/usr/lib/python2.7/dist-packages/guardian/backends.py is in python-django-guardian 1.4.1-1.
This file is owned by root:root, with mode 0o644.
The actual contents of the file can be viewed below.
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from django.db import models
from guardian.compat import get_user_model
from guardian.conf import settings
from guardian.exceptions import WrongAppError
from guardian.core import ObjectPermissionChecker
def check_object_support(obj):
"""
Returns ``True`` if given ``obj`` is supported
"""
# Backend checks only object permissions (isinstance implies that obj
# is not None)
# Backend checks only permissions for Django models
return isinstance(obj, models.Model)
def check_user_support(user_obj):
"""
Returns a tuple of checkresult and ``user_obj`` which should be used for
permission checks
Checks if the given user is supported. Anonymous users need explicit
activation via ANONYMOUS_USER_ID
"""
# This is how we support anonymous users - simply try to retrieve User
# instance and perform checks for that predefined user
if not user_obj.is_authenticated():
# If anonymous user permission is disabled then they are always unauthorized
if settings.ANONYMOUS_USER_ID is None:
return False, user_obj
user_obj = get_user_model().objects.get(pk=settings.ANONYMOUS_USER_ID)
return True, user_obj
def check_support(user_obj, obj):
"""
Combination of ``check_object_support`` and ``check_user_support``
"""
obj_support = check_object_support(obj)
user_support, user_obj = check_user_support(user_obj)
return obj_support and user_support, user_obj
class ObjectPermissionBackend(object):
supports_object_permissions = True
supports_anonymous_user = True
supports_inactive_user = True
def authenticate(self, username, password):
return None
def has_perm(self, user_obj, perm, obj=None):
"""
Returns ``True`` if given ``user_obj`` has ``perm`` for ``obj``. If no
``obj`` is given, ``False`` is returned.
.. note::
Remember, that if user is not *active*, all checks would return
``False``.
Main difference between Django's ``ModelBackend`` is that we can pass
``obj`` instance here and ``perm`` doesn't have to contain
``app_label`` as it can be retrieved from given ``obj``.
**Inactive user support**
If user is authenticated but inactive at the same time, all checks
always returns ``False``.
"""
# check if user_obj and object are supported
support, user_obj = check_support(user_obj, obj)
if not support:
return False
if '.' in perm:
app_label, perm = perm.split('.')
if app_label != obj._meta.app_label:
raise WrongAppError("Passed perm has app label of '%s' and "
"given obj has '%s'" % (app_label, obj._meta.app_label))
check = ObjectPermissionChecker(user_obj)
return check.has_perm(perm, obj)
def get_all_permissions(self, user_obj, obj=None):
"""
Returns a set of permission strings that the given ``user_obj`` has for ``obj``
"""
# check if user_obj and object are supported
support, user_obj = check_support(user_obj, obj)
if not support:
return set()
check = ObjectPermissionChecker(user_obj)
return check.get_perms(obj)
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