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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.
10
11"""
12
13# Authors: Piers Lauder (original)
14#          Guido van Rossum (Windows support and cleanup)
15#          Gregory P. Smith (tty support & GetPassWarning)
16
17import contextlib
18import io
19import os
20import sys
21
22__all__ = ["getpass","getuser","GetPassWarning"]
23
24
25class GetPassWarning(UserWarning): pass
26
27
28def unix_getpass(prompt='Password: ', stream=None):
29    """Prompt for a password, with echo turned off.
30
31    Args:
32      prompt: Written on stream to ask for the input.  Default: 'Password: '
33      stream: A writable file object to display the prompt.  Defaults to
34              the tty.  If no tty is available defaults to sys.stderr.
35    Returns:
36      The seKr3t input.
37    Raises:
38      EOFError: If our input tty or stdin was closed.
39      GetPassWarning: When we were unable to turn echo off on the input.
40
41    Always restores terminal settings before returning.
42    """
43    passwd = None
44    with contextlib.ExitStack() as stack:
45        try:
46            # Always try reading and writing directly on the tty first.
47            fd = os.open('/dev/tty', os.O_RDWR|os.O_NOCTTY)
48            tty = io.FileIO(fd, 'w+')
49            stack.enter_context(tty)
50            input = io.TextIOWrapper(tty)
51            stack.enter_context(input)
52            if not stream:
53                stream = input
54        except OSError:
55            # If that fails, see if stdin can be controlled.
56            stack.close()
57            try:
58                fd = sys.stdin.fileno()
59            except (AttributeError, ValueError):
60                fd = None
61                passwd = fallback_getpass(prompt, stream)
62            input = sys.stdin
63            if not stream:
64                stream = sys.stderr
65
66        if fd is not None:
67            try:
68                old = termios.tcgetattr(fd)     # a copy to save
69                new = old[:]
70                new[3] &= ~termios.ECHO  # 3 == 'lflags'
71                tcsetattr_flags = termios.TCSAFLUSH
72                if hasattr(termios, 'TCSASOFT'):
73                    tcsetattr_flags |= termios.TCSASOFT
74                try:
75                    termios.tcsetattr(fd, tcsetattr_flags, new)
76                    passwd = _raw_input(prompt, stream, input=input)
77                finally:
78                    termios.tcsetattr(fd, tcsetattr_flags, old)
79                    stream.flush()  # issue7208
80            except termios.error:
81                if passwd is not None:
82                    # _raw_input succeeded.  The final tcsetattr failed.  Reraise
83                    # instead of leaving the terminal in an unknown state.
84                    raise
85                # We can't control the tty or stdin.  Give up and use normal IO.
86                # fallback_getpass() raises an appropriate warning.
87                if stream is not input:
88                    # clean up unused file objects before blocking
89                    stack.close()
90                passwd = fallback_getpass(prompt, stream)
91
92        stream.write('\n')
93        return passwd
94
95
96def win_getpass(prompt='Password: ', stream=None):
97    """Prompt for password with echo off, using Windows getwch()."""
98    if sys.stdin is not sys.__stdin__:
99        return fallback_getpass(prompt, stream)
100
101    for c in prompt:
102        msvcrt.putwch(c)
103    pw = ""
104    while 1:
105        c = msvcrt.getwch()
106        if c == '\r' or c == '\n':
107            break
108        if c == '\003':
109            raise KeyboardInterrupt
110        if c == '\b':
111            pw = pw[:-1]
112        else:
113            pw = pw + c
114    msvcrt.putwch('\r')
115    msvcrt.putwch('\n')
116    return pw
117
118
119def fallback_getpass(prompt='Password: ', stream=None):
120    import warnings
121    warnings.warn("Can not control echo on the terminal.", GetPassWarning,
122                  stacklevel=2)
123    if not stream:
124        stream = sys.stderr
125    print("Warning: Password input may be echoed.", file=stream)
126    return _raw_input(prompt, stream)
127
128
129def _raw_input(prompt="", stream=None, input=None):
130    # This doesn't save the string in the GNU readline history.
131    if not stream:
132        stream = sys.stderr
133    if not input:
134        input = sys.stdin
135    prompt = str(prompt)
136    if prompt:
137        try:
138            stream.write(prompt)
139        except UnicodeEncodeError:
140            # Use replace error handler to get as much as possible printed.
141            prompt = prompt.encode(stream.encoding, 'replace')
142            prompt = prompt.decode(stream.encoding)
143            stream.write(prompt)
144        stream.flush()
145    # NOTE: The Python C API calls flockfile() (and unlock) during readline.
146    line = input.readline()
147    if not line:
148        raise EOFError
149    if line[-1] == '\n':
150        line = line[:-1]
151    return line
152
153
154def getuser():
155    """Get the username from the environment or password database.
156
157    First try various environment variables, then the password
158    database.  This works on Windows as long as USERNAME is set.
159    Any failure to find a username raises OSError.
160
161    .. versionchanged:: 3.13
162        Previously, various exceptions beyond just :exc:`OSError`
163        were raised.
164    """
165
166    for name in ('LOGNAME', 'USER', 'LNAME', 'USERNAME'):
167        user = os.environ.get(name)
168        if user:
169            return user
170
171    try:
172        import pwd
173        return pwd.getpwuid(os.getuid())[0]
174    except (ImportError, KeyError) as e:
175        raise OSError('No username set in the environment') from e
176
177
178# Bind the name getpass to the appropriate function
179try:
180    import termios
181    # it's possible there is an incompatible termios from the
182    # McMillan Installer, make sure we have a UNIX-compatible termios
183    termios.tcgetattr, termios.tcsetattr
184except (ImportError, AttributeError):
185    try:
186        import msvcrt
187    except ImportError:
188        getpass = fallback_getpass
189    else:
190        getpass = win_getpass
191else:
192    getpass = unix_getpass
193