add python getter in capa system

common/lib/xmodule/xmodule/capa_module.py

@@ -11,7 +11,9 @@ import dogstats_wrapper as dog_stats_api
 from capa import responsetypes
 from xmodule.exceptions import NotFoundError, ProcessingError
 from xmodule.raw_module import RawDescriptor
+from xmodule.contentstore.django import contentstore
 from xmodule.util.misc import escape_html_characters
+from xmodule.util.sandboxing import get_python_lib_zip
 from xmodule.x_module import DEPRECATION_VSCOMPAT_EVENT, XModule, module_attr
 
 from .capa_base import CapaFields, CapaMixin, ComplexEncoder
@@ -331,7 +333,6 @@ class CapaDescriptor(CapaFields, RawDescriptor):
         if limit_responses == 0:
             # Don't even start collecting answers
             return
-
         capa_system = LoncapaSystem(
             ajax_url=None,
             # TODO set anonymous_student_id to the anonymous ID of the user which answered each problem
@@ -341,7 +342,7 @@ class CapaDescriptor(CapaFields, RawDescriptor):
             anonymous_student_id=None,
             cache=None,
             can_execute_unsafe_code=lambda: None,
-            get_python_lib_zip=lambda: None,
+            get_python_lib_zip=(lambda: get_python_lib_zip(contentstore, self.runtime.course_id)),
             DEBUG=None,
             filestore=self.runtime.resources_fs,
             i18n=self.runtime.service(self, "i18n"),

common/lib/xmodule/xmodule/modulestore/django.py

@@ -28,7 +28,7 @@ from openedx.core.djangoapps.request_cache.middleware import RequestCache
 from xmodule.contentstore.django import contentstore
 from xmodule.modulestore.draft_and_published import BranchSettingMixin
 from xmodule.modulestore.mixed import MixedModuleStore
-from xmodule.util.django import get_current_request_hostname
+from xmodule.util.xmodule_django import get_current_request_hostname
 
 # We also may not always have the current request user (crum) module available
 try:

common/lib/xmodule/xmodule/modulestore/tests/django_utils.py

@@ -271,7 +271,7 @@ class ModuleStoreIsolationMixin(CacheIsolationMixin, SignalIsolationMixin):
 
     # List of modulestore signals enabled for this test. Defaults to an empty
     # list. The list of signals available is found on the SignalHandler class,
-    # in /common/lib/xmodule/xmodule/modulestore/django.py
+    # in /common/lib/xmodule/xmodule/modulestore/xmodule_django.py
     #
     # You must use the signal itself, and not its name. So for example:
     #

common/lib/xmodule/xmodule/tests/test_utils_django.py

@@ -1,5 +1,5 @@
 """Tests for methods defined in util/django.py"""
-from xmodule.util.django import get_current_request, get_current_request_hostname
+from xmodule.util.xmodule_django import get_current_request, get_current_request_hostname
 from nose.tools import assert_is_none
 from unittest import TestCase
 

common/lib/xmodule/xmodule/util/sandboxing.py

@@ -0,0 +1,40 @@
+import re
+from django.conf import settings
+
+DEFAULT_PYTHON_LIB_FILENAME = 'python_lib.zip'
+
+
+def can_execute_unsafe_code(course_id):
+    """
+    Determine if this course is allowed to run unsafe code.
+
+    For use from the ModuleStore.  Checks the `course_id` against a list of whitelisted
+    regexes.
+
+    Returns a boolean, true if the course can run outside the sandbox.
+
+    """
+    # To decide if we can run unsafe code, we check the course id against
+    # a list of regexes configured on the server.
+    # If this is not defined in the environment variables then default to the most restrictive, which
+    # is 'no unsafe courses'
+    # TODO: This should be a database configuration, where we can mark individual courses as being
+    # safe/unsafe. Someone in the future should switch us over to that rather than using regexes
+    # in a settings file
+    # To others using this: the code as-is is brittle and likely to be changed in the future,
+    # as per the TODO, so please consider carefully before adding more values to COURSES_WITH_UNSAFE_CODE
+    for regex in getattr(settings, 'COURSES_WITH_UNSAFE_CODE', []):
+        if re.match(regex, unicode(course_id)):
+            return True
+    return False
+
+
+def get_python_lib_zip(contentstore, course_id):
+    """Return the bytes of the course code library file, if it exists."""
+    python_lib_filename = getattr(settings, 'PYTHON_LIB_FILENAME', DEFAULT_PYTHON_LIB_FILENAME)
+    asset_key = course_id.make_asset_key("asset", python_lib_filename)
+    zip_lib = contentstore().find(asset_key, throw_on_not_found=False)
+    if zip_lib is not None:
+        return zip_lib.data
+    else:
+        return None