gh-108308: Replace PyDict_GetItem() with PyDict_GetItemRef() (#108309)

Replace PyDict_GetItem() calls with PyDict_GetItemRef()
or PyDict_GetItemWithError() to handle errors.

* Replace PyLong_AS_LONG() with _PyLong_AsInt()
  and check for errors.
* Check for PyDict_Contains() error.
* pycore_init_builtins() checks for _PyType_Lookup() failure.

1 files changed, 18 insertions, 6 deletions

diff --git a/Python/pylifecycle.c b/Python/pylifecycle.c
index 9837e0f..8c321fb 100644
--- a/Python/pylifecycle.c
+++ b/Python/pylifecycle.c
@@ -762,18 +762,30 @@ pycore_init_builtins(PyThreadState *tstate)
     }
     interp->builtins = Py_NewRef(builtins_dict);
 
-    PyObject *isinstance = PyDict_GetItem(builtins_dict, &_Py_ID(isinstance));
-    assert(isinstance);
+    PyObject *isinstance = PyDict_GetItemWithError(builtins_dict, &_Py_ID(isinstance));
+    if (!isinstance) {
+        goto error;
+    }
     interp->callable_cache.isinstance = isinstance;
-    PyObject *len = PyDict_GetItem(builtins_dict, &_Py_ID(len));
-    assert(len);
+
+    PyObject *len = PyDict_GetItemWithError(builtins_dict, &_Py_ID(len));
+    if (!len) {
+        goto error;
+    }
     interp->callable_cache.len = len;
+
     PyObject *list_append = _PyType_Lookup(&PyList_Type, &_Py_ID(append));
-    assert(list_append);
+    if (list_append == NULL) {
+        goto error;
+    }
     interp->callable_cache.list_append = list_append;
+
     PyObject *object__getattribute__ = _PyType_Lookup(&PyBaseObject_Type, &_Py_ID(__getattribute__));
-    assert(object__getattribute__);
+    if (object__getattribute__ == NULL) {
+        goto error;
+    }
     interp->callable_cache.object__getattribute__ = object__getattribute__;
+
     if (_PyBuiltins_AddExceptions(bimod) < 0) {
         return _PyStatus_ERR("failed to add exceptions to builtins");
     }