gh-160782: replace symlinked files in the venv directory

Author: NekoAsakura

Lib/test/test_venv.py

@@ -663,6 +663,29 @@ def test_unoverwritable_fails(self):
             self.assertRaises((ValueError, OSError), venv.create, self.env_dir)
             self.clear_directory(self.env_dir)
 
+    @unittest.skipUnless(can_symlink(), 'Needs symlinks')
+    def test_symlinked_file_replaced(self):
+        """
+        Test that venv creation replaces a symlink where it writes a file.
+        """
+        outside_dir = tempfile.mkdtemp()
+        self.addCleanup(rmtree, outside_dir)
+        outside = os.path.join(outside_dir, 'outside')
+        with open(outside, 'w', encoding='utf-8') as f:
+            f.write('untouched\n')
+        links = ['pyvenv.cfg', '.gitignore',
+                 os.path.join(self.bindir, 'activate')]
+        os.mkdir(os.path.join(self.env_dir, self.bindir))
+        for link in links:
+            os.symlink(outside, self.get_env_file(link))
+        venv.create(self.env_dir, scm_ignore_files={'git'})
+        for link in links:
+            with self.subTest(link=link):
+                self.assertFalse(os.path.islink(self.get_env_file(link)))
+                self.assertTrue(os.path.isfile(self.get_env_file(link)))
+        with open(outside, encoding='utf-8') as f:
+            self.assertEqual(f.read(), 'untouched\n')
+
     def test_upgrade(self):
         """
         Test upgrading an existing environment directory.

Lib/venv/__init__.py

@@ -18,6 +18,11 @@
 logger = logging.getLogger(__name__)
 
 
+def _unlink_symlink(path):
+    if os.path.islink(path):
+        os.unlink(path)
+
+
 class EnvBuilder:
     """
     This class exists to allow virtual environment creation to be
@@ -223,6 +228,7 @@ def create_configuration(self, context):
                         being processed.
         """
         context.cfg_path = path = os.path.join(context.env_dir, 'pyvenv.cfg')
+        _unlink_symlink(path)
         with open(path, 'w', encoding='utf-8') as f:
             f.write('home = %s\n' % context.python_dir)
             if self.system_site_packages:
@@ -291,6 +297,7 @@ def create_git_ignore_file(self, context):
         ignored by git.
         """
         gitignore_path = os.path.join(context.env_dir, '.gitignore')
+        _unlink_symlink(gitignore_path)
         with open(gitignore_path, 'w', encoding='utf-8') as file:
             file.write('# Created by venv; '
                        'see https://docs.python.org/3/library/venv.html\n')
@@ -585,6 +592,7 @@ def skip_file(f):
                 if not os.path.exists(dstdir):
                     os.makedirs(dstdir)
                 dstfile = os.path.join(dstdir, f)
+                _unlink_symlink(dstfile)
                 if os.name == 'nt' and srcfile.endswith(('.exe', '.pdb')):
                     shutil.copy2(srcfile, dstfile)
                     continue

Misc/NEWS.d/next/Library/2026-10-30-10-43-07.gh-issue-160782.AHKQl6.rst

@@ -0,0 +1,2 @@
+:mod:`venv`: a symbolic link in place of ``pyvenv.cfg``, ``.gitignore`` or
+an activation script is now replaced instead of written through.