Add a configurable limit for real time.

codejail/jail_code.py

@@ -70,6 +70,8 @@ if hasattr(sys, 'real_prefix'):
 LIMITS = {
     # CPU seconds, defaulting to 1.
     "CPU": 1,
+    # Real time, defaulting to 1 second.
+    "REALTIME": 1,
     # Total process virutal memory, in bytes, defaulting to 30 Mb.
     "VMEM": 30000000,
 }
@@ -88,6 +90,9 @@ def set_limit(limit_name, value):
         * `"CPU"`: the maximum number of CPU seconds the jailed code can use.
             The value is an integer, defaulting to 1.
 
+        * `"REALTIME"`: the maximum number of seconds the jailed code can run,
+            in real time.  The default is 1 second.
+
         * `"VMEM"`: the total virtual memory available to the jailed code, in
             bytes.  The default is 30 Mb.
 
@@ -168,8 +173,10 @@ def jail_code(command, code=None, files=None, argv=None, stdin=None):
         )
 
         # Start the time killer thread.
-        killer = ProcessKillerThread(subproc, limit=1.0)
-        killer.start()
+        realtime = LIMITS["REALTIME"]
+        if realtime:
+            killer = ProcessKillerThread(subproc, limit=realtime)
+            killer.start()
 
         result = JailResult()
         result.stdout, result.stderr = subproc.communicate(stdin)

codejail/tests/test_jailpy.py

@@ -143,14 +143,25 @@ class TestLimits(JailCodeHelpers, unittest.TestCase):
         self.assertNotEqual(res.status, 0)
 
     def test_cant_use_too_much_time(self):
-        res = jailpy(code="""\
-                import time
-                time.sleep(5)
-                print 'Done!'
-                """)
+        # Default time limit is 1 second.  Sleep for 1.5 seconds.
+        res = jailpy(code="import time; time.sleep(1.5); print 'Done!'")
         self.assertNotEqual(res.status, 0)
         self.assertEqual(res.stdout, "")
 
+    def test_changing_realtime_limit(self):
+        # Change time limit to 2 seconds, sleeping for 1.5 will be fine.
+        set_limit('REALTIME', 2)
+        res = jailpy(code="import time; time.sleep(1.5); print 'Done!'")
+        self.assertResultOk(res)
+        self.assertEqual(res.stdout, "Done!\n")
+
+    def test_disabling_realtime_limit(self):
+        # Disable the time limit, sleeping for 1.5 will be fine.
+        set_limit('REALTIME', 0)
+        res = jailpy(code="import time; time.sleep(1.5); print 'Done!'")
+        self.assertResultOk(res)
+        self.assertEqual(res.stdout, "Done!\n")
+
     def test_cant_write_files(self):
         res = jailpy(code="""\
                 print "Trying"