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, 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  # 3 == 'lflags'
  66             try:
  67                 termios.tcsetattr(fd, termios.TCSADRAIN, new)
  68                 passwd = _raw_input(prompt, stream, input=input)
  69             finally:
  70                 termios.tcsetattr(fd, termios.TCSADRAIN, old)
  71         except termios.error, e:
  72             if passwd is not None:
  73                 # _raw_input succeeded.  The final tcsetattr failed.  Reraise
  74                 # instead of leaving the terminal in an unknown state.
  75                 raise
  76             # We can't control the tty or stdin.  Give up and use normal IO.
  77             # fallback_getpass() raises an appropriate warning.
  78             del input, tty  # clean up unused file objects before blocking
  79             passwd = fallback_getpass(prompt, stream)
  80
  81     stream.write('\n')
  82     return passwd
  83
  84
  85 def win_getpass(prompt='Password: ', stream=None):
  86     """Prompt for password with echo off, using Windows getch()."""
  87     if sys.stdin is not sys.__stdin__:
  88         return fallback_getpass(prompt, stream)
  89     import msvcrt
  90     for c in prompt:
  91         msvcrt.putch(c)
  92     pw = ""
  93     while 1:
  94         c = msvcrt.getch()
  95         if c == '\r' or c == '\n':
  96             break
  97         if c == '\003':
  98             raise KeyboardInterrupt
  99         if c == '\b':
 100             pw = pw[:-1]
 101         else:
 102             pw = pw + c
 103     msvcrt.putch('\r')
 104     msvcrt.putch('\n')
 105     return pw
 106
 107
 108 def fallback_getpass(prompt='Password: ', stream=None):
 109     warnings.warn("Can not control echo on the terminal.", GetPassWarning,
 110                   stacklevel=2)
 111     if not stream:
 112         stream = sys.stderr
 113     print >>stream, "Warning: Password input may be echoed."
 114     return _raw_input(prompt, stream)
 115
 116
 117 def _raw_input(prompt="", stream=None, input=None):
 118     # A raw_input() replacement that doesn't save the string in the
 119     # GNU readline history.
 120     if not stream:
 121         stream = sys.stderr
 122     if not input:
 123         input = sys.stdin
 124     prompt = str(prompt)
 125     if prompt:
 126         stream.write(prompt)
 127         stream.flush()
 128     line = input.readline()
 129     if not line:
 130         raise EOFError
 131     if line[-1] == '\n':
 132         line = line[:-1]
 133     return line
 134
 135
 136 def getuser():
 137     """Get the username from the environment or password database.
 138
 139     First try various environment variables, then the password
 140     database.  This works on Windows as long as USERNAME is set.
 141
 142     """
 143
 144     import os
 145
 146     for name in ('LOGNAME', 'USER', 'LNAME', 'USERNAME'):
 147         user = os.environ.get(name)
 148         if user:
 149             return user
 150
 151     # If this fails, the exception will "explain" why
 152     import pwd
 153     return pwd.getpwuid(os.getuid())[0]
 154
 155 # Bind the name getpass to the appropriate function
 156 try:
 157     import termios
 158     # it's possible there is an incompatible termios from the
 159     # McMillan Installer, make sure we have a UNIX-compatible termios
 160     termios.tcgetattr, termios.tcsetattr
 161 except (ImportError, AttributeError):
 162     try:
 163         import msvcrt
 164     except ImportError:
 165         try:
 166             from EasyDialogs import AskPassword
 167         except ImportError:
 168             getpass = fallback_getpass
 169         else:
 170             getpass = AskPassword
 171     else:
 172         getpass = win_getpass
 173 else:
 174     getpass = unix_getpass