_PyStack_UnpackDict() now returns -1 on error

vstinner · vstinner · commit 998c20962ca3 · 2017-01-17T01:57:29.000+01:00
Issue python#29286. Change _PyStack_UnpackDict() prototype to be able to notify of failure when args is NULL.
diff --git a/Include/abstract.h b/Include/abstract.h
@@ -177,20 +177,23 @@ PyAPI_FUNC(PyObject *) _PyStack_AsDict(
     PyObject **values,
     PyObject *kwnames);
 
-/* Convert (args, nargs, kwargs) into a (stack, nargs, kwnames).
+/* Convert (args, nargs, kwargs: dict) into a (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_ParseStackAndKeywords). */
-PyAPI_FUNC(PyObject **) _PyStack_UnpackDict(
+PyAPI_FUNC(int) _PyStack_UnpackDict(
     PyObject **args,
     Py_ssize_t nargs,
     PyObject *kwargs,
-    PyObject **kwnames,
+    PyObject ***p_stack,
+    PyObject **p_kwnames,
     PyObject *func);
 
 /* Suggested size (number of positional arguments) for arrays of PyObject*
diff --git a/Objects/abstract.c b/Objects/abstract.c
@@ -2421,9 +2421,9 @@ _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 *func)
 {
     PyObject **stack, **kwstack;
     Py_ssize_t nkwargs;
@@ -2435,25 +2435,26 @@ _PyStack_UnpackDict(PyObject **args, Py_ssize_t nargs, PyObject *kwargs,
     assert(kwargs == NULL || PyDict_CheckExact(kwargs));
 
     if (kwargs == NULL || (nkwargs = PyDict_GET_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) */
@@ -2472,8 +2473,9 @@ _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
@@ -240,8 +240,8 @@ _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, func_obj) < 0) {
             return NULL;
         }
 

Original file line number	Diff line number	Diff line change
`@@ -2421,9 +2421,9 @@ _PyStack_AsDict(PyObject *values, PyObject kwnames)`
`2421`	`2421`	`return kwdict;`
`2422`	`2422`	`}`
`2423`	`2423`
`2424`		`-PyObject **`
	`2424`	`+int`
`2425`	`2425`	`_PyStack_UnpackDict(PyObject *args, Py_ssize_t nargs, PyObject kwargs,`
`2426`		`- PyObject *p_kwnames, PyObject func)`
	`2426`	`+ PyObject *p_stack, PyObject p_kwnames, PyObject *func)`
`2427`	`2427`	`{`
`2428`	`2428`	`PyObject stack, kwstack;`
`2429`	`2429`	`Py_ssize_t nkwargs;`
`@@ -2435,25 +2435,26 @@ _PyStack_UnpackDict(PyObject *args, Py_ssize_t nargs, PyObject kwargs,`
`2435`	`2435`	`assert(kwargs == NULL \|\| PyDict_CheckExact(kwargs));`
`2436`	`2436`
`2437`	`2437`	`if (kwargs == NULL \|\| (nkwargs = PyDict_GET_SIZE(kwargs)) == 0) {`
	`2438`	`+ *p_stack = args;`
`2438`	`2439`	`*p_kwnames = NULL;`
`2439`		`- return args;`
	`2440`	`+ return 0;`
`2440`	`2441`	`}`
`2441`	`2442`
`2442`	`2443`	`if ((size_t)nargs > PY_SSIZE_T_MAX / sizeof(stack[0]) - (size_t)nkwargs) {`
`2443`	`2444`	`PyErr_NoMemory();`
`2444`		`- return NULL;`
	`2445`	`+ return -1;`
`2445`	`2446`	`}`
`2446`	`2447`
`2447`	`2448`	`stack = PyMem_Malloc((nargs + nkwargs) * sizeof(stack[0]));`
`2448`	`2449`	`if (stack == NULL) {`
`2449`	`2450`	`PyErr_NoMemory();`
`2450`		`- return NULL;`
	`2451`	`+ return -1;`
`2451`	`2452`	`}`
`2452`	`2453`
`2453`	`2454`	`kwnames = PyTuple_New(nkwargs);`
`2454`	`2455`	`if (kwnames == NULL) {`
`2455`	`2456`	`PyMem_Free(stack);`
`2456`		`- return NULL;`
	`2457`	`+ return -1;`
`2457`	`2458`	`}`
`2458`	`2459`
`2459`	`2460`	`/* Copy position arguments (borrowed references) */`
`@@ -2472,8 +2473,9 @@ _PyStack_UnpackDict(PyObject *args, Py_ssize_t nargs, PyObject kwargs,`
`2472`	`2473`	`i++;`
`2473`	`2474`	`}`
`2474`	`2475`
	`2476`	`+ *p_stack = stack;`
`2475`	`2477`	`*p_kwnames = kwnames;`
`2476`		`- return stack;`
	`2478`	`+ return 0;`
`2477`	`2479`	`}`
`2478`	`2480`
`2479`	`2481`	`PyObject *`
Original file line number	Diff line number	Diff line change
`@@ -240,8 +240,8 @@ _PyCFunction_FastCallDict(PyObject func_obj, PyObject *args, Py_ssize_t nargs,`
`240`	`240`	`PyObject *kwnames;`
`241`	`241`	`_PyCFunctionFast fastmeth = (_PyCFunctionFast)meth;`
`242`	`242`
`243`		`- stack = _PyStack_UnpackDict(args, nargs, kwargs, &kwnames, func_obj);`
`244`		`- if (stack == NULL) {`
	`243`	`+ if (_PyStack_UnpackDict(args, nargs, kwargs,`
	`244`	`+ &stack, &kwnames, func_obj) < 0) {`
`245`	`245`	`return NULL;`
`246`	`246`	`}`
`247`	`247`