276 lines
8.7 KiB
Python
276 lines
8.7 KiB
Python
# GNU MediaGoblin -- federated, autonomous media hosting
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# Copyright (C) 2011, 2012 MediaGoblin contributors. See AUTHORS.
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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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from __future__ import absolute_import
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import shutil
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import uuid
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import six
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from werkzeug.utils import secure_filename
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from mediagoblin.tools import common
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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 (not directory) at filepath.
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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_dir(self, dirpath, recursive=False):
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"""Delete the directory at dirpath
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:param recursive: Usually, a directory must not contain any
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files for the delete to succeed. If True, containing files
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and subdirectories within dirpath will be recursively
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deleted.
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:returns: True in case of success, False otherwise.
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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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# Note: this will copy in small chunks
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shutil.copy(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 open(dest_path, 'wb') as dest_file:
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# Copy from remote storage in 4M chunks
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shutil.copyfileobj(source_file, dest_file, length=4*1048576)
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def copy_local_to_storage(self, filename, filepath):
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"""
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Copy this file from locally to the storage system.
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This is kind of the opposite of copy_locally. It's likely you
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could override this method with something more appropriate to
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your storage system.
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"""
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with self.get_file(filepath, 'wb') as dest_file:
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with open(filename, 'rb') as source_file:
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# Copy to storage system in 4M chunks
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shutil.copyfileobj(source_file, dest_file, length=4*1048576)
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def get_file_size(self, filepath):
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"""
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Return the size of the file in bytes.
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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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###########
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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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six.text_type(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(six.iteritems(config_section))
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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.filestorage:BasicFileStorage'
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storage_class = common.import_component(storage_class)
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return storage_class(**config_params)
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from . import filestorage
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