Function unix_getpass

Lib/getpass.py:68–153

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. echo_char: A sing

(prompt='Password: ', stream=None, *, echo_char=None)

def unix_getpass(prompt='Password: ', stream=None, *, echo_char=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.
      echo_char: A single ASCII character to mask input (e.g., '*').
              If None, input is hidden.
    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.
    """
    _check_echo_char(echo_char)

    passwd = None
    with contextlib.ExitStack() as stack:
        try:
            # Always try reading and writing directly on the tty first.
            fd = os.open('/dev/tty', os.O_RDWR|os.O_NOCTTY)
            tty = io.FileIO(fd, 'w+')
            stack.enter_context(tty)
            input = io.TextIOWrapper(tty)
            stack.enter_context(input)
            if not stream:
                stream = input
        except OSError:
            # If that fails, see if stdin can be controlled.
            stack.close()
            try:
                fd = sys.stdin.fileno()
            except (AttributeError, ValueError):
                fd = None
                passwd = fallback_getpass(prompt, stream)
            input = sys.stdin
            if not stream:
                stream = sys.stderr

        if fd is not None:
            try:
                old = termios.tcgetattr(fd)     # a copy to save
                new = old[:]
                new[3] &= ~termios.ECHO  # 3 == 'lflags'
                # Extract control characters before changing terminal mode.
                term_ctrl_chars = None
                if echo_char:
                    # ICANON enables canonical (line-buffered) mode where
                    # the terminal handles line editing. Disable it so we
                    # can read input char by char and handle editing ourselves.
                    new[3] &= ~termios.ICANON
                    # IEXTEN enables implementation-defined input processing
                    # such as LNEXT (Ctrl+V). Disable it so the terminal
                    # driver does not intercept these characters before our
                    # code can handle them.