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gh-109521: Fix obscure cases handling in PyImport_GetImporter() #109522

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Sep 23, 2023
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gh-109521: Fix obscure cases handling in PyImport_GetImporter() #109522

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gh-109521: Fix obscure cases handling in PyImport_GetImporter()
serhiy-storchaka Sep 17, 2023
d6b9a14
Update Misc/NEWS.d/next/C API/2023-09-17-21-47-31.gh-issue-109521.JDF…
serhiy-storchaka Sep 18, 2023
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5 changes: 5 additions & 0 deletions Misc/NEWS.d/next/C API/2023-09-17-21-47-31.gh-issue-109521.JDF6i9.rst
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Original file line number Diff line number Diff line change
@@ -0,0 +1,5 @@
:c:func:`PyImport_GetImporter` now sets RuntimeError if it fails to get
:data:`sys.path_hooks` or :data:`sys.path_importer_cache` or they are not
list and dict correspondingly. Previously it could return NULL without
setting error in obscure cases, crash or raise SystemError if these
attributes have wrong type.
26 changes: 21 additions & 5 deletions Python/import.c
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Original file line number Diff line number Diff line change
Expand Up @@ -2363,9 +2363,14 @@ get_path_importer(PyThreadState *tstate, PyObject *path_importer_cache,
PyObject *importer;
Py_ssize_t j, nhooks;

/* These conditions are the caller's responsibility: */
assert(PyList_Check(path_hooks));
assert(PyDict_Check(path_importer_cache));
if (!PyList_Check(path_hooks)) {
PyErr_SetString(PyExc_RuntimeError, "sys.path_hooks is not a list");
return NULL;
}
if (!PyDict_Check(path_importer_cache)) {
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You might replace PyDict_GetItemWithError() with PyDict_GetItemRef() below to avoid _PyErr_Occurred() call.

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I am going to backport this change.

BTW, I have a separate branch in which most of PyDict_GetItemWithError() are replaced with PyDict_GetItemRef(). I will make a PR or several PRs from it in future.

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I am going to backport this change.

Oh right. In this case, just ignore my remark. It's more a "coding style" change than a fix, the current code is correct.

PyErr_SetString(PyExc_RuntimeError, "sys.path_importer_cache is not a dict");
return NULL;
}

nhooks = PyList_Size(path_hooks);
if (nhooks < 0)
Expand Down Expand Up @@ -2408,11 +2413,22 @@ PyImport_GetImporter(PyObject *path)
{
PyThreadState *tstate = _PyThreadState_GET();
PyObject *path_importer_cache = PySys_GetObject("path_importer_cache");
if (path_importer_cache == NULL) {
PyErr_SetString(PyExc_RuntimeError, "lost sys.path_importer_cache");
return NULL;
}
Py_INCREF(path_importer_cache);
PyObject *path_hooks = PySys_GetObject("path_hooks");
if (path_importer_cache == NULL || path_hooks == NULL) {
if (path_hooks == NULL) {
PyErr_SetString(PyExc_RuntimeError, "lost sys.path_hooks");
Py_DECREF(path_importer_cache);
return NULL;
}
return get_path_importer(tstate, path_importer_cache, path_hooks, path);
Py_INCREF(path_hooks);
PyObject *importer = get_path_importer(tstate, path_importer_cache, path_hooks, path);
Py_DECREF(path_hooks);
Py_DECREF(path_importer_cache);
return importer;
}


Expand Down