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Pytype_GenericAlloc(): round up size so we zap all four bytes of the

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__dict__ slot for string subtypes.

subtype_dealloc(): properly use _PyObject_GetDictPtr() to get the
(potentially negative) dict offset.  Don't copy things into local
variables that are used only once.

type_new(): properly calculate a negative dict offset when tp_itemsize
is nonzero.  The __dict__ attribute, if present, is now a calculated
attribute rather than a structure member.
This commit is contained in:
Guido van Rossum 2001-08-30 20:00:07 +00:00
parent 702ca4ffcb
commit 6fb3fdec7c
1 changed files with 51 additions and 16 deletions
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67
Objects/typeobject.c
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@ -166,11 +166,19 @@ type_call(PyTypeObject *type, PyObject *args, PyObject *kwds)
PyObject *
PyType_GenericAlloc(PyTypeObject *type, int nitems)
{
#define PTRSIZE (sizeof(PyObject *))
int size;
PyObject *obj;
/* Inline PyObject_New() so we can zero the memory */
size = _PyObject_VAR_SIZE(type, nitems);
/* Round up size, if necessary, so we fully zero out __dict__ */
if (type->tp_itemsize % PTRSIZE != 0) {
size += PTRSIZE - 1;
size /= PTRSIZE;
size *= PTRSIZE;
}
if (PyType_IS_GC(type)) {
obj = _PyObject_GC_Malloc(type, nitems);
}
@ -202,8 +210,6 @@ PyType_GenericNew(PyTypeObject *type, PyObject *args, PyObject *kwds)
static void
subtype_dealloc(PyObject *self)
{
int dictoffset = self->ob_type->tp_dictoffset;
int weaklistoffset = self->ob_type->tp_weaklistoffset;
PyTypeObject *type, *base;
destructor f;
@ -218,17 +224,19 @@ subtype_dealloc(PyObject *self)
}
/* If we added a dict, DECREF it */
if (dictoffset && !base->tp_dictoffset) {
PyObject **dictptr = (PyObject **) ((char *)self + dictoffset);
PyObject *dict = *dictptr;
if (dict != NULL) {
Py_DECREF(dict);
*dictptr = NULL;
if (type->tp_dictoffset && !base->tp_dictoffset) {
PyObject **dictptr = _PyObject_GetDictPtr(self);
if (dictptr != NULL) {
PyObject *dict = *dictptr;
if (dict != NULL) {
Py_DECREF(dict);
*dictptr = NULL;
}
}
}
/* If we added weaklist, we clear it */
if (weaklistoffset && !base->tp_weaklistoffset)
if (type->tp_weaklistoffset && !base->tp_weaklistoffset)
PyObject_ClearWeakRefs(self);
/* Finalize GC if the base doesn't do GC and we do */
@ -579,6 +587,33 @@ solid_base(PyTypeObject *type)
staticforward void object_dealloc(PyObject *);
staticforward int object_init(PyObject *, PyObject *, PyObject *);
static PyObject *
subtype_dict(PyObject *obj, void *context)
{
PyObject **dictptr = _PyObject_GetDictPtr(obj);
PyObject *dict;
if (dictptr == NULL) {
PyErr_SetString(PyExc_AttributeError,
"This object has no __dict__");
return NULL;
}
dict = *dictptr;
if (dict == NULL) {
Py_INCREF(Py_None);
return Py_None;
}
else {
Py_INCREF(dict);
return dict;
}
}
struct getsetlist subtype_getsets[] = {
{"__dict__", subtype_dict, NULL, NULL},
{0},
};
static PyObject *
type_new(PyTypeObject *metatype, PyObject *args, PyObject *kwds)
{
@ -732,7 +767,6 @@ type_new(PyTypeObject *metatype, PyObject *args, PyObject *kwds)
if (slots == NULL && base->tp_dictoffset == 0 &&
(base->tp_setattro == PyObject_GenericSetAttr ||
base->tp_setattro == NULL)) {
nslots++;
add_dict++;
}
if (slots == NULL && base->tp_weaklistoffset == 0 &&
@ -829,15 +863,15 @@ type_new(PyTypeObject *metatype, PyObject *args, PyObject *kwds)
}
else {
if (add_dict) {
type->tp_dictoffset = slotoffset;
mp->name = "__dict__";
mp->type = T_OBJECT;
mp->offset = slotoffset;
mp->readonly = 1;
mp++;
if (base->tp_itemsize)
type->tp_dictoffset = -sizeof(PyObject *);
else
type->tp_dictoffset = slotoffset;
slotoffset += sizeof(PyObject *);
type->tp_getset = subtype_getsets;
}
if (add_weak) {
assert(!base->tp_itemsize);
type->tp_weaklistoffset = slotoffset;
mp->name = "__weakref__";
mp->type = T_OBJECT;
@ -848,6 +882,7 @@ type_new(PyTypeObject *metatype, PyObject *args, PyObject *kwds)
}
}
type->tp_basicsize = slotoffset;
type->tp_itemsize = base->tp_itemsize;
type->tp_members = et->members;
/* Special case some slots */