Expose time module in Python Scripts (#9736)

* Expose time module in Python Scripts

* Make dt_util available in Python Scripts

* Limit methods in time module

* Add time.mktime

* Limit access to datetime

* Add warning to time.sleep

* Lint

homeassistant/components/python_script.py

@@ -1,8 +1,9 @@
 """Component to allow running Python scripts."""
-import glob
-import os
-import logging
 import datetime
+import glob
+import logging
+import os
+import time
 
 import voluptuous as vol
 
@@ -10,6 +11,7 @@ from homeassistant.const import SERVICE_RELOAD
 from homeassistant.exceptions import HomeAssistantError
 from homeassistant.loader import bind_hass
 from homeassistant.util import sanitize_filename
+import homeassistant.util.dt as dt_util
 
 DOMAIN = 'python_script'
 REQUIREMENTS = ['restrictedpython==4.0a3']
@@ -25,6 +27,13 @@ ALLOWED_EVENTBUS = set(['fire'])
 ALLOWED_STATEMACHINE = set(['entity_ids', 'all', 'get', 'is_state',
                             'is_state_attr', 'remove', 'set'])
 ALLOWED_SERVICEREGISTRY = set(['services', 'has_service', 'call'])
+ALLOWED_TIME = set(['sleep', 'strftime', 'strptime', 'gmtime', 'localtime',
+                    'ctime', 'time', 'mktime'])
+ALLOWED_DATETIME = set(['date', 'time', 'datetime', 'timedelta', 'tzinfo'])
+ALLOWED_DT_UTIL = set([
+    'utcnow', 'now', 'as_utc', 'as_timestamp', 'as_local',
+    'utc_from_timestamp', 'start_of_local_day', 'parse_datetime', 'parse_date',
+    'get_age'])
 
 
 class ScriptError(HomeAssistantError):
@@ -111,7 +120,10 @@ def execute(hass, filename, source, data=None):
         elif (obj is hass and name not in ALLOWED_HASS or
               obj is hass.bus and name not in ALLOWED_EVENTBUS or
               obj is hass.states and name not in ALLOWED_STATEMACHINE or
-              obj is hass.services and name not in ALLOWED_SERVICEREGISTRY):
+              obj is hass.services and name not in ALLOWED_SERVICEREGISTRY or
+              obj is dt_util and name not in ALLOWED_DT_UTIL or
+              obj is datetime and name not in ALLOWED_DATETIME or
+              isinstance(obj, TimeWrapper) and name not in ALLOWED_TIME):
             raise ScriptError('Not allowed to access {}.{}'.format(
                 obj.__class__.__name__, name))
 
@@ -120,6 +132,8 @@ def execute(hass, filename, source, data=None):
     builtins = safe_builtins.copy()
     builtins.update(utility_builtins)
     builtins['datetime'] = datetime
+    builtins['time'] = TimeWrapper()
+    builtins['dt_util'] = dt_util
     restricted_globals = {
         '__builtins__': builtins,
         '_print_': StubPrinter,
@@ -159,3 +173,24 @@ class StubPrinter:
         # pylint: disable=no-self-use
         _LOGGER.warning(
             "Don't use print() inside scripts. Use logger.info() instead.")
+
+
+class TimeWrapper:
+    """Wrapper of the time module."""
+
+    # Class variable, only going to warn once per Home Assistant run
+    warned = False
+
+    # pylint: disable=no-self-use
+    def sleep(self, *args, **kwargs):
+        """Sleep method that warns once."""
+        if not TimeWrapper.warned:
+            TimeWrapper.warned = True
+            _LOGGER.warning('Using time.sleep can reduce the performance of '
+                            'Home Assistant')
+
+        time.sleep(*args, **kwargs)
+
+    def __getattr__(self, attr):
+        """Fetch an attribute from Time module."""
+        return getattr(time, attr)