"""Utilities to get a password and/or the current user name.

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getpass(prompt[, stream]) - Prompt for a password, with echo turned off.

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getuser() - Get the user name from the environment or password database.

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GetPassWarning - This UserWarning is issued when getpass() cannot prevent

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echoing of the password contents while reading.

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On Windows, the msvcrt module will be used.

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"""

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# Authors: Piers Lauder (original)

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# Guido van Rossum (Windows support and cleanup)

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# Gregory P. Smith (tty support & GetPassWarning)

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import contextlib

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import io

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import os

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import sys

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import warnings

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__all__ = ["getpass","getuser","GetPassWarning"]

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class GetPassWarning(UserWarning): pass

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def unix_getpass(prompt='Password: ', stream=None):

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"""Prompt for a password, with echo turned off.

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Args:

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prompt: Written on stream to ask for the input. Default: 'Password: '

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stream: A writable file object to display the prompt. Defaults to

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the tty. If no tty is available defaults to sys.stderr.

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Returns:

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The seKr3t input.

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Raises:

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EOFError: If our input tty or stdin was closed.

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GetPassWarning: When we were unable to turn echo off on the input.

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Always restores terminal settings before returning.

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"""

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passwd = None

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with contextlib.ExitStack() as stack:

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try:

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# Always try reading and writing directly on the tty first.

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fd = os.open('/dev/tty', os.O_RDWR|os.O_NOCTTY)

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tty = io.FileIO(fd, 'w+')

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stack.enter_context(tty)

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input = io.TextIOWrapper(tty)

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stack.enter_context(input)

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if not stream:

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stream = input

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except OSError as e:

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# If that fails, see if stdin can be controlled.

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stack.close()

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try:

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fd = sys.stdin.fileno()

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except (AttributeError, ValueError):

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fd = None

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passwd = fallback_getpass(prompt, stream)

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input = sys.stdin

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if not stream:

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stream = sys.stderr

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if fd is not None:

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try:

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old = termios.tcgetattr(fd) # a copy to save

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new = old[:]

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new[3] &= ~termios.ECHO # 3 == 'lflags'

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tcsetattr_flags = termios.TCSAFLUSH

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if hasattr(termios, 'TCSASOFT'):

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tcsetattr_flags |= termios.TCSASOFT

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try:

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termios.tcsetattr(fd, tcsetattr_flags, new)

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passwd = _raw_input(prompt, stream, input=input)

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finally:

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termios.tcsetattr(fd, tcsetattr_flags, old)

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stream.flush() # issue7208

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except termios.error:

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if passwd is not None:

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# _raw_input succeeded. The final tcsetattr failed. Reraise

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# instead of leaving the terminal in an unknown state.

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raise

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# We can't control the tty or stdin. Give up and use normal IO.

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# fallback_getpass() raises an appropriate warning.

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if stream is not input:

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# clean up unused file objects before blocking

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stack.close()

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passwd = fallback_getpass(prompt, stream)

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stream.write('\n')

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return passwd

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def win_getpass(prompt='Password: ', stream=None):

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"""Prompt for password with echo off, using Windows getch()."""

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if sys.stdin is not sys.__stdin__:

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return fallback_getpass(prompt, stream)

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for c in prompt:

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msvcrt.putwch(c)

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pw = ""

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while 1:

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c = msvcrt.getwch()

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if c == '\r' or c == '\n':

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break

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if c == '\003':

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raise KeyboardInterrupt

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if c == '\b':

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pw = pw[:-1]

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else:

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pw = pw + c

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msvcrt.putwch('\r')

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msvcrt.putwch('\n')

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return pw

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def fallback_getpass(prompt='Password: ', stream=None):

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warnings.warn("Can not control echo on the terminal.", GetPassWarning,

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stacklevel=2)

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if not stream:

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stream = sys.stderr

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print("Warning: Password input may be echoed.", file=stream)

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return _raw_input(prompt, stream)

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def _raw_input(prompt="", stream=None, input=None):

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# This doesn't save the string in the GNU readline history.

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if not stream:

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stream = sys.stderr

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if not input:

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input = sys.stdin

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prompt = str(prompt)

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if prompt:

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try:

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stream.write(prompt)

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except UnicodeEncodeError:

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# Use replace error handler to get as much as possible printed.

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prompt = prompt.encode(stream.encoding, 'replace')

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prompt = prompt.decode(stream.encoding)

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stream.write(prompt)

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stream.flush()

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# NOTE: The Python C API calls flockfile() (and unlock) during readline.

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line = input.readline()

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if not line:

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raise EOFError

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if line[-1] == '\n':

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line = line[:-1]

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return line

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def getuser():

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"""Get the username from the environment or password database.

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First try various environment variables, then the password

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database. This works on Windows as long as USERNAME is set.

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"""

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for name in ('LOGNAME', 'USER', 'LNAME', 'USERNAME'):

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user = os.environ.get(name)

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if user:

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return user

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# If this fails, the exception will "explain" why

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import pwd

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return pwd.getpwuid(os.getuid())[0]

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# Bind the name getpass to the appropriate function

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try:

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import termios

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# it's possible there is an incompatible termios from the

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# McMillan Installer, make sure we have a UNIX-compatible termios

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termios.tcgetattr, termios.tcsetattr

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except (ImportError, AttributeError):

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try:

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import msvcrt

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except ImportError:

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getpass = fallback_getpass

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else:

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getpass = win_getpass

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else:

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getpass = unix_getpass

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