gh-143698: correctly check scheduler type for os.posix_spawn[p]

Author: picnixz

Lib/test/test_os/test_posix.py

@@ -2096,6 +2096,12 @@ def test_setsigdef_wrong_type(self):
                             [sys.executable, "-c", "pass"],
                             os.environ, setsigdef=[signal.NSIG, signal.NSIG+1])
 
+    @support.subTests("scheduler", [None, 1, [1, 2]])
+    def test_invalid_scheduler_param(self, scheduler):
+        path, args = self.NOOP_PROGRAM[0], self.NOOP_PROGRAM
+        with self.assertRaisesRegex(TypeError, "scheduler must be a tuple"):
+            self.spawn_func(path, args, os.environ, scheduler=scheduler)
+
     @requires_sched
     @unittest.skipIf(sys.platform.startswith(('freebsd', 'netbsd')),
                      "bpo-34685: test can fail on BSD")

Misc/NEWS.d/next/Library/2026-01-11-16-59-22.gh-issue-143698.b-Cpeb.rst

@@ -0,0 +1,3 @@
+Raise :exc:`TypeError` instead of :exc:`SystemError` when the *scheduler*
+in :func:`os.posix_spawn` or :func:`os.posix_spawnp` is not a tuple.
+Patch by Bénédikt Tran.

Modules/posixmodule.c

@@ -7611,6 +7611,7 @@ parse_posix_spawn_flags(PyObject *module, const char *func_name, PyObject *setpg
                         PyObject *setsigdef, PyObject *scheduler,
                         posix_spawnattr_t *attrp)
 {
+    assert(scheduler == NULL || PyTuple_Check(scheduler));
     long all_flags = 0;
 
     errno = posix_spawnattr_init(attrp);
@@ -7917,6 +7918,12 @@ py_posix_spawn(int use_posix_spawnp, PyObject *module, path_t *path, PyObject *a
         goto exit;
     }
 
+    if (scheduler && !PyTuple_Check(scheduler)) {
+        PyErr_Format(PyExc_TypeError,
+                     "%s: scheduler must be a tuple", func_name);
+        goto exit;
+    }
+
     argvlist = parse_arglist(argv, &argc);
     if (argvlist == NULL) {
         goto exit;