From 0488f676a565a2a91ab2c46cf7dd66ae4781e930 Mon Sep 17 00:00:00 2001
From: Lumir Balhar <lbalhar@redhat.com>
Date: Thu, 24 Sep 2026 13:43:51 +0200
Subject: [PATCH] gh-158068: venv: do not clear env_dir if it's a symlink or a
 file

Previously `venv --clear` called clear_directory() on env_dir whenever
it existed. If env_dir was a symlink to a directory, this followed the
link and wiped the contents of the target directory -- possible data
loss. If it was a regular file it failed with an unclear error.

Now creating a venv over an existing symlink or file raises ValueError
before anything is removed, matching the check already done for the
non-clear case.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
---
 Lib/test/test_venv.py                         | 28 +++++++++++++++++++
 Lib/venv/__init__.py                          |  7 +++--
 ...-09-24-14-00-00.gh-issue-158068.Xf2ogr.rst |  4 +++
 3 files changed, 37 insertions(+), 2 deletions(-)
 create mode 100644 Misc/NEWS.d/next/Library/2026-09-24-14-00-00.gh-issue-158068.Xf2ogr.rst

diff --git a/Lib/test/test_venv.py b/Lib/test/test_venv.py
index 2f30d3108021dc..ad11b7c5f854cc 100644
--- a/Lib/test/test_venv.py
+++ b/Lib/test/test_venv.py
@@ -663,6 +663,34 @@ 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_clear_symlink_not_followed(self):
+        # gh-158068: venv --clear must not wipe the contents of a directory
+        # that env_dir merely points to via a symlink.
+        target = os.path.join(self.env_dir, 'target')
+        os.mkdir(target)
+        keep = os.path.join(target, 'keep')
+        with open(keep, 'wb') as f:
+            f.write(b'Still here?')
+        link = os.path.join(self.env_dir, 'link')
+        os.symlink(target, link)
+
+        with self.assertRaises(ValueError):
+            venv.create(link, clear=True)
+        # The symlink target and its content are left untouched.
+        self.assertTrue(os.path.islink(link))
+        self.assertTrue(os.path.exists(keep))
+
+    def test_clear_file_not_removed(self):
+        # gh-158068: venv --clear must not treat a regular file as env_dir.
+        target = os.path.join(self.env_dir, 'afile')
+        with open(target, 'wb') as f:
+            f.write(b'Still here?')
+
+        with self.assertRaises(ValueError):
+            venv.create(target, clear=True)
+        self.assertTrue(os.path.isfile(target))
+
     def test_upgrade(self):
         """
         Test upgrading an existing environment directory.
diff --git a/Lib/venv/__init__.py b/Lib/venv/__init__.py
index 38e1bfe0c5fdb9..0759d572f995ed 100644
--- a/Lib/venv/__init__.py
+++ b/Lib/venv/__init__.py
@@ -149,8 +149,11 @@ def create_if_needed(d):
         if os.pathsep in os.fspath(env_dir):
             raise ValueError(f'Refusing to create a venv in {env_dir} because '
                              f'it contains the PATH separator {os.pathsep}.')
-        if os.path.exists(env_dir) and self.clear:
-            self.clear_directory(env_dir)
+        if self.clear:
+            if os.path.islink(env_dir) or os.path.isfile(env_dir):
+                raise ValueError('Unable to create directory %r' % env_dir)
+            if os.path.exists(env_dir):
+                self.clear_directory(env_dir)
         context = types.SimpleNamespace()
         context.env_dir = env_dir
         context.env_name = os.path.split(env_dir)[1]
diff --git a/Misc/NEWS.d/next/Library/2026-09-24-14-00-00.gh-issue-158068.Xf2ogr.rst b/Misc/NEWS.d/next/Library/2026-09-24-14-00-00.gh-issue-158068.Xf2ogr.rst
new file mode 100644
index 00000000000000..29b2f4ef11ec93
--- /dev/null
+++ b/Misc/NEWS.d/next/Library/2026-09-24-14-00-00.gh-issue-158068.Xf2ogr.rst
@@ -0,0 +1,4 @@
+:mod:`venv` no longer clears the target directory when it is a symlink or a
+regular file. Previously ``venv --clear`` followed a symlink and could delete
+the contents of the linked directory. It now raises :exc:`ValueError` before
+removing anything.