https://github.com/python/cpython/commit/500ea3b0ee04ee3589597dcbe6a2b9fb8251fc65
commit: 500ea3b0ee04ee3589597dcbe6a2b9fb8251fc65
branch: 3.12
author: Miss Islington (bot) <31488909+miss-isling...@users.noreply.github.com>
committer: vstinner <vstin...@python.org>
date: 2025-02-28T08:28:14Z
summary:
[3.12] gh-129726: Break `gzip.GzipFile` reference loop (GH-130055) (#130670)
gh-129726: Break `gzip.GzipFile` reference loop (GH-130055)
A reference loop was resulting in the `fileobj` held by the `GzipFile`
being closed before the `GzipFile`.
The issue started with gh-89550 in 3.12, but was hidden in most cases
until 3.13 when gh-62948 made it more visible.
(cherry picked from commit 7f39137662f637518a74228286e7ec675fa4e27d)
Co-authored-by: Cody Maloney <cmalo...@users.noreply.github.com>
files:
A Misc/NEWS.d/next/Library/2025-02-12-12-38-24.gh-issue-129726.jB0sxu.rst
M Lib/gzip.py
M Lib/test/test_gzip.py
diff --git a/Lib/gzip.py b/Lib/gzip.py
index 177f9080dc5af8..01a791e5824a0b 100644
--- a/Lib/gzip.py
+++ b/Lib/gzip.py
@@ -5,11 +5,15 @@
# based on Andrew Kuchling's minigzip.py distributed with the zlib module
-import struct, sys, time, os
-import zlib
+import _compression
import builtins
import io
-import _compression
+import os
+import struct
+import sys
+import time
+import weakref
+import zlib
__all__ = ["BadGzipFile", "GzipFile", "open", "compress", "decompress"]
@@ -124,10 +128,13 @@ class BadGzipFile(OSError):
class _WriteBufferStream(io.RawIOBase):
"""Minimal object to pass WriteBuffer flushes into GzipFile"""
def __init__(self, gzip_file):
- self.gzip_file = gzip_file
+ self.gzip_file = weakref.ref(gzip_file)
def write(self, data):
- return self.gzip_file._write_raw(data)
+ gzip_file = self.gzip_file()
+ if gzip_file is None:
+ raise RuntimeError("lost gzip_file")
+ return gzip_file._write_raw(data)
def seekable(self):
return False
diff --git a/Lib/test/test_gzip.py b/Lib/test/test_gzip.py
index d220c7d06e50c9..e0dc07cdadd035 100644
--- a/Lib/test/test_gzip.py
+++ b/Lib/test/test_gzip.py
@@ -3,12 +3,14 @@
import array
import functools
+import gc
import io
import os
import struct
import sys
import unittest
from subprocess import PIPE, Popen
+from test.support import catch_unraisable_exception
from test.support import import_helper
from test.support import os_helper
from test.support import _4G, bigmemtest, requires_subprocess
@@ -836,6 +838,17 @@ def test_write_seek_write(self):
self.assertEqual(gzip.decompress(data), message * 2)
+ def test_refloop_unraisable(self):
+ # Ensure a GzipFile referring to a temporary fileobj deletes cleanly.
+ # Previously an unraisable exception would occur on close because the
+ # fileobj would be closed before the GzipFile as the result of a
+ # reference loop. See issue gh-129726
+ with catch_unraisable_exception() as cm:
+ gzip.GzipFile(fileobj=io.BytesIO(), mode="w")
+ gc.collect()
+ self.assertIsNone(cm.unraisable)
+
+
class TestOpen(BaseTest):
def test_binary_modes(self):
uncompressed = data1 * 50
diff --git
a/Misc/NEWS.d/next/Library/2025-02-12-12-38-24.gh-issue-129726.jB0sxu.rst
b/Misc/NEWS.d/next/Library/2025-02-12-12-38-24.gh-issue-129726.jB0sxu.rst
new file mode 100644
index 00000000000000..31032b59b5ea36
--- /dev/null
+++ b/Misc/NEWS.d/next/Library/2025-02-12-12-38-24.gh-issue-129726.jB0sxu.rst
@@ -0,0 +1,3 @@
+Fix :class:`gzip.GzipFile` raising an unraisable exception during garbage
+collection when referring to a temporary object by breaking the reference
+loop with :mod:`weakref`.
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