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gh-98257: Make _PyEval_SetTrace() reentrant (#98258)

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Make sys.setprofile() and sys.settrace() functions reentrant.  They
can no long fail with: RuntimeError("Cannot install a trace function
while another trace function is being installed").

Make _PyEval_SetTrace() and _PyEval_SetProfile() functions reentrant,
rather than detecting and rejecting reentrant calls. Only delete the
reference to function arguments once the new function is fully set,
when a reentrant call is safe. Call also _PySys_Audit() earlier.
This commit is contained in:
Victor Stinner 2022-10-20 00:31:47 +02:00 • committed by GitHub
parent 4bd63f66cd
commit a8fe4bbd6b
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GPG key ID: 4AEE18F83AFDEB23
4 changed files with 20 additions and 56 deletions
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57
Python/ceval.c
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@ -6343,38 +6343,23 @@ _PyEval_SetProfile(PyThreadState *tstate, Py_tracefunc func, PyObject *arg)
/* The caller must hold the GIL */
assert(PyGILState_Check());
static int reentrant = 0;
if (reentrant) {
_PyErr_SetString(tstate, PyExc_RuntimeError, "Cannot install a profile function "
"while another profile function is being installed");
reentrant = 0;
return -1;
}
reentrant = 1;
/* Call _PySys_Audit() in the context of the current thread state,
even if tstate is not the current thread state. */
PyThreadState *current_tstate = _PyThreadState_GET();
if (_PySys_Audit(current_tstate, "sys.setprofile", NULL) < 0) {
reentrant = 0;
return -1;
}
PyObject *profileobj = tstate->c_profileobj;
tstate->c_profilefunc = NULL;
tstate->c_profileobj = NULL;
/* Must make sure that tracing is not ignored if 'profileobj' is freed */
_PyThreadState_UpdateTracingState(tstate);
Py_XDECREF(profileobj);
Py_XINCREF(arg);
tstate->c_profileobj = arg;
tstate->c_profilefunc = func;
PyObject *old_profileobj = tstate->c_profileobj;
tstate->c_profileobj = Py_XNewRef(arg);
/* Flag that tracing or profiling is turned on */
_PyThreadState_UpdateTracingState(tstate);
reentrant = 0;
// gh-98257: Only call Py_XDECREF() once the new profile function is fully
// set, so it's safe to call sys.setprofile() again (reentrant call).
Py_XDECREF(old_profileobj);
return 0;
}
@ -6416,39 +6401,23 @@ _PyEval_SetTrace(PyThreadState *tstate, Py_tracefunc func, PyObject *arg)
/* The caller must hold the GIL */
assert(PyGILState_Check());
static int reentrant = 0;
if (reentrant) {
_PyErr_SetString(tstate, PyExc_RuntimeError, "Cannot install a trace function "
"while another trace function is being installed");
reentrant = 0;
return -1;
}
reentrant = 1;
/* Call _PySys_Audit() in the context of the current thread state,
even if tstate is not the current thread state. */
PyThreadState *current_tstate = _PyThreadState_GET();
if (_PySys_Audit(current_tstate, "sys.settrace", NULL) < 0) {
reentrant = 0;
return -1;
}
PyObject *traceobj = tstate->c_traceobj;
tstate->c_tracefunc = NULL;
tstate->c_traceobj = NULL;
/* Must make sure that profiling is not ignored if 'traceobj' is freed */
_PyThreadState_UpdateTracingState(tstate);
Py_XINCREF(arg);
Py_XDECREF(traceobj);
tstate->c_traceobj = arg;
tstate->c_tracefunc = func;
PyObject *old_traceobj = tstate->c_traceobj;
tstate->c_traceobj = Py_XNewRef(arg);
/* Flag that tracing or profiling is turned on */
_PyThreadState_UpdateTracingState(tstate);
reentrant = 0;
// gh-98257: Only call Py_XDECREF() once the new trace function is fully
// set, so it's safe to call sys.settrace() again (reentrant call).
Py_XDECREF(old_traceobj);
return 0;
}