ptyprocess.py 文件源码

def _setecho(fd, state):
    errmsg = 'setecho() may not be called on this platform'

    try:
        attr = termios.tcgetattr(fd)
    except termios.error as err:
        if err.args[0] == errno.EINVAL:
            raise IOError(err.args[0], '%s: %s.' % (err.args[1], errmsg))
        raise

    if state:
        attr[3] = attr[3] | termios.ECHO
    else:
        attr[3] = attr[3] & ~termios.ECHO

    try:
        # I tried TCSADRAIN and TCSAFLUSH, but these were inconsistent and
        # blocked on some platforms. TCSADRAIN would probably be ideal.
        termios.tcsetattr(fd, termios.TCSANOW, attr)
    except IOError as err:
        if err.args[0] == errno.EINVAL:
            raise IOError(err.args[0], '%s: %s.' % (err.args[1], errmsg))
        raise