Don't set gi_frame to Py_None, use NULL instead, eliminating some insane

pointer dereferences.

diff --git a/Include/genobject.h b/Include/genobject.h
index 1ecd7ad773c46107dacf1264e4674ae210c7ca7c..ca8443203c79e5a7e9b9e07c83386a9a583abb89 100644 (file)
--- a/Include/genobject.h
+++ b/Include/genobject.h
@@ -13,6 +13,7 @@ typedef struct {
        PyObject_HEAD
        /* The gi_ prefix is intended to remind of generator-iterator. */
 
+       /* Note: gi_frame can be NULL if the generator is "finished" */
        struct _frame *gi_frame;
 
        /* True if generator is being executed. */

diff --git a/Objects/genobject.c b/Objects/genobject.c
index f5d0a5e7b36a532efd5f7013b5421459d67e4197..367b4de0272ab033d4f0a96fd59c1bc34f1da5dc 100644 (file)
--- a/Objects/genobject.c
+++ b/Objects/genobject.c
@@ -10,7 +10,8 @@
 static int
 gen_traverse(PyGenObject *gen, visitproc visit, void *arg)
 {
-       return visit((PyObject *)gen->gi_frame, arg);
+       Py_VISIT(gen->gi_frame);
+       return 0;
 }
 
 static void
@@ -26,7 +27,7 @@ gen_dealloc(PyGenObject *gen)
 
        _PyObject_GC_TRACK(self);
 
-       if (gen->gi_frame->f_stacktop!=NULL) {
+       if (gen->gi_frame!=NULL && gen->gi_frame->f_stacktop!=NULL) {
                /* Generator is paused, so we need to close */
                gen->ob_type->tp_del(self);
                if (self->ob_refcnt > 0)
@@ -51,7 +52,7 @@ gen_send_ex(PyGenObject *gen, PyObject *arg, int exc)
                                "generator already executing");
                return NULL;
        }
-       if ((PyObject *)f == Py_None || f->f_stacktop == NULL) {
+       if (f==NULL || f->f_stacktop == NULL) {
                /* Only set exception if called from send() */
                if (arg && !exc) PyErr_SetNone(PyExc_StopIteration);
                return NULL;
@@ -98,8 +99,7 @@ gen_send_ex(PyGenObject *gen, PyObject *arg, int exc)
        if (!result || f->f_stacktop == NULL) {
                /* generator can't be rerun, so release the frame */
                Py_DECREF(f);
-               gen->gi_frame = (PyFrameObject *)Py_None;
-               Py_INCREF(Py_None);
+               gen->gi_frame = NULL;
        }
 
        return result;
@@ -147,7 +147,7 @@ gen_del(PyObject *self)
         PyObject *error_type, *error_value, *error_traceback;
        PyGenObject *gen = (PyGenObject *)self;
 
-       if ((PyObject *)gen->gi_frame == Py_None || gen->gi_frame->f_stacktop==NULL)
+       if (!gen->gi_frame || gen->gi_frame->f_stacktop==NULL)
                /* Generator isn't paused, so no need to close */
                return;
 
@@ -366,7 +366,7 @@ PyGen_NeedsFinalizing(PyGenObject *gen)
        int i;
        PyFrameObject *f = gen->gi_frame;
 
-       if ((PyObject *)f == Py_None || f->f_stacktop==NULL || f->f_iblock<=0)
+       if (f == NULL || f->f_stacktop==NULL || f->f_iblock<=0)
                return 0; /* no frame or no blockstack == no finalization */
 
        for (i=f->f_iblock; i>=0; i--) {