getpass.py 文件源码

def unix_getpass(prompt='Password: ', stream=None):
    """Prompt for a password, with echo turned off.

    Args:
      prompt: Written on stream to ask for the input.  Default: 'Password: '
      stream: A writable file object to display the prompt.  Defaults to
              the tty.  If no tty is available defaults to sys.stderr.
    Returns:
      The seKr3t input.
    Raises:
      EOFError: If our input tty or stdin was closed.
      GetPassWarning: When we were unable to turn echo off on the input.

    Always restores terminal settings before returning.
    """
    fd = None
    tty = None
    try:
        # Always try reading and writing directly on the tty first.
        fd = os.open('/dev/tty', os.O_RDWR|os.O_NOCTTY)
        tty = os.fdopen(fd, 'w+', 1)
        input = tty
        if not stream:
            stream = tty
    except EnvironmentError, e:
        # If that fails, see if stdin can be controlled.
        try:
            fd = sys.stdin.fileno()
        except (AttributeError, ValueError):
            passwd = fallback_getpass(prompt, stream)
        input = sys.stdin
        if not stream:
            stream = sys.stderr

    if fd is not None:
        passwd = None
        try:
            old = termios.tcgetattr(fd)     # a copy to save
            new = old[:]
            new[3] &= ~termios.ECHO  # 3 == 'lflags'
            tcsetattr_flags = termios.TCSAFLUSH
            if hasattr(termios, 'TCSASOFT'):
                tcsetattr_flags |= termios.TCSASOFT
            try:
                termios.tcsetattr(fd, tcsetattr_flags, new)
                passwd = _raw_input(prompt, stream, input=input)
            finally:
                termios.tcsetattr(fd, tcsetattr_flags, old)
                stream.flush()  # issue7208
        except termios.error, e:
            if passwd is not None:
                # _raw_input succeeded.  The final tcsetattr failed.  Reraise
                # instead of leaving the terminal in an unknown state.
                raise
            # We can't control the tty or stdin.  Give up and use normal IO.
            # fallback_getpass() raises an appropriate warning.
            del input, tty  # clean up unused file objects before blocking
            passwd = fallback_getpass(prompt, stream)

    stream.write('\n')
    return passwd