test_ioctl.py 文件源码

def _check_ioctl_mutate_len(self, nbytes=None):
        buf = array.array('i')
        intsize = buf.itemsize
        ids = (os.getpgrp(), os.getsid(0))
        # A fill value unlikely to be in `ids`
        fill = -12345
        if nbytes is not None:
            # Extend the buffer so that it is exactly `nbytes` bytes long
            buf.extend([fill] * (nbytes // intsize))
            self.assertEqual(len(buf) * intsize, nbytes)   # sanity check
        else:
            buf.append(fill)
        with open("/dev/tty", "r") as tty:
            r = fcntl.ioctl(tty, termios.TIOCGPGRP, buf, 1)
        rpgrp = buf[0]
        self.assertEqual(r, 0)
        self.assertIn(rpgrp, ids)