Bundled path.py should not modify the os module

IPython/external/path/_path.py

@@ -1,1267 +1,1267 b''
 #
 # Copyright (c) 2010 Mikhail Gusarov
 #
 # Permission is hereby granted, free of charge, to any person obtaining a copy
 # of this software and associated documentation files (the "Software"), to deal
 # in the Software without restriction, including without limitation the rights
 # to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
 # copies of the Software, and to permit persons to whom the Software is
 # furnished to do so, subject to the following conditions:
 #
 # The above copyright notice and this permission notice shall be included in
 # all copies or substantial portions of the Software.
 #
 # THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 # IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 # FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
 # AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 # LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
 # OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
 # SOFTWARE.
 #
 
 """ path.py - An object representing a path to a file or directory.
 
 Original author:
  Jason Orendorff <jason.orendorff\x40gmail\x2ecom>
 
 Current maintainer:
  Jason R. Coombs <[e-mail]>
 
 Contributors:
  Mikhail Gusarov <[e-mail]>
  Marc Abramowitz <[e-mail]>
  Jason R. Coombs <[e-mail]>
  Jason Chu <[e-mail]>
  Vojislav Stojkovic <[e-mail]>
 
 Example::
 
     from path import path
     d = path('/home/guido/bin')
     for f in d.files('*.py'):
         f.chmod(0755)
 
 path.py requires Python 2.5 or later.
 """
 
 from __future__ import with_statement
 
 import sys
 import warnings
 import os
 import fnmatch
 import glob
 import shutil
 import codecs
 import hashlib
 import errno
 import tempfile
 import functools
 import operator
 import re
 
 try:
     import win32security
 except ImportError:
     pass
 
 try:
     import pwd
 except ImportError:
     pass
 
 ################################
 # Monkey patchy python 3 support
 try:
     basestring
 except NameError:
     basestring = str
 
 try:
     unicode
 except NameError:
     unicode = str
 
 try:
-    os.getcwdu
+    getcwdu = os.getcwdu
 except AttributeError:
-    os.getcwdu = os.getcwd
+    getcwdu = os.getcwd
 
 if sys.version < '3':
     def u(x):
         return codecs.unicode_escape_decode(x)[0]
 else:
     def u(x):
         return x
 
 o777 = 511
 o766 = 502
 o666 = 438
 o554 = 364
 ################################
 
 __version__ = '4.3'
 __all__ = ['path']
 
 
 class TreeWalkWarning(Warning):
     pass
 
 
 def simple_cache(func):
     """
     Save results for the 'using_module' classmethod.
     When Python 3.2 is available, use functools.lru_cache instead.
     """
     saved_results = {}
 
     def wrapper(cls, module):
         if module in saved_results:
             return saved_results[module]
         saved_results[module] = func(cls, module)
         return saved_results[module]
     return wrapper
 
 
 class ClassProperty(property):
     def __get__(self, cls, owner):
         return self.fget.__get__(None, owner)()
 
 
 class multimethod(object):
     """
     Acts like a classmethod when invoked from the class and like an
     instancemethod when invoked from the instance.
     """
     def __init__(self, func):
         self.func = func
 
     def __get__(self, instance, owner):
         return (
             functools.partial(self.func, owner) if instance is None
             else functools.partial(self.func, owner, instance)
         )
 
 
 class path(unicode):
     """ Represents a filesystem path.
 
     For documentation on individual methods, consult their
     counterparts in os.path.
     """
 
     module = os.path
     "The path module to use for path operations."
 
     def __init__(self, other=''):
         if other is None:
             raise TypeError("Invalid initial value for path: None")
 
     @classmethod
     @simple_cache
     def using_module(cls, module):
         subclass_name = cls.__name__ + '_' + module.__name__
         bases = (cls,)
         ns = {'module': module}
         return type(subclass_name, bases, ns)
 
     @ClassProperty
     @classmethod
     def _next_class(cls):
         """
         What class should be used to construct new instances from this class
         """
         return cls
 
     # --- Special Python methods.
 
     def __repr__(self):
         return '%s(%s)' % (type(self).__name__, super(path, self).__repr__())
 
     # Adding a path and a string yields a path.
     def __add__(self, more):
         try:
             return self._next_class(super(path, self).__add__(more))
         except TypeError:  # Python bug
             return NotImplemented
 
     def __radd__(self, other):
         if not isinstance(other, basestring):
             return NotImplemented
         return self._next_class(other.__add__(self))
 
     # The / operator joins paths.
     def __div__(self, rel):
         """ fp.__div__(rel) == fp / rel == fp.joinpath(rel)
 
         Join two path components, adding a separator character if
         needed.
         """
         return self._next_class(self.module.join(self, rel))
 
     # Make the / operator work even when true division is enabled.
     __truediv__ = __div__
 
     def __enter__(self):
         self._old_dir = self.getcwd()
         os.chdir(self)
         return self
 
     def __exit__(self, *_):
         os.chdir(self._old_dir)
 
     @classmethod
     def getcwd(cls):
         """ Return the current working directory as a path object. """
-        return cls(os.getcwdu())
+        return cls(getcwdu())
 
     #
     # --- Operations on path strings.
 
     def abspath(self):
         return self._next_class(self.module.abspath(self))
 
     def normcase(self):
         return self._next_class(self.module.normcase(self))
 
     def normpath(self):
         return self._next_class(self.module.normpath(self))
 
     def realpath(self):
         return self._next_class(self.module.realpath(self))
 
     def expanduser(self):
         return self._next_class(self.module.expanduser(self))
 
     def expandvars(self):
         return self._next_class(self.module.expandvars(self))
 
     def dirname(self):
         return self._next_class(self.module.dirname(self))
 
     def basename(self):
         return self._next_class(self.module.basename(self))
 
     def expand(self):
         """ Clean up a filename by calling expandvars(),
         expanduser(), and normpath() on it.
 
         This is commonly everything needed to clean up a filename
         read from a configuration file, for example.
         """
         return self.expandvars().expanduser().normpath()
 
     @property
     def namebase(self):
         """ The same as path.name, but with one file extension stripped off.
 
         For example, path('/home/guido/python.tar.gz').name == 'python.tar.gz',
         but          path('/home/guido/python.tar.gz').namebase == 'python.tar'
         """
         base, ext = self.module.splitext(self.name)
         return base
 
     @property
     def ext(self):
         """ The file extension, for example '.py'. """
         f, ext = self.module.splitext(self)
         return ext
 
     @property
     def drive(self):
         """ The drive specifier, for example 'C:'.
         This is always empty on systems that don't use drive specifiers.
         """
         drive, r = self.module.splitdrive(self)
         return self._next_class(drive)
 
     parent = property(
         dirname, None, None,
         """ This path's parent directory, as a new path object.
 
         For example,
         path('/usr/local/lib/libpython.so').parent == path('/usr/local/lib')
         """)
 
     name = property(
         basename, None, None,
         """ The name of this file or directory without the full path.
 
         For example, path('/usr/local/lib/libpython.so').name == 'libpython.so'
         """)
 
     def splitpath(self):
         """ p.splitpath() -> Return (p.parent, p.name). """
         parent, child = self.module.split(self)
         return self._next_class(parent), child
 
     def splitdrive(self):
         """ p.splitdrive() -> Return (p.drive, <the rest of p>).
 
         Split the drive specifier from this path.  If there is
         no drive specifier, p.drive is empty, so the return value
         is simply (path(''), p).  This is always the case on Unix.
         """
         drive, rel = self.module.splitdrive(self)
         return self._next_class(drive), rel
 
     def splitext(self):
         """ p.splitext() -> Return (p.stripext(), p.ext).
 
         Split the filename extension from this path and return
         the two parts.  Either part may be empty.
 
         The extension is everything from '.' to the end of the
         last path segment.  This has the property that if
         (a, b) == p.splitext(), then a + b == p.
         """
         filename, ext = self.module.splitext(self)
         return self._next_class(filename), ext
 
     def stripext(self):
         """ p.stripext() -> Remove one file extension from the path.
 
         For example, path('/home/guido/python.tar.gz').stripext()
         returns path('/home/guido/python.tar').
         """
         return self.splitext()[0]
 
     def splitunc(self):
         unc, rest = self.module.splitunc(self)
         return self._next_class(unc), rest
 
     @property
     def uncshare(self):
         """
         The UNC mount point for this path.
         This is empty for paths on local drives.
         """
         unc, r = self.module.splitunc(self)
         return self._next_class(unc)
 
     @multimethod
     def joinpath(cls, first, *others):
         """
         Join first to zero or more path components, adding a separator
         character (first.module.sep) if needed.  Returns a new instance of
         first._next_class.
         """
         if not isinstance(first, cls):
             first = cls(first)
         return first._next_class(first.module.join(first, *others))
 
     def splitall(self):
         r""" Return a list of the path components in this path.
 
         The first item in the list will be a path.  Its value will be
         either os.curdir, os.pardir, empty, or the root directory of
         this path (for example, ``'/'`` or ``'C:\\'``).  The other items in
         the list will be strings.
 
         ``path.path.joinpath(*result)`` will yield the original path.
         """
         parts = []
         loc = self
         while loc != os.curdir and loc != os.pardir:
             prev = loc
             loc, child = prev.splitpath()
             if loc == prev:
                 break
             parts.append(child)
         parts.append(loc)
         parts.reverse()
         return parts
 
     def relpath(self, start='.'):
         """ Return this path as a relative path,
         based from start, which defaults to the current working directory.
         """
         cwd = self._next_class(start)
         return cwd.relpathto(self)
 
     def relpathto(self, dest):
         """ Return a relative path from self to dest.
 
         If there is no relative path from self to dest, for example if
         they reside on different drives in Windows, then this returns
         dest.abspath().
         """
         origin = self.abspath()
         dest = self._next_class(dest).abspath()
 
         orig_list = origin.normcase().splitall()
         # Don't normcase dest!  We want to preserve the case.
         dest_list = dest.splitall()
 
         if orig_list[0] != self.module.normcase(dest_list[0]):
             # Can't get here from there.
             return dest
 
         # Find the location where the two paths start to differ.
         i = 0
         for start_seg, dest_seg in zip(orig_list, dest_list):
             if start_seg != self.module.normcase(dest_seg):
                 break
             i += 1
 
         # Now i is the point where the two paths diverge.
         # Need a certain number of "os.pardir"s to work up
         # from the origin to the point of divergence.
         segments = [os.pardir] * (len(orig_list) - i)
         # Need to add the diverging part of dest_list.
         segments += dest_list[i:]
         if len(segments) == 0:
             # If they happen to be identical, use os.curdir.
             relpath = os.curdir
         else:
             relpath = self.module.join(*segments)
         return self._next_class(relpath)
 
     # --- Listing, searching, walking, and matching
 
     def listdir(self, pattern=None):
         """ D.listdir() -> List of items in this directory.
 
         Use D.files() or D.dirs() instead if you want a listing
         of just files or just subdirectories.
 
         The elements of the list are path objects.
 
         With the optional 'pattern' argument, this only lists
         items whose names match the given pattern.
         """
         names = os.listdir(self)
         if pattern is not None:
             names = fnmatch.filter(names, pattern)
         return [self / child for child in names]
 
     def dirs(self, pattern=None):
         """ D.dirs() -> List of this directory's subdirectories.
 
         The elements of the list are path objects.
         This does not walk recursively into subdirectories
         (but see path.walkdirs).
 
         With the optional 'pattern' argument, this only lists
         directories whose names match the given pattern.  For
         example, ``d.dirs('build-*')``.
         """
         return [p for p in self.listdir(pattern) if p.isdir()]
 
     def files(self, pattern=None):
         """ D.files() -> List of the files in this directory.
 
         The elements of the list are path objects.
         This does not walk into subdirectories (see path.walkfiles).
 
         With the optional 'pattern' argument, this only lists files
         whose names match the given pattern.  For example,
         ``d.files('*.pyc')``.
         """
 
         return [p for p in self.listdir(pattern) if p.isfile()]
 
     def walk(self, pattern=None, errors='strict'):
         """ D.walk() -> iterator over files and subdirs, recursively.
 
         The iterator yields path objects naming each child item of
         this directory and its descendants.  This requires that
         D.isdir().
 
         This performs a depth-first traversal of the directory tree.
         Each directory is returned just before all its children.
 
         The errors= keyword argument controls behavior when an
         error occurs.  The default is 'strict', which causes an
         exception.  The other allowed values are 'warn', which
         reports the error via warnings.warn(), and 'ignore'.
         """
         if errors not in ('strict', 'warn', 'ignore'):
             raise ValueError("invalid errors parameter")
 
         try:
             childList = self.listdir()
         except Exception:
             if errors == 'ignore':
                 return
             elif errors == 'warn':
                 warnings.warn(
                     "Unable to list directory '%s': %s"
                     % (self, sys.exc_info()[1]),
                     TreeWalkWarning)
                 return
             else:
                 raise
 
         for child in childList:
             if pattern is None or child.fnmatch(pattern):
                 yield child
             try:
                 isdir = child.isdir()
             except Exception:
                 if errors == 'ignore':
                     isdir = False
                 elif errors == 'warn':
                     warnings.warn(
                         "Unable to access '%s': %s"
                         % (child, sys.exc_info()[1]),
                         TreeWalkWarning)
                     isdir = False
                 else:
                     raise
 
             if isdir:
                 for item in child.walk(pattern, errors):
                     yield item
 
     def walkdirs(self, pattern=None, errors='strict'):
         """ D.walkdirs() -> iterator over subdirs, recursively.
 
         With the optional 'pattern' argument, this yields only
         directories whose names match the given pattern.  For
         example, ``mydir.walkdirs('*test')`` yields only directories
         with names ending in 'test'.
 
         The errors= keyword argument controls behavior when an
         error occurs.  The default is 'strict', which causes an
         exception.  The other allowed values are 'warn', which
         reports the error via warnings.warn(), and 'ignore'.
         """
         if errors not in ('strict', 'warn', 'ignore'):
             raise ValueError("invalid errors parameter")
 
         try:
             dirs = self.dirs()
         except Exception:
             if errors == 'ignore':
                 return
             elif errors == 'warn':
                 warnings.warn(
                     "Unable to list directory '%s': %s"
                     % (self, sys.exc_info()[1]),
                     TreeWalkWarning)
                 return
             else:
                 raise
 
         for child in dirs:
             if pattern is None or child.fnmatch(pattern):
                 yield child
             for subsubdir in child.walkdirs(pattern, errors):
                 yield subsubdir
 
     def walkfiles(self, pattern=None, errors='strict'):
         """ D.walkfiles() -> iterator over files in D, recursively.
 
         The optional argument, pattern, limits the results to files
         with names that match the pattern.  For example,
         ``mydir.walkfiles('*.tmp')`` yields only files with the .tmp
         extension.
         """
         if errors not in ('strict', 'warn', 'ignore'):
             raise ValueError("invalid errors parameter")
 
         try:
             childList = self.listdir()
         except Exception:
             if errors == 'ignore':
                 return
             elif errors == 'warn':
                 warnings.warn(
                     "Unable to list directory '%s': %s"
                     % (self, sys.exc_info()[1]),
                     TreeWalkWarning)
                 return
             else:
                 raise
 
         for child in childList:
             try:
                 isfile = child.isfile()
                 isdir = not isfile and child.isdir()
             except:
                 if errors == 'ignore':
                     continue
                 elif errors == 'warn':
                     warnings.warn(
                         "Unable to access '%s': %s"
                         % (self, sys.exc_info()[1]),
                         TreeWalkWarning)
                     continue
                 else:
                     raise
 
             if isfile:
                 if pattern is None or child.fnmatch(pattern):
                     yield child
             elif isdir:
                 for f in child.walkfiles(pattern, errors):
                     yield f
 
     def fnmatch(self, pattern):
         """ Return True if self.name matches the given pattern.
 
         pattern - A filename pattern with wildcards,
             for example ``'*.py'``.
         """
         return fnmatch.fnmatch(self.name, pattern)
 
     def glob(self, pattern):
         """ Return a list of path objects that match the pattern.
 
         pattern - a path relative to this directory, with wildcards.
 
         For example, path('/users').glob('*/bin/*') returns a list
         of all the files users have in their bin directories.
         """
         cls = self._next_class
         return [cls(s) for s in glob.glob(self / pattern)]
 
     #
     # --- Reading or writing an entire file at once.
 
     def open(self, *args, **kwargs):
         """ Open this file.  Return a file object. """
         return open(self, *args, **kwargs)
 
     def bytes(self):
         """ Open this file, read all bytes, return them as a string. """
         with self.open('rb') as f:
             return f.read()
 
     def chunks(self, size, *args, **kwargs):
         """ Returns a generator yielding chunks of the file, so it can
             be read piece by piece with a simple for loop.
 
            Any argument you pass after `size` will be passed to `open()`.
 
            :example:
 
                >>> for chunk in path("file.txt").chunk(8192):
                ...    print(chunk)
 
             This will read the file by chunks of 8192 bytes.
         """
         with open(self, *args, **kwargs) as f:
             while True:
                 d = f.read(size)
                 if not d:
                     break
                 yield d
 
     def write_bytes(self, bytes, append=False):
         """ Open this file and write the given bytes to it.
 
         Default behavior is to overwrite any existing file.
         Call p.write_bytes(bytes, append=True) to append instead.
         """
         if append:
             mode = 'ab'
         else:
             mode = 'wb'
         with self.open(mode) as f:
             f.write(bytes)
 
     def text(self, encoding=None, errors='strict'):
         r""" Open this file, read it in, return the content as a string.
 
         This method uses 'U' mode, so '\r\n' and '\r' are automatically
         translated to '\n'.
 
         Optional arguments:
 
         encoding - The Unicode encoding (or character set) of
             the file.  If present, the content of the file is
             decoded and returned as a unicode object; otherwise
             it is returned as an 8-bit str.
         errors - How to handle Unicode errors; see help(str.decode)
             for the options.  Default is 'strict'.
         """
         if encoding is None:
             # 8-bit
             with self.open('U') as f:
                 return f.read()
         else:
             # Unicode
             with codecs.open(self, 'r', encoding, errors) as f:
                 # (Note - Can't use 'U' mode here, since codecs.open
                 # doesn't support 'U' mode.)
                 t = f.read()
             return (t.replace(u('\r\n'), u('\n'))
                      .replace(u('\r\x85'), u('\n'))
                      .replace(u('\r'), u('\n'))
                      .replace(u('\x85'), u('\n'))
                      .replace(u('\u2028'), u('\n')))
 
     def write_text(self, text, encoding=None, errors='strict',
                    linesep=os.linesep, append=False):
         r""" Write the given text to this file.
 
         The default behavior is to overwrite any existing file;
         to append instead, use the 'append=True' keyword argument.
 
         There are two differences between path.write_text() and
         path.write_bytes(): newline handling and Unicode handling.
         See below.
 
         Parameters:
 
           - text - str/unicode - The text to be written.
 
           - encoding - str - The Unicode encoding that will be used.
             This is ignored if 'text' isn't a Unicode string.
 
           - errors - str - How to handle Unicode encoding errors.
             Default is 'strict'.  See help(unicode.encode) for the
             options.  This is ignored if 'text' isn't a Unicode
             string.
 
           - linesep - keyword argument - str/unicode - The sequence of
             characters to be used to mark end-of-line.  The default is
             os.linesep.  You can also specify None; this means to
             leave all newlines as they are in 'text'.
 
           - append - keyword argument - bool - Specifies what to do if
             the file already exists (True: append to the end of it;
             False: overwrite it.)  The default is False.
 
 
         --- Newline handling.
 
         write_text() converts all standard end-of-line sequences
         ('\n', '\r', and '\r\n') to your platform's default end-of-line
         sequence (see os.linesep; on Windows, for example, the
         end-of-line marker is '\r\n').
 
         If you don't like your platform's default, you can override it
         using the 'linesep=' keyword argument.  If you specifically want
         write_text() to preserve the newlines as-is, use 'linesep=None'.
 
         This applies to Unicode text the same as to 8-bit text, except
         there are three additional standard Unicode end-of-line sequences:
         u'\x85', u'\r\x85', and u'\u2028'.
 
         (This is slightly different from when you open a file for
         writing with fopen(filename, "w") in C or open(filename, 'w')
         in Python.)
 
 
         --- Unicode
 
         If 'text' isn't Unicode, then apart from newline handling, the
         bytes are written verbatim to the file.  The 'encoding' and
         'errors' arguments are not used and must be omitted.
 
         If 'text' is Unicode, it is first converted to bytes using the
         specified 'encoding' (or the default encoding if 'encoding'
         isn't specified).  The 'errors' argument applies only to this
         conversion.
 
         """
         if isinstance(text, unicode):
             if linesep is not None:
                 # Convert all standard end-of-line sequences to
                 # ordinary newline characters.
                 text = (text.replace(u('\r\n'), u('\n'))
                             .replace(u('\r\x85'), u('\n'))
                             .replace(u('\r'), u('\n'))
                             .replace(u('\x85'), u('\n'))
                             .replace(u('\u2028'), u('\n')))
                 text = text.replace(u('\n'), linesep)
             if encoding is None:
                 encoding = sys.getdefaultencoding()
             bytes = text.encode(encoding, errors)
         else:
             # It is an error to specify an encoding if 'text' is
             # an 8-bit string.
             assert encoding is None
 
             if linesep is not None:
                 text = (text.replace('\r\n', '\n')
                             .replace('\r', '\n'))
                 bytes = text.replace('\n', linesep)
 
         self.write_bytes(bytes, append)
 
     def lines(self, encoding=None, errors='strict', retain=True):
         r""" Open this file, read all lines, return them in a list.
 
         Optional arguments:
             encoding - The Unicode encoding (or character set) of
                 the file.  The default is None, meaning the content
                 of the file is read as 8-bit characters and returned
                 as a list of (non-Unicode) str objects.
             errors - How to handle Unicode errors; see help(str.decode)
                 for the options.  Default is 'strict'
             retain - If true, retain newline characters; but all newline
                 character combinations ('\r', '\n', '\r\n') are
                 translated to '\n'.  If false, newline characters are
                 stripped off.  Default is True.
 
         This uses 'U' mode.
         """
         if encoding is None and retain:
             with self.open('U') as f:
                 return f.readlines()
         else:
             return self.text(encoding, errors).splitlines(retain)
 
     def write_lines(self, lines, encoding=None, errors='strict',
                     linesep=os.linesep, append=False):
         r""" Write the given lines of text to this file.
 
         By default this overwrites any existing file at this path.
 
         This puts a platform-specific newline sequence on every line.
         See 'linesep' below.
 
         lines - A list of strings.
 
         encoding - A Unicode encoding to use.  This applies only if
             'lines' contains any Unicode strings.
 
         errors - How to handle errors in Unicode encoding.  This
             also applies only to Unicode strings.
 
         linesep - The desired line-ending.  This line-ending is
             applied to every line.  If a line already has any
             standard line ending ('\r', '\n', '\r\n', u'\x85',
             u'\r\x85', u'\u2028'), that will be stripped off and
             this will be used instead.  The default is os.linesep,
             which is platform-dependent ('\r\n' on Windows, '\n' on
             Unix, etc.)  Specify None to write the lines as-is,
             like file.writelines().
 
         Use the keyword argument append=True to append lines to the
         file.  The default is to overwrite the file.  Warning:
         When you use this with Unicode data, if the encoding of the
         existing data in the file is different from the encoding
         you specify with the encoding= parameter, the result is
         mixed-encoding data, which can really confuse someone trying
         to read the file later.
         """
         if append:
             mode = 'ab'
         else:
             mode = 'wb'
         with self.open(mode) as f:
             for line in lines:
                 isUnicode = isinstance(line, unicode)
                 if linesep is not None:
                     # Strip off any existing line-end and add the
                     # specified linesep string.
                     if isUnicode:
                         if line[-2:] in (u('\r\n'), u('\x0d\x85')):
                             line = line[:-2]
                         elif line[-1:] in (u('\r'), u('\n'),
                                            u('\x85'), u('\u2028')):
                             line = line[:-1]
                     else:
                         if line[-2:] == '\r\n':
                             line = line[:-2]
                         elif line[-1:] in ('\r', '\n'):
                             line = line[:-1]
                     line += linesep
                 if isUnicode:
                     if encoding is None:
                         encoding = sys.getdefaultencoding()
                     line = line.encode(encoding, errors)
                 f.write(line)
 
     def read_md5(self):
         """ Calculate the md5 hash for this file.
 
         This reads through the entire file.
         """
         return self.read_hash('md5')
 
     def _hash(self, hash_name):
         """ Returns a hash object for the file at the current path.
 
             `hash_name` should be a hash algo name such as 'md5' or 'sha1'
             that's available in the `hashlib` module.
         """
         m = hashlib.new(hash_name)
         for chunk in self.chunks(8192):
             m.update(chunk)
         return m
 
     def read_hash(self, hash_name):
         """ Calculate given hash for this file.
 
         List of supported hashes can be obtained from hashlib package. This
         reads the entire file.
         """
         return self._hash(hash_name).digest()
 
     def read_hexhash(self, hash_name):
         """ Calculate given hash for this file, returning hexdigest.
 
         List of supported hashes can be obtained from hashlib package. This
         reads the entire file.
         """
         return self._hash(hash_name).hexdigest()
 
     # --- Methods for querying the filesystem.
     # N.B. On some platforms, the os.path functions may be implemented in C
     # (e.g. isdir on Windows, Python 3.2.2), and compiled functions don't get
     # bound. Playing it safe and wrapping them all in method calls.
 
     def isabs(self):
         return self.module.isabs(self)
 
     def exists(self):
         return self.module.exists(self)
 
     def isdir(self):
         return self.module.isdir(self)
 
     def isfile(self):
         return self.module.isfile(self)
 
     def islink(self):
         return self.module.islink(self)
 
     def ismount(self):
         return self.module.ismount(self)
 
     def samefile(self, other):
         return self.module.samefile(self, other)
 
     def getatime(self):
         return self.module.getatime(self)
 
     atime = property(
         getatime, None, None,
         """ Last access time of the file. """)
 
     def getmtime(self):
         return self.module.getmtime(self)
 
     mtime = property(
         getmtime, None, None,
         """ Last-modified time of the file. """)
 
     def getctime(self):
         return self.module.getctime(self)
 
     ctime = property(
         getctime, None, None,
         """ Creation time of the file. """)
 
     def getsize(self):
         return self.module.getsize(self)
 
     size = property(
         getsize, None, None,
         """ Size of the file, in bytes. """)
 
     if hasattr(os, 'access'):
         def access(self, mode):
             """ Return true if current user has access to this path.
 
             mode - One of the constants os.F_OK, os.R_OK, os.W_OK, os.X_OK
             """
             return os.access(self, mode)
 
     def stat(self):
         """ Perform a stat() system call on this path. """
         return os.stat(self)
 
     def lstat(self):
         """ Like path.stat(), but do not follow symbolic links. """
         return os.lstat(self)
 
     def __get_owner_windows(self):
         r"""
         Return the name of the owner of this file or directory. Follow
         symbolic links.
 
         Return a name of the form ur'DOMAIN\User Name'; may be a group.
         """
         desc = win32security.GetFileSecurity(
             self, win32security.OWNER_SECURITY_INFORMATION)
         sid = desc.GetSecurityDescriptorOwner()
         account, domain, typecode = win32security.LookupAccountSid(None, sid)
         return domain + u('\\') + account
 
     def __get_owner_unix(self):
         """
         Return the name of the owner of this file or directory. Follow
         symbolic links.
         """
         st = self.stat()
         return pwd.getpwuid(st.st_uid).pw_name
 
     def __get_owner_not_implemented(self):
         raise NotImplementedError("Ownership not available on this platform.")
 
     if 'win32security' in globals():
         get_owner = __get_owner_windows
     elif 'pwd' in globals():
         get_owner = __get_owner_unix
     else:
         get_owner = __get_owner_not_implemented
 
     owner = property(
         get_owner, None, None,
         """ Name of the owner of this file or directory. """)
 
     if hasattr(os, 'statvfs'):
         def statvfs(self):
             """ Perform a statvfs() system call on this path. """
             return os.statvfs(self)
 
     if hasattr(os, 'pathconf'):
         def pathconf(self, name):
             return os.pathconf(self, name)
 
     #
     # --- Modifying operations on files and directories
 
     def utime(self, times):
         """ Set the access and modified times of this file. """
         os.utime(self, times)
         return self
 
     def chmod(self, mode):
         os.chmod(self, mode)
         return self
 
     if hasattr(os, 'chown'):
         def chown(self, uid=-1, gid=-1):
             os.chown(self, uid, gid)
             return self
 
     def rename(self, new):
         os.rename(self, new)
         return self._next_class(new)
 
     def renames(self, new):
         os.renames(self, new)
         return self._next_class(new)
 
     #
     # --- Create/delete operations on directories
 
     def mkdir(self, mode=o777):
         os.mkdir(self, mode)
         return self
 
     def mkdir_p(self, mode=o777):
         try:
             self.mkdir(mode)
         except OSError:
             _, e, _ = sys.exc_info()
             if e.errno != errno.EEXIST:
                 raise
         return self
 
     def makedirs(self, mode=o777):
         os.makedirs(self, mode)
         return self
 
     def makedirs_p(self, mode=o777):
         try:
             self.makedirs(mode)
         except OSError:
             _, e, _ = sys.exc_info()
             if e.errno != errno.EEXIST:
                 raise
         return self
 
     def rmdir(self):
         os.rmdir(self)
         return self
 
     def rmdir_p(self):
         try:
             self.rmdir()
         except OSError:
             _, e, _ = sys.exc_info()
             if e.errno != errno.ENOTEMPTY and e.errno != errno.EEXIST:
                 raise
         return self
 
     def removedirs(self):
         os.removedirs(self)
         return self
 
     def removedirs_p(self):
         try:
             self.removedirs()
         except OSError:
             _, e, _ = sys.exc_info()
             if e.errno != errno.ENOTEMPTY and e.errno != errno.EEXIST:
                 raise
         return self
 
     # --- Modifying operations on files
 
     def touch(self):
         """ Set the access/modified times of this file to the current time.
         Create the file if it does not exist.
         """
         fd = os.open(self, os.O_WRONLY | os.O_CREAT, o666)
         os.close(fd)
         os.utime(self, None)
         return self
 
     def remove(self):
         os.remove(self)
         return self
 
     def remove_p(self):
         try:
             self.unlink()
         except OSError:
             _, e, _ = sys.exc_info()
             if e.errno != errno.ENOENT:
                 raise
         return self
 
     def unlink(self):
         os.unlink(self)
         return self
 
     def unlink_p(self):
         self.remove_p()
         return self
 
     # --- Links
 
     if hasattr(os, 'link'):
         def link(self, newpath):
             """ Create a hard link at 'newpath', pointing to this file. """
             os.link(self, newpath)
             return self._next_class(newpath)
 
     if hasattr(os, 'symlink'):
         def symlink(self, newlink):
             """ Create a symbolic link at 'newlink', pointing here. """
             os.symlink(self, newlink)
             return self._next_class(newlink)
 
     if hasattr(os, 'readlink'):
         def readlink(self):
             """ Return the path to which this symbolic link points.
 
             The result may be an absolute or a relative path.
             """
             return self._next_class(os.readlink(self))
 
         def readlinkabs(self):
             """ Return the path to which this symbolic link points.
 
             The result is always an absolute path.
             """
             p = self.readlink()
             if p.isabs():
                 return p
             else:
                 return (self.parent / p).abspath()
 
     #
     # --- High-level functions from shutil
 
     copyfile = shutil.copyfile
     copymode = shutil.copymode
     copystat = shutil.copystat
     copy = shutil.copy
     copy2 = shutil.copy2
     copytree = shutil.copytree
     if hasattr(shutil, 'move'):
         move = shutil.move
     rmtree = shutil.rmtree
 
     def rmtree_p(self):
         try:
             self.rmtree()
         except OSError:
             _, e, _ = sys.exc_info()
             if e.errno != errno.ENOENT:
                 raise
         return self
 
     def chdir(self):
         os.chdir(self)
 
     cd = chdir
 
     #
     # --- Special stuff from os
 
     if hasattr(os, 'chroot'):
         def chroot(self):
             os.chroot(self)
 
     if hasattr(os, 'startfile'):
         def startfile(self):
             os.startfile(self)
             return self
 
 
 class tempdir(path):
     """
     A temporary directory via tempfile.mkdtemp, and constructed with the
     same parameters that you can use as a context manager.
 
     Example:
 
         with tempdir() as d:
             # do stuff with the path object "d"
 
         # here the directory is deleted automatically
     """
 
     @ClassProperty
     @classmethod
     def _next_class(cls):
         return path
 
     def __new__(cls, *args, **kwargs):
         dirname = tempfile.mkdtemp(*args, **kwargs)
         return super(tempdir, cls).__new__(cls, dirname)
 
     def __init__(self, *args, **kwargs):
         pass
 
     def __enter__(self):
         return self
 
     def __exit__(self, exc_type, exc_value, traceback):
         if not exc_value:
             self.rmtree()
 
 
 def _permission_mask(mode):
     """
     Convert a Unix chmod symbolic mode like 'ugo+rwx' to a function
     suitable for applying to a mask to affect that change.
 
     >>> mask = _permission_mask('ugo+rwx')
     >>> oct(mask(o554))
     'o777'
 
     >>> oct(_permission_mask('gw-x')(o777))
     'o766'
     """
     parsed = re.match('(?P<who>[ugo]+)(?P<op>[-+])(?P<what>[rwx]+)$', mode)
     if not parsed:
         raise ValueError("Unrecognized symbolic mode", mode)
     spec_map = dict(r=4, w=2, x=1)
     spec = reduce(operator.or_, [spec_map[perm]
                   for perm in parsed.group('what')])
     # now apply spec to each in who
     shift_map = dict(u=6, g=3, o=0)
     mask = reduce(operator.or_, [spec << shift_map[subj]
                   for subj in parsed.group('who')])
 
     op = parsed.group('op')
     # if op is -, invert the mask
     if op == '-':
         mask ^= o777
 
     op_map = {'+': operator.or_, '-': operator.and_}
     return functools.partial(op_map[op], mask)