fixed use of reference in pytalloc

The previous code caused memory leaks, and also caused situations
where talloc_free could be called on pointers with multiple parents

The new approach is to have two functions:

  py_talloc_import : steals the pointer, so it becomes wholly owned by
                     the python object
  py_talloc_reference: uses a reference, so it is owned by both python
                     and C

2 files changed, 24 insertions, 3 deletions

diff --git a/lib/talloc/pytalloc.c b/lib/talloc/pytalloc.c
index 30da9ee5c2..3ce49d6d61 100644
--- a/lib/talloc/pytalloc.c
+++ b/lib/talloc/pytalloc.c
@@ -43,7 +43,27 @@ PyObject *py_talloc_import_ex(PyTypeObject *py_type, TALLOC_CTX *mem_ctx,
 	if (ret->talloc_ctx == NULL) {
 		return NULL;
 	}
-	if (talloc_reference(ret->talloc_ctx, mem_ctx) == NULL) {
+	if (talloc_steal(ret->talloc_ctx, mem_ctx) == NULL) {
+		return NULL;
+	}
+	ret->ptr = ptr;
+	return (PyObject *)ret;
+}
+
+
+/**
+ * Import an existing talloc pointer into a Python object, leaving the
+ * original parent, and creating a reference to the object in the python
+ * object
+ */
+PyObject *py_talloc_reference(PyTypeObject *py_type, void *ptr)
+{
+	py_talloc_Object *ret = (py_talloc_Object *)py_type->tp_alloc(py_type, 0);
+	ret->talloc_ctx = talloc_new(NULL);
+	if (ret->talloc_ctx == NULL) {
+		return NULL;
+	}
+	if (talloc_reference(ret->talloc_ctx, ptr) == NULL) {
 		return NULL;
 	}
 	ret->ptr = ptr;
@@ -58,6 +78,6 @@ PyObject *py_talloc_default_repr(PyObject *obj)
 	py_talloc_Object *talloc_obj = (py_talloc_Object *)obj;
 	PyTypeObject *type = (PyTypeObject*)PyObject_Type(obj);
 
-	return PyString_FromFormat("<%s talloc object at 0x%x>", 
-				   type->tp_name, (intptr_t)talloc_obj->ptr);
+	return PyString_FromFormat("<%s talloc object at 0x%p>", 
+				   type->tp_name, talloc_obj->ptr);
 }
diff --git a/lib/talloc/pytalloc.h b/lib/talloc/pytalloc.h
index c5a1428b29..00282c4ba0 100644
--- a/lib/talloc/pytalloc.h
+++ b/lib/talloc/pytalloc.h
@@ -43,6 +43,7 @@ void py_talloc_dealloc(PyObject* self);
 #define py_talloc_get_mem_ctx(py_obj)  ((py_talloc_Object *)py_obj)->talloc_ctx
 
 PyObject *py_talloc_import_ex(PyTypeObject *py_type, TALLOC_CTX *mem_ctx, void *ptr);
+PyObject *py_talloc_reference(PyTypeObject *py_type, void *ptr);
 #define py_talloc_import(py_type, talloc_ptr) py_talloc_import_ex(py_type, talloc_ptr, talloc_ptr)
 
 /* Sane default implementation of reprfunc. */