gh-107735: Add C API tests for PySys_GetObject() and PySys_SetObject() (GH-107736)

Lib/test/test_capi/test_misc.py

@@ -51,6 +51,8 @@ _testcapi = import_helper.import_module('_testcapi')
 import _testinternalcapi
 
 
+NULL = None
+
 def decode_stderr(err):
     return err.decode('utf-8', 'replace').replace('\r', '')
 
@@ -2576,5 +2578,46 @@ class TestUops(unittest.TestCase):
             with self.assertRaises(StopIteration):
                 next(it)
 
+    def test_sys_getobject(self):
+        getobject = _testcapi.sys_getobject
+
+        self.assertIs(getobject(b'stdout'), sys.stdout)
+        with support.swap_attr(sys, '\U0001f40d', 42):
+            self.assertEqual(getobject('\U0001f40d'.encode()), 42)
+
+        self.assertIs(getobject(b'nonexisting'), AttributeError)
+        self.assertIs(getobject(b'\xff'), AttributeError)
+        # CRASHES getobject(NULL)
+
+    def test_sys_setobject(self):
+        setobject = _testcapi.sys_setobject
+
+        value = ['value']
+        value2 = ['value2']
+        try:
+            self.assertEqual(setobject(b'newattr', value), 0)
+            self.assertIs(sys.newattr, value)
+            self.assertEqual(setobject(b'newattr', value2), 0)
+            self.assertIs(sys.newattr, value2)
+            self.assertEqual(setobject(b'newattr', NULL), 0)
+            self.assertFalse(hasattr(sys, 'newattr'))
+            self.assertEqual(setobject(b'newattr', NULL), 0)
+        finally:
+            with contextlib.suppress(AttributeError):
+                del sys.newattr
+        try:
+            self.assertEqual(setobject('\U0001f40d'.encode(), value), 0)
+            self.assertIs(getattr(sys, '\U0001f40d'), value)
+            self.assertEqual(setobject('\U0001f40d'.encode(), NULL), 0)
+            self.assertFalse(hasattr(sys, '\U0001f40d'))
+        finally:
+            with contextlib.suppress(AttributeError):
+                delattr(sys, '\U0001f40d')
+
+        with self.assertRaises(UnicodeDecodeError):
+            setobject(b'\xff', value)
+        # CRASHES setobject(NULL, value)
+
+
 if __name__ == "__main__":
     unittest.main()

Modules/_testcapimodule.c

@@ -44,6 +44,16 @@
 // Include definitions from there.
 #include "_testcapi/parts.h"
 
+#define NULLABLE(x) do { if (x == Py_None) x = NULL; } while (0);
+
+#define RETURN_INT(value) do {          \
+        int _ret = (value);             \
+        if (_ret == -1) {               \
+            return NULL;                \
+        }                               \
+        return PyLong_FromLong(_ret);   \
+    } while (0)
+
 // Forward declarations
 static struct PyModuleDef _testcapimodule;
 static PyObject *TestError;     /* set to exception object in init */
@@ -3505,6 +3515,35 @@ error:
 }
 
 
+static PyObject *
+sys_getobject(PyObject *Py_UNUSED(module), PyObject *arg)
+{
+    const char *name;
+    Py_ssize_t size;
+    if (!PyArg_Parse(arg, "z#", &name, &size)) {
+        return NULL;
+    }
+    PyObject *result = PySys_GetObject(name);
+    if (result == NULL) {
+        result = PyExc_AttributeError;
+    }
+    return Py_NewRef(result);
+}
+
+static PyObject *
+sys_setobject(PyObject *Py_UNUSED(module), PyObject *args)
+{
+    const char *name;
+    Py_ssize_t size;
+    PyObject *value;
+    if (!PyArg_ParseTuple(args, "z#O", &name, &size, &value)) {
+        return NULL;
+    }
+    NULLABLE(value);
+    RETURN_INT(PySys_SetObject(name, value));
+}
+
+
 static PyMethodDef TestMethods[] = {
     {"set_errno",               set_errno,                       METH_VARARGS},
     {"test_config",             test_config,                     METH_NOARGS},
@@ -3640,6 +3679,8 @@ static PyMethodDef TestMethods[] = {
     {"check_pyimport_addmodule", check_pyimport_addmodule, METH_VARARGS},
     {"test_weakref_capi", test_weakref_capi, METH_NOARGS},
     {"test_dict_capi", test_dict_capi, METH_NOARGS},
+    {"sys_getobject", sys_getobject, METH_O},
+    {"sys_setobject", sys_setobject, METH_VARARGS},
     {NULL, NULL} /* sentinel */
 };