bpo-42006: Stop using PyDict_GetItem, PyDict_GetItemString and _PyDict_GetItemId. (GH-22648)

These functions are considered not safe because they suppress all internal errors
and can return wrong result.  PyDict_GetItemString and _PyDict_GetItemId can
also silence current exception in rare cases.

Remove no longer used _PyDict_GetItemId.
Add _PyDict_ContainsId and rename _PyDict_Contains into
_PyDict_Contains_KnownHash.

Include/cpython/dictobject.h

@@ -46,7 +46,8 @@ PyAPI_FUNC(int) _PyDict_Next(
 
 /* Get the number of items of a dictionary. */
 #define PyDict_GET_SIZE(mp)  (assert(PyDict_Check(mp)),((PyDictObject *)mp)->ma_used)
-PyAPI_FUNC(int) _PyDict_Contains(PyObject *mp, PyObject *key, Py_hash_t hash);
+PyAPI_FUNC(int) _PyDict_Contains_KnownHash(PyObject *, PyObject *, Py_hash_t);
+PyAPI_FUNC(int) _PyDict_ContainsId(PyObject *, struct _Py_Identifier *);
 PyAPI_FUNC(PyObject *) _PyDict_NewPresized(Py_ssize_t minused);
 PyAPI_FUNC(void) _PyDict_MaybeUntrack(PyObject *mp);
 PyAPI_FUNC(int) _PyDict_HasOnlyStringKeys(PyObject *mp);
@@ -63,7 +64,6 @@ PyObject *_PyDict_FromKeys(PyObject *, PyObject *, PyObject *);
    argument is raised.
 */
 PyAPI_FUNC(int) _PyDict_MergeEx(PyObject *mp, PyObject *other, int override);
-PyAPI_FUNC(PyObject *) _PyDict_GetItemId(PyObject *dp, struct _Py_Identifier *key);
 PyAPI_FUNC(int) _PyDict_SetItemId(PyObject *dp, struct _Py_Identifier *key, PyObject *item);
 
 PyAPI_FUNC(int) _PyDict_DelItemId(PyObject *mp, struct _Py_Identifier *key);

Modules/_decimal/_decimal.c

@@ -3186,6 +3186,31 @@ dotsep_as_utf8(const char *s)
     return utf8;
 }
 
+static int
+dict_get_item_string(PyObject *dict, const char *key, PyObject **valueobj, const char **valuestr)
+{
+    *valueobj = NULL;
+    PyObject *keyobj = PyUnicode_FromString(key);
+    if (keyobj == NULL) {
+        return -1;
+    }
+    PyObject *value = PyDict_GetItemWithError(dict, keyobj);
+    Py_DECREF(keyobj);
+    if (value == NULL) {
+        if (PyErr_Occurred()) {
+            return -1;
+        }
+        return 0;
+    }
+    value = PyUnicode_AsUTF8String(value);
+    if (value == NULL) {
+        return -1;
+    }
+    *valueobj = value;
+    *valuestr = PyBytes_AS_STRING(value);
+    return 0;
+}
+
 /* Formatted representation of a PyDecObject. */
 static PyObject *
 dec_format(PyObject *dec, PyObject *args)
@@ -3256,24 +3281,12 @@ dec_format(PyObject *dec, PyObject *args)
                 "optional argument must be a dict");
             goto finish;
         }
-        if ((dot = PyDict_GetItemString(override, "decimal_point"))) {
+        if (dict_get_item_string(override, "decimal_point", &dot, &spec.dot) ||
-            if ((dot = PyUnicode_AsUTF8String(dot)) == NULL) {
+            dict_get_item_string(override, "thousands_sep", &sep, &spec.sep) ||
+            dict_get_item_string(override, "grouping", &grouping, &spec.grouping))
+        {
             goto finish;
         }
-            spec.dot = PyBytes_AS_STRING(dot);
-        }
-        if ((sep = PyDict_GetItemString(override, "thousands_sep"))) {
-            if ((sep = PyUnicode_AsUTF8String(sep)) == NULL) {
-                goto finish;
-            }
-            spec.sep = PyBytes_AS_STRING(sep);
-        }
-        if ((grouping = PyDict_GetItemString(override, "grouping"))) {
-            if ((grouping = PyUnicode_AsUTF8String(grouping)) == NULL) {
-                goto finish;
-            }
-            spec.grouping = PyBytes_AS_STRING(grouping);
-        }
         if (mpd_validate_lconv(&spec) < 0) {
             PyErr_SetString(PyExc_ValueError,
                 "invalid override dict");

Modules/_threadmodule.c

@@ -816,10 +816,14 @@ local_clear(localobject *self)
         for(tstate = PyInterpreterState_ThreadHead(tstate->interp);
             tstate;
             tstate = PyThreadState_Next(tstate))
-            if (tstate->dict && PyDict_GetItem(tstate->dict, self->key)) {
+            if (tstate->dict) {
-                if (PyDict_DelItem(tstate->dict, self->key)) {
+                PyObject *v = _PyDict_Pop(tstate->dict, self->key, Py_None);
+                if (v == NULL) {
                     PyErr_Clear();
                 }
+                else {
+                    Py_DECREF(v);
+                }
             }
     }
     return 0;

Modules/_zoneinfo.c

@@ -722,17 +722,16 @@ zoneinfo__unpickle(PyTypeObject *cls, PyObject *args)
 static PyObject *
 load_timedelta(long seconds)
 {
-    PyObject *rv = NULL;
+    PyObject *rv;
     PyObject *pyoffset = PyLong_FromLong(seconds);
     if (pyoffset == NULL) {
         return NULL;
     }
-    int contains = PyDict_Contains(TIMEDELTA_CACHE, pyoffset);
+    rv = PyDict_GetItemWithError(TIMEDELTA_CACHE, pyoffset);
-    if (contains == -1) {
+    if (rv == NULL) {
+        if (PyErr_Occurred()) {
             goto error;
         }
-
-    if (!contains) {
         PyObject *tmp = PyDateTimeAPI->Delta_FromDelta(
             0, seconds, 0, 1, PyDateTimeAPI->DeltaType);
 
@@ -743,12 +742,9 @@ load_timedelta(long seconds)
         rv = PyDict_SetDefault(TIMEDELTA_CACHE, pyoffset, tmp);
         Py_DECREF(tmp);
     }
-    else {
-        rv = PyDict_GetItem(TIMEDELTA_CACHE, pyoffset);
-    }
 
+    Py_XINCREF(rv);
     Py_DECREF(pyoffset);
-    Py_INCREF(rv);
     return rv;
 error:
     Py_DECREF(pyoffset);

Modules/signalmodule.c

@@ -1427,10 +1427,9 @@ signal_exec(PyObject *m)
          return -1;
 #endif
 
-    IntHandler = PyDict_GetItemString(d, "default_int_handler");
+    IntHandler = PyMapping_GetItemString(d, "default_int_handler");
     if (!IntHandler)
         return -1;
-    Py_INCREF(IntHandler);
 
     _Py_atomic_store_relaxed(&Handlers[0].tripped, 0);
     for (int i = 1; i < NSIG; i++) {

Modules/socketmodule.c

@@ -324,7 +324,7 @@ static FlagRuntimeInfo win_runtime_flags[] = {
     {14393, "TCP_FASTOPEN"}
 };
 
-static void
+static int
 remove_unusable_flags(PyObject *m)
 {
     PyObject *dict;
@@ -333,7 +333,7 @@ remove_unusable_flags(PyObject *m)
 
     dict = PyModule_GetDict(m);
     if (dict == NULL) {
-        return;
+        return -1;
     }
 
     /* set to Windows 10, except BuildNumber. */
@@ -359,19 +359,19 @@ remove_unusable_flags(PyObject *m)
             break;
         }
         else {
-            if (PyDict_GetItemString(
+            PyObject *flag_name = PyUnicode_FromString(win_runtime_flags[i].flag_name);
-                    dict,
+            if (flag_name == NULL) {
-                    win_runtime_flags[i].flag_name) != NULL)
+                return -1;
-            {
+            }
-                if (PyDict_DelItemString(
+            PyObject *v = _PyDict_Pop(dict, flag_name, Py_None);
-                        dict,
+            Py_DECREF(flag_name);
-                        win_runtime_flags[i].flag_name))
+            if (v == NULL) {
-                {
+                return -1;
-                    PyErr_Clear();
+            }
-                }
+            Py_DECREF(v);
-            }
         }
     }
+    return 0;
 }
 
 #endif
@@ -8382,7 +8382,10 @@ PyInit__socket(void)
 
 #ifdef MS_WINDOWS
     /* remove some flags on older version Windows during run-time */
-    remove_unusable_flags(m);
+    if (remove_unusable_flags(m) < 0) {
+        Py_DECREF(m);
+        return NULL;
+    }
 #endif
 
     return m;

Objects/dictobject.c

@@ -3434,7 +3434,7 @@ PyDict_Contains(PyObject *op, PyObject *key)
 
 /* Internal version of PyDict_Contains used when the hash value is already known */
 int
-_PyDict_Contains(PyObject *op, PyObject *key, Py_hash_t hash)
+_PyDict_Contains_KnownHash(PyObject *op, PyObject *key, Py_hash_t hash)
 {
     PyDictObject *mp = (PyDictObject *)op;
     PyObject *value;
@@ -3446,6 +3446,16 @@ _PyDict_Contains(PyObject *op, PyObject *key, Py_hash_t hash)
     return (ix != DKIX_EMPTY && value != NULL);
 }
 
+int
+_PyDict_ContainsId(PyObject *op, struct _Py_Identifier *key)
+{
+    PyObject *kv = _PyUnicode_FromId(key); /* borrowed */
+    if (kv == NULL) {
+        return -1;
+    }
+    return PyDict_Contains(op, kv);
+}
+
 /* Hack to implement "key in dict" */
 static PySequenceMethods dict_as_sequence = {
     0,                          /* sq_length */
@@ -3590,18 +3600,6 @@ PyTypeObject PyDict_Type = {
     .tp_vectorcall = dict_vectorcall,
 };
 
-PyObject *
-_PyDict_GetItemId(PyObject *dp, struct _Py_Identifier *key)
-{
-    PyObject *kv;
-    kv = _PyUnicode_FromId(key); /* borrowed */
-    if (kv == NULL) {
-        PyErr_Clear();
-        return NULL;
-    }
-    return PyDict_GetItem(dp, kv);
-}
-
 /* For backward compatibility with old dictionary interface */
 
 PyObject *

Objects/moduleobject.c

@@ -477,10 +477,12 @@ PyModule_GetNameObject(PyObject *m)
     }
     d = ((PyModuleObject *)m)->md_dict;
     if (d == NULL ||
-        (name = _PyDict_GetItemId(d, &PyId___name__)) == NULL ||
+        (name = _PyDict_GetItemIdWithError(d, &PyId___name__)) == NULL ||
         !PyUnicode_Check(name))
     {
+        if (!PyErr_Occurred()) {
             PyErr_SetString(PyExc_SystemError, "nameless module");
+        }
         return NULL;
     }
     Py_INCREF(name);
@@ -509,10 +511,12 @@ PyModule_GetFilenameObject(PyObject *m)
     }
     d = ((PyModuleObject *)m)->md_dict;
     if (d == NULL ||
-        (fileobj = _PyDict_GetItemId(d, &PyId___file__)) == NULL ||
+        (fileobj = _PyDict_GetItemIdWithError(d, &PyId___file__)) == NULL ||
         !PyUnicode_Check(fileobj))
     {
+        if (!PyErr_Occurred()) {
             PyErr_SetString(PyExc_SystemError, "module filename missing");
+        }
         return NULL;
     }
     Py_INCREF(fileobj);
@@ -721,14 +725,21 @@ module_getattro(PyModuleObject *m, PyObject *name)
     PyErr_Clear();
     if (m->md_dict) {
         _Py_IDENTIFIER(__getattr__);
-        getattr = _PyDict_GetItemId(m->md_dict, &PyId___getattr__);
+        getattr = _PyDict_GetItemIdWithError(m->md_dict, &PyId___getattr__);
         if (getattr) {
             return PyObject_CallOneArg(getattr, name);
         }
-        mod_name = _PyDict_GetItemId(m->md_dict, &PyId___name__);
+        if (PyErr_Occurred()) {
+            return NULL;
+        }
+        mod_name = _PyDict_GetItemIdWithError(m->md_dict, &PyId___name__);
         if (mod_name && PyUnicode_Check(mod_name)) {
             Py_INCREF(mod_name);
-            PyObject *spec = _PyDict_GetItemId(m->md_dict, &PyId___spec__);
+            PyObject *spec = _PyDict_GetItemIdWithError(m->md_dict, &PyId___spec__);
+            if (spec == NULL && PyErr_Occurred()) {
+                Py_DECREF(mod_name);
+                return NULL;
+            }
             Py_XINCREF(spec);
             if (_PyModuleSpec_IsInitializing(spec)) {
                 PyErr_Format(PyExc_AttributeError,
@@ -746,6 +757,9 @@ module_getattro(PyModuleObject *m, PyObject *name)
             Py_DECREF(mod_name);
             return NULL;
         }
+        else if (PyErr_Occurred()) {
+            return NULL;
+        }
     }
     PyErr_Format(PyExc_AttributeError,
                 "module has no attribute '%U'", name);

Objects/setobject.c

@@ -1498,7 +1498,7 @@ set_difference(PySetObject *so, PyObject *other)
         while (set_next(so, &pos, &entry)) {
             key = entry->key;
             hash = entry->hash;
-            rv = _PyDict_Contains(other, key, hash);
+            rv = _PyDict_Contains_KnownHash(other, key, hash);
             if (rv < 0) {
                 Py_DECREF(result);
                 return NULL;

Objects/structseq.c

@@ -19,20 +19,33 @@ static const char unnamed_fields_key[] = "n_unnamed_fields";
 /* Fields with this name have only a field index, not a field name.
    They are only allowed for indices < n_visible_fields. */
 const char * const PyStructSequence_UnnamedField = "unnamed field";
+
 _Py_IDENTIFIER(n_sequence_fields);
 _Py_IDENTIFIER(n_fields);
 _Py_IDENTIFIER(n_unnamed_fields);
 
-#define VISIBLE_SIZE(op) Py_SIZE(op)
+static ssize_t
-#define VISIBLE_SIZE_TP(tp) PyLong_AsSsize_t( \
+get_type_attr_as_size(PyTypeObject *tp, _Py_Identifier *id)
-                      _PyDict_GetItemId((tp)->tp_dict, &PyId_n_sequence_fields))
+{
+    PyObject *name = _PyUnicode_FromId(id);
+    if (name == NULL) {
+        return -1;
+    }
+    PyObject *v = PyDict_GetItemWithError(tp->tp_dict, name);
+    if (v == NULL && !PyErr_Occurred()) {
+        PyErr_Format(PyExc_TypeError,
+                     "Missed attribute '%U' of type %s",
+                     name, tp->tp_name);
+    }
+    return PyLong_AsSsize_t(v);
+}
 
-#define REAL_SIZE_TP(tp) PyLong_AsSsize_t( \
+#define VISIBLE_SIZE(op) Py_SIZE(op)
-                      _PyDict_GetItemId((tp)->tp_dict, &PyId_n_fields))
+#define VISIBLE_SIZE_TP(tp) get_type_attr_as_size(tp, &PyId_n_sequence_fields)
+#define REAL_SIZE_TP(tp) get_type_attr_as_size(tp, &PyId_n_fields)
 #define REAL_SIZE(op) REAL_SIZE_TP(Py_TYPE(op))
 
-#define UNNAMED_FIELDS_TP(tp) PyLong_AsSsize_t( \
+#define UNNAMED_FIELDS_TP(tp) get_type_attr_as_size(tp, &PyId_n_unnamed_fields)
-                      _PyDict_GetItemId((tp)->tp_dict, &PyId_n_unnamed_fields))
 #define UNNAMED_FIELDS(op) UNNAMED_FIELDS_TP(Py_TYPE(op))
 
 
@@ -41,13 +54,20 @@ PyStructSequence_New(PyTypeObject *type)
 {
     PyStructSequence *obj;
     Py_ssize_t size = REAL_SIZE_TP(type), i;
+    if (size < 0) {
+        return NULL;
+    }
+    Py_ssize_t vsize = VISIBLE_SIZE_TP(type);
+    if (vsize < 0) {
+        return NULL;
+    }
 
     obj = PyObject_GC_NewVar(PyStructSequence, type, size);
     if (obj == NULL)
         return NULL;
     /* Hack the size of the variable object, so invisible fields don't appear
      to Python code. */
-    Py_SET_SIZE(obj, VISIBLE_SIZE_TP(type));
+    Py_SET_SIZE(obj, vsize);
     for (i = 0; i < size; i++)
         obj->ob_item[i] = NULL;
 
@@ -121,6 +141,19 @@ structseq_new_impl(PyTypeObject *type, PyObject *arg, PyObject *dict)
     PyStructSequence *res = NULL;
     Py_ssize_t len, min_len, max_len, i, n_unnamed_fields;
 
+    min_len = VISIBLE_SIZE_TP(type);
+    if (min_len < 0) {
+        return NULL;
+    }
+    max_len = REAL_SIZE_TP(type);
+    if (max_len < 0) {
+        return NULL;
+    }
+    n_unnamed_fields = UNNAMED_FIELDS_TP(type);
+    if (n_unnamed_fields < 0) {
+        return NULL;
+    }
+
     arg = PySequence_Fast(arg, "constructor requires a sequence");
 
     if (!arg) {
@@ -136,10 +169,6 @@ structseq_new_impl(PyTypeObject *type, PyObject *arg, PyObject *dict)
     }
 
     len = PySequence_Fast_GET_SIZE(arg);
-    min_len = VISIBLE_SIZE_TP(type);
-    max_len = REAL_SIZE_TP(type);
-    n_unnamed_fields = UNNAMED_FIELDS_TP(type);
-
     if (min_len != max_len) {
         if (len < min_len) {
             PyErr_Format(PyExc_TypeError,
@@ -177,18 +206,26 @@ structseq_new_impl(PyTypeObject *type, PyObject *arg, PyObject *dict)
         Py_INCREF(v);
         res->ob_item[i] = v;
     }
+    Py_DECREF(arg);
     for (; i < max_len; ++i) {
-        if (dict && (ob = PyDict_GetItemString(
+        if (dict == NULL) {
-            dict, type->tp_members[i-n_unnamed_fields].name))) {
+            ob = Py_None;
         }
         else {
+            ob = _PyDict_GetItemStringWithError(dict,
+                type->tp_members[i-n_unnamed_fields].name);
+            if (ob == NULL) {
+                if (PyErr_Occurred()) {
+                    Py_DECREF(res);
+                    return NULL;
+                }
                 ob = Py_None;
             }
+        }
         Py_INCREF(ob);
         res->ob_item[i] = ob;
     }
 
-    Py_DECREF(arg);
     _PyObject_GC_TRACK(res);
     return (PyObject*) res;
 }
@@ -288,8 +325,14 @@ structseq_reduce(PyStructSequence* self, PyObject *Py_UNUSED(ignored))
     Py_ssize_t n_fields, n_visible_fields, n_unnamed_fields, i;
 
     n_fields = REAL_SIZE(self);
+    if (n_fields < 0) {
+        return NULL;
+    }
     n_visible_fields = VISIBLE_SIZE(self);
     n_unnamed_fields = UNNAMED_FIELDS(self);
+    if (n_unnamed_fields < 0) {
+        return NULL;
+    }
     tup = _PyTuple_FromArray(self->ob_item, n_visible_fields);
     if (!tup)
         goto error;

Objects/typeobject.c

@@ -4767,8 +4767,11 @@ object___reduce_ex___impl(PyObject *self, int protocol)
     _Py_IDENTIFIER(__reduce__);
 
     if (objreduce == NULL) {
-        objreduce = _PyDict_GetItemId(PyBaseObject_Type.tp_dict,
+        objreduce = _PyDict_GetItemIdWithError(PyBaseObject_Type.tp_dict,
                                                &PyId___reduce__);
+        if (objreduce == NULL && PyErr_Occurred()) {
+            return NULL;
+        }
     }
 
     if (_PyObject_LookupAttrId(self, &PyId___reduce__, &reduce) < 0) {
@@ -5181,14 +5184,14 @@ overrides_hash(PyTypeObject *type)
     _Py_IDENTIFIER(__eq__);
 
     assert(dict != NULL);
-    if (_PyDict_GetItemId(dict, &PyId___eq__) != NULL)
+    int r = _PyDict_ContainsId(dict, &PyId___eq__);
-        return 1;
+    if (r == 0) {
-    if (_PyDict_GetItemId(dict, &PyId___hash__) != NULL)
+        r = _PyDict_ContainsId(dict, &PyId___hash__);
-        return 1;
+    }
-    return 0;
+    return r;
 }
 
-static void
+static int
 inherit_slots(PyTypeObject *type, PyTypeObject *base)
 {
     PyTypeObject *basebase;
@@ -5331,13 +5334,18 @@ inherit_slots(PyTypeObject *type, PyTypeObject *base)
         /* Copy comparison-related slots only when
            not overriding them anywhere */
         if (type->tp_richcompare == NULL &&
-            type->tp_hash == NULL &&
+            type->tp_hash == NULL)
-            !overrides_hash(type))
         {
+            int r = overrides_hash(type);
+            if (r < 0) {
+                return -1;
+            }
+            if (!r) {
                 type->tp_richcompare = base->tp_richcompare;
                 type->tp_hash = base->tp_hash;
             }
         }
+    }
     {
         COPYSLOT(tp_iter);
         COPYSLOT(tp_iternext);
@@ -5378,6 +5386,7 @@ inherit_slots(PyTypeObject *type, PyTypeObject *base)
          * obvious to be done -- the type is on its own.
          */
     }
+    return 0;
 }
 
 static int add_operators(PyTypeObject *);
@@ -5507,8 +5516,11 @@ PyType_Ready(PyTypeObject *type)
     n = PyTuple_GET_SIZE(bases);
     for (i = 1; i < n; i++) {
         PyObject *b = PyTuple_GET_ITEM(bases, i);
-        if (PyType_Check(b))
+        if (PyType_Check(b)) {
-            inherit_slots(type, (PyTypeObject *)b);
+            if (inherit_slots(type, (PyTypeObject *)b) < 0) {
+                goto error;
+            }
+        }
     }
 
     /* All bases of statically allocated type should be statically allocated */

Python/ceval.c

@@ -1446,11 +1446,18 @@ _PyEval_EvalFrameDefault(PyThreadState *tstate, PyFrameObject *f, int throwflag)
     }
 
 #ifdef LLTRACE
-    lltrace = _PyDict_GetItemId(f->f_globals, &PyId___ltrace__) != NULL;
+    {
+        int r = _PyDict_ContainsId(f->f_globals, &PyId___ltrace__);
+        if (r < 0) {
+            goto exit_eval_frame;
+        }
+        lltrace = r;
+    }
 #endif
 
-    if (throwflag) /* support for generator.throw() */
+    if (throwflag) { /* support for generator.throw() */
         goto error;
+    }
 
 #ifdef Py_DEBUG
     /* _PyEval_EvalFrameDefault() must not be called with an exception set,

Python/compile.c

@@ -489,8 +489,8 @@ dictbytype(PyObject *src, int scope_type, int flag, Py_ssize_t offset)
         /* XXX this should probably be a macro in symtable.h */
         long vi;
         k = PyList_GET_ITEM(sorted_keys, key_i);
-        v = PyDict_GetItem(src, k);
+        v = PyDict_GetItemWithError(src, k);
-        assert(PyLong_Check(v));
+        assert(v && PyLong_Check(v));
         vi = PyLong_AS_LONG(v);
         scope = (vi >> SCOPE_OFFSET) & SCOPE_MASK;
 
@@ -1889,7 +1889,7 @@ static int
 compiler_lookup_arg(PyObject *dict, PyObject *name)
 {
     PyObject *v;
-    v = PyDict_GetItem(dict, name);
+    v = PyDict_GetItemWithError(dict, name);
     if (v == NULL)
         return -1;
     return PyLong_AS_LONG(v);

Python/pylifecycle.c

@@ -160,7 +160,7 @@ init_importlib(PyThreadState *tstate, PyObject *sysmod)
     interp->importlib = importlib;
     Py_INCREF(interp->importlib);
 
-    interp->import_func = PyDict_GetItemString(interp->builtins, "__import__");
+    interp->import_func = _PyDict_GetItemStringWithError(interp->builtins, "__import__");
     if (interp->import_func == NULL)
         return _PyStatus_ERR("__import__ not found");
     Py_INCREF(interp->import_func);
@@ -1683,7 +1683,10 @@ add_main_module(PyInterpreterState *interp)
     }
     Py_DECREF(ann_dict);
 
-    if (PyDict_GetItemString(d, "__builtins__") == NULL) {
+    if (_PyDict_GetItemStringWithError(d, "__builtins__") == NULL) {
+        if (PyErr_Occurred()) {
+            return _PyStatus_ERR("Failed to test __main__.__builtins__");
+        }
         PyObject *bimod = PyImport_ImportModule("builtins");
         if (bimod == NULL) {
             return _PyStatus_ERR("Failed to retrieve builtins module");
@@ -1700,8 +1703,11 @@ add_main_module(PyInterpreterState *interp)
      * be set if __main__ gets further initialized later in the startup
      * process.
      */
-    loader = PyDict_GetItemString(d, "__loader__");
+    loader = _PyDict_GetItemStringWithError(d, "__loader__");
     if (loader == NULL || loader == Py_None) {
+        if (PyErr_Occurred()) {
+            return _PyStatus_ERR("Failed to test __main__.__loader__");
+        }
         PyObject *loader = PyObject_GetAttrString(interp->importlib,
                                                   "BuiltinImporter");
         if (loader == NULL) {

Python/pythonrun.c

@@ -351,7 +351,10 @@ PyRun_SimpleFileExFlags(FILE *fp, const char *filename, int closeit,
         return -1;
     Py_INCREF(m);
     d = PyModule_GetDict(m);
-    if (PyDict_GetItemString(d, "__file__") == NULL) {
+    if (_PyDict_GetItemStringWithError(d, "__file__") == NULL) {
+        if (PyErr_Occurred()) {
+            goto done;
+        }
         PyObject *f;
         f = PyUnicode_DecodeFSDefault(filename);
         if (f == NULL)
@@ -1116,9 +1119,11 @@ run_eval_code_obj(PyThreadState *tstate, PyCodeObject *co, PyObject *globals, Py
     _Py_UnhandledKeyboardInterrupt = 0;
 
     /* Set globals['__builtins__'] if it doesn't exist */
-    if (globals != NULL && PyDict_GetItemString(globals, "__builtins__") == NULL) {
+    if (globals != NULL && _PyDict_GetItemStringWithError(globals, "__builtins__") == NULL) {
-        if (PyDict_SetItemString(globals, "__builtins__",
+        if (PyErr_Occurred() ||
-                                 tstate->interp->builtins) < 0) {
+            PyDict_SetItemString(globals, "__builtins__",
+                                 tstate->interp->builtins) < 0)
+        {
             return NULL;
         }
     }

Python/symtable.c

@@ -392,7 +392,7 @@ PySymtable_Lookup(struct symtable *st, void *key)
 static long
 _PyST_GetSymbol(PySTEntryObject *ste, PyObject *name)
 {
-    PyObject *v = PyDict_GetItem(ste->ste_symbols, name);
+    PyObject *v = PyDict_GetItemWithError(ste->ste_symbols, name);
     if (!v)
         return 0;
     assert(PyLong_Check(v));
@@ -634,7 +634,7 @@ update_symbols(PyObject *symbols, PyObject *scopes,
         long scope, flags;
         assert(PyLong_Check(v));
         flags = PyLong_AS_LONG(v);
-        v_scope = PyDict_GetItem(scopes, name);
+        v_scope = PyDict_GetItemWithError(scopes, name);
         assert(v_scope && PyLong_Check(v_scope));
         scope = PyLong_AS_LONG(v_scope);
         flags |= (scope << SCOPE_OFFSET);
@@ -1071,9 +1071,12 @@ symtable_add_def_helper(struct symtable *st, PyObject *name, int flag, struct _s
         /* XXX need to update DEF_GLOBAL for other flags too;
            perhaps only DEF_FREE_GLOBAL */
         val = flag;
-        if ((o = PyDict_GetItem(st->st_global, mangled))) {
+        if ((o = PyDict_GetItemWithError(st->st_global, mangled))) {
             val |= PyLong_AS_LONG(o);
         }
+        else if (PyErr_Occurred()) {
+            goto error;
+        }
         o = PyLong_FromLong(val);
         if (o == NULL)
             goto error;

Python/sysmodule.c

@@ -68,7 +68,13 @@ sys_get_object_id(PyThreadState *tstate, _Py_Identifier *key)
     if (sd == NULL) {
         return NULL;
     }
-    return _PyDict_GetItemId(sd, key);
+    PyObject *exc_type, *exc_value, *exc_tb;
+    _PyErr_Fetch(tstate, &exc_type, &exc_value, &exc_tb);
+    PyObject *value = _PyDict_GetItemIdWithError(sd, key);
+    /* XXX Suppress a new exception if it was raised and restore
+     * the old one. */
+    _PyErr_Restore(tstate, exc_type, exc_value, exc_tb);
+    return value;
 }
 
 PyObject *
@@ -86,24 +92,39 @@ PySys_GetObject(const char *name)
     if (sd == NULL) {
         return NULL;
     }
-    return PyDict_GetItemString(sd, name);
+    PyObject *exc_type, *exc_value, *exc_tb;
+    _PyErr_Fetch(tstate, &exc_type, &exc_value, &exc_tb);
+    PyObject *value = _PyDict_GetItemStringWithError(sd, name);
+    /* XXX Suppress a new exception if it was raised and restore
+     * the old one. */
+    _PyErr_Restore(tstate, exc_type, exc_value, exc_tb);
+    return value;
+}
+
+static int
+sys_set_object(PyThreadState *tstate, PyObject *key, PyObject *v)
+{
+    if (key == NULL) {
+        return -1;
+    }
+    PyObject *sd = tstate->interp->sysdict;
+    if (v == NULL) {
+        v = _PyDict_Pop(sd, key, Py_None);
+        if (v == NULL) {
+            return -1;
+        }
+        Py_DECREF(v);
+        return 0;
+    }
+    else {
+        return PyDict_SetItem(sd, key, v);
+    }
 }
 
 static int
 sys_set_object_id(PyThreadState *tstate, _Py_Identifier *key, PyObject *v)
 {
-    PyObject *sd = tstate->interp->sysdict;
+    return sys_set_object(tstate, _PyUnicode_FromId(key), v);
-    if (v == NULL) {
-        if (_PyDict_GetItemId(sd, key) == NULL) {
-            return 0;
-        }
-        else {
-            return _PyDict_DelItemId(sd, key);
-        }
-    }
-    else {
-        return _PyDict_SetItemId(sd, key, v);
-    }
 }
 
 int
@@ -114,27 +135,20 @@ _PySys_SetObjectId(_Py_Identifier *key, PyObject *v)
 }
 
 static int
-sys_set_object(PyThreadState *tstate, const char *name, PyObject *v)
+sys_set_object_str(PyThreadState *tstate, const char *name, PyObject *v)
 {
-    PyObject *sd = tstate->interp->sysdict;
+    PyObject *key = v ? PyUnicode_InternFromString(name)
-    if (v == NULL) {
+                      : PyUnicode_FromString(name);
-        if (PyDict_GetItemString(sd, name) == NULL) {
+    int r = sys_set_object(tstate, key, v);
-            return 0;
+    Py_XDECREF(key);
-        }
+    return r;
-        else {
-            return PyDict_DelItemString(sd, name);
-        }
-    }
-    else {
-        return PyDict_SetItemString(sd, name, v);
-    }
 }
 
 int
 PySys_SetObject(const char *name, PyObject *v)
 {
     PyThreadState *tstate = _PyThreadState_GET();
-    return sys_set_object(tstate, name, v);
+    return sys_set_object_str(tstate, name, v);
 }
 
 
@@ -3083,7 +3097,7 @@ PySys_SetArgvEx(int argc, wchar_t **argv, int updatepath)
     if (av == NULL) {
         Py_FatalError("no mem for sys.argv");
     }
-    if (sys_set_object(tstate, "argv", av) != 0) {
+    if (sys_set_object_str(tstate, "argv", av) != 0) {
         Py_DECREF(av);
         Py_FatalError("can't assign sys.argv");
     }