tools_parser.py: return booleans indicating the success of parsers in…

…stead of using os.exit

modes/tools_parser.py

@@ -107,22 +107,22 @@ def get_supported_tools(self) -> Tuple[str]:
                 supported_tools.add(parser.tool_name)
         return supported_tools
 
-    def start_parsers(self):
+    def start_parsers(self) -> bool:
         """
         runs each parser in a separate proc and returns when they're all done
         :param print_stats_event: the thread will set this event when it's
         done reading the ground truth flows and
         started reading slips and suricata flows so the print_stats
         thread can start printing
-        :return: 0 if all good, 1 if an error occured
+        returns True if all parsers started and ended successfully
         """
         # the gt parsers should finish first before starting tool parsers
         processes: List[Process] = self.start_gt_parsers()
         for proc in processes:
             proc.join()
             if proc.exitcode != 0:
                 # terminate, dont start the rest of the parsers
-                os._exit(1)
+                return False
 
         self.print_stats_event.set()
 
@@ -131,9 +131,10 @@ def start_parsers(self):
             proc.join()
             if proc.exitcode != 0:
                 # terminate, dont start the rest of the parsers
-                os._exit(1)
+                return False
+        return True
 
-        os._exit(0)
+