__init__.py 文件源码

def __pty_make_controlling_tty(self, tty_fd):
        '''This makes the pseudo-terminal the controlling tty. This should be
        more portable than the pty.fork() function. Specifically, this should
        work on Solaris. '''

        child_name = os.ttyname(tty_fd)

        # Disconnect from controlling tty, if any.  Raises OSError of ENXIO
        # if there was no controlling tty to begin with, such as when
        # executed by a cron(1) job.
        try:
            fd = os.open("/dev/tty", os.O_RDWR | os.O_NOCTTY)
            os.close(fd)
        except OSError as err:
            if err.errno != errno.ENXIO:
                raise

        os.setsid()

        # Verify we are disconnected from controlling tty by attempting to open
        # it again.  We expect that OSError of ENXIO should always be raised.
        try:
            fd = os.open("/dev/tty", os.O_RDWR | os.O_NOCTTY)
            os.close(fd)
            raise ExceptionPexpect("OSError of errno.ENXIO should be raised.")
        except OSError as err:
            if err.errno != errno.ENXIO:
                raise

        # Verify we can open child pty.
        fd = os.open(child_name, os.O_RDWR)
        os.close(fd)

        # Verify we now have a controlling tty.
        fd = os.open("/dev/tty", os.O_WRONLY)
        os.close(fd)