246 lines
8.7 KiB
Python
246 lines
8.7 KiB
Python
import os
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import errno
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import urlparse
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from django.conf import settings
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from django.core.exceptions import ImproperlyConfigured, SuspiciousOperation
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from django.core.files import locks, File
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from django.core.files.move import file_move_safe
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from django.utils.encoding import force_unicode
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from django.utils.functional import LazyObject
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from django.utils.text import get_valid_filename
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from django.utils._os import safe_join
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__all__ = ('Storage', 'FileSystemStorage', 'DefaultStorage', 'default_storage')
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class Storage(object):
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"""
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A base storage class, providing some default behaviors that all other
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storage systems can inherit or override, as necessary.
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"""
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# The following methods represent a public interface to private methods.
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# These shouldn't be overridden by subclasses unless absolutely necessary.
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def open(self, name, mode='rb', mixin=None):
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"""
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Retrieves the specified file from storage, using the optional mixin
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class to customize what features are available on the File returned.
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"""
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file = self._open(name, mode)
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if mixin:
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# Add the mixin as a parent class of the File returned from storage.
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file.__class__ = type(mixin.__name__, (mixin, file.__class__), {})
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return file
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def save(self, name, content):
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"""
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Saves new content to the file specified by name. The content should be a
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proper File object, ready to be read from the beginning.
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"""
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# Get the proper name for the file, as it will actually be saved.
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if name is None:
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name = content.name
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name = self.get_available_name(name)
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name = self._save(name, content)
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# Store filenames with forward slashes, even on Windows
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return force_unicode(name.replace('\\', '/'))
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# These methods are part of the public API, with default implementations.
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def get_valid_name(self, name):
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"""
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Returns a filename, based on the provided filename, that's suitable for
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use in the target storage system.
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"""
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return get_valid_filename(name)
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def get_available_name(self, name):
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"""
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Returns a filename that's free on the target storage system, and
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available for new content to be written to.
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"""
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# If the filename already exists, keep adding an underscore to the name
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# of the file until the filename doesn't exist.
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while self.exists(name):
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try:
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dot_index = name.rindex('.')
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except ValueError: # filename has no dot
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name += '_'
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else:
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name = name[:dot_index] + '_' + name[dot_index:]
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return name
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def path(self, name):
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"""
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Returns a local filesystem path where the file can be retrieved using
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Python's built-in open() function. Storage systems that can't be
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accessed using open() should *not* implement this method.
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"""
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raise NotImplementedError("This backend doesn't support absolute paths.")
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# The following methods form the public API for storage systems, but with
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# no default implementations. Subclasses must implement *all* of these.
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def delete(self, name):
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"""
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Deletes the specified file from the storage system.
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"""
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raise NotImplementedError()
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def exists(self, name):
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"""
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Returns True if a file referened by the given name already exists in the
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storage system, or False if the name is available for a new file.
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"""
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raise NotImplementedError()
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def listdir(self, path):
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"""
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Lists the contents of the specified path, returning a 2-tuple of lists;
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the first item being directories, the second item being files.
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"""
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raise NotImplementedError()
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def size(self, name):
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"""
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Returns the total size, in bytes, of the file specified by name.
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"""
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raise NotImplementedError()
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def url(self, name):
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"""
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Returns an absolute URL where the file's contents can be accessed
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directly by a web browser.
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"""
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raise NotImplementedError()
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# Needed by django.utils.functional.LazyObject (via DefaultStorage).
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def get_all_members(self):
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return self.__members__
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class FileSystemStorage(Storage):
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"""
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Standard filesystem storage
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"""
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def __init__(self, location=None, base_url=None):
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if location is None:
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location = settings.MEDIA_ROOT
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if base_url is None:
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base_url = settings.MEDIA_URL
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self.location = os.path.abspath(location)
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self.base_url = base_url
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def _open(self, name, mode='rb'):
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return File(open(self.path(name), mode))
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def _save(self, name, content):
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full_path = self.path(name)
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directory = os.path.dirname(full_path)
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if not os.path.exists(directory):
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os.makedirs(directory)
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elif not os.path.isdir(directory):
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raise IOError("%s exists and is not a directory." % directory)
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# There's a potential race condition between get_available_name and
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# saving the file; it's possible that two threads might return the
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# same name, at which point all sorts of fun happens. So we need to
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# try to create the file, but if it already exists we have to go back
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# to get_available_name() and try again.
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while True:
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try:
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# This file has a file path that we can move.
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if hasattr(content, 'temporary_file_path'):
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file_move_safe(content.temporary_file_path(), full_path)
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content.close()
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# This is a normal uploadedfile that we can stream.
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else:
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# This fun binary flag incantation makes os.open throw an
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# OSError if the file already exists before we open it.
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fd = os.open(full_path, os.O_WRONLY | os.O_CREAT | os.O_EXCL | getattr(os, 'O_BINARY', 0))
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try:
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locks.lock(fd, locks.LOCK_EX)
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for chunk in content.chunks():
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os.write(fd, chunk)
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finally:
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locks.unlock(fd)
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os.close(fd)
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except OSError, e:
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if e.errno == errno.EEXIST:
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# Ooops, the file exists. We need a new file name.
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name = self.get_available_name(name)
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full_path = self.path(name)
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else:
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raise
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else:
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# OK, the file save worked. Break out of the loop.
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break
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if settings.FILE_UPLOAD_PERMISSIONS is not None:
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os.chmod(full_path, settings.FILE_UPLOAD_PERMISSIONS)
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return name
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def delete(self, name):
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name = self.path(name)
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# If the file exists, delete it from the filesystem.
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if os.path.exists(name):
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os.remove(name)
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def exists(self, name):
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return os.path.exists(self.path(name))
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def listdir(self, path):
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path = self.path(path)
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directories, files = [], []
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for entry in os.listdir(path):
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if os.path.isdir(os.path.join(path, entry)):
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directories.append(entry)
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else:
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files.append(entry)
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return directories, files
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def path(self, name):
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try:
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path = safe_join(self.location, name)
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except ValueError:
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raise SuspiciousOperation("Attempted access to '%s' denied." % name)
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return os.path.normpath(path)
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def size(self, name):
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return os.path.getsize(self.path(name))
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def url(self, name):
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if self.base_url is None:
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raise ValueError("This file is not accessible via a URL.")
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return urlparse.urljoin(self.base_url, name).replace('\\', '/')
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def get_storage_class(import_path=None):
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if import_path is None:
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import_path = settings.DEFAULT_FILE_STORAGE
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try:
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dot = import_path.rindex('.')
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except ValueError:
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raise ImproperlyConfigured("%s isn't a storage module." % import_path)
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module, classname = import_path[:dot], import_path[dot+1:]
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try:
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mod = __import__(module, {}, {}, [''])
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except ImportError, e:
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raise ImproperlyConfigured('Error importing storage module %s: "%s"' % (module, e))
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try:
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return getattr(mod, classname)
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except AttributeError:
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raise ImproperlyConfigured('Storage module "%s" does not define a "%s" class.' % (module, classname))
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class DefaultStorage(LazyObject):
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def _setup(self):
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self._wrapped = get_storage_class()()
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default_storage = DefaultStorage()
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