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# Copyright 2011 Canonical Ltd.
#
# This file is part of u1db.
#
# u1db is free software: you can redistribute it and/or modify
# it under the terms of the GNU Lesser General Public License version 3
# as published by the Free Software Foundation.
#
# u1db 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 Lesser General Public License for more details.
#
# You should have received a copy of the GNU Lesser General Public License
# along with u1db. If not, see <http://www.gnu.org/licenses/>.
"""A U1DB implementation that uses SQLCipher as its persistence layer."""
import os
from pysqlcipher import dbapi2
import time
from u1db.backends.sqlite_backend import (
SQLiteDatabase,
SQLitePartialExpandDatabase,
)
from u1db import (
errors,
)
from leap.soledad.backends.leap_backend import LeapDocument
def open(path, password, create=True, document_factory=None, soledad=None):
"""Open a database at the given location.
Will raise u1db.errors.DatabaseDoesNotExist if create=False and the
database does not already exist.
:param path: The filesystem path for the database to open.
:param create: True/False, should the database be created if it doesn't
already exist?
:param document_factory: A function that will be called with the same
parameters as Document.__init__.
:return: An instance of Database.
"""
return SQLCipherDatabase.open_database(
path, password, create=create, document_factory=document_factory,
soledad=soledad)
class DatabaseIsNotEncrypted(Exception):
"""
Exception raised when trying to open non-encrypted databases.
"""
pass
class SQLCipherDatabase(SQLitePartialExpandDatabase):
"""A U1DB implementation that uses SQLCipher as its persistence layer."""
_index_storage_value = 'expand referenced encrypted'
@classmethod
def set_pragma_key(cls, db_handle, key):
db_handle.cursor().execute("PRAGMA key = '%s'" % key)
def __init__(self, sqlite_file, password, document_factory=None,
soledad=None):
"""Create a new sqlcipher file."""
self._check_if_db_is_encrypted(sqlite_file)
self._db_handle = dbapi2.connect(sqlite_file)
SQLCipherDatabase.set_pragma_key(self._db_handle, password)
self._real_replica_uid = None
self._ensure_schema()
self._soledad = soledad
def factory(doc_id=None, rev=None, json='{}', has_conflicts=False,
encrypted_json=None, syncable=True):
return LeapDocument(doc_id=doc_id, rev=rev, json=json,
has_conflicts=has_conflicts,
encrypted_json=encrypted_json,
syncable=syncable, soledad=self._soledad)
self.set_document_factory(factory)
def _check_if_db_is_encrypted(self, sqlite_file):
if not os.path.exists(sqlite_file):
return
else:
try:
# try to open an encrypted database with the regular u1db
# backend should raise a DatabaseError exception.
SQLitePartialExpandDatabase(sqlite_file)
raise DatabaseIsNotEncrypted()
except dbapi2.DatabaseError:
pass
@classmethod
def _open_database(cls, sqlite_file, password, document_factory=None,
soledad=None):
if not os.path.isfile(sqlite_file):
raise errors.DatabaseDoesNotExist()
tries = 2
while True:
# Note: There seems to be a bug in sqlite 3.5.9 (with python2.6)
# where without re-opening the database on Windows, it
# doesn't see the transaction that was just committed
db_handle = dbapi2.connect(sqlite_file)
SQLCipherDatabase.set_pragma_key(db_handle, password)
c = db_handle.cursor()
v, err = cls._which_index_storage(c)
db_handle.close()
if v is not None:
break
# possibly another process is initializing it, wait for it to be
# done
if tries == 0:
raise err # go for the richest error?
tries -= 1
time.sleep(cls.WAIT_FOR_PARALLEL_INIT_HALF_INTERVAL)
return SQLCipherDatabase._sqlite_registry[v](
sqlite_file, password, document_factory=document_factory,
soledad=soledad)
@classmethod
def open_database(cls, sqlite_file, password, create, backend_cls=None,
document_factory=None, soledad=None):
try:
return cls._open_database(sqlite_file, password,
document_factory=document_factory,
soledad=soledad)
except errors.DatabaseDoesNotExist:
if not create:
raise
if backend_cls is None:
# default is SQLCipherPartialExpandDatabase
backend_cls = SQLCipherDatabase
return backend_cls(sqlite_file, password,
document_factory=document_factory,
soledad=soledad)
def sync(self, url, creds=None, autocreate=True):
"""
Synchronize encrypted documents with remote replica exposed at url.
"""
from u1db.sync import Synchronizer
from leap.soledad.backends.leap_backend import LeapSyncTarget
return Synchronizer(
self,
LeapSyncTarget(url,
creds=creds,
soledad=self._soledad)).sync(autocreate=autocreate)
def _extra_schema_init(self, c):
c.execute(
'ALTER TABLE document '
'ADD COLUMN syncable BOOL NOT NULL DEFAULT TRUE')
def _put_and_update_indexes(self, old_doc, doc):
super(SQLCipherDatabase, self)._put_and_update_indexes(old_doc, doc)
c = self._db_handle.cursor()
c.execute('UPDATE document SET syncable=? WHERE doc_id=?',
(doc.syncable, doc.doc_id))
def _get_doc(self, doc_id, check_for_conflicts=False):
doc = super(SQLCipherDatabase, self)._get_doc(doc_id,
check_for_conflicts)
if doc:
c = self._db_handle.cursor()
c.execute('SELECT syncable FROM document WHERE doc_id=?',
(doc.doc_id,))
doc.syncable = bool(c.fetchone()[0])
return doc
SQLiteDatabase.register_implementation(SQLCipherDatabase)
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