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Diffstat (limited to 'gdatastore/datastore.py')
| -rw-r--r-- | gdatastore/datastore.py | 473 |
1 files changed, 473 insertions, 0 deletions
diff --git a/gdatastore/datastore.py b/gdatastore/datastore.py new file mode 100644 index 0000000..1cb8555 --- /dev/null +++ b/gdatastore/datastore.py @@ -0,0 +1,473 @@ +# +# Author: Sascha Silbe <sascha-pgp@silbe.org> +# +# This program is free software; you can redistribute it and/or modify +# it under the terms of the GNU General Public License version 3 +# as published by the Free Software Foundation. +# +# This program is distributed in the hope that it will be useful, +# but WITHOUT ANY WARRANTY; without even the implied warranty of +# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the +# GNU General Public License for more details. +# +# You should have received a copy of the GNU General Public License +# along with this program. If not, see <http://www.gnu.org/licenses/>. +""" +Gdatastore D-Bus service API +""" + +import hashlib +import logging +import os +import shutil +from subprocess import Popen, PIPE +import tempfile +import time +import uuid + +import dbus +import dbus.service +import gconf + +from gdatastore.index import Index + + +DBUS_SERVICE_NATIVE_V1 = 'org.silbe.GDataStore' +DBUS_INTERFACE_NATIVE_V1 = 'org.silbe.GDataStore1' +DBUS_PATH_NATIVE_V1 = '/org/silbe/GDataStore1' + +DBUS_SERVICE_SUGAR_V2 = 'org.laptop.sugar.DataStore' +DBUS_INTERFACE_SUGAR_V2 = 'org.laptop.sugar.DataStore' +DBUS_PATH_SUGAR_V2 = '/org/laptop/sugar/DataStore' + +DBUS_SERVICE_SUGAR_V3 = 'org.laptop.sugar.DataStore' +DBUS_INTERFACE_SUGAR_V3 = 'org.laptop.sugar.DataStore2' +DBUS_PATH_SUGAR_V3 = '/org/laptop/sugar/DataStore2' + + +class DataStoreError(Exception): + pass + + +class GitError(DataStoreError): + def __init__(self, returncode, stderr): + self.returncode = returncode + self.stderr = unicode(stderr) + Exception.__init__(self) + + def __unicode__(self): + return u'Git returned with exit code #%d: %s' % (self.returncode, + self.stderr) + + def __str__(self): + return self.__unicode__() + + +class DBusApiSugarV2(dbus.service.Object): + """Compatibility layer for the Sugar 0.84+ data store D-Bus API + """ + + def __init__(self, internal_api): + self._internal_api = internal_api + bus_name = dbus.service.BusName(DBUS_SERVICE_SUGAR_V2, + bus=dbus.SessionBus(), + replace_existing=False, + allow_replacement=False) + dbus.service.Object.__init__(self, bus_name, DBUS_PATH_SUGAR_V2) + + @dbus.service.method(DBUS_INTERFACE_SUGAR_V2, + in_signature='a{sv}sb', out_signature='s', + async_callbacks=('async_cb', 'async_err_cb'), + byte_arrays=True) + def create(self, props, file_path, transfer_ownership, + async_cb, async_err_cb): + def success_cb(tree_id, child_id): + self.Created(tree_id) + async_cb(tree_id) + + self._internal_api.save(tree_id='', parent_id='', metadata=props, + path=file_path, + delete_after=transfer_ownership, + async_cb=success_cb, + async_err_cb=async_err_cb) + + @dbus.service.signal(DBUS_INTERFACE_SUGAR_V2, signature='s') + def Created(self, uid): + # pylint: disable-msg=C0103 + pass + + @dbus.service.method(DBUS_INTERFACE_SUGAR_V2, + in_signature='sa{sv}sb', out_signature='', + async_callbacks=('async_cb', 'async_err_cb'), + byte_arrays=True) + def update(self, uid, props, file_path, transfer_ownership, + async_cb, async_err_cb): + def success_cb(tree_id, child_id): + self.Updated(tree_id) + async_cb() + + latest_versions = self._get_latest(uid) + if not latest_versions: + raise ValueError('Trying to update non-existant entry %s - wanted' + ' to use create()?' % (uid, )) + + parent = latest_versions[0] + object_id = parent['tree_id'], parent['version_id'] + if self._compare_checksums(parent, file_path): + self._internal_api.change_metadata(object_id, props) + return success_cb(uid, None) + + self._internal_api.save(tree_id=uid, + parent_id=parent['version_id'], metadata=props, + path=file_path, delete_after=transfer_ownership, + async_cb=success_cb, async_err_cb=async_err_cb) + + @dbus.service.signal(DBUS_INTERFACE_SUGAR_V2, signature='s') + def Updated(self, uid): + # pylint: disable-msg=C0103 + pass + + @dbus.service.method(DBUS_INTERFACE_SUGAR_V2, + in_signature='a{sv}as', out_signature='aa{sv}u') + def find(self, query, properties): + if 'uid' in properties: + properties.append('tree_id') + properties.remove('uid') + + options = {'metadata': properties} + for name in ['offset', 'limit', 'order_by']: + if name in query: + options[name] = query.pop(name) + + if 'uid' in query: + query['tree_id'] = query.pop('uid') + + results, count = self._internal_api.find(query, options, + query.pop('query', None)) + + if not properties or 'tree_id' in properties: + for entry in results: + entry['uid'] = entry.pop('tree_id') + + return results, count + + @dbus.service.method(DBUS_INTERFACE_SUGAR_V2, + in_signature='s', out_signature='s', + sender_keyword='sender') + def get_filename(self, uid, sender=None): + latest_versions = self._get_latest(uid) + if not latest_versions: + raise ValueError('Entry %s does not exist' % (uid, )) + + object_id = (uid, latest_versions[0]['version_id']) + return self._internal_api.get_data_path(object_id, sender=sender) + + @dbus.service.method(DBUS_INTERFACE_SUGAR_V2, + in_signature='s', out_signature='a{sv}') + def get_properties(self, uid): + latest_versions = self._get_latest(uid) + if not latest_versions: + raise ValueError('Entry %s does not exist' % (uid, )) + + latest_versions[0]['uid'] = latest_versions[0].pop('tree_id') + del latest_versions[0]['version_id'] + return latest_versions[0] + + @dbus.service.method(DBUS_INTERFACE_SUGAR_V2, + in_signature='sa{sv}', out_signature='as') + def get_uniquevaluesfor(self, propertyname, query=None): + return self._internal_api.find_unique_values(query, propertyname) + + @dbus.service.method(DBUS_INTERFACE_SUGAR_V2, + in_signature='s', out_signature='') + def delete(self, uid): + latest_versions = self._get_latest(uid) + if not latest_versions: + raise ValueError('Entry %s does not exist' % (uid, )) + + self._internal_api.delete((uid, latest_versions[0]['version_id'])) + self.Deleted(uid) + + @dbus.service.signal(DBUS_INTERFACE_SUGAR_V2, signature='s') + def Deleted(self, uid): + # pylint: disable-msg=C0103 + pass + + @dbus.service.method(DBUS_INTERFACE_SUGAR_V2, + in_signature='', out_signature='aa{sv}') + def mounts(self): + return [{'id': 1}] + + @dbus.service.signal(DBUS_INTERFACE_SUGAR_V2, signature='a{sv}') + def Mounted(self, descriptior): + # pylint: disable-msg=C0103 + pass + + @dbus.service.signal(DBUS_INTERFACE_SUGAR_V2, signature='a{sv}') + def Unmounted(self, descriptor): + # pylint: disable-msg=C0103 + pass + + def _get_latest(self, uid): + return self._internal_api.find({'tree_id': uid}, + {'limit': 1, 'order_by': ['+timestamp']})[0] + + def _compare_checksums(self, parent, child_data_path): + parent_object_id = (parent['tree_id'], parent['version_id']) + parent_data_path = self._internal_api.get_data_path(parent_object_id) + if bool(child_data_path) ^ bool(parent_data_path): + return False + elif not child_data_path: + return True + + return False + parent_checksum = self._internal_api.get_data_checksum( + parent_object_id) + child_checksum = calculate_checksum(child_data_path) + return parent_checksum == child_checksum + + +class InternalApi(object): + def __init__(self, base_dir): + self._base_dir = base_dir + self._checkouts_dir = os.path.join(base_dir, 'checkouts') + if not os.path.exists(self._checkouts_dir): + os.makedirs(self._checkouts_dir) + self._git_dir = os.path.join(base_dir, 'git') + self._git_env = {} + gconf_client = gconf.client_get_default() + self._max_versions = gconf_client.get_int( + '/desktop/sugar/datastore/max_versions') + logging.debug('max_versions=%r', self._max_versions) + self._index = Index(os.path.join(self._base_dir, 'index')) + self._migrate() + self._metadata = {} + + def change_metadata(self, object_id, metadata): + logging.debug('change_metadata(%r, %r)', object_id, metadata) + metadata['tree_id'], metadata['version_id'] = object_id + if 'creation_time' not in metadata: + old_metadata = self._metadata[object_id] + metadata['creation_time'] = old_metadata['creation_time'] + + self._index.store(object_id, metadata) + self._metadata[object_id] = metadata + + def delete(self, object_id): + logging.debug('delete(%r)', object_id) + self._index.delete(object_id) + del self._metadata[object_id] + self._git_call('update-ref', ['-d', _format_ref(*object_id)]) + + def get_data_path(self, (tree_id, version_id), sender=None): + logging.debug('get_data_path((%r, %r), %r)', tree_id, version_id, + sender) + ref_name = _format_ref(tree_id, version_id) + top_level_entries = self._git_call('ls-tree', + [ref_name]).splitlines() + if len(top_level_entries) == 1 and \ + top_level_entries[0].endswith('\tdata'): + blob_hash = top_level_entries[0].split('\t')[0].split(' ')[2] + return self._checkout_file(blob_hash) + + return self._checkout_dir(ref_name) + + def find(self, query_dict, options, query_string=None): + logging.debug('find(%r, %r, %r)', query_dict, options, query_string) + entries, total_count = self._index.find(query_dict, query_string, + options) + #logging.debug('object_ids=%r', object_ids) + property_names = options.pop('metadata', None) + for entry in entries: + for name in entry.keys(): + if property_names and name not in property_names: + del entry[name] + elif isinstance(entry[name], str): + entry[name] = dbus.ByteArray(entry[name]) + + return entries, total_count + + def find_unique_values(self, query, name): + logging.debug('find_unique_values(%r, %r)', query, name) + return ['org.sugarlabs.DataStoreTest1', 'org.sugarlabs.DataStoreTest2'] + + def save(self, tree_id, parent_id, metadata, path, delete_after, async_cb, + async_err_cb): + logging.debug('save(%r, %r, %r, %r, %r)', tree_id, parent_id, + metadata, path, delete_after) + + if path: + path = os.path.realpath(path) + if not os.access(path, os.R_OK): + raise ValueError('Invalid path given.') + + if delete_after and not os.access(os.path.dirname(path), os.W_OK): + raise ValueError('Deletion requested for read-only directory') + + if (not tree_id) and parent_id: + raise ValueError('tree_id is empty but parent_id is not') + + if tree_id and not parent_id: + if self.find({'tree_id': tree_id}, {'limit': 1})[1]: + raise ValueError('No parent_id given but tree_id already ' + 'exists') + + elif parent_id: + if not self._index.contains((tree_id, parent_id)): + raise ValueError('Given parent does not exist') + + if not tree_id: + tree_id = self._gen_uuid() + + child_id = metadata.get('version_id') + if not child_id: + child_id = self._gen_uuid() + elif not tree_id: + raise ValueError('No tree_id given but metadata contains' + ' version_id') + elif self._index.contains((tree_id, child_id)): + raise ValueError('There is an existing entry with the same tree_id' + ' and version_id') + + if 'timestamp' not in metadata: + metadata['timestamp'] = time.time() + + if 'creation_time' not in metadata: + metadata['creation_time'] = metadata['timestamp'] + + if os.path.isfile(path): + metadata['filesize'] = str(os.stat(path).st_size) + elif not path: + metadata['filesize'] = '0' + + tree_id = str(tree_id) + parent_id = str(parent_id) + child_id = str(child_id) + + metadata['tree_id'] = tree_id + metadata['version_id'] = child_id + + # TODO: check metadata for validity first (index?) + self._store_entry(tree_id, child_id, parent_id, path, metadata) + self._metadata[(tree_id, child_id)] = metadata + self._index.store((tree_id, child_id), metadata) + async_cb(tree_id, child_id) + + def stop(self): + logging.debug('stop()') + self._index.close() + + def _add_to_index(self, index_path, path): + if os.path.isdir(path): + self._git_call('add', ['-A'], work_dir=path, index_path=index_path) + elif os.path.isfile(path): + object_hash = self._git_call('hash-object', ['-w', path]).strip() + mode = os.stat(path).st_mode + self._git_call('update-index', + ['--add', + '--cacheinfo', oct(mode), object_hash, 'data'], + index_path=index_path) + else: + raise DataStoreError('Refusing to store special object %r' % (path, )) + + def _check_max_versions(self, tree_id): + if not self._max_versions: + return + + options = {'all_versions': True, 'offset': self._max_versions, + 'metadata': ['tree_id', 'version_id', 'timestamp'], + 'order_by': ['+timestamp']} + old_versions = self.find({'tree_id': tree_id}, options)[0] + logging.info('Deleting old versions: %r', old_versions) + for entry in old_versions: + self.delete((entry['tree_id'], entry['version_id'])) + + def _checkout_file(self, blob_hash): + fd, file_name = tempfile.mkstemp(dir=self._checkouts_dir) + try: + self._git_call('cat-file', ['blob', blob_hash], stdout_fd=fd) + finally: + os.close(fd) + return file_name + + def _checkout_dir(self, ref_name): + # FIXME + return '' + + def _create_repo(self): + os.makedirs(self._git_dir) + self._git_call('init', ['-q', '--bare']) + + def _find_git_parent(self, tree_id, parent_id): + if not parent_id: + return None + + return self._git_call('rev-parse', + [_format_ref(tree_id, parent_id)]).strip() + + def _format_commit_message(self, metadata): + return repr(metadata) + + def _gen_uuid(self): + return str(uuid.uuid4()) + + def _git_call(self, command, args=None, input=None, input_fd=None, + stdout_fd=None, work_dir=None, index_path=None): + env = dict(self._git_env) + if work_dir: + env['GIT_WORK_TREE'] = work_dir + if index_path: + env['GIT_INDEX_FILE'] = index_path + logging.debug('calling git %s, env=%r', ['git', command] + (args or []), env) + pipe = Popen(['git', command] + (args or []), stdin=input_fd or PIPE, + stdout=stdout_fd or PIPE, stderr=PIPE, close_fds=True, + cwd=self._git_dir, env=env) + stdout, stderr = pipe.communicate(input) + if pipe.returncode: + raise GitError(pipe.returncode, stderr) + return stdout + + def _migrate(self): + if not os.path.exists(self._git_dir): + return self._create_repo() + + def _store_entry(self, tree_id, version_id, parent_id, path, metadata): + parent_hash = self._find_git_parent(tree_id, parent_id) + commit_message = self._format_commit_message(metadata) + tree_hash = self._write_tree(path) + commit_options = [tree_hash] + if parent_hash: + commit_options += ['-p', parent_hash] + commit_hash = self._git_call('commit-tree', commit_options, + input=commit_message).strip() + self._git_call('update-ref', [_format_ref(tree_id, version_id), + commit_hash]) + + def _write_tree(self, path): + if not path: + return self._git_call('hash-object', + ['-w', '-t', 'tree', '--stdin'], + input='').strip() + + index_dir = tempfile.mkdtemp(prefix='gdatastore-') + index_path = os.path.join(index_dir, 'index') + try: + self._add_to_index(index_path, path) + return self._git_call('write-tree', index_path=index_path).strip() + finally: + shutil.rmtree(index_dir) + + +def calculate_checksum(path): + checksum = hashlib.sha1() + f = file(path) + while True: + chunk = f.read(65536) + if not chunk: + return checksum.hexdigest() + + checksum.update(chunk) + + +def _format_ref(tree_id, version_id): + return 'refs/gdatastore/%s/%s' % (tree_id, version_id) |