Fix _empty_path AttributeError for path fieldtype

On Python 3.11 and lower, the returned path object from .parent did not
have _empty_path variable set due to how pathlib creates the path object

Fixes #131

flow/record/fieldtypes/__init__.py

@@ -32,8 +32,8 @@
 
 UTC = timezone.utc
 
-PY_311 = sys.version_info >= (3, 11, 0)
-PY_312 = sys.version_info >= (3, 12, 0)
+PY_311_OR_HIGHER = sys.version_info >= (3, 11, 0)
+PY_312_OR_HIGHER = sys.version_info >= (3, 12, 0)
 
 TYPE_POSIX = 0
 TYPE_WINDOWS = 1
@@ -288,7 +288,7 @@ def __new__(cls, *args, **kwargs):
                 # - Python 3.10 and older requires "T" between date and time in fromisoformat()
                 #
                 # There are other incompatibilities, but we don't care about those for now.
-                if not PY_311:
+                if not PY_311_OR_HIGHER:
                     # Convert Z to +00:00 so that fromisoformat() works correctly on Python 3.10 and older
                     if arg[-1] == "Z":
                         arg = arg[:-1] + "+00:00"
@@ -633,6 +633,8 @@ def _is_windowslike_path(path: Any):
 
 
 class path(pathlib.PurePath, FieldType):
+    _empty_path = False
+
     def __new__(cls, *args):
         # This is modelled after pathlib.PurePath's __new__(), which means you
         # will never get an instance of path, only instances of either
@@ -647,7 +649,7 @@ def __new__(cls, *args):
             for path_part in args:
                 if isinstance(path_part, pathlib.PureWindowsPath):
                     cls = windows_path
-                    if not PY_312:
+                    if not PY_312_OR_HIGHER:
                         # For Python < 3.12, the (string) representation of a
                         # pathlib.PureWindowsPath is not round trip equivalent if a path
                         # starts with a \ or / followed by a drive letter, e.g.: \C:\...
@@ -670,7 +672,7 @@ def __new__(cls, *args):
                     # This handles any custom PurePath based implementations that have a windows
                     # like path separator (\).
                     cls = windows_path
-                    if not PY_312:
+                    if not PY_312_OR_HIGHER:
                         args = tuple(str(arg) for arg in args)
                 elif _is_posixlike_path(path_part):
                     # This handles any custom PurePath based implementations that don't have a
@@ -680,7 +682,7 @@ def __new__(cls, *args):
                     continue
                 break
 
-        if PY_312:
+        if PY_312_OR_HIGHER:
             obj = super().__new__(cls)
         else:
             obj = cls._from_parts(args)
@@ -693,8 +695,8 @@ def __new__(cls, *args):
     def __eq__(self, other: Any) -> bool:
         if isinstance(other, str):
             return str(self) == other or self == self.__class__(other)
-        if self._empty_path:
-            return isinstance(other, self.__class__) and other._empty_path
+        elif isinstance(other, self.__class__) and (self._empty_path or other._empty_path):
+            return self._empty_path == other._empty_path
         return super().__eq__(other)
 
     def __str__(self) -> str:
@@ -705,6 +707,12 @@ def __str__(self) -> str:
     def __repr__(self) -> str:
         return repr(str(self))
 
+    @property
+    def parent(self):
+        if self._empty_path:
+            return self
+        return super().parent
+
     def _pack(self):
         path_type = TYPE_WINDOWS if isinstance(self, windows_path) else TYPE_POSIX
         return (str(self), path_type)

tests/test_fieldtypes.py

@@ -13,7 +13,7 @@
 import flow.record.fieldtypes
 from flow.record import RecordDescriptor, RecordReader, RecordWriter, fieldtypes
 from flow.record.fieldtypes import (
-    PY_312,
+    PY_312_OR_HIGHER,
     TYPE_POSIX,
     TYPE_WINDOWS,
     _is_posixlike_path,
@@ -543,7 +543,7 @@ def custom_pure_path(sep, altsep):
     # The flavour property of Path's is replaced by a link to e.g.
     # posixpath or ntpath.
     # See also: https://github.com/python/cpython/issues/88302
-    if PY_312:
+    if PY_312_OR_HIGHER:
 
         class CustomFlavour:
             def __new__(cls, *args, **kwargs):
@@ -1154,13 +1154,15 @@ def test_empty_path(path_cls) -> None:
     assert p1._empty_path
     assert str(p1) == ""
     assert p1 != path_cls(".")
+    assert path_cls(".") != p1
 
     # initialize without any arguments
     p2 = path_cls()
     assert p2 == ""
     assert p2._empty_path
     assert str(p2) == ""
     assert p2 != path_cls(".")
+    assert path_cls(".") != p2
 
     assert p1 == p2
 
@@ -1213,5 +1215,41 @@ def test_empty_path_serialization(tmp_path) -> None:
             assert record.value == ""
 
 
+def test_empty_windows_path_parent() -> None:
+    # test that the parent of an empty path is also an empty path
+    path = fieldtypes.windows_path("")
+    assert path.parent == ""
+    assert path.parent.parent == ""
+    assert path._empty_path
+    assert path.parent._empty_path
+    assert list(path.parents) == []
+
+    path = fieldtypes.windows_path("c:/windows/temp")
+    assert path.parent == "c:/windows"
+    assert path.parent.parent == "c:/"
+    assert path.parent.parent.parent == "c:/"
+    assert not path.parent._empty_path
+    assert not path._empty_path
+    assert list(path.parents) == ["c:/windows", "c:/"]
+
+
+def test_empty_posix_path_parent() -> None:
+    # test that the parent of an empty path is also an empty path
+    path = fieldtypes.posix_path("")
+    assert path.parent == ""
+    assert path.parent.parent == ""
+    assert path._empty_path
+    assert path.parent._empty_path
+    assert list(path.parents) == []
+
+    path = fieldtypes.posix_path("/var/log")
+    assert path.parent == "/var"
+    assert path.parent.parent == "/"
+    assert path.parent.parent.parent == "/"
+    assert not path.parent._empty_path
+    assert not path._empty_path
+    assert list(path.parents) == ["/var", "/"]
+
+
 if __name__ == "__main__":
     __import__("standalone_test").main(globals())