bpo-41194: The _ast module cannot be loaded more than once (GH-21290)
Fix a crash in the _ast module: it can no longer be loaded more than
once. It now uses a global state rather than a module state.
* Move _ast module state: use a global state instead.
* Set _astmodule.m_size to -1, so the extension cannot be loaded more
than once.
diff --git a/Parser/asdl_c.py b/Parser/asdl_c.py
index 39e216b..f029ca6 100755
--- a/Parser/asdl_c.py
+++ b/Parser/asdl_c.py
@@ -691,7 +691,7 @@
Py_ssize_t i, numfields = 0;
int res = -1;
PyObject *key, *value, *fields;
- astmodulestate *state = astmodulestate_global;
+ astmodulestate *state = get_global_ast_state();
if (_PyObject_LookupAttr((PyObject*)Py_TYPE(self), state->_fields, &fields) < 0) {
goto cleanup;
}
@@ -760,7 +760,7 @@
static PyObject *
ast_type_reduce(PyObject *self, PyObject *unused)
{
- astmodulestate *state = astmodulestate_global;
+ astmodulestate *state = get_global_ast_state();
PyObject *dict;
if (_PyObject_LookupAttr(self, state->__dict__, &dict) < 0) {
return NULL;
@@ -971,19 +971,7 @@
self.emit("static int init_types(void)",0)
self.emit("{", 0)
- self.emit("PyObject *module = PyState_FindModule(&_astmodule);", 1)
- self.emit("if (module == NULL) {", 1)
- self.emit("module = PyModule_Create(&_astmodule);", 2)
- self.emit("if (!module) {", 2)
- self.emit("return 0;", 3)
- self.emit("}", 2)
- self.emit("if (PyState_AddModule(module, &_astmodule) < 0) {", 2)
- self.emit("return 0;", 3)
- self.emit("}", 2)
- self.emit("}", 1)
- self.emit("", 0)
-
- self.emit("astmodulestate *state = get_ast_state(module);", 1)
+ self.emit("astmodulestate *state = get_global_ast_state();", 1)
self.emit("if (state->initialized) return 1;", 1)
self.emit("if (init_identifiers(state) < 0) return 0;", 1)
self.emit("state->AST_type = PyType_FromSpec(&AST_type_spec);", 1)
@@ -1061,13 +1049,16 @@
self.emit("PyMODINIT_FUNC", 0)
self.emit("PyInit__ast(void)", 0)
self.emit("{", 0)
- self.emit("PyObject *m;", 1)
- self.emit("if (!init_types()) return NULL;", 1)
- self.emit('m = PyState_FindModule(&_astmodule);', 1)
- self.emit("if (!m) return NULL;", 1)
+ self.emit("PyObject *m = PyModule_Create(&_astmodule);", 1)
+ self.emit("if (!m) {", 1)
+ self.emit("return NULL;", 2)
+ self.emit("}", 1)
self.emit('astmodulestate *state = get_ast_state(m);', 1)
self.emit('', 1)
+ self.emit("if (!init_types()) {", 1)
+ self.emit("goto error;", 2)
+ self.emit("}", 1)
self.emit('if (PyModule_AddObject(m, "AST", state->AST_type) < 0) {', 1)
self.emit('goto error;', 2)
self.emit('}', 1)
@@ -1084,6 +1075,7 @@
for dfn in mod.dfns:
self.visit(dfn)
self.emit("return m;", 1)
+ self.emit("", 0)
self.emit("error:", 0)
self.emit("Py_DECREF(m);", 1)
self.emit("return NULL;", 1)
@@ -1263,9 +1255,11 @@
CODE = """
PyObject* PyAST_mod2obj(mod_ty t)
{
- if (!init_types())
+ if (!init_types()) {
return NULL;
- astmodulestate *state = astmodulestate_global;
+ }
+
+ astmodulestate *state = get_global_ast_state();
return ast2obj_mod(state, t);
}
@@ -1279,7 +1273,7 @@
return NULL;
}
- astmodulestate *state = astmodulestate_global;
+ astmodulestate *state = get_global_ast_state();
PyObject *req_type[3];
req_type[0] = state->Module_type;
req_type[1] = state->Expression_type;
@@ -1287,8 +1281,9 @@
assert(0 <= mode && mode <= 2);
- if (!init_types())
+ if (!init_types()) {
return NULL;
+ }
isinstance = PyObject_IsInstance(ast, req_type[mode]);
if (isinstance == -1)
@@ -1308,9 +1303,11 @@
int PyAST_Check(PyObject* obj)
{
- if (!init_types())
+ if (!init_types()) {
return -1;
- astmodulestate *state = astmodulestate_global;
+ }
+
+ astmodulestate *state = get_global_ast_state();
return PyObject_IsInstance(obj, state->AST_type);
}
"""
@@ -1361,13 +1358,12 @@
f.write(' PyObject *' + s + ';\n')
f.write('} astmodulestate;\n\n')
f.write("""
+static astmodulestate global_ast_state;
+
static astmodulestate *
-get_ast_state(PyObject *module)
+get_ast_state(PyObject *Py_UNUSED(module))
{
- assert(module != NULL);
- void *state = PyModule_GetState(module);
- assert(state != NULL);
- return (astmodulestate *)state;
+ return &global_ast_state;
}
static int astmodule_clear(PyObject *module)
@@ -1396,17 +1392,14 @@
static struct PyModuleDef _astmodule = {
PyModuleDef_HEAD_INIT,
- "_ast",
- NULL,
- sizeof(astmodulestate),
- NULL,
- NULL,
- astmodule_traverse,
- astmodule_clear,
- astmodule_free,
+ .m_name = "_ast",
+ .m_size = -1,
+ .m_traverse = astmodule_traverse,
+ .m_clear = astmodule_clear,
+ .m_free = astmodule_free,
};
-#define astmodulestate_global get_ast_state(PyState_FindModule(&_astmodule))
+#define get_global_ast_state() (&global_ast_state)
""")
f.write('static int init_identifiers(astmodulestate *state)\n')