Add Path.delete.avoids_symlink_attacks

Doc/library/pathlib.rst

@@ -1670,11 +1670,13 @@ Copying, renaming and deleting
 
    .. note::
 
-      On platforms that lack the necessary file descriptor-based functions,
-      :func:`~Path.delete` implementation is susceptible to a symlink attack:
-      given proper timing and circumstances, attackers can manipulate symlinks
-      on the filesystem to delete files they would not be able to access
-      otherwise.
+      When deleting non-empty directories on platforms that lack the necessary
+      file descriptor-based functions, the :meth:`Path.delete` implementation
+      is susceptible to a symlink attack: given proper timing and
+      circumstances, attackers can manipulate symlinks on the filesystem to
+      delete files they would not be able to access otherwise. Applications
+      can use the :data:`Path.delete.avoids_symlink_attacks` method attribute
+      to determine whether the implementation is immune to this attack.
 
    .. versionadded:: 3.14
 

Lib/pathlib/_abc.py

@@ -959,6 +959,7 @@ def on_error(err):
         except OSError as err:
             err.filename = str(self)
             on_error(err)
+    delete.avoids_symlink_attacks = False
 
     def owner(self, *, follow_symlinks=True):
         """

Lib/pathlib/_local.py

@@ -3,6 +3,7 @@
 import operator
 import os
 import posixpath
+import shutil
 import sys
 from glob import _StringGlobber
 from itertools import chain
@@ -846,7 +847,6 @@ def delete(self, ignore_errors=False, on_error=None):
                 def onexc(func, filename, err):
                     err.filename = filename
                     on_error(err)
-            import shutil
             shutil.rmtree(str(self), ignore_errors, onexc=onexc)
         else:
             try:
@@ -858,6 +858,7 @@ def onexc(func, filename, err):
                     else:
                         raise
 
+    delete.avoids_symlink_attacks = shutil.rmtree.avoids_symlink_attacks
 
     def rename(self, target):
         """

Lib/test/test_pathlib/test_pathlib.py

@@ -864,6 +864,7 @@ def test_group_no_follow_symlinks(self):
 
     def test_delete_uses_safe_fd_version_if_available(self):
         if delete_use_fd_functions:
+            self.assertTrue(self.cls.delete.avoids_symlink_attacks)
             d = self.cls(self.base, 'a')
             d.mkdir()
             try:
@@ -879,6 +880,8 @@ def _raiser(*args, **kwargs):
                 self.assertRaises(Called, d.delete)
             finally:
                 os.open = real_open
+        else:
+            self.assertFalse(self.cls.delete.avoids_symlink_attacks)
 
     @unittest.skipIf(sys.platform[:6] == 'cygwin',
                      "This test can't be run on Cygwin (issue #1071513).")