:Constant hash for _PyNone_Type

Author: yonillasky

Include/object.h

@@ -691,6 +691,8 @@ PyAPI_DATA(PyObject) _Py_NotImplementedStruct; /* Don't use this directly */
 /* Macro for returning Py_NotImplemented from a function */
 #define Py_RETURN_NOTIMPLEMENTED return Py_NewRef(Py_NotImplemented)
 
+extern Py_ssize_t _PyHASH_NONE;
+
 /* Rich comparison opcodes */
 #define Py_LT 0
 #define Py_LE 1

Objects/object.c

@@ -1638,6 +1638,16 @@ none_bool(PyObject *v)
     return 0;
 }
 
+Py_ssize_t _PyHASH_NONE;
+
+static Py_hash_t none_hash(PyObject *v)
+{
+#ifdef Py_DEBUG
+    assert(_Py_HashSecret_Initialized);
+#endif
+    return _PyHASH_NONE;
+}
+
 static PyNumberMethods none_as_number = {
     0,                          /* nb_add */
     0,                          /* nb_subtract */
@@ -1689,7 +1699,7 @@ PyTypeObject _PyNone_Type = {
     &none_as_number,    /*tp_as_number*/
     0,                  /*tp_as_sequence*/
     0,                  /*tp_as_mapping*/
-    0,                  /*tp_hash */
+    (hashfunc)none_hash,/* tp_hash */
     0,                  /*tp_call */
     0,                  /*tp_str */
     0,                  /*tp_getattro */

Python/bootstrap_hash.c

@@ -543,6 +543,11 @@ _PyOS_URandomNonblock(void *buffer, Py_ssize_t size)
     return pyurandom(buffer, size, 0, 1);
 }
 
+void
+_Py_InitNoneHash() {
+    const unsigned char data[] = {0xFC, 0xA8, 0x64, 0x20};
+    _PyHASH_NONE = _Py_HashBytes(data, sizeof(data));
+}
 
 PyStatus
 _Py_HashRandomization_Init(const PyConfig *config)
@@ -576,14 +581,15 @@ _Py_HashRandomization_Init(const PyConfig *config)
            pyurandom() is non-blocking mode (blocking=0): see the PEP 524. */
         res = pyurandom(secret, secret_size, 0, 0);
         if (res < 0) {
+            _Py_HashSecret_Initialized = 0;
             return _PyStatus_ERR("failed to get random numbers "
                                  "to initialize Python");
         }
     }
+    _Py_InitNoneHash();
     return _PyStatus_OK();
 }
 
-
 void
 _Py_HashRandomization_Fini(void)
 {