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from __future__ import unicode_literals
import os
import sys
import tempfile
from os.path import abspath, dirname, isabs, join, normcase, normpath, sep
from django.core.exceptions import SuspiciousFileOperation
from django.utils import six
from django.utils.encoding import force_text
if six.PY2:
fs_encoding = sys.getfilesystemencoding() or sys.getdefaultencoding()
# Under Python 2, define our own abspath function that can handle joining
# unicode paths to a current working directory that has non-ASCII characters
# in it. This isn't necessary on Windows since the Windows version of abspath
# handles this correctly. It also handles drive letters differently than the
# pure Python implementation, so it's best not to replace it.
if six.PY3 or os.name == 'nt':
abspathu = abspath
else:
def abspathu(path):
"""
Version of os.path.abspath that uses the unicode representation
of the current working directory, thus avoiding a UnicodeDecodeError
in join when the cwd has non-ASCII characters.
"""
if not isabs(path):
path = join(os.getcwdu(), path)
return normpath(path)
def upath(path):
"""
Always return a unicode path.
"""
if six.PY2 and not isinstance(path, six.text_type):
return path.decode(fs_encoding)
return path
def npath(path):
"""
Always return a native path, that is unicode on Python 3 and bytestring on
Python 2.
"""
if six.PY2 and not isinstance(path, bytes):
return path.encode(fs_encoding)
return path
def safe_join(base, *paths):
"""
Joins one or more path components to the base path component intelligently.
Returns a normalized, absolute version of the final path.
The final path must be located inside of the base path component (otherwise
a ValueError is raised).
"""
base = force_text(base)
paths = [force_text(p) for p in paths]
final_path = abspathu(join(base, *paths))
base_path = abspathu(base)
# Ensure final_path starts with base_path (using normcase to ensure we
# don't false-negative on case insensitive operating systems like Windows),
# further, one of the following conditions must be true:
# a) The next character is the path separator (to prevent conditions like
# safe_join("/dir", "/../d"))
# b) The final path must be the same as the base path.
# c) The base path must be the most root path (meaning either "/" or "C:\\")
if (not normcase(final_path).startswith(normcase(base_path + sep)) and
normcase(final_path) != normcase(base_path) and
dirname(normcase(base_path)) != normcase(base_path)):
raise SuspiciousFileOperation(
'The joined path ({}) is located outside of the base path '
'component ({})'.format(final_path, base_path))
return final_path
def symlinks_supported():
"""
A function to check if creating symlinks are supported in the
host platform and/or if they are allowed to be created (e.g.
on Windows it requires admin permissions).
"""
tmpdir = tempfile.mkdtemp()
original_path = os.path.join(tmpdir, 'original')
symlink_path = os.path.join(tmpdir, 'symlink')
os.makedirs(original_path)
try:
os.symlink(original_path, symlink_path)
supported = True
except (OSError, NotImplementedError, AttributeError):
supported = False
else:
os.remove(symlink_path)
finally:
os.rmdir(original_path)
os.rmdir(tmpdir)
return supported
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