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
21import warnings
22
23__all__ = ["getpass","getuser","GetPassWarning"]
24
25
26class GetPassWarning(UserWarning): pass
27
28
29def unix_getpass(prompt='Password: ', stream=None):
30    """Prompt for a password, with echo turned off.
31
32    Args:
33      prompt: Written on stream to ask for the input.  Default: 'Password: '
34      stream: A writable file object to display the prompt.  Defaults to
35              the tty.  If no tty is available defaults to sys.stderr.
36    Returns:
37      The seKr3t input.
38    Raises:
39      EOFError: If our input tty or stdin was closed.
40      GetPassWarning: When we were unable to turn echo off on the input.
41
42    Always restores terminal settings before returning.
43    """
44    passwd = None
45    with contextlib.ExitStack() as stack:
46        try:
47            # Always try reading and writing directly on the tty first.
48            fd = os.open('/dev/tty', os.O_RDWR|os.O_NOCTTY)
49            tty = io.FileIO(fd, 'w+')
50            stack.enter_context(tty)
51            input = io.TextIOWrapper(tty)
52            stack.enter_context(input)
53            if not stream:
54                stream = input
55        except OSError:
56            # If that fails, see if stdin can be controlled.
57            stack.close()
58            try:
59                fd = sys.stdin.fileno()
60            except (AttributeError, ValueError):
61                fd = None
62                passwd = fallback_getpass(prompt, stream)
63            input = sys.stdin
64            if not stream:
65                stream = sys.stderr
66
67        if fd is not None:
68            try:
69                old = termios.tcgetattr(fd)     # a copy to save
70                new = old[:]
71                new[3] &= ~termios.ECHO  # 3 == 'lflags'
72                tcsetattr_flags = termios.TCSAFLUSH
73                if hasattr(termios, 'TCSASOFT'):
74                    tcsetattr_flags |= termios.TCSASOFT
75                try:
76                    termios.tcsetattr(fd, tcsetattr_flags, new)
77                    passwd = _raw_input(prompt, stream, input=input)
78                finally:
79                    termios.tcsetattr(fd, tcsetattr_flags, old)
80                    stream.flush()  # issue7208
81            except termios.error:
82                if passwd is not None:
83                    # _raw_input succeeded.  The final tcsetattr failed.  Reraise
84                    # instead of leaving the terminal in an unknown state.
85                    raise
86                # We can't control the tty or stdin.  Give up and use normal IO.
87                # fallback_getpass() raises an appropriate warning.
88                if stream is not input:
89                    # clean up unused file objects before blocking
90                    stack.close()
91                passwd = fallback_getpass(prompt, stream)
92
93        stream.write('\n')
94        return passwd
95
96
97def win_getpass(prompt='Password: ', stream=None):
98    """Prompt for password with echo off, using Windows getwch()."""
99    if sys.stdin is not sys.__stdin__:
100        return fallback_getpass(prompt, stream)
101
102    for c in prompt:
103        msvcrt.putwch(c)
104    pw = ""
105    while 1:
106        c = msvcrt.getwch()
107        if c == '\r' or c == '\n':
108            break
109        if c == '\003':
110            raise KeyboardInterrupt
111        if c == '\b':
112            pw = pw[:-1]
113        else:
114            pw = pw + c
115    msvcrt.putwch('\r')
116    msvcrt.putwch('\n')
117    return pw
118
119
120def fallback_getpass(prompt='Password: ', stream=None):
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
160    """
161
162    for name in ('LOGNAME', 'USER', 'LNAME', 'USERNAME'):
163        user = os.environ.get(name)
164        if user:
165            return user
166
167    # If this fails, the exception will "explain" why
168    import pwd
169    return pwd.getpwuid(os.getuid())[0]
170
171# Bind the name getpass to the appropriate function
172try:
173    import termios
174    # it's possible there is an incompatible termios from the
175    # McMillan Installer, make sure we have a UNIX-compatible termios
176    termios.tcgetattr, termios.tcsetattr
177except (ImportError, AttributeError):
178    try:
179        import msvcrt
180    except ImportError:
181        getpass = fallback_getpass
182    else:
183        getpass = win_getpass
184else:
185    getpass = unix_getpass
186