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
11 """
12
13 # Authors: Piers Lauder (original)
14 # Guido van Rossum (Windows support and cleanup)
15 # Gregory P. Smith (tty support & GetPassWarning)
16
17 import contextlib
18 import io
19 import os
20 import sys
21 import warnings
22
23 __all__ = ["getpass","getuser","GetPassWarning"]
24
25
26 class ESC[4;38;5;81mGetPassWarning(ESC[4;38;5;149mUserWarning): pass
27
28
29 def 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
97 def 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
120 def 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
129 def _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
154 def 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
172 try:
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
177 except (ImportError, AttributeError):
178 try:
179 import msvcrt
180 except ImportError:
181 getpass = fallback_getpass
182 else:
183 getpass = win_getpass
184 else:
185 getpass = unix_getpass