506 lines
16 KiB
Python
506 lines
16 KiB
Python
# GNU MediaGoblin -- federated, autonomous media hosting
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# Copyright (C) 2011 Free Software Foundation, Inc
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#
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# This program is free software: you can redistribute it and/or modify
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# it under the terms of the GNU Affero General Public License as published by
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# the Free Software Foundation, either version 3 of the License, or
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# (at your option) any later version.
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#
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# This program is distributed in the hope that it will be useful,
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# but WITHOUT ANY WARRANTY; without even the implied warranty of
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# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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# GNU Affero General Public License for more details.
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#
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# You should have received a copy of the GNU Affero General Public License
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# along with this program. If not, see <http://www.gnu.org/licenses/>.
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import os
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import shutil
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import urlparse
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import uuid
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import cloudfiles
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import mimetypes
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from werkzeug.utils import secure_filename
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from mediagoblin import util
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########
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# Errors
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########
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class Error(Exception):
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pass
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class InvalidFilepath(Error):
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pass
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class NoWebServing(Error):
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pass
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class NotImplementedError(Error):
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pass
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###############################################
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# Storage interface & basic file implementation
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###############################################
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class StorageInterface(object):
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"""
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Interface for the storage API.
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This interface doesn't actually provide behavior, but it defines
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what kind of storage patterns subclasses should provide.
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It is important to note that the storage API idea of a "filepath"
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is actually like ['dir1', 'dir2', 'file.jpg'], so keep that in
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mind while reading method documentation.
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You should set up your __init__ method with whatever keyword
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arguments are appropriate to your storage system, but you should
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also passively accept all extraneous keyword arguments like:
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def __init__(self, **kwargs):
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pass
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See BasicFileStorage as a simple implementation of the
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StorageInterface.
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"""
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# Whether this file store is on the local filesystem.
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local_storage = False
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def __raise_not_implemented(self):
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"""
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Raise a warning about some component not implemented by a
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subclass of this interface.
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"""
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raise NotImplementedError(
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"This feature not implemented in this storage API implementation.")
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def file_exists(self, filepath):
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"""
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Return a boolean asserting whether or not file at filepath
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exists in our storage system.
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Returns:
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True / False depending on whether file exists or not.
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"""
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# Subclasses should override this method.
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self.__raise_not_implemented()
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def get_file(self, filepath, mode='r'):
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"""
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Return a file-like object for reading/writing from this filepath.
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Should create directories, buckets, whatever, as necessary.
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"""
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# Subclasses should override this method.
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self.__raise_not_implemented()
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def delete_file(self, filepath):
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"""
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Delete or dereference the file at filepath.
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This might need to delete directories, buckets, whatever, for
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cleanliness. (Be sure to avoid race conditions on that though)
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"""
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# Subclasses should override this method.
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self.__raise_not_implemented()
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def file_url(self, filepath):
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"""
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Get the URL for this file. This assumes our storage has been
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mounted with some kind of URL which makes this possible.
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"""
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# Subclasses should override this method.
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self.__raise_not_implemented()
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def get_unique_filepath(self, filepath):
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"""
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If a filename at filepath already exists, generate a new name.
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Eg, if the filename doesn't exist:
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>>> storage_handler.get_unique_filename(['dir1', 'dir2', 'fname.jpg'])
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[u'dir1', u'dir2', u'fname.jpg']
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But if a file does exist, let's get one back with at uuid tacked on:
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>>> storage_handler.get_unique_filename(['dir1', 'dir2', 'fname.jpg'])
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[u'dir1', u'dir2', u'd02c3571-dd62-4479-9d62-9e3012dada29-fname.jpg']
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"""
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# Make sure we have a clean filepath to start with, since
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# we'll be possibly tacking on stuff to the filename.
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filepath = clean_listy_filepath(filepath)
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if self.file_exists(filepath):
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return filepath[:-1] + ["%s-%s" % (uuid.uuid4(), filepath[-1])]
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else:
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return filepath
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def get_local_path(self, filepath):
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"""
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If this is a local_storage implementation, give us a link to
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the local filesystem reference to this file.
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>>> storage_handler.get_local_path(['foo', 'bar', 'baz.jpg'])
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u'/path/to/mounting/foo/bar/baz.jpg'
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"""
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# Subclasses should override this method, if applicable.
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self.__raise_not_implemented()
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def copy_locally(self, filepath, dest_path):
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"""
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Copy this file locally.
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A basic working method for this is provided that should
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function both for local_storage systems and remote storge
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systems, but if more efficient systems for copying locally
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apply to your system, override this method with something more
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appropriate.
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"""
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if self.local_storage:
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shutil.copy(
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self.get_local_path(filepath), dest_path)
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else:
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with self.get_file(filepath, 'rb') as source_file:
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with file(dest_path, 'wb') as dest_file:
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dest_file.write(source_file.read())
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class BasicFileStorage(StorageInterface):
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"""
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Basic local filesystem implementation of storage API
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"""
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local_storage = True
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def __init__(self, base_dir, base_url=None, **kwargs):
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"""
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Keyword arguments:
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- base_dir: Base directory things will be served out of. MUST
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be an absolute path.
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- base_url: URL files will be served from
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"""
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self.base_dir = base_dir
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self.base_url = base_url
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def _resolve_filepath(self, filepath):
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"""
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Transform the given filepath into a local filesystem filepath.
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"""
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return os.path.join(
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self.base_dir, *clean_listy_filepath(filepath))
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def file_exists(self, filepath):
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return os.path.exists(self._resolve_filepath(filepath))
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def get_file(self, filepath, mode='r'):
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# Make directories if necessary
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if len(filepath) > 1:
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directory = self._resolve_filepath(filepath[:-1])
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if not os.path.exists(directory):
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os.makedirs(directory)
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# Grab and return the file in the mode specified
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return open(self._resolve_filepath(filepath), mode)
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def delete_file(self, filepath):
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# TODO: Also delete unused directories if empty (safely, with
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# checks to avoid race conditions).
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os.remove(self._resolve_filepath(filepath))
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def file_url(self, filepath):
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if not self.base_url:
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raise NoWebServing(
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"base_url not set, cannot provide file urls")
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return urlparse.urljoin(
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self.base_url,
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'/'.join(clean_listy_filepath(filepath)))
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def get_local_path(self, filepath):
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return self._resolve_filepath(filepath)
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class CloudFilesStorage(StorageInterface):
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def __init__(self, **kwargs):
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self.param_container = kwargs.get('cloudfiles_container')
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self.param_user = kwargs.get('cloudfiles_user')
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self.param_api_key = kwargs.get('cloudfiles_api_key')
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self.param_host = kwargs.get('cloudfiles_host')
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self.param_use_servicenet = kwargs.get('cloudfiles_use_servicenet')
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if not self.param_host:
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print('No CloudFiles host URL specified, '
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'defaulting to Rackspace US')
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self.connection = cloudfiles.get_connection(
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username=self.param_user,
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api_key=self.param_api_key,
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servicenet=True if self.param_use_servicenet == 'true' or \
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self.param_use_servicenet == True else False)
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if not self.param_container == \
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self.connection.get_container(self.param_container):
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self.container = self.connection.create_container(
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self.param_container)
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self.container.make_public(
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ttl=60 * 60 * 2)
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else:
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self.container = self.connection.get_container(
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self.param_container)
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self.container_uri = self.container.public_uri()
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def _resolve_filepath(self, filepath):
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return '/'.join(
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clean_listy_filepath(filepath))
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def file_exists(self, filepath):
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try:
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object = self.container.get_object(
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self._resolve_filepath(filepath))
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return True
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except cloudfiles.errors.NoSuchObject:
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return False
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def get_file(self, filepath, mode='r'):
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try:
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obj = self.container.get_object(
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self._resolve_filepath(filepath))
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except cloudfiles.errors.NoSuchObject:
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obj = self.container.create_object(
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self._resolve_filepath(filepath))
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mimetype = mimetypes.guess_type(
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filepath[-1])
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if mimetype:
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obj.content_type = mimetype[0]
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return obj
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def delete_file(self, filepath):
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# TODO: Also delete unused directories if empty (safely, with
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# checks to avoid race conditions).
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self.container.delete_object(filepath)
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def file_url(self, filepath):
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return '/'.join([
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self.container_uri,
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self._resolve_filepath(filepath)])
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class MountStorage(StorageInterface):
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"""
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Experimental "Mount" virtual Storage Interface
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This isn't an interface to some real storage, instead it's a
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redirecting interface, that redirects requests to other
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"StorageInterface"s.
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For example, say you have the paths:
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1. ['user_data', 'cwebber', 'avatar.jpg']
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2. ['user_data', 'elrond', 'avatar.jpg']
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3. ['media_entries', '34352f304c3f4d0ad8ad0f043522b6f2', 'thumb.jpg']
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You could mount media_entries under CloudFileStorage and user_data
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under BasicFileStorage. Then 1 would be passed to
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BasicFileStorage under the path ['cwebber', 'avatar.jpg'] and 3
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would be passed to CloudFileStorage under
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['34352f304c3f4d0ad8ad0f043522b6f2', 'thumb.jpg'].
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In other words, this is kind of like mounting /home/ and /etc/
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under different filesystems on your operating system... but with
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mediagoblin filestorages :)
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To set this up, you currently need to call the mount() method with
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the target path and a backend, that shall be available under that
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target path. You have to mount things in a sensible order,
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especially you can't mount ["a", "b"] before ["a"].
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"""
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def __init__(self, **kwargs):
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self.mounttab = {}
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def mount(self, dirpath, backend):
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"""
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Mount a new backend under dirpath
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"""
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new_ent = clean_listy_filepath(dirpath)
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print "Mounting:", repr(new_ent)
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already, rem_1, table, rem_2 = self._resolve_to_backend(new_ent, True)
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print "===", repr(already), repr(rem_1), repr(rem_2), len(table)
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assert (len(rem_2) > 0) or (None not in table), \
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"That path is already mounted"
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assert (len(rem_2) > 0) or (len(table)==0), \
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"A longer path is already mounted here"
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for part in rem_2:
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table[part] = {}
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table = table[part]
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table[None] = backend
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def _resolve_to_backend(self, filepath, extra_info = False):
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"""
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extra_info = True is for internal use!
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Normally, returns the backend and the filepath inside that backend.
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With extra_info = True it returns the last directory node and the
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remaining filepath from there in addition.
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"""
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table = self.mounttab
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filepath = filepath[:]
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res_fp = None
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while True:
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new_be = table.get(None)
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if (new_be is not None) or res_fp is None:
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res_be = new_be
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res_fp = filepath[:]
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res_extra = (table, filepath[:])
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# print "... New res: %r, %r, %r" % (res_be, res_fp, res_extra)
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if len(filepath) == 0:
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break
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query = filepath.pop(0)
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entry = table.get(query)
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if entry is not None:
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table = entry
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res_extra = (table, filepath[:])
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else:
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break
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if extra_info:
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return (res_be, res_fp) + res_extra
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else:
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return (res_be, res_fp)
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def resolve_to_backend(self, filepath):
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backend, filepath = self._resolve_to_backend(filepath)
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if backend is None:
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raise Error("Path not mounted")
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return backend, filepath
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def __repr__(self, table = None, indent = []):
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res = []
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if table is None:
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res.append("MountStorage<")
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table = self.mounttab
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v = table.get(None)
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if v:
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res.append(" " * len(indent) + repr(indent) + ": " + repr(v))
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for k, v in table.iteritems():
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if k == None:
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continue
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res.append(" " * len(indent) + repr(k) + ":")
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res += self.__repr__(v, indent + [k])
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if table is self.mounttab:
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res.append(">")
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return "\n".join(res)
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else:
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return res
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def file_exists(self, filepath):
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backend, filepath = self.resolve_to_backend(filepath)
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return backend.file_exists(filepath)
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def get_file(self, filepath, mode='r'):
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backend, filepath = self.resolve_to_backend(filepath)
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return backend.get_file(filepath, mode)
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def delete_file(self, filepath):
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backend, filepath = self.resolve_to_backend(filepath)
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return backend.delete_file(filepath)
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def file_url(self, filepath):
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backend, filepath = self.resolve_to_backend(filepath)
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return backend.file_url(filepath)
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def get_local_path(self, filepath):
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backend, filepath = self.resolve_to_backend(filepath)
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return backend.get_local_path(filepath)
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def copy_locally(self, filepath, dest_path):
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"""
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Need to override copy_locally, because the local_storage
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attribute is not correct.
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"""
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backend, filepath = self.resolve_to_backend(filepath)
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backend.copy_locally(filepath, dest_path)
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###########
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# Utilities
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###########
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def clean_listy_filepath(listy_filepath):
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"""
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Take a listy filepath (like ['dir1', 'dir2', 'filename.jpg']) and
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clean out any nastiness from it.
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>>> clean_listy_filepath([u'/dir1/', u'foo/../nasty', u'linooks.jpg'])
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[u'dir1', u'foo_.._nasty', u'linooks.jpg']
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Args:
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- listy_filepath: a list of filepath components, mediagoblin
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storage API style.
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Returns:
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A cleaned list of unicode objects.
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"""
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cleaned_filepath = [
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unicode(secure_filename(filepath))
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for filepath in listy_filepath]
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if u'' in cleaned_filepath:
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raise InvalidFilepath(
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"A filename component could not be resolved into a usable name.")
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return cleaned_filepath
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def storage_system_from_config(config_section):
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"""
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Utility for setting up a storage system from a config section.
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Note that a special argument may be passed in to
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the config_section which is "storage_class" which will provide an
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import path to a storage system. This defaults to
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"mediagoblin.storage:BasicFileStorage" if otherwise undefined.
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Arguments:
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- config_section: dictionary of config parameters
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Returns:
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An instantiated storage system.
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Example:
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storage_system_from_config(
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{'base_url': '/media/',
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'base_dir': '/var/whatever/media/'})
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Will return:
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BasicFileStorage(
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base_url='/media/',
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base_dir='/var/whatever/media')
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"""
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# This construct is needed, because dict(config) does
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# not replace the variables in the config items.
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config_params = dict(config_section.iteritems())
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if 'storage_class' in config_params:
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storage_class = config_params['storage_class']
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config_params.pop('storage_class')
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else:
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storage_class = "mediagoblin.storage:BasicFileStorage"
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storage_class = util.import_component(storage_class)
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return storage_class(**config_params)
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