May 21, 2025 · May 21, 2025
diff --git a/Lib/_pyio.py b/Lib/_pyio.py
                    if not isinstance(fd, int):
                        raise TypeError('expected integer from opener')
                    if fd < 0:
                        raise OSError('Negative file descriptor')
                        # bpo-27066: Raise a ValueError for bad value.
                        raise ValueError(f'opener returned {fd}')
                owned_fd = fd
                if not noinherit_flag:
                    os.set_inheritable(fd, False)
diff --git a/Lib/test/test_io.py b/Lib/test/test_io.py
        def badopener(fname, flags):
            return -1
        with self.assertRaises(ValueError) as cm:
            open('non-existent', 'r', opener=badopener)
 self.open('non-existent', 'r', opener=badopener)
        self.assertEqual(str(cm.exception), 'opener returned -1')

    def test_bad_opener_other_negative(self):
        # Issue #27066.
        def badopener(fname, flags):
            return -2
        with self.assertRaises(ValueError) as cm:
            open('non-existent', 'r', opener=badopener)
 self.open('non-existent', 'r', opener=badopener)
        self.assertEqual(str(cm.exception), 'opener returned -2')

    def test_opener_invalid_fd(self):
diff --git a/Misc/NEWS.d/next/Library/2025-05-13-18-21-59.gh-issue-71253.-3Sf_K.rst b/Misc/NEWS.d/next/Library/2025-05-13-18-21-59.gh-issue-71253.-3Sf_K.rst
 Raise:exc:`ValueError` in:func:`open` if *opener* returns a negative
 file-descriptor in the Python implementation of:mod:`io` to match the
 C implementation.
Original file line number	Diff line number	Diff line change
Expand Up		@@ -1559,7 +1559,8 @@ def __init__(self, file, mode='r', closefd=True, opener=None):
		if not isinstance(fd, int):
		raise TypeError('expected integer from opener')
		if fd < 0:
		raise OSError('Negative file descriptor')
		# bpo-27066: Raise a ValueError for bad value.
		raise ValueError(f'opener returned {fd}')
		owned_fd = fd
		if not noinherit_flag:
		os.set_inheritable(fd, False)
Expand Down
Original file line number	Diff line number	Diff line change
Expand Up		@@ -894,15 +894,15 @@ def test_bad_opener_negative_1(self):
		def badopener(fname, flags):
		return -1
		with self.assertRaises(ValueError) as cm:
		open('non-existent', 'r', opener=badopener)
		self.open('non-existent', 'r', opener=badopener)
		self.assertEqual(str(cm.exception), 'opener returned -1')

		def test_bad_opener_other_negative(self):
		# Issue #27066.
		def badopener(fname, flags):
		return -2
		with self.assertRaises(ValueError) as cm:
		open('non-existent', 'r', opener=badopener)
		self.open('non-existent', 'r', opener=badopener)
		self.assertEqual(str(cm.exception), 'opener returned -2')

		def test_opener_invalid_fd(self):
Expand Down
Original file line number	Diff line number	Diff line change
		@@ -0,0 +1,3 @@
		Raise:exc:`ValueError` in:func:`open` if opener returns a negative
		file-descriptor in the Python implementation of:mod:`io` to match the
		C implementation.