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#include "Python.h"
#include "frameobject.h"
#include "pycore_code.h" // stats
#include "pycore_frame.h"
#include "pycore_object.h" // _PyObject_GC_UNTRACK()
#include "opcode.h"
int
_PyFrame_Traverse(_PyInterpreterFrame *frame, visitproc visit, void *arg)
{
Py_VISIT(frame->frame_obj);
Py_VISIT(frame->f_locals);
Py_VISIT(frame->f_func);
Py_VISIT(frame->f_code);
/* locals */
PyObject **locals = _PyFrame_GetLocalsArray(frame);
int i = 0;
/* locals and stack */
for (; i <frame->stacktop; i++) {
Py_VISIT(locals[i]);
}
return 0;
}
PyFrameObject *
_PyFrame_MakeAndSetFrameObject(_PyInterpreterFrame *frame)
{
assert(frame->frame_obj == NULL);
PyObject *error_type, *error_value, *error_traceback;
PyErr_Fetch(&error_type, &error_value, &error_traceback);
PyFrameObject *f = _PyFrame_New_NoTrack(frame->f_code);
if (f == NULL) {
Py_XDECREF(error_type);
Py_XDECREF(error_value);
Py_XDECREF(error_traceback);
return NULL;
}
PyErr_Restore(error_type, error_value, error_traceback);
if (frame->frame_obj) {
// GH-97002: How did we get into this horrible situation? Most likely,
// allocating f triggered a GC collection, which ran some code that
// *also* created the same frame... while we were in the middle of
// creating it! See test_sneaky_frame_object in test_frame.py for a
// concrete example.
//
// Regardless, just throw f away and use that frame instead, since it's
// already been exposed to user code. It's actually a bit tricky to do
// this, since we aren't backed by a real _PyInterpreterFrame anymore.
// Just pretend that we have an owned, cleared frame so frame_dealloc
// doesn't make the situation worse:
f->f_frame = (_PyInterpreterFrame *)f->_f_frame_data;
f->f_frame->owner = FRAME_CLEARED;
f->f_frame->frame_obj = f;
Py_DECREF(f);
return frame->frame_obj;
}
assert(frame->owner != FRAME_OWNED_BY_FRAME_OBJECT);
assert(frame->owner != FRAME_CLEARED);
f->f_frame = frame;
frame->frame_obj = f;
return f;
}
void
_PyFrame_Copy(_PyInterpreterFrame *src, _PyInterpreterFrame *dest)
{
assert(src->stacktop >= src->f_code->co_nlocalsplus);
Py_ssize_t size = ((char*)&src->localsplus[src->stacktop]) - (char *)src;
memcpy(dest, src, size);
// Don't leave a dangling pointer to the old frame when creating generators
// and coroutines:
dest->previous = NULL;
}
static void
take_ownership(PyFrameObject *f, _PyInterpreterFrame *frame)
{
assert(frame->owner != FRAME_OWNED_BY_FRAME_OBJECT);
assert(frame->owner != FRAME_CLEARED);
Py_ssize_t size = ((char*)&frame->localsplus[frame->stacktop]) - (char *)frame;
memcpy((_PyInterpreterFrame *)f->_f_frame_data, frame, size);
frame = (_PyInterpreterFrame *)f->_f_frame_data;
f->f_frame = frame;
frame->owner = FRAME_OWNED_BY_FRAME_OBJECT;
if (_PyFrame_IsIncomplete(frame)) {
// This may be a newly-created generator or coroutine frame. Since it's
// dead anyways, just pretend that the first RESUME ran:
PyCodeObject *code = frame->f_code;
frame->prev_instr = _PyCode_CODE(code) + code->_co_firsttraceable;
}
assert(!_PyFrame_IsIncomplete(frame));
assert(f->f_back == NULL);
_PyInterpreterFrame *prev = frame->previous;
while (prev && _PyFrame_IsIncomplete(prev)) {
prev = prev->previous;
}
if (prev) {
/* Link PyFrameObjects.f_back and remove link through _PyInterpreterFrame.previous */
PyFrameObject *back = _PyFrame_GetFrameObject(prev);
if (back == NULL) {
/* Memory error here. */
assert(PyErr_ExceptionMatches(PyExc_MemoryError));
/* Nothing we can do about it */
PyErr_Clear();
}
else {
f->f_back = (PyFrameObject *)Py_NewRef(back);
}
frame->previous = NULL;
}
if (!_PyObject_GC_IS_TRACKED((PyObject *)f)) {
_PyObject_GC_TRACK((PyObject *)f);
}
}
void
_PyFrame_Clear(_PyInterpreterFrame *frame)
{
/* It is the responsibility of the owning generator/coroutine
* to have cleared the enclosing generator, if any. */
assert(frame->owner != FRAME_OWNED_BY_GENERATOR ||
_PyFrame_GetGenerator(frame)->gi_frame_state == FRAME_CLEARED);
if (frame->frame_obj) {
PyFrameObject *f = frame->frame_obj;
frame->frame_obj = NULL;
if (Py_REFCNT(f) > 1) {
take_ownership(f, frame);
Py_DECREF(f);
return;
}
Py_DECREF(f);
}
assert(frame->stacktop >= 0);
for (int i = 0; i < frame->stacktop; i++) {
Py_XDECREF(frame->localsplus[i]);
}
Py_XDECREF(frame->frame_obj);
Py_XDECREF(frame->f_locals);
Py_DECREF(frame->f_func);
Py_DECREF(frame->f_code);
}
/* Consumes reference to func */
_PyInterpreterFrame *
_PyFrame_Push(PyThreadState *tstate, PyFunctionObject *func)
{
PyCodeObject *code = (PyCodeObject *)func->func_code;
size_t size = code->co_nlocalsplus + code->co_stacksize + FRAME_SPECIALS_SIZE;
CALL_STAT_INC(frames_pushed);
_PyInterpreterFrame *new_frame = _PyThreadState_BumpFramePointer(tstate, size);
if (new_frame == NULL) {
Py_DECREF(func);
return NULL;
}
_PyFrame_InitializeSpecials(new_frame, func, NULL, code->co_nlocalsplus);
return new_frame;
}
int
_PyInterpreterFrame_GetLine(_PyInterpreterFrame *frame)
{
int addr = _PyInterpreterFrame_LASTI(frame) * sizeof(_Py_CODEUNIT);
return PyCode_Addr2Line(frame->f_code, addr);
}
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