.set_inheritable and POSIX_SPAWN_CLOSE are both unnecessary.

Documentation states that all FDs are non-inheritable by default in Python 3.4+, and I have confirmed this in Python 3.6.6.

from ptyprocess.

fd & tty should be non-inheritable already (by default), so there would be no race and the os.set_inheritable and POSIX_SPAWN_CLOSE are both unnecessary.

Documentation states that all FDs are non-inheritable by default in Python 3.4+, and I have confirmed this in Python 3.6.6.

The race is in os.openpty(). Since openpty() returns an inheritable master and slave, a parallel for made after openpty() returns but before inheritable is cleared would inherit those FDs.

if (openpty(&master_fd, &slave_fd, NULL, NULL, NULL) != 0)
    goto posix_error;

if (_Py_set_inheritable(master_fd, 0, NULL) < 0)
    goto error;
if (_Py_set_inheritable(slave_fd, 0, NULL) < 0)
    goto error;

but yes, the os.set_inheritable and POSIX_SPAWN_CLOSE could be dropped

from ptyprocess.

That region of code is protected by the GIL. No race.

from ptyprocess.

(Copying my comment from #52)

I don't know how to combine the os.spawn* functions - or anything that doesn't involve a fork - with setting up a new pty as the controlling terminal of the child process. I suspect it's not possible, but it would be very nice if it was. If you figure it out, please let me know!

from ptyprocess.