test/test_dwarf_locationattr.py

   1 #-------------------------------------------------------------------------------
   2 # elftools tests
   3 #
   4 # Eli Bendersky (eliben@gmail.com)
   5 # This code is in the public domain
   6 #-------------------------------------------------------------------------------
   7 import unittest
   8
   9 from elftools.dwarf.locationlists import LocationParser
  10 from elftools.dwarf.die import AttributeValue
  11
  12 class TestLocationAttrubute(unittest.TestCase):
  13     def test_has_location(self):
  14         # This attribute comes from a DWARFv3 binary that doesn't have a location lists
  15         # section. Before the patch, pyelftools would interpret it as an attribute with a
  16         # location, more specifically with a location list offset (as opposed to an expression).
  17         # Meanwhile, by the spec, DW_AT_data_member_location is not even capable
  18         # of storing a location list offset (since structure layout
  19         # can't vary by code location). DWARFv3 spec also provides that DW_AT_data_member_location
  20         # may be a small integer with an offset from the structure's base address, and that
  21         # seems to be the case here. Ergo, pyelftools should not claim this attribute a location.
  22         # Since the location/loclist parse function uses the same check, ths fix will
  23         # prevent such attribute values from being misparsed, also.
  24         #
  25         # The notion that member location in a structure had to be a DWARF expression
  26         # was a misnomer all along - how often does one see a compound datatype
  27         # with a static member set but a dynamic layout?
  28         attr = AttributeValue(name='DW_AT_data_member_location', form='DW_FORM_data1', value=0, raw_value=0, offset=402, indirection_length=0)
  29         self.assertFalse(LocationParser.attribute_has_location(attr, 3))
  30
  31         # This attribute comes from a DWARFv5 binary. Its form unambiguously tells us it's a
  32         # location expression. Before the patch, pyelftools would not recognize it as one,
  33         # because it has a hard-coded list of attributes that may contain a location, and
  34         # DW_AT_call_target was not in that list.
  35         attr = AttributeValue(name='DW_AT_call_target', form='DW_FORM_exprloc', value=[80], raw_value=[80], offset=8509, indirection_length=0)
  36         self.assertTrue(LocationParser.attribute_has_location(attr, 5))
  37
  38
  39 if __name__ == '__main__':
  40     unittest.main()