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

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

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

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

echoing of the password contents while reading.

On Windows, the msvcrt module will be used.

"""

# Authors: Piers Lauder (original)

# Guido van Rossum (Windows support and cleanup)

# Gregory P. Smith (tty support & GetPassWarning)

import contextlib

import io

import os

import sys

import warnings

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

class GetPassWarning(UserWarning): pass

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:

# 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('\n')

return passwd

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

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

if sys.stdin is not sys.__stdin__:

return fallback_getpass(prompt, stream)

for c in prompt:

msvcrt.putwch(c)

pw = ""

while 1:

c = msvcrt.getwch()

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

break

if c == '\003':

raise KeyboardInterrupt

if c == '\b':

pw = pw[:-1]

else:

pw = pw + c

msvcrt.putwch('\r')

msvcrt.putwch('\n')

return pw

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

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

stacklevel=2)

if not stream:

stream = sys.stderr

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

return _raw_input(prompt, stream)

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] == '\n':

line = line[:-1]

return line

def getuser():

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

First try various environment variables, then the password

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

"""

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

user = os.environ.get(name)

if user:

return user

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

import pwd

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

# Bind the name getpass to the appropriate function

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