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#------------------------------------------------------------------------------
# Copyright (c) 2008, Riverbank Computing Limited
# All rights reserved.
#
# This software is provided without warranty under the terms of the BSD
# license included in enthought/LICENSE.txt and may be redistributed only
# under the conditions described in the aforementioned license. The license
# is also available online at http://www.enthought.com/licenses/BSD.txt
# Thanks for using Enthought open source!
#
# Author: Riverbank Computing Limited
# Description: <Enthought permissions package component>
#------------------------------------------------------------------------------
# Enthought library imports.
from traits.api import HasTraits, Instance, provides
# Local imports.
from i_policy_storage import IPolicyStorage, PolicyStorageError
from persistent import Persistent, PersistentError
@provides(IPolicyStorage)
class PolicyStorage(HasTraits):
"""This implements a policy database that pickles its data in a local file.
"""
#### Private interface ####################################################
# The persisted database. The database itself is a tuple of the role and
# assignment dictionaries. The role dictionary is keyed by the role name,
# and has a value that is a tuple of the description and the list of
# permission names. The assigment dictionary is keyed by the user name and
# has a value that is the list of role names.
_db = Instance(Persistent)
###########################################################################
# 'IPolicyStorage' interface.
###########################################################################
def add_role(self, name, description, perm_ids):
"""Add a new role."""
self._db.lock()
try:
roles, assigns = self._db.read()
if roles.has_key(name):
raise PolicyStorageError("The role \"%s\" already exists." % name)
roles[name] = (description, perm_ids)
self._db.write((roles, assigns))
finally:
self._db.unlock()
def all_roles(self):
"""Return a list of all roles."""
roles, _ = self._readonly_copy()
return [(name, description) for name, (description, _) in roles.items()]
def delete_role(self, name):
"""Delete a role."""
self._db.lock()
try:
roles, assigns = self._db.read()
if not roles.has_key(name):
raise PolicyStorageError("The role \"%s\" does not exist." % name)
del roles[name]
# Remove the role from any users who have it.
for user, role_names in assigns.items():
try:
role_names.remove(name)
except ValueError:
continue
assigns[user] = role_names
self._db.write((roles, assigns))
finally:
self._db.unlock()
def get_assignment(self, user_name):
"""Return the details of the assignment for the given user name."""
_, assigns = self._readonly_copy()
try:
role_names = assigns[user_name]
except KeyError:
return '', []
return user_name, role_names
def get_policy(self, user_name):
"""Return the details of the policy for the given user name."""
roles, assigns = self._readonly_copy()
try:
role_names = assigns[user_name]
except KeyError:
return '', []
perm_ids = []
for r in role_names:
_, perms = roles[r]
perm_ids.extend(perms)
return user_name, perm_ids
def is_empty(self):
"""See if the database is empty."""
roles, assigns = self._readonly_copy()
# Both have to be non-empty for the whole thing to be non-empty.
return (len(roles) == 0 or len(assigns) == 0)
def matching_roles(self, name):
"""Return the full name, description and permissions of all the roles
that match the given name."""
roles, _ = self._readonly_copy()
# Return any role that starts with the name.
roles = [(full_name, description, perm_ids)
for full_name, (description, perm_ids) in roles.items()
if full_name.startswith(name)]
return sorted(roles)
def modify_role(self, name, description, perm_ids):
"""Update the description and permissions for the given role."""
self._db.lock()
try:
roles, assigns = self._db.read()
if not roles.has_key(name):
raise PolicyStorageError("The role \"%s\" does not exist." % name)
roles[name] = (description, perm_ids)
self._db.write((roles, assigns))
finally:
self._db.unlock()
def set_assignment(self, user_name, role_names):
"""Save the roles assigned to a user."""
self._db.lock()
try:
roles, assigns = self._db.read()
if len(role_names) == 0:
# Delete the user, but don't worry if there is no current
# assignment.
try:
del assigns[user_name]
except KeyError:
pass
else:
assigns[user_name] = role_names
self._db.write((roles, assigns))
finally:
self._db.unlock()
###########################################################################
# Trait handlers.
###########################################################################
def __db_default(self):
"""Return the default persisted database."""
return Persistent(self._db_factory, 'ets_perms_policydb',
"the policy database")
###########################################################################
# Private interface.
###########################################################################
def _readonly_copy(self):
"""Return the policy database (which should not be modified)."""
try:
self._db.lock()
try:
data = self._db.read()
finally:
self._db.unlock()
except PersistentError, e:
raise PolicyStorageError(str(e))
return data
@staticmethod
def _db_factory():
"""Return an empty policy database."""
return ({}, {})
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