[3.9] gh-97897: Prevent os.mkfifo and os.mknod segfaults with macOS 13 SDK (GH-97944) (#97968)

The macOS 13 SDK includes support for the `mkfifoat` and `mknodat` system calls.
 Using the `dir_fd` option with either `os.mkfifo` or `os.mknod` could result in a
 segfault if cpython is built with the macOS 13 SDK but run on an earlier
 version of macOS. Prevent this by adding runtime support for detection of
 these system calls ("weaklinking") as is done for other newer syscalls on
 macOS.
(cherry picked from commit 6d0a0191a4e5477bd843e62c24d7f3bcad4fd5fc)

Co-authored-by: Ned Deily <nad@python.org>

1 files changed, 22 insertions, 0 deletions

diff --git a/Lib/test/test_posix.py b/Lib/test/test_posix.py
index 6ba1454..3c0ddeb 100644
--- a/Lib/test/test_posix.py
+++ b/Lib/test/test_posix.py
@@ -2040,6 +2040,28 @@ class TestPosixWeaklinking(unittest.TestCase):
             with self.assertRaisesRegex(NotImplementedError, "dir_fd unavailable"):
                 os.mkdir("dir", dir_fd=0)
 
+    def test_mkfifo(self):
+        self._verify_available("HAVE_MKFIFOAT")
+        if self.mac_ver >= (13, 0):
+            self.assertIn("HAVE_MKFIFOAT", posix._have_functions)
+
+        else:
+            self.assertNotIn("HAVE_MKFIFOAT", posix._have_functions)
+
+            with self.assertRaisesRegex(NotImplementedError, "dir_fd unavailable"):
+                os.mkfifo("path", dir_fd=0)
+
+    def test_mknod(self):
+        self._verify_available("HAVE_MKNODAT")
+        if self.mac_ver >= (13, 0):
+            self.assertIn("HAVE_MKNODAT", posix._have_functions)
+
+        else:
+            self.assertNotIn("HAVE_MKNODAT", posix._have_functions)
+
+            with self.assertRaisesRegex(NotImplementedError, "dir_fd unavailable"):
+                os.mknod("path", dir_fd=0)
+
     def test_rename_replace(self):
         self._verify_available("HAVE_RENAMEAT")
         if self.mac_ver >= (10, 10):