https://github.com/python/cpython/commit/6c81e8c57a1d291863c6beaa42392a7f1cf52854
commit: 6c81e8c57a1d291863c6beaa42392a7f1cf52854
branch: main
author: Victor Stinner <vstin...@python.org>
committer: vstinner <vstin...@python.org>
date: 2025-07-08T18:39:47+02:00
summary:
gh-136156: Allow using linkat() with TemporaryFile (#136281)
tempfile.TemporaryFile() no longer uses os.O_EXCL with os.O_TMPFILE,
so it's possible to use linkat() on the file descriptor.
files:
A Misc/NEWS.d/next/Library/2025-07-04-12-53-02.gh-issue-136156.OYlXoz.rst
M Lib/tempfile.py
M Lib/test/test_tempfile.py
diff --git a/Lib/tempfile.py b/Lib/tempfile.py
index 5e3ccab5f48502..53d14ff5c67131 100644
--- a/Lib/tempfile.py
+++ b/Lib/tempfile.py
@@ -656,7 +656,7 @@ def TemporaryFile(mode='w+b', buffering=-1, encoding=None,
fd = None
def opener(*args):
nonlocal fd
- flags2 = (flags | _os.O_TMPFILE) & ~_os.O_CREAT
+ flags2 = (flags | _os.O_TMPFILE) & ~_os.O_CREAT & ~_os.O_EXCL
fd = _os.open(dir, flags2, 0o600)
return fd
try:
diff --git a/Lib/test/test_tempfile.py b/Lib/test/test_tempfile.py
index 52b13b98cbcce5..36151b016ea35b 100644
--- a/Lib/test/test_tempfile.py
+++ b/Lib/test/test_tempfile.py
@@ -1594,6 +1594,29 @@ def test_unexpected_error(self):
mock_close.assert_called()
self.assertEqual(os.listdir(dir), [])
+ @unittest.skipUnless(tempfile._O_TMPFILE_WORKS, 'need os.O_TMPFILE')
+ @unittest.skipUnless(os.path.exists('/proc/self/fd'),
+ 'need /proc/self/fd')
+ def test_link_tmpfile(self):
+ dir = tempfile.mkdtemp()
+ self.addCleanup(os_helper.rmtree, dir)
+ filename = os.path.join(dir, "link")
+
+ with tempfile.TemporaryFile('w', dir=dir) as tmp:
+ # the flag can become False on Linux <= 3.11
+ if not tempfile._O_TMPFILE_WORKS:
+ self.skipTest("O_TMPFILE doesn't work")
+
+ tmp.write("hello")
+ tmp.flush()
+ fd = tmp.fileno()
+
+ os.link(f'/proc/self/fd/{fd}',
+ filename,
+ follow_symlinks=True)
+ with open(filename) as fp:
+ self.assertEqual(fp.read(), "hello")
+
# Helper for test_del_on_shutdown
class NulledModules:
diff --git
a/Misc/NEWS.d/next/Library/2025-07-04-12-53-02.gh-issue-136156.OYlXoz.rst
b/Misc/NEWS.d/next/Library/2025-07-04-12-53-02.gh-issue-136156.OYlXoz.rst
new file mode 100644
index 00000000000000..95606790e991a4
--- /dev/null
+++ b/Misc/NEWS.d/next/Library/2025-07-04-12-53-02.gh-issue-136156.OYlXoz.rst
@@ -0,0 +1,3 @@
+:func:`tempfile.TemporaryFile` no longer uses :data:`os.O_EXCL` with
+:data:`os.O_TMPFILE`, so it's possible to use ``linkat()`` on the file
+descriptor. Patch by Victor Stinner.
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