[Predator] Add TouchCrashedFileMetaFeature.

appengine/findit/crash/crash_util.py

 # Copyright 2016 The Chromium Authors. All rights reserved.
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 
 from collections import defaultdict
 
 
 def IsSameFilePath(path_1, path_2):
   """Determines if two paths represent same path.
 
   First we split each path into a list of directories (via split('/')),
   then we treat those lists as multisets (i.e., ignore the order of
   directories, but keep track of their multiplicities) and take the
   multiset intersection. Finally, we return whether the number of elements
   in the intersection is at least 3 (or, when one of the paths has
   fewer than 3 parts, we return whether all those parts are also in the
   other path)
 
   Args:
     path_1 (str): First path.
     path_2 (str): Second path to compare.
 
   Returns:
     Boolean, True if it they are thought to be a same path, False otherwise.
   """
+  if not path_1 and not path_2:
+    return True
+
+  if not path_1 or not path_2:
+    return False
+
   # TODO(katesonia): Think of better way to determine whether 2 paths are the
   # same or not.
   path_parts_1 = path_1.lower().split('/')
   path_parts_2 = path_2.lower().split('/')
 
   if path_parts_1[-1] != path_parts_2[-1]:
     return False
 
   def _GetPathPartsCount(path_parts):
     path_parts_count = defaultdict(int)
 
     for path_part in path_parts:
       path_parts_count[path_part] += 1
 
     return path_parts_count
 
   parts_count_1 = _GetPathPartsCount(path_parts_1)
   parts_count_2 = _GetPathPartsCount(path_parts_2)
 
   # Get number of same path parts between path_1 and path_2. For example:
   # a/b/b/b/f.cc and a/b/b/c/d/f.cc have 4 path parts the same in total.
   total_same_parts = sum([min(parts_count_1[part], parts_count_2[part]) for
                           part in parts_count_1 if part in path_parts_2])
 
   return total_same_parts >= (min(3, min(len(path_parts_1), len(path_parts_2))))