Fix tarfile FilterError handling to skip member extraction

mattprodani · mattprodani · commit c981c3d267c7 · 2023-12-01T15:13:17.000-05:00
In `tarfile` library, FilterError with error_level set to 0 correctly logged a debugging
message but did not properly skip extraction of a member. Updates filter
functions to return None when a FilterError is seen, as stated in docs.
diff --git a/Lib/tarfile.py b/Lib/tarfile.py
@@ -2309,21 +2309,21 @@ def _get_extract_tarinfo(self, member, filter_function, path):
         else:
             tarinfo = member
 
-        unfiltered = tarinfo
+        filtered = None
         try:
-            tarinfo = filter_function(tarinfo, path)
+            filtered = filter_function(tarinfo, path)
         except (OSError, FilterError) as e:
             self._handle_fatal_error(e)
         except ExtractError as e:
             self._handle_nonfatal_error(e)
-        if tarinfo is None:
-            self._dbg(2, "tarfile: Excluded %r" % unfiltered.name)
+        if filtered is None:
+            self._dbg(2, "tarfile: Excluded %r" % tarinfo.name)
             return None
         # Prepare the link target for makelink().
-        if tarinfo.islnk():
-            tarinfo = copy.copy(tarinfo)
-            tarinfo._link_target = os.path.join(path, tarinfo.linkname)
-        return tarinfo
+        if filtered.islnk():
+            filtered = copy.copy(filtered)
+            filtered._link_target = os.path.join(path, filtered.linkname)
+        return filtered
 
     def _extract_one(self, tarinfo, path, set_attrs, numeric_owner):
         """Extract from filtered tarinfo to disk"""
