From 2b9c948db41c4600725051fab211b88e844c507c Mon Sep 17 00:00:00 2001
From: Jeong YunWon <jeong@youknowone.org>
Date: Mon, 12 Oct 2026 02:18:17 +0900
Subject: [PATCH] gh-159182: Preserve empty ranges in os.closerange

---
 Lib/test/test_os/test_os.py                   | 28 +++++++++++++++++++
 ...-10-11-17-15-00.gh-issue-159182.aQ3tX2.rst |  2 ++
 Modules/posixmodule.c                         |  5 +++-
 3 files changed, 34 insertions(+), 1 deletion(-)
 create mode 100644 Misc/NEWS.d/next/Library/2026-10-11-17-15-00.gh-issue-159182.aQ3tX2.rst

diff --git a/Lib/test/test_os/test_os.py b/Lib/test/test_os/test_os.py
index 81b3043eb7e75bc..ee901c97522117d 100644
--- a/Lib/test/test_os/test_os.py
+++ b/Lib/test/test_os/test_os.py
@@ -225,6 +225,34 @@ def test_closerange(self):
         os.closerange(first, first + 2)
         self.assertRaises(OSError, os.write, first, b"a")
 
+    @support.requires_subprocess()
+    def test_closerange_empty(self):
+        # Run in a subprocess: a regression could close the standard streams
+        # and the test runner's own file descriptors.
+        code = textwrap.dedent("""\
+            import os
+            import sys
+
+            fd = os.open(os.devnull, os.O_RDONLY)
+            try:
+                result = os.closerange(int(sys.argv[1]), int(sys.argv[2]))
+                os.fstat(fd)
+            except BaseException:
+                os._exit(1)
+            os._exit(0 if result is None else 2)
+        """)
+        int_min = -(1 << (struct.calcsize('i') * 8 - 1))
+        int_max = -int_min - 1
+        for low, high in ((0, 0), (1, 0), (10, 5), (-1, 0), (-2, -1),
+                          (-1, -1), (int_min, int_min), (0, int_min),
+                          (int_max, int_max)):
+            with self.subTest(low=low, high=high):
+                proc = subprocess.run(
+                    [sys.executable, '-I', '-c', code, str(low), str(high)],
+                    stdin=subprocess.DEVNULL, stdout=subprocess.DEVNULL,
+                    stderr=subprocess.DEVNULL, timeout=support.SHORT_TIMEOUT)
+                self.assertEqual(proc.returncode, 0)
+
     @support.cpython_only
     def test_rename(self):
         path = os_helper.TESTFN
diff --git a/Misc/NEWS.d/next/Library/2026-10-11-17-15-00.gh-issue-159182.aQ3tX2.rst b/Misc/NEWS.d/next/Library/2026-10-11-17-15-00.gh-issue-159182.aQ3tX2.rst
new file mode 100644
index 000000000000000..45d3a09fc1ccd60
--- /dev/null
+++ b/Misc/NEWS.d/next/Library/2026-10-11-17-15-00.gh-issue-159182.aQ3tX2.rst
@@ -0,0 +1,2 @@
+Fix :func:`os.closerange` closing unrelated file descriptors for empty or
+negative-only ranges on platforms using ``close_range()``.
diff --git a/Modules/posixmodule.c b/Modules/posixmodule.c
index 028270e7b841fda..e86def1ba7159cd 100644
--- a/Modules/posixmodule.c
+++ b/Modules/posixmodule.c
@@ -11895,7 +11895,10 @@ os_closerange_impl(PyObject *module, int fd_low, int fd_high)
 /*[clinic end generated code: output=0ce5c20fcda681c2 input=5855a3d053ebd4ec]*/
 {
     Py_BEGIN_ALLOW_THREADS
-    _Py_closerange(fd_low, fd_high - 1);
+    /* Check the exclusive upper bound before converting it to inclusive. */
+    if (fd_high > 0 && fd_low < fd_high) {
+        _Py_closerange(fd_low, fd_high - 1);
+    }
     Py_END_ALLOW_THREADS
     Py_RETURN_NONE;
 }