Lib/getpass.py

   1 """Utilities to get a password and/or the current user name.
   2
   3 getpass(prompt[, stream]) - Prompt for a password, with echo turned off.
   4 getuser() - Get the user name from the environment or password database.
   5
   6 GetPassWarning - This UserWarning is issued when getpass() cannot prevent
   7                  echoing of the password contents while reading.
   8
   9 On Windows, the msvcrt module will be used.
  10 On the Mac EasyDialogs.AskPassword is used, if available.
  11
  12 """
  13
  14 # Authors: Piers Lauder (original)
  15 #          Guido van Rossum (Windows support and cleanup)
  16 #          Gregory P. Smith (tty support & GetPassWarning)
  17
  18 import os, sys, warnings
  19
  20 __all__ = ["getpass","getuser","GetPassWarning"]
  21
  22
  23 class GetPassWarning(UserWarning): pass
  24
  25
  26 def unix_getpass(prompt='Password: ', stream=None):
  27     """Prompt for a password, with echo turned off.
  28
  29     Args:
  30       prompt: Written on stream to ask for the input.  Default: 'Password: '
  31       stream: A writable file object to display the prompt.  Defaults to
  32               the tty.  If no tty is available defaults to sys.stderr.
  33     Returns:
  34       The seKr3t input.
  35     Raises:
  36       EOFError: If our input tty or stdin was closed.
  37       GetPassWarning: When we were unable to turn echo off on the input.
  38
  39     Always restores terminal settings before returning.
  40     """
  41     fd = None
  42     tty = None
  43     try:
  44         # Always try reading and writing directly on the tty first.
  45         fd = os.open('/dev/tty', os.O_RDWR|os.O_NOCTTY)
  46         tty = os.fdopen(fd, 'w+', 1)
  47         input = tty
  48         if not stream:
  49             stream = tty
  50     except EnvironmentError as e:
  51         # If that fails, see if stdin can be controlled.
  52         try:
  53             fd = sys.stdin.fileno()
  54         except (AttributeError, ValueError):
  55             passwd = fallback_getpass(prompt, stream)
  56         input = sys.stdin
  57         if not stream:
  58             stream = sys.stderr
  59
  60     if fd is not None:
  61         passwd = None
  62         try:
  63             old = termios.tcgetattr(fd)     # a copy to save
  64             new = old[:]
  65             new[3] &= ~(termios.ECHO|termios.ISIG)  # 3 == 'lflags'
  66             tcsetattr_flags = termios.TCSAFLUSH
  67             if hasattr(termios, 'TCSASOFT'):
  68                 tcsetattr_flags |= termios.TCSASOFT
  69             try:
  70                 termios.tcsetattr(fd, tcsetattr_flags, new)
  71                 passwd = _raw_input(prompt, stream, input=input)
  72             finally:
  73                 termios.tcsetattr(fd, tcsetattr_flags, old)
  74                 stream.flush()  # issue7208
  75         except termios.error as e:
  76             if passwd is not None:
  77                 # _raw_input succeeded.  The final tcsetattr failed.  Reraise
  78                 # instead of leaving the terminal in an unknown state.
  79                 raise
  80             # We can't control the tty or stdin.  Give up and use normal IO.
  81             # fallback_getpass() raises an appropriate warning.
  82             del input, tty  # clean up unused file objects before blocking
  83             passwd = fallback_getpass(prompt, stream)
  84
  85     stream.write('\n')
  86     return passwd
  87
  88
  89 def win_getpass(prompt='Password: ', stream=None):
  90     """Prompt for password with echo off, using Windows getch()."""
  91     if sys.stdin is not sys.__stdin__:
  92         return fallback_getpass(prompt, stream)
  93     import msvcrt
  94     for c in prompt:
  95         msvcrt.putwch(c)
  96     pw = ""
  97     while 1:
  98         c = msvcrt.getwch()
  99         if c == '\r' or c == '\n':
 100             break
 101         if c == '\003':
 102             raise KeyboardInterrupt
 103         if c == '\b':
 104             pw = pw[:-1]
 105         else:
 106             pw = pw + c
 107     msvcrt.putwch('\r')
 108     msvcrt.putwch('\n')
 109     return pw
 110
 111
 112 def fallback_getpass(prompt='Password: ', stream=None):
 113     warnings.warn("Can not control echo on the terminal.", GetPassWarning,
 114                   stacklevel=2)
 115     if not stream:
 116         stream = sys.stderr
 117     print("Warning: Password input may be echoed.", file=stream)
 118     return _raw_input(prompt, stream)
 119
 120
 121 def _raw_input(prompt="", stream=None, input=None):
 122     # This doesn't save the string in the GNU readline history.
 123     if not stream:
 124         stream = sys.stderr
 125     if not input:
 126         input = sys.stdin
 127     prompt = str(prompt)
 128     if prompt:
 129         stream.write(prompt)
 130         stream.flush()
 131     # NOTE: The Python C API calls flockfile() (and unlock) during readline.
 132     line = input.readline()
 133     if not line:
 134         raise EOFError
 135     if line[-1] == '\n':
 136         line = line[:-1]
 137     return line
 138
 139
 140 def getuser():
 141     """Get the username from the environment or password database.
 142
 143     First try various environment variables, then the password
 144     database.  This works on Windows as long as USERNAME is set.
 145
 146     """
 147
 148     import os
 149
 150     for name in ('LOGNAME', 'USER', 'LNAME', 'USERNAME'):
 151         user = os.environ.get(name)
 152         if user:
 153             return user
 154
 155     # If this fails, the exception will "explain" why
 156     import pwd
 157     return pwd.getpwuid(os.getuid())[0]
 158
 159 # Bind the name getpass to the appropriate function
 160 try:
 161     import termios
 162     # it's possible there is an incompatible termios from the
 163     # McMillan Installer, make sure we have a UNIX-compatible termios
 164     termios.tcgetattr, termios.tcsetattr
 165 except (ImportError, AttributeError):
 166     try:
 167         import msvcrt
 168     except ImportError:
 169         try:
 170             from EasyDialogs import AskPassword
 171         except ImportError:
 172             getpass = fallback_getpass
 173         else:
 174             getpass = AskPassword
 175     else:
 176         getpass = win_getpass
 177 else:
 178     getpass = unix_getpass