python · vstinner · Jun 9, 2017 · May 31, 2017
diff --git a/Include/abstract.h b/Include/abstract.h
@@ -290,21 +290,23 @@ xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx*/
        PyObject **values,
        PyObject *kwnames);

-    /* Convert (args, nargs, kwargs) into a (stack, nargs, kwnames).
+    /* Convert (args, nargs, kwargs: dict) into (stack, nargs, kwnames: tuple).

-       Return a new stack which should be released by PyMem_Free(), or return
-       args unchanged if kwargs is NULL or an empty dictionary.
+       Return 0 on success, raise an exception and return -1 on error.
+
+       Write the new stack into *p_stack. If *p_stack is differen than args, it
+       must be released by PyMem_Free().

       The stack uses borrowed references.

       The type of keyword keys is not checked, these checks should be done
-       later (ex: _PyArg_ParseStack). */
-    PyAPI_FUNC(PyObject **) _PyStack_UnpackDict(
+       later (ex: _PyArg_ParseStackAndKeywords). */
+    PyAPI_FUNC(int) _PyStack_UnpackDict(
        PyObject **args,
        Py_ssize_t nargs,
        PyObject *kwargs,
-        PyObject **kwnames,
-        PyObject *func);
+        PyObject ***p_stack,
+        PyObject **p_kwnames);

    /* Call the callable object func with the "fast call" calling convention:
       args is a C array for positional arguments (nargs is the number of

diff --git a/Objects/abstract.c b/Objects/abstract.c
@@ -2389,9 +2389,9 @@ _PyStack_AsDict(PyObject **values, PyObject *kwnames)
    return kwdict;
 }

-PyObject **
+int
 _PyStack_UnpackDict(PyObject **args, Py_ssize_t nargs, PyObject *kwargs,
-                    PyObject **p_kwnames, PyObject *func)
+                    PyObject ***p_stack, PyObject **p_kwnames)
 {
    PyObject **stack, **kwstack;
    Py_ssize_t nkwargs;
@@ -2402,27 +2402,27 @@ _PyStack_UnpackDict(PyObject **args, Py_ssize_t nargs, PyObject *kwargs,
    assert(nargs >= 0);
    assert(kwargs == NULL || PyDict_CheckExact(kwargs));

-    nkwargs = (kwargs != NULL) ? PyDict_Size(kwargs) : 0;
-    if (!nkwargs) {
+    if (kwargs == NULL || (nkwargs = PyDict_Size(kwargs)) == 0) {
+        *p_stack = args;
        *p_kwnames = NULL;
-        return args;
+        return 0;
    }

    if ((size_t)nargs > PY_SSIZE_T_MAX / sizeof(stack[0]) - (size_t)nkwargs) {
        PyErr_NoMemory();
-        return NULL;
+        return -1;
    }

    stack = PyMem_Malloc((nargs + nkwargs) * sizeof(stack[0]));
    if (stack == NULL) {
        PyErr_NoMemory();
-        return NULL;
+        return -1;
    }

    kwnames = PyTuple_New(nkwargs);
    if (kwnames == NULL) {
        PyMem_Free(stack);
-        return NULL;
+        return -1;
    }

    /* Copy position arguments (borrowed references) */
@@ -2441,8 +2441,9 @@ _PyStack_UnpackDict(PyObject **args, Py_ssize_t nargs, PyObject *kwargs,
        i++;
    }

+    *p_stack = stack;
    *p_kwnames = kwnames;
-    return stack;
+    return 0;
 }

 PyObject *

diff --git a/Objects/methodobject.c b/Objects/methodobject.c
@@ -243,8 +243,7 @@ _PyCFunction_FastCallDict(PyObject *func_obj, PyObject **args, Py_ssize_t nargs,
        PyObject *kwnames;
        _PyCFunctionFast fastmeth = (_PyCFunctionFast)meth;

-        stack = _PyStack_UnpackDict(args, nargs, kwargs, &kwnames, func_obj);
-        if (stack == NULL) {
+        if (_PyStack_UnpackDict(args, nargs, kwargs, &stack, &kwnames) < 0) {
            return NULL;
        }