From 747ddb1b97d37fd57efae3c99c2bd188a14df308 Mon Sep 17 00:00:00 2001
From: Mark Wooding <mdw@distorted.org.uk>
Date: Sun, 20 Oct 2019 21:18:08 +0100
Subject: [PATCH] pyke/pyke.[ch]: Make type skeleton structures be read-only.

We couldn't do this before because `INITTYPE_META' would write the
direct superclass to the `tp_base' slot in the skeleton before calling
`inittype'.  To make this work, then, we adjust `inittype' to take the
direct superclass as an extra argument and plug it into the newly
created heap-type; and `INITTYPE_META' needs adjusting to pass this
argument rather than trying to write to the skeleton directly.

Of course, then we need to actually mark the type skeletons as `const'.
---
 mapping.c | 4 ++--
 pyke.c    | 5 +++--
 pyke.h    | 9 ++++-----
 3 files changed, 9 insertions(+), 9 deletions(-)

diff --git a/mapping.c b/mapping.c
index 7080ca5..e97fcb0 100644
--- a/mapping.c
+++ b/mapping.c
@@ -54,7 +54,7 @@ static PyObject *itemiter_pynext(PyObject *me)
   return (rc);
 }
 
-static PyTypeObject itemiter_pytype_skel = {
+static const PyTypeObject itemiter_pytype_skel = {
   PyObject_HEAD_INIT(0) 0,		/* Header */
   "ItemIter",				/* @tp_name@ */
   sizeof(iter_pyobj),			/* @tp_basicsize@ */
@@ -112,7 +112,7 @@ static PyObject *valiter_pynext(PyObject *me)
   return (rc);
 }
 
-static PyTypeObject valiter_pytype_skel = {
+static const PyTypeObject valiter_pytype_skel = {
   PyObject_HEAD_INIT(0) 0,		/* Header */
   "ValueIter",				/* @tp_name@ */
   sizeof(iter_pyobj),			/* @tp_basicsize@ */
diff --git a/pyke.c b/pyke.c
index b462a1f..f19c9e4 100644
--- a/pyke.c
+++ b/pyke.c
@@ -218,7 +218,6 @@ void *newtype(PyTypeObject *metaty,
     (PyHeapTypeObject *)_PyObject_GC_Malloc(_PyObject_VAR_SIZE(metaty, 0));
   if (!skel) skel = &emptytype;
   memcpy(ty, skel, sizeof(*skel));
-  if (ty->ht_type.tp_base) Py_INCREF(ty->ht_type.tp_base);
 #define COPY(blah) do {							\
     if (ty->ht_type.tp_as_##blah) {					\
       memcpy(&ty->as_##blah,						\
@@ -249,9 +248,11 @@ void typeready(PyTypeObject *ty)
   PyDict_SetItemString(ty->tp_dict, "__module__", modname);
 }
 
-PyTypeObject *inittype(PyTypeObject *tyskel, PyTypeObject *meta)
+PyTypeObject *inittype(const PyTypeObject *tyskel,
+		       PyTypeObject *base, PyTypeObject *meta)
 {
   PyTypeObject *ty = newtype(meta, tyskel, 0);
+  if (base) { ty->tp_base = base; Py_INCREF(base); }
   ty->tp_flags |= Py_TPFLAGS_HEAPTYPE;
   typeready(ty);
   return (ty);
diff --git a/pyke.h b/pyke.h
index 3076bb5..138a9fb 100644
--- a/pyke.h
+++ b/pyke.h
@@ -208,11 +208,11 @@ extern void *newtype(PyTypeObject */*meta*/,
 extern void typeready(PyTypeObject *);
   /* The type object is now ready to be used. */
 
-extern PyTypeObject *inittype(PyTypeObject */*skel*/,
+extern PyTypeObject *inittype(const PyTypeObject */*skel*/,
+			      PyTypeObject */*base*/,
 			      PyTypeObject */*meta*/);
   /* All-in-one function to construct a working type from a type skeleton
-   * SKEL, with metaclass META.  The caller is expected to have filled in the
-   * direct superclass in SKEL->tp_base.
+   * SKEL, with known base type BASE (null for `object') and metaclass.
    */
 
 /* Alias for built-in types, to fit in with Pyke naming conventions. */
@@ -220,8 +220,7 @@ extern PyTypeObject *inittype(PyTypeObject */*skel*/,
 #define type_pytype &PyType_Type
 
 #define INITTYPE_META(ty, base, meta) do {				\
-  ty##_pytype_skel.tp_base = base##_pytype;				\
-  ty##_pytype = inittype(&ty##_pytype_skel, meta##_pytype);		\
+  ty##_pytype = inittype(&ty##_pytype_skel, base##_pytype, meta##_pytype); \
 } while (0)
 #define INITTYPE(ty, base) INITTYPE_META(ty, base, type)
   /* Macros to initialize a type from its skeleton. */
-- 
2.11.0