getpass.py

"""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)

importcontextlib
importio
importos
importsys
importwarnings

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


classGetPassWarning(UserWarning): pass


defunix_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
withcontextlib.ExitStack() asstack:
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)
ifnotstream:
stream=input
exceptOSErrorase:
# 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
ifnotstream:
stream=sys.stderr

iffdisnotNone:
try:
old=termios.tcgetattr(fd) # a copy to save
new=old[:]
new[3] &=~termios.ECHO# 3 == 'lflags'
tcsetattr_flags=termios.TCSAFLUSH
ifhasattr(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
excepttermios.error:
ifpasswdisnotNone:
# _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.
ifstreamisnotinput:
# clean up unused file objects before blocking
stack.close()
passwd=fallback_getpass(prompt, stream)

stream.write('\n')
returnpasswd


defwin_getpass(prompt='Password: ', stream=None):
"""Prompt for password with echo off, using Windows getch()."""
ifsys.stdinisnotsys.__stdin__:
returnfallback_getpass(prompt, stream)

forcinprompt:
msvcrt.putwch(c)
pw=""
while1:
c=msvcrt.getwch()
ifc=='\r'orc=='\n':
break
ifc=='\003':
raiseKeyboardInterrupt
ifc=='\b':
pw=pw[:-1]
else:
pw=pw+c
msvcrt.putwch('\r')
msvcrt.putwch('\n')
returnpw


deffallback_getpass(prompt='Password: ', stream=None):
warnings.warn("Can not control echo on the terminal.", GetPassWarning,
stacklevel=2)
ifnotstream:
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.
ifnotstream:
stream=sys.stderr
ifnotinput:
input=sys.stdin
prompt=str(prompt)
ifprompt:
try:
stream.write(prompt)
exceptUnicodeEncodeError:
# 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()
ifnotline:
raiseEOFError
ifline[-1] =='\n':
line=line[:-1]
returnline


defgetuser():
"""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.

 """

fornamein ('LOGNAME', 'USER', 'LNAME', 'USERNAME'):
user=os.environ.get(name)
ifuser:
returnuser

# If this fails, the exception will "explain" why
importpwd
returnpwd.getpwuid(os.getuid())[0]

# Bind the name getpass to the appropriate function
try:
importtermios
# 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:
importmsvcrt
exceptImportError:
getpass=fallback_getpass
else:
getpass=win_getpass
else:
getpass=unix_getpass