getpass.py 5.93 KB
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"""Utilities to get a password and/or the current user name.

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getpass(prompt[, stream]) - Prompt for a password, with echo turned off.
getuser() - Get the user name from the environment or password database.

GetPassWarning - This UserWarning is issued when getpass() cannot prevent
                 echoing of the password contents while reading.
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On Windows, the msvcrt module will be used.
On the Mac EasyDialogs.AskPassword is used, if available.

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"""

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# Authors: Piers Lauder (original)
#          Guido van Rossum (Windows support and cleanup)
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#          Gregory P. Smith (tty support & GetPassWarning)
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import contextlib
import io
import os
import sys
import warnings
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__all__ = ["getpass","getuser","GetPassWarning"]
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class GetPassWarning(UserWarning): pass
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def unix_getpass(prompt='Password: ', stream=None):
    """Prompt for a password, with echo turned off.
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    Args:
      prompt: Written on stream to ask for the input.  Default: 'Password: '
      stream: A writable file object to display the prompt.  Defaults to
              the tty.  If no tty is available defaults to sys.stderr.
    Returns:
      The seKr3t input.
    Raises:
      EOFError: If our input tty or stdin was closed.
      GetPassWarning: When we were unable to turn echo off on the input.

    Always restores terminal settings before returning.
    """
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    passwd = None
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    with contextlib.ExitStack() as stack:
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        try:
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            # Always try reading and writing directly on the tty first.
            fd = os.open('/dev/tty', os.O_RDWR|os.O_NOCTTY)
            tty = io.FileIO(fd, 'w+')
            stack.enter_context(tty)
            input = io.TextIOWrapper(tty)
            stack.enter_context(input)
            if not stream:
                stream = input
        except OSError as e:
            # If that fails, see if stdin can be controlled.
            stack.close()
            try:
                fd = sys.stdin.fileno()
            except (AttributeError, ValueError):
                fd = None
                passwd = fallback_getpass(prompt, stream)
            input = sys.stdin
            if not stream:
                stream = sys.stderr

        if fd is not None:
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            try:
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                old = termios.tcgetattr(fd)     # a copy to save
                new = old[:]
                new[3] &= ~termios.ECHO  # 3 == 'lflags'
                tcsetattr_flags = termios.TCSAFLUSH
                if hasattr(termios, 'TCSASOFT'):
                    tcsetattr_flags |= termios.TCSASOFT
                try:
                    termios.tcsetattr(fd, tcsetattr_flags, new)
                    passwd = _raw_input(prompt, stream, input=input)
                finally:
                    termios.tcsetattr(fd, tcsetattr_flags, old)
                    stream.flush()  # issue7208
            except termios.error:
                if passwd is not None:
                    # _raw_input succeeded.  The final tcsetattr failed.  Reraise
                    # instead of leaving the terminal in an unknown state.
                    raise
                # We can't control the tty or stdin.  Give up and use normal IO.
                # fallback_getpass() raises an appropriate warning.
                if stream is not input:
                    # clean up unused file objects before blocking
                    stack.close()
                passwd = fallback_getpass(prompt, stream)

        stream.write('\n')
        return passwd
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def win_getpass(prompt='Password: ', stream=None):
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    """Prompt for password with echo off, using Windows getch()."""
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    if sys.stdin is not sys.__stdin__:
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        return fallback_getpass(prompt, stream)
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    import msvcrt
    for c in prompt:
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        msvcrt.putwch(c)
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    pw = ""
    while 1:
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        c = msvcrt.getwch()
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        if c == '\r' or c == '\n':
            break
        if c == '\003':
            raise KeyboardInterrupt
        if c == '\b':
            pw = pw[:-1]
        else:
            pw = pw + c
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    msvcrt.putwch('\r')
    msvcrt.putwch('\n')
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    return pw
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def fallback_getpass(prompt='Password: ', stream=None):
    warnings.warn("Can not control echo on the terminal.", GetPassWarning,
                  stacklevel=2)
    if not stream:
        stream = sys.stderr
    print("Warning: Password input may be echoed.", file=stream)
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    return _raw_input(prompt, stream)
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def _raw_input(prompt="", stream=None, input=None):
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    # This doesn't save the string in the GNU readline history.
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    if not stream:
        stream = sys.stderr
    if not input:
        input = sys.stdin
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    prompt = str(prompt)
    if prompt:
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        try:
            stream.write(prompt)
        except UnicodeEncodeError:
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            # Use replace error handler to get as much as possible printed.
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            prompt = prompt.encode(stream.encoding, 'replace')
            prompt = prompt.decode(stream.encoding)
            stream.write(prompt)
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        stream.flush()
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    # NOTE: The Python C API calls flockfile() (and unlock) during readline.
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    line = input.readline()
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    if not line:
        raise EOFError
    if line[-1] == '\n':
        line = line[:-1]
    return line
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def getuser():
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    """Get the username from the environment or password database.
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    First try various environment variables, then the password
    database.  This works on Windows as long as USERNAME is set.
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    """
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    for name in ('LOGNAME', 'USER', 'LNAME', 'USERNAME'):
        user = os.environ.get(name)
        if user:
            return user
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    # If this fails, the exception will "explain" why
    import pwd
    return pwd.getpwuid(os.getuid())[0]
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# Bind the name getpass to the appropriate function
try:
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    import termios
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    # it's possible there is an incompatible termios from the
    # McMillan Installer, make sure we have a UNIX-compatible termios
    termios.tcgetattr, termios.tcsetattr
except (ImportError, AttributeError):
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    try:
        import msvcrt
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    except ImportError:
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        getpass = fallback_getpass
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    else:
        getpass = win_getpass
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else:
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    getpass = unix_getpass