bpo-35370: Add _PyEval_SetTrace() function (GH-18975)

* sys.settrace(), sys.setprofile() and _lsprof.Profiler.enable() now
  properly report PySys_Audit() error if "sys.setprofile" or
  "sys.settrace" audit event is denied.
* Add _PyEval_SetProfile() and _PyEval_SetTrace() function: similar
  to PyEval_SetProfile() and PyEval_SetTrace() but take a tstate
  parameter and return -1 on error.
* Add _PyObject_FastCallTstate() function.

1 files changed, 54 insertions, 20 deletions

diff --git a/Python/ceval.c b/Python/ceval.c
index ccd1c06a39..fc4f718de2 100644
--- a/Python/ceval.c
+++ b/Python/ceval.c
@@ -4586,51 +4586,85 @@ maybe_call_line_trace(Py_tracefunc func, PyObject *obj,
     return result;
 }
 
-void
-PyEval_SetProfile(Py_tracefunc func, PyObject *arg)
+int
+_PyEval_SetProfile(PyThreadState *tstate, Py_tracefunc func, PyObject *arg)
 {
+    assert(tstate != NULL);
+    /* The caller must hold the GIL */
+    assert(PyGILState_Check());
+
+    /* Call PySys_Audit() in the context of the current thread state,
+       even if tstate is not the current thread state. */
     if (PySys_Audit("sys.setprofile", NULL) < 0) {
-        return;
+        return -1;
     }
 
-    PyThreadState *tstate = _PyThreadState_GET();
-    PyObject *temp = tstate->c_profileobj;
-    Py_XINCREF(arg);
+    PyObject *profileobj = tstate->c_profileobj;
+
     tstate->c_profilefunc = NULL;
     tstate->c_profileobj = NULL;
-    /* Must make sure that tracing is not ignored if 'temp' is freed */
+    /* Must make sure that tracing is not ignored if 'profileobj' is freed */
     tstate->use_tracing = tstate->c_tracefunc != NULL;
-    Py_XDECREF(temp);
-    tstate->c_profilefunc = func;
+    Py_XDECREF(profileobj);
+
+    Py_XINCREF(arg);
     tstate->c_profileobj = arg;
+    tstate->c_profilefunc = func;
+
     /* Flag that tracing or profiling is turned on */
     tstate->use_tracing = (func != NULL) || (tstate->c_tracefunc != NULL);
+    return 0;
 }
 
 void
-PyEval_SetTrace(Py_tracefunc func, PyObject *arg)
+PyEval_SetProfile(Py_tracefunc func, PyObject *arg)
+{
+    PyThreadState *tstate = _PyThreadState_GET();
+    (void)_PyEval_SetProfile(tstate, func, arg);
+}
+
+int
+_PyEval_SetTrace(PyThreadState *tstate, Py_tracefunc func, PyObject *arg)
 {
+    assert(tstate != NULL);
+    /* The caller must hold the GIL */
+    assert(PyGILState_Check());
+
+    /* Call PySys_Audit() in the context of the current thread state,
+       even if tstate is not the current thread state. */
     if (PySys_Audit("sys.settrace", NULL) < 0) {
-        return;
+        return -1;
     }
 
-    _PyRuntimeState *runtime = &_PyRuntime;
-    PyThreadState *tstate = _PyRuntimeState_GetThreadState(runtime);
-    PyObject *temp = tstate->c_traceobj;
-    runtime->ceval.tracing_possible += (func != NULL) - (tstate->c_tracefunc != NULL);
-    Py_XINCREF(arg);
+    struct _ceval_runtime_state *ceval = &tstate->interp->runtime->ceval;
+    PyObject *traceobj = tstate->c_traceobj;
+    ceval->tracing_possible += (func != NULL) - (tstate->c_tracefunc != NULL);
+
     tstate->c_tracefunc = NULL;
     tstate->c_traceobj = NULL;
-    /* Must make sure that profiling is not ignored if 'temp' is freed */
-    tstate->use_tracing = tstate->c_profilefunc != NULL;
-    Py_XDECREF(temp);
-    tstate->c_tracefunc = func;
+    /* Must make sure that profiling is not ignored if 'traceobj' is freed */
+    tstate->use_tracing = (tstate->c_profilefunc != NULL);
+    Py_XDECREF(traceobj);
+
+    Py_XINCREF(arg);
     tstate->c_traceobj = arg;
+    tstate->c_tracefunc = func;
+
     /* Flag that tracing or profiling is turned on */
     tstate->use_tracing = ((func != NULL)
                            || (tstate->c_profilefunc != NULL));
+
+    return 0;
+}
+
+void
+PyEval_SetTrace(Py_tracefunc func, PyObject *arg)
+{
+    PyThreadState *tstate = _PyThreadState_GET();
+    (void)_PyEval_SetTrace(tstate, func, arg);
 }
 
+
 void
 _PyEval_SetCoroutineOriginTrackingDepth(PyThreadState *tstate, int new_depth)
 {