gh-128911: Add PyImport_ImportModuleAttr() function (#128912)

Add PyImport_ImportModuleAttr() and
PyImport_ImportModuleAttrString() functions.

* Add unit tests.
* Replace _PyImport_GetModuleAttr()
  with PyImport_ImportModuleAttr().
* Replace _PyImport_GetModuleAttrString()
  with PyImport_ImportModuleAttrString().
* Remove "pycore_import.h" includes, no longer needed.

Author: vstinner

Doc/c-api/import.rst

@@ -325,3 +325,24 @@ Importing Modules
    If Python is initialized multiple times, :c:func:`PyImport_AppendInittab` or
    :c:func:`PyImport_ExtendInittab` must be called before each Python
    initialization.
+
+
+.. c:function:: PyObject* PyImport_ImportModuleAttr(PyObject *mod_name, PyObject *attr_name)
+
+   Import the module *mod_name* and get its attribute *attr_name*.
+
+   Names must be Python :class:`str` objects.
+
+   Helper function combining :c:func:`PyImport_Import` and
+   :c:func:`PyObject_GetAttr`. For example, it can raise :exc:`ImportError` if
+   the module is not found, and :exc:`AttributeError` if the attribute doesn't
+   exist.
+
+   .. versionadded:: 3.14
+
+.. c:function:: PyObject* PyImport_ImportModuleAttrString(const char *mod_name, const char *attr_name)
+
+   Similar to :c:func:`PyImport_ImportModuleAttr`, but names are UTF-8 encoded
+   strings instead of Python :class:`str` objects.
+
+   .. versionadded:: 3.14

Doc/data/refcounts.dat

@@ -3052,3 +3052,11 @@ _Py_c_quot:Py_complex:divisor::
 _Py_c_sum:Py_complex:::
 _Py_c_sum:Py_complex:left::
 _Py_c_sum:Py_complex:right::
+
+PyImport_ImportModuleAttr:PyObject*::+1:
+PyImport_ImportModuleAttr:PyObject*:mod_name:0:
+PyImport_ImportModuleAttr:PyObject*:attr_name:0:
+
+PyImport_ImportModuleAttrString:PyObject*::+1:
+PyImport_ImportModuleAttrString:const char *:mod_name::
+PyImport_ImportModuleAttrString:const char *:attr_name::

Doc/whatsnew/3.14.rst

@@ -1322,6 +1322,11 @@ New features
 * Add :c:func:`PyUnstable_IsImmortal` for determining whether an object is :term:`immortal`,
   for debugging purposes.
 
+* Add :c:func:`PyImport_ImportModuleAttr` and
+  :c:func:`PyImport_ImportModuleAttrString` helper functions to import a module
+  and get an attribute of the module.
+  (Contributed by Victor Stinner in :gh:`128911`.)
+
 
 Limited C API changes
 ---------------------

Include/cpython/import.h

@@ -21,3 +21,10 @@ struct _frozen {
    collection of frozen modules: */
 
 PyAPI_DATA(const struct _frozen *) PyImport_FrozenModules;
+
+PyAPI_FUNC(PyObject*) PyImport_ImportModuleAttr(
+    PyObject *mod_name,
+    PyObject *attr_name);
+PyAPI_FUNC(PyObject*) PyImport_ImportModuleAttrString(
+    const char *mod_name,
+    const char *attr_name);

Include/internal/pycore_import.h

@@ -31,12 +31,6 @@ extern int _PyImport_FixupBuiltin(
     PyObject *modules
     );
 
-// Export for many shared extensions, like '_json'
-PyAPI_FUNC(PyObject*) _PyImport_GetModuleAttr(PyObject *, PyObject *);
-
-// Export for many shared extensions, like '_datetime'
-PyAPI_FUNC(PyObject*) _PyImport_GetModuleAttrString(const char *, const char *);
-
 
 struct _import_runtime_state {
     /* The builtin modules (defined in config.c). */

Lib/test/test_capi/test_import.py

@@ -7,6 +7,7 @@
 from test.support import import_helper
 from test.support.warnings_helper import check_warnings
 
+_testcapi = import_helper.import_module('_testcapi')
 _testlimitedcapi = import_helper.import_module('_testlimitedcapi')
 NULL = None
 
@@ -148,7 +149,7 @@ def check_frozen_import(self, import_frozen_module):
         try:
             self.assertEqual(import_frozen_module('zipimport'), 1)
 
-            # import zipimport again
+            # import zipimport again
             self.assertEqual(import_frozen_module('zipimport'), 1)
         finally:
             sys.modules['zipimport'] = old_zipimport
@@ -317,6 +318,59 @@ def test_executecodemoduleobject(self):
         # CRASHES execute_code_func(NULL, code, NULL, NULL)
         # CRASHES execute_code_func(name, NULL, NULL, NULL)
 
+    def check_importmoduleattr(self, importmoduleattr):
+        self.assertIs(importmoduleattr('sys', 'argv'), sys.argv)
+        self.assertIs(importmoduleattr('types', 'ModuleType'), types.ModuleType)
+
+        # module name containing a dot
+        attr = importmoduleattr('email.message', 'Message')
+        from email.message import Message
+        self.assertIs(attr, Message)
+
+        with self.assertRaises(ImportError):
+            # nonexistent module
+            importmoduleattr('nonexistentmodule', 'attr')
+        with self.assertRaises(AttributeError):
+            # nonexistent attribute
+            importmoduleattr('sys', 'nonexistentattr')
+        with self.assertRaises(AttributeError):
+            # attribute name containing a dot
+            importmoduleattr('sys', 'implementation.name')
+
+    def test_importmoduleattr(self):
+        # Test PyImport_ImportModuleAttr()
+        importmoduleattr = _testcapi.PyImport_ImportModuleAttr
+        self.check_importmoduleattr(importmoduleattr)
+
+        # Invalid module name type
+        for mod_name in (object(), 123, b'bytes'):
+            with self.subTest(mod_name=mod_name):
+                with self.assertRaises(TypeError):
+                    importmoduleattr(mod_name, "attr")
+
+        # Invalid attribute name type
+        for attr_name in (object(), 123, b'bytes'):
+            with self.subTest(attr_name=attr_name):
+                with self.assertRaises(TypeError):
+                    importmoduleattr("sys", attr_name)
+
+        with self.assertRaises(SystemError):
+            importmoduleattr(NULL, "argv")
+        # CRASHES importmoduleattr("sys", NULL)
+
+    def test_importmoduleattrstring(self):
+        # Test PyImport_ImportModuleAttrString()
+        importmoduleattr = _testcapi.PyImport_ImportModuleAttrString
+        self.check_importmoduleattr(importmoduleattr)
+
+        with self.assertRaises(UnicodeDecodeError):
+            importmoduleattr(b"sys\xff", "argv")
+        with self.assertRaises(UnicodeDecodeError):
+            importmoduleattr("sys", b"argv\xff")
+
+        # CRASHES importmoduleattr(NULL, "argv")
+        # CRASHES importmoduleattr("sys", NULL)
+
     # TODO: test PyImport_GetImporter()
     # TODO: test PyImport_ReloadModule()
     # TODO: test PyImport_ExtendInittab()

Misc/NEWS.d/next/C_API/2025-01-16-12-47-01.gh-issue-128911.mHVJ4x.rst

@@ -0,0 +1,3 @@
+Add :c:func:`PyImport_ImportModuleAttr` and :c:func:`PyImport_ImportModuleAttrString`
+helper functions to import a module and get an attribute of the module. Patch
+by Victor Stinner.

Modules/Setup.stdlib.in

@@ -162,7 +162,7 @@
 @MODULE__XXTESTFUZZ_TRUE@_xxtestfuzz _xxtestfuzz/_xxtestfuzz.c _xxtestfuzz/fuzzer.c
 @MODULE__TESTBUFFER_TRUE@_testbuffer _testbuffer.c
 @MODULE__TESTINTERNALCAPI_TRUE@_testinternalcapi _testinternalcapi.c _testinternalcapi/test_lock.c _testinternalcapi/pytime.c _testinternalcapi/set.c _testinternalcapi/test_critical_sections.c
-@MODULE__TESTCAPI_TRUE@_testcapi _testcapimodule.c _testcapi/vectorcall.c _testcapi/heaptype.c _testcapi/abstract.c _testcapi/unicode.c _testcapi/dict.c _testcapi/set.c _testcapi/list.c _testcapi/tuple.c _testcapi/getargs.c _testcapi/datetime.c _testcapi/docstring.c _testcapi/mem.c _testcapi/watchers.c _testcapi/long.c _testcapi/float.c _testcapi/complex.c _testcapi/numbers.c _testcapi/structmember.c _testcapi/exceptions.c _testcapi/code.c _testcapi/buffer.c _testcapi/pyatomic.c _testcapi/run.c _testcapi/file.c _testcapi/codec.c _testcapi/immortal.c _testcapi/gc.c _testcapi/hash.c _testcapi/time.c _testcapi/bytes.c _testcapi/object.c _testcapi/monitoring.c  _testcapi/config.c
+@MODULE__TESTCAPI_TRUE@_testcapi _testcapimodule.c _testcapi/vectorcall.c _testcapi/heaptype.c _testcapi/abstract.c _testcapi/unicode.c _testcapi/dict.c _testcapi/set.c _testcapi/list.c _testcapi/tuple.c _testcapi/getargs.c _testcapi/datetime.c _testcapi/docstring.c _testcapi/mem.c _testcapi/watchers.c _testcapi/long.c _testcapi/float.c _testcapi/complex.c _testcapi/numbers.c _testcapi/structmember.c _testcapi/exceptions.c _testcapi/code.c _testcapi/buffer.c _testcapi/pyatomic.c _testcapi/run.c _testcapi/file.c _testcapi/codec.c _testcapi/immortal.c _testcapi/gc.c _testcapi/hash.c _testcapi/time.c _testcapi/bytes.c _testcapi/object.c _testcapi/monitoring.c _testcapi/config.c _testcapi/import.c
 @MODULE__TESTLIMITEDCAPI_TRUE@_testlimitedcapi _testlimitedcapi.c _testlimitedcapi/abstract.c _testlimitedcapi/bytearray.c _testlimitedcapi/bytes.c _testlimitedcapi/codec.c _testlimitedcapi/complex.c _testlimitedcapi/dict.c _testlimitedcapi/eval.c _testlimitedcapi/float.c _testlimitedcapi/heaptype_relative.c _testlimitedcapi/import.c _testlimitedcapi/list.c _testlimitedcapi/long.c _testlimitedcapi/object.c _testlimitedcapi/pyos.c _testlimitedcapi/set.c _testlimitedcapi/sys.c _testlimitedcapi/tuple.c _testlimitedcapi/unicode.c _testlimitedcapi/vectorcall_limited.c _testlimitedcapi/version.c
 @MODULE__TESTCLINIC_TRUE@_testclinic _testclinic.c
 @MODULE__TESTCLINIC_LIMITED_TRUE@_testclinic_limited _testclinic_limited.c

Modules/_ctypes/callbacks.c

@@ -492,7 +492,7 @@ long Call_GetClassObject(REFCLSID rclsid, REFIID riid, LPVOID *ppv)
     if (context == NULL)
         context = PyUnicode_InternFromString("_ctypes.DllGetClassObject");
 
-    func = _PyImport_GetModuleAttrString("ctypes", "DllGetClassObject");
+    func = PyImport_ImportModuleAttrString("ctypes", "DllGetClassObject");
     if (!func) {
         PyErr_WriteUnraisable(context ? context : Py_None);
         /* There has been a warning before about this already */

Modules/_ctypes/stgdict.c

@@ -257,7 +257,7 @@ PyCStructUnionType_update_stginfo(PyObject *type, PyObject *fields, int isStruct
         goto error;
     }
 
-    PyObject *layout_func = _PyImport_GetModuleAttrString("ctypes._layout",
+    PyObject *layout_func = PyImport_ImportModuleAttrString("ctypes._layout",
                                                           "get_layout");
     if (!layout_func) {
         goto error;