address review comments

Author: mayeut

Lib/test/test_venv.py

@@ -900,20 +900,17 @@ def test_executable_symlink(self):
         Test creation using a symlink to python executable.
         """
         rmtree(self.env_dir)
-        with tempfile.TemporaryDirectory() as symlink_dir:
-            executable_symlink = os.path.join(
-                os.path.realpath(symlink_dir),
-                os.path.basename(sys.executable))
-            os.symlink(os.path.abspath(sys.executable), executable_symlink)
-            cmd = [executable_symlink, "-m", "venv", "--without-pip",
-                   self.env_dir]
+        exe = pathlib.Path(sys.executable).absolute()
+        with tempfile.TemporaryDirectory() as tmp_dir:
+            symlink_dir = pathlib.Path(tmp_dir).resolve(strict=True)
+            exe_symlink = symlink_dir / exe.name
+            exe_symlink.symlink_to(exe)
+            cmd = [exe_symlink, "-m", "venv", "--without-pip", self.env_dir]
             subprocess.check_call(cmd)
         data = self.get_text_file_contents('pyvenv.cfg')
-        executable = sys._base_executable
-        path = os.path.dirname(executable)
+        path = os.path.dirname(sys._base_executable)
         self.assertIn('home = %s' % path, data)
-        self.assertIn('executable = %s' %
-                      os.path.realpath(sys.executable), data)
+        self.assertIn('executable = %s' % exe.resolve(), data)
 
     @requires_subprocess()
     @unittest.skipIf(os.name == 'nt', 'not relevant on Windows')
@@ -924,24 +921,18 @@ def test_tree_symlink(self):
         Test creation using a symlink to python tree.
         """
         rmtree(self.env_dir)
-        executable_abspath = os.path.abspath(sys._base_executable)
-        tree_abspath = os.path.dirname(os.path.dirname(executable_abspath))
-        with tempfile.TemporaryDirectory() as symlink_dir:
-            tree_symlink = os.path.join(
-                os.path.realpath(symlink_dir),
-                os.path.basename(tree_abspath))
-            executable_symlink = os.path.join(
-                tree_symlink,
-                os.path.basename(os.path.dirname(executable_abspath)),
-                os.path.basename(sys._base_executable))
-            os.symlink(tree_abspath, tree_symlink)
-            cmd = [executable_symlink, "-m", "venv", "--without-pip",
-                   self.env_dir]
+        exe = pathlib.Path(sys._base_executable).absolute()
+        tree = exe.parent.parent
+        with tempfile.TemporaryDirectory() as tmp_dir:
+            symlink_dir = pathlib.Path(tmp_dir).resolve(strict=True)
+            tree_symlink = symlink_dir / tree.name
+            exe_symlink = tree_symlink / exe.relative_to(tree)
+            tree_symlink.symlink_to(tree)
+            cmd = [exe_symlink, "-m", "venv", "--without-pip", self.env_dir]
             subprocess.check_call(cmd)
         data = self.get_text_file_contents('pyvenv.cfg')
         self.assertIn('home = %s' % tree_symlink, data)
-        self.assertIn('executable = %s' %
-                      os.path.realpath(sys._base_executable), data)
+        self.assertIn('executable = %s' % exe.resolve(), data)
 
 
 @requireVenvCreate

Lib/venv/__init__.py

@@ -133,6 +133,26 @@ def _same_path(cls, path1, path2):
         else:
             return path1 == path2
 
+    @classmethod
+    def _abspath_resolve_leaf(cls, path):
+        """Returns the absolute path, resolving links to the last component.
+
+        If there's a cycle, os.path.abspath(path) is returned
+        """
+        path = os.path.abspath(path)
+        result = path
+        while os.path.islink(result):
+            link = os.readlink(result)
+            if os.path.isabs(link):
+                result = link
+            else:
+                result = os.path.join(os.path.dirname(result), link)
+                result = os.path.abspath(result)
+            if result == path:
+                # circular links
+                break
+        return result
+
     def ensure_directories(self, env_dir):
         """
         Create the directories for the environment.
@@ -164,15 +184,7 @@ def create_if_needed(d):
                              'check that your PATH environment variable is '
                              'correctly set.')
         # only resolve executable symlinks, not the full chain, see gh-106045
-        # we don't want to overwrite the executable used in context
-        executable_ = os.path.abspath(executable)
-        while os.path.islink(executable_):
-            link = os.readlink(executable_)
-            if os.path.isabs(link):
-                executable_ = link
-            else:
-                executable_ = os.path.join(os.path.dirname(executable_), link)
-        dirname, exename = os.path.split(executable_)
+        dirname, exename = os.path.split(self._abspath_resolve_leaf(executable))
         if sys.platform == 'win32':
             # Always create the simplest name in the venv. It will either be a
             # link back to executable, or a copy of the appropriate launcher