From 41f0608645155d78ec249b8bf51687fb8bf0a938 Mon Sep 17 00:00:00 2001
From: lipengyu <lipengyu@kylinos.cn>
Date: Thu, 20 Aug 2026 09:59:31 +0800
Subject: [PATCH 1/2] gh-156078: Prevent ZipFile.mkdir() during an active write

Fix `ZipFile.mkdir()` so that it raises `ValueError` when another writable
member handle returned by `ZipFile.open(..., mode="w")` is still open.
---
 Lib/test/test_zipfile/test_core.py                           | 2 ++
 Lib/zipfile/__init__.py                                      | 5 +++++
 .../Library/2026-08-20-09-56-45.gh-issue-156078.-E7gZc.rst   | 3 +++
 3 files changed, 10 insertions(+)
 create mode 100644 Misc/NEWS.d/next/Library/2026-08-20-09-56-45.gh-issue-156078.-E7gZc.rst

diff --git a/Lib/test/test_zipfile/test_core.py b/Lib/test/test_zipfile/test_core.py
index 1c6e3a9f0a9a2de..a2dcbc36352ec14 100644
--- a/Lib/test/test_zipfile/test_core.py
+++ b/Lib/test/test_zipfile/test_core.py
@@ -4598,6 +4598,8 @@ def test_open_conflicting_handles(self):
                     zipf.writestr('str', 'abcde')
                 with self.assertRaises(ValueError):
                     zipf.write(__file__, 'file')
+                with self.assertRaises(ValueError):
+                    zipf.mkdir('directory')
                 with self.assertRaises(ValueError):
                     zipf.close()
                 w1.write(msg2)
diff --git a/Lib/zipfile/__init__.py b/Lib/zipfile/__init__.py
index 7a81aa8f44c8f4c..1868d467161bd6e 100644
--- a/Lib/zipfile/__init__.py
+++ b/Lib/zipfile/__init__.py
@@ -2596,6 +2596,11 @@ def mkdir(self, zinfo_or_directory_name, mode=511):
         else:
             raise TypeError("Expected type str or ZipInfo")
 
+        if self._writing:
+            raise ValueError(
+                "Can't write to ZIP archive while an open writing handle exists."
+            )
+
         with self._lock:
             if self._seekable:
                 self.fp.seek(self.start_dir)
diff --git a/Misc/NEWS.d/next/Library/2026-08-20-09-56-45.gh-issue-156078.-E7gZc.rst b/Misc/NEWS.d/next/Library/2026-08-20-09-56-45.gh-issue-156078.-E7gZc.rst
new file mode 100644
index 000000000000000..43c35dba56a4b7b
--- /dev/null
+++ b/Misc/NEWS.d/next/Library/2026-08-20-09-56-45.gh-issue-156078.-E7gZc.rst
@@ -0,0 +1,3 @@
+Fix :meth:`zipfile.ZipFile.mkdir` to raise :exc:`ValueError` when called
+while a writable member handle is open, preventing corruption of the ZIP
+archive.

From 60a6c3815720b7cb6ddb5521366b2df0b0640195 Mon Sep 17 00:00:00 2001
From: lipengyu <lipengyu@kylinos.cn>
Date: Thu, 20 Aug 2026 19:01:02 +0800
Subject: [PATCH 2/2] Add the missing closed-archive check

---
 Lib/test/test_zipfile/test_core.py | 3 +++
 Lib/zipfile/__init__.py            | 3 +++
 2 files changed, 6 insertions(+)

diff --git a/Lib/test/test_zipfile/test_core.py b/Lib/test/test_zipfile/test_core.py
index a2dcbc36352ec14..f37696be8a3eb4b 100644
--- a/Lib/test/test_zipfile/test_core.py
+++ b/Lib/test/test_zipfile/test_core.py
@@ -5520,6 +5520,9 @@ def test_mkdir(self):
             zf.extractall(target)
             self.assertEqual(set(os.listdir(target)), {"directory", "directory2", "directory3", "directory4"})
 
+        with self.assertRaises(ValueError):
+            zf.mkdir("closed")
+
     def test_create_directory_with_write(self):
         with zipfile.ZipFile(TESTFN, "w") as zf:
             zf.writestr(zipfile.ZipInfo('directory/'), '')
diff --git a/Lib/zipfile/__init__.py b/Lib/zipfile/__init__.py
index 1868d467161bd6e..36e844a3f9089b7 100644
--- a/Lib/zipfile/__init__.py
+++ b/Lib/zipfile/__init__.py
@@ -2596,6 +2596,9 @@ def mkdir(self, zinfo_or_directory_name, mode=511):
         else:
             raise TypeError("Expected type str or ZipInfo")
 
+        if not self.fp:
+            raise ValueError(
+                "Attempt to write to ZIP archive that was already closed")
         if self._writing:
             raise ValueError(
                 "Can't write to ZIP archive while an open writing handle exists."