gh-128911: Add tests on the PyImport C API

Lib/test/test_capi/test_import.py

@@ -55,9 +55,12 @@ def test_getmodule(self):
 
         nonexistent = 'nonexistent'
         self.assertNotIn(nonexistent, sys.modules)
-        self.assertIsNone(_testlimitedcapi.PyImport_GetModule(nonexistent))
-        self.assertIsNone(_testlimitedcapi.PyImport_GetModule(''))
-        self.assertIsNone(_testlimitedcapi.PyImport_GetModule(object()))
+        for name in (nonexistent, '', object()):
+            with self.subTest(name=name):
+                with self.assertRaises(KeyError):
+                    _testlimitedcapi.PyImport_GetModule(name)
+
+        # CRASHES PyImport_GetModule(NULL)
 
     def check_addmodule(self, add_module, accept_nonstr=False):
         # create a new module
@@ -84,6 +87,8 @@ def test_addmoduleobject(self):
         self.check_addmodule(_testlimitedcapi.PyImport_AddModuleObject,
                              accept_nonstr=True)
 
+        # CRASHES PyImport_AddModuleObject(NULL)
+
     def test_addmodule(self):
         # Test PyImport_AddModule()
         self.check_addmodule(_testlimitedcapi.PyImport_AddModule)
@@ -110,15 +115,22 @@ def test_import(self):
         # Test PyImport_Import()
         self.check_import_func(_testlimitedcapi.PyImport_Import)
 
+        with self.assertRaises(SystemError):
+            _testlimitedcapi.PyImport_Import(NULL)
+
     def test_importmodule(self):
         # Test PyImport_ImportModule()
         self.check_import_func(_testlimitedcapi.PyImport_ImportModule)
 
+        # CRASHES PyImport_ImportModule(NULL)
+
     def test_importmodulenoblock(self):
         # Test deprecated PyImport_ImportModuleNoBlock()
         with check_warnings(('', DeprecationWarning)):
             self.check_import_func(_testlimitedcapi.PyImport_ImportModuleNoBlock)
 
+        # CRASHES PyImport_ImportModuleNoBlock(NULL)
+
     def check_frozen_import(self, import_frozen_module):
         # Importing a frozen module executes its code, so start by unloading
         # the module to execute the code in a new (temporary) module.
@@ -199,12 +211,19 @@ def test_executecodemodule(self):
 
     def test_executecodemoduleex(self):
         # Test PyImport_ExecCodeModuleEx()
-        pathname = os.path.abspath('pathname')
 
-        def execute_code(name, code):
+        # Test NULL path (it should not crash)
+        def execute_code1(name, code):
+            return _testlimitedcapi.PyImport_ExecCodeModuleEx(name, code,
+                                                              NULL)
+        self.check_executecodemodule(execute_code1)
+
+        # Test non-NULL path
+        pathname = os.path.abspath('pathname')
+        def execute_code2(name, code):
             return _testlimitedcapi.PyImport_ExecCodeModuleEx(name, code,
                                                               pathname)
-        self.check_executecodemodule(execute_code, pathname)
+        self.check_executecodemodule(execute_code2, pathname)
 
     def check_executecode_pathnames(self, execute_code_func):
         # Test non-NULL pathname and NULL cpathname

Modules/_testlimitedcapi/import.c

@@ -39,9 +39,11 @@ static PyObject *
 pyimport_getmodule(PyObject *Py_UNUSED(module), PyObject *name)
 {
     assert(!PyErr_Occurred());
+    NULLABLE(name);
     PyObject *module = PyImport_GetModule(name);
     if (module == NULL && !PyErr_Occurred()) {
-        Py_RETURN_NONE;
+        PyErr_SetString(PyExc_KeyError, "PyImport_GetModule() returned NULL");
+        return NULL;
     }
     return module;
 }
@@ -51,6 +53,7 @@ pyimport_getmodule(PyObject *Py_UNUSED(module), PyObject *name)
 static PyObject *
 pyimport_addmoduleobject(PyObject *Py_UNUSED(module), PyObject *name)
 {
+    NULLABLE(name);
     return Py_XNewRef(PyImport_AddModuleObject(name));
 }
 
@@ -60,7 +63,7 @@ static PyObject *
 pyimport_addmodule(PyObject *Py_UNUSED(module), PyObject *args)
 {
     const char *name;
-    if (!PyArg_ParseTuple(args, "s", &name)) {
+    if (!PyArg_ParseTuple(args, "z", &name)) {
         return NULL;
     }
 
@@ -85,6 +88,7 @@ pyimport_addmoduleref(PyObject *Py_UNUSED(module), PyObject *args)
 static PyObject *
 pyimport_import(PyObject *Py_UNUSED(module), PyObject *name)
 {
+    NULLABLE(name);
     return PyImport_Import(name);
 }
 
@@ -94,7 +98,7 @@ static PyObject *
 pyimport_importmodule(PyObject *Py_UNUSED(module), PyObject *args)
 {
     const char *name;
-    if (!PyArg_ParseTuple(args, "s", &name)) {
+    if (!PyArg_ParseTuple(args, "z", &name)) {
         return NULL;
     }
 
@@ -107,7 +111,7 @@ static PyObject *
 pyimport_importmodulenoblock(PyObject *Py_UNUSED(module), PyObject *args)
 {
     const char *name;
-    if (!PyArg_ParseTuple(args, "s", &name)) {
+    if (!PyArg_ParseTuple(args, "z", &name)) {
         return NULL;
     }
 
@@ -128,6 +132,9 @@ pyimport_importmoduleex(PyObject *Py_UNUSED(module), PyObject *args)
                           &name, &globals, &locals, &fromlist)) {
         return NULL;
     }
+    NULLABLE(globals);
+    NULLABLE(locals);
+    NULLABLE(fromlist);
 
     return PyImport_ImportModuleEx(name, globals, locals, fromlist);
 }
@@ -144,6 +151,9 @@ pyimport_importmodulelevel(PyObject *Py_UNUSED(module), PyObject *args)
                           &name, &globals, &locals, &fromlist, &level)) {
         return NULL;
     }
+    NULLABLE(globals);
+    NULLABLE(locals);
+    NULLABLE(fromlist);
 
     return PyImport_ImportModuleLevel(name, globals, locals, fromlist, level);
 }
@@ -159,6 +169,10 @@ pyimport_importmodulelevelobject(PyObject *Py_UNUSED(module), PyObject *args)
                           &name, &globals, &locals, &fromlist, &level)) {
         return NULL;
     }
+    NULLABLE(name);
+    NULLABLE(globals);
+    NULLABLE(locals);
+    NULLABLE(fromlist);
 
     return PyImport_ImportModuleLevelObject(name, globals, locals, fromlist, level);
 }
@@ -174,10 +188,7 @@ pyimport_importfrozenmodule(PyObject *Py_UNUSED(module), PyObject *args)
     }
 
     int res = PyImport_ImportFrozenModule(name);
-    if (res < 0) {
-        return NULL;
-    }
-    return PyLong_FromLong(res);
+    RETURN_INT(res);
 }
 
 
@@ -214,7 +225,7 @@ pyimport_executecodemoduleex(PyObject *Py_UNUSED(module), PyObject *args)
     const char *name;
     PyObject *code;
     const char *pathname;
-    if (!PyArg_ParseTuple(args, "sOs", &name, &code, &pathname)) {
+    if (!PyArg_ParseTuple(args, "zOz", &name, &code, &pathname)) {
         return NULL;
     }
 
@@ -230,7 +241,7 @@ pyimport_executecodemodulewithpathnames(PyObject *Py_UNUSED(module), PyObject *a
     PyObject *code;
     const char *pathname;
     const char *cpathname;
-    if (!PyArg_ParseTuple(args, "sOzz", &name, &code, &pathname, &cpathname)) {
+    if (!PyArg_ParseTuple(args, "zOzz", &name, &code, &pathname, &cpathname)) {
         return NULL;
     }