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1"""Utilities to get a password and/or the current user name.
2
3getpass(prompt[, stream]) - Prompt for a password, with echo turned off.
4getuser() - Get the user name from the environment or password database.
5
6GetPassWarning - This UserWarning is issued when getpass() cannot prevent
7                 echoing of the password contents while reading.
8
9On Windows, the msvcrt module will be used.
10On 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
18import os, sys, warnings
19
20__all__ = ["getpass","getuser","GetPassWarning"]
21
22
23class GetPassWarning(UserWarning): pass
24
25
26def 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            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, 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
89def 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.putch(c)
96    pw = ""
97    while 1:
98        c = msvcrt.getch()
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.putch('\r')
108    msvcrt.putch('\n')
109    return pw
110
111
112def 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 >>stream, "Warning: Password input may be echoed."
118    return _raw_input(prompt, stream)
119
120
121def _raw_input(prompt="", stream=None, input=None):
122    # A raw_input() replacement that doesn't save the string in the
123    # GNU readline history.
124    if not stream:
125        stream = sys.stderr
126    if not input:
127        input = sys.stdin
128    prompt = str(prompt)
129    if prompt:
130        stream.write(prompt)
131        stream.flush()
132    # NOTE: The Python C API calls flockfile() (and unlock) during readline.
133    line = input.readline()
134    if not line:
135        raise EOFError
136    if line[-1] == '\n':
137        line = line[:-1]
138    return line
139
140
141def getuser():
142    """Get the username from the environment or password database.
143
144    First try various environment variables, then the password
145    database.  This works on Windows as long as USERNAME is set.
146
147    """
148
149    import os
150
151    for name in ('LOGNAME', 'USER', 'LNAME', 'USERNAME'):
152        user = os.environ.get(name)
153        if user:
154            return user
155
156    # If this fails, the exception will "explain" why
157    import pwd
158    return pwd.getpwuid(os.getuid())[0]
159
160# Bind the name getpass to the appropriate function
161try:
162    import termios
163    # it's possible there is an incompatible termios from the
164    # McMillan Installer, make sure we have a UNIX-compatible termios
165    termios.tcgetattr, termios.tcsetattr
166except (ImportError, AttributeError):
167    try:
168        import msvcrt
169    except ImportError:
170        try:
171            from EasyDialogs import AskPassword
172        except ImportError:
173            getpass = fallback_getpass
174        else:
175            getpass = AskPassword
176    else:
177        getpass = win_getpass
178else:
179    getpass = unix_getpass
180