分分钟提升命令行模式下密码输入逼格

【简介】

　　今天突然想到一个事，linux-termial  下一个优秀的程序在输入密码的时候整个窗口是看不到密码的明文的；我前一段时间总是用input来接收输入的信息，

　　明显没有逼格啊！而且我坚信 python 中一定已经有这个轮子了。

【三行代码成就有逼格的密码输入】

　　总的来说就是用getpass模块的getpass函数(和input的用法一样哈！)

In [1]: import getpass                                                          

In [2]: password = getpass.getpass("user password:")                            
user password:

In [3]: password                                                                
Out[3]: '12345678'

【源码的关键部分】

　　可以看到 getpass 和 input 的低层实现都是 sys.stdin 

def _raw_input(prompt="", stream=None, input=None):
    # This doesn't save the string in the GNU readline history.
    if not stream:
        stream = sys.stderr
    if not input:
        input = sys.stdin
    prompt = str(prompt)
    if prompt:
        try:
            stream.write(prompt)
        except UnicodeEncodeError:
            # Use replace error handler to get as much as possible printed.
            prompt = prompt.encode(stream.encoding, 'replace')
            prompt = prompt.decode(stream.encoding)
            stream.write(prompt)
        stream.flush()
    # NOTE: The Python C API calls flockfile() (and unlock) during readline.
    line = input.readline()
    if not line:
        raise EOFError
    if line[-1] == '
':
        line = line[:-1]
    return line



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.
    """
    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 as e:
            # 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'
                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:
                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.
                if stream is not input:
                    # clean up unused file objects before blocking
                    stack.close()
                passwd = fallback_getpass(prompt, stream)

        stream.write('
')
        return passwd


try:
    import termios
    # it's possible there is an incompatible termios from the
    # McMillan Installer, make sure we have a UNIX-compatible termios
    termios.tcgetattr, termios.tcsetattr
except (ImportError, AttributeError):
    try:
        import msvcrt
    except ImportError:
        getpass = fallback_getpass
    else:
        getpass = win_getpass
else:
    getpass = unix_getpass

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