gh-128911: Add PyImport_ImportModuleAttr() function

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_GetModuleAttr(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_GetModuleAttrString(const char *mod_name, const char *attr_name)
+
+   Similar to :c:func:`PyImport_GetModuleAttr`, 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_GetModuleAttr:PyObject*::+1:
+PyImport_GetModuleAttr:PyObject*:mod_name:0:
+PyImport_GetModuleAttr:PyObject*:attr_name:0:
+
+PyImport_GetModuleAttrString:PyObject*::+1:
+PyImport_GetModuleAttrString:const char *:mod_name::
+PyImport_GetModuleAttrString:const char *:attr_name::

Doc/whatsnew/3.14.rst

@@ -1301,6 +1301,11 @@ New features
   bit-packing Python version numbers.
   (Contributed by Petr Viktorin in :gh:`128629`.)
 
+* Add :c:func:`PyImport_GetModuleAttr` and
+  :c:func:`PyImport_GetModuleAttrString` helper functions to import a module
+  and get an attribute of the module.
+  (Contributed by Victor Stinner in :gh:`128911`.)
+
 
 Porting to Python 3.14
 ----------------------

Include/cpython/import.h

@@ -23,3 +23,10 @@ struct _frozen {
    collection of frozen modules: */
 
 PyAPI_DATA(const struct _frozen *) PyImport_FrozenModules;
+
+PyAPI_FUNC(PyObject*) PyImport_GetModuleAttr(
+    PyObject *mod_name,
+    PyObject *attr_name);
+PyAPI_FUNC(PyObject*) PyImport_GetModuleAttrString(
+    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
 
@@ -317,6 +318,44 @@ def test_executecodemoduleobject(self):
         # CRASHES execute_code_func(NULL, code, NULL, NULL)
         # CRASHES execute_code_func(name, NULL, NULL, NULL)
 
+    def check_getmoduleattr(self, getmoduleattr):
+        self.assertIs(getmoduleattr('sys', 'argv'), sys.argv)
+        self.assertIs(getmoduleattr('types', 'ModuleType'), types.ModuleType)
+
+    def test_getmoduleattr(self):
+        # Test PyImport_GetModuleAttr()
+        getmoduleattr = _testcapi.PyImport_GetModuleAttr
+        self.check_getmoduleattr(getmoduleattr)
+
+        # Invalid module name type
+        for mod_name in (object(), 123, b'bytes'):
+            with self.subTest(mod_name=mod_name):
+                with self.assertRaises(TypeError):
+                    getmoduleattr(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):
+                    getmoduleattr("sys", attr_name)
+
+        with self.assertRaises(SystemError):
+            getmoduleattr(NULL, "argv")
+        # CRASHES getmoduleattr("sys", NULL)
+
+    def test_getmoduleattrstring(self):
+        # Test PyImport_GetModuleAttrString()
+        getmoduleattr = _testcapi.PyImport_GetModuleAttrString
+        self.check_getmoduleattr(getmoduleattr)
+
+        with self.assertRaises(UnicodeDecodeError):
+            getmoduleattr(b"sys\xff", "argv")
+        with self.assertRaises(UnicodeDecodeError):
+            getmoduleattr("sys", b"argv\xff")
+
+        # CRASHES getmoduleattr(NULL, "argv")
+        # CRASHES getmoduleattr("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_GetModuleAttr` and :c:func:`PyImport_GetModuleAttrString`
+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_GetModuleAttrString("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_GetModuleAttrString("ctypes._layout",
                                                           "get_layout");
     if (!layout_func) {
         goto error;

Modules/_cursesmodule.c

@@ -226,7 +226,7 @@ _PyCursesCheckFunction(int called, const char *funcname)
     if (called == TRUE) {
         return 1;
     }
-    PyObject *exc = _PyImport_GetModuleAttrString("_curses", "error");
+    PyObject *exc = PyImport_GetModuleAttrString("_curses", "error");
     if (exc != NULL) {
         PyErr_Format(exc, "must call %s() first", funcname);
         Py_DECREF(exc);

Modules/_datetimemodule.c

@@ -1839,7 +1839,7 @@ wrap_strftime(PyObject *object, PyObject *format, PyObject *timetuple,
     assert(object && format && timetuple);
     assert(PyUnicode_Check(format));
 
-    PyObject *strftime = _PyImport_GetModuleAttrString("time", "strftime");
+    PyObject *strftime = PyImport_GetModuleAttrString("time", "strftime");
     if (strftime == NULL) {
         return NULL;
     }
@@ -2021,7 +2021,7 @@ static PyObject *
 time_time(void)
 {
     PyObject *result = NULL;
-    PyObject *time = _PyImport_GetModuleAttrString("time", "time");
+    PyObject *time = PyImport_GetModuleAttrString("time", "time");
 
     if (time != NULL) {
         result = PyObject_CallNoArgs(time);
@@ -2039,7 +2039,7 @@ build_struct_time(int y, int m, int d, int hh, int mm, int ss, int dstflag)
     PyObject *struct_time;
     PyObject *result;
 
-    struct_time = _PyImport_GetModuleAttrString("time", "struct_time");
+    struct_time = PyImport_GetModuleAttrString("time", "struct_time");
     if (struct_time == NULL) {
         return NULL;
     }

Modules/_decimal/_decimal.c

@@ -3464,7 +3464,7 @@ pydec_format(PyObject *dec, PyObject *context, PyObject *fmt, decimal_state *sta
     PyObject *u;
 
     if (state->PyDecimal == NULL) {
-        state->PyDecimal = _PyImport_GetModuleAttrString("_pydecimal", "Decimal");
+        state->PyDecimal = PyImport_GetModuleAttrString("_pydecimal", "Decimal");
         if (state->PyDecimal == NULL) {
             return NULL;
         }

Modules/_elementtree.c

@@ -16,7 +16,6 @@
 #endif
 
 #include "Python.h"
-#include "pycore_import.h"        // _PyImport_GetModuleAttrString()
 #include "pycore_pyhash.h"        // _Py_HashSecret
 
 #include <stddef.h>               // offsetof()
@@ -4393,7 +4392,7 @@ module_exec(PyObject *m)
     CREATE_TYPE(m, st->Element_Type, &element_spec);
     CREATE_TYPE(m, st->XMLParser_Type, &xmlparser_spec);
 
-    st->deepcopy_obj = _PyImport_GetModuleAttrString("copy", "deepcopy");
+    st->deepcopy_obj = PyImport_GetModuleAttrString("copy", "deepcopy");
     if (st->deepcopy_obj == NULL) {
         goto error;
     }
@@ -4403,7 +4402,7 @@ module_exec(PyObject *m)
         goto error;
 
     /* link against pyexpat */
-    if (!(st->expat_capsule = _PyImport_GetModuleAttrString("pyexpat", "expat_CAPI")))
+    if (!(st->expat_capsule = PyImport_GetModuleAttrString("pyexpat", "expat_CAPI")))
         goto error;
     if (!(st->expat_capi = PyCapsule_GetPointer(st->expat_capsule, PyExpat_CAPSULE_NAME)))
         goto error;

Modules/_json.c

@@ -302,7 +302,7 @@ raise_errmsg(const char *msg, PyObject *s, Py_ssize_t end)
     /* Use JSONDecodeError exception to raise a nice looking ValueError subclass */
     _Py_DECLARE_STR(json_decoder, "json.decoder");
     PyObject *JSONDecodeError =
-         _PyImport_GetModuleAttr(&_Py_STR(json_decoder), &_Py_ID(JSONDecodeError));
+         PyImport_GetModuleAttr(&_Py_STR(json_decoder), &_Py_ID(JSONDecodeError));
     if (JSONDecodeError == NULL) {
         return;
     }

Modules/_lsprof.c

@@ -775,7 +775,7 @@ _lsprof_Profiler_enable_impl(ProfilerObject *self, int subcalls,
         return NULL;
     }
 
-    PyObject* monitoring = _PyImport_GetModuleAttrString("sys", "monitoring");
+    PyObject* monitoring = PyImport_GetModuleAttrString("sys", "monitoring");
     if (!monitoring) {
         return NULL;
     }
@@ -857,7 +857,7 @@ _lsprof_Profiler_disable_impl(ProfilerObject *self)
     }
     if (self->flags & POF_ENABLED) {
         PyObject* result = NULL;
-        PyObject* monitoring = _PyImport_GetModuleAttrString("sys", "monitoring");
+        PyObject* monitoring = PyImport_GetModuleAttrString("sys", "monitoring");
 
         if (!monitoring) {
             return NULL;
@@ -973,7 +973,7 @@ profiler_init_impl(ProfilerObject *self, PyObject *timer, double timeunit,
     Py_XSETREF(self->externalTimer, Py_XNewRef(timer));
     self->tool_id = PY_MONITORING_PROFILER_ID;
 
-    PyObject* monitoring = _PyImport_GetModuleAttrString("sys", "monitoring");
+    PyObject* monitoring = PyImport_GetModuleAttrString("sys", "monitoring");
     if (!monitoring) {
         return -1;
     }

Modules/_operator.c

@@ -1868,7 +1868,7 @@ methodcaller_reduce(methodcallerobject *mc, PyObject *Py_UNUSED(ignored))
         PyObject *constructor;
         PyObject *newargs[2];
 
-        partial = _PyImport_GetModuleAttrString("functools", "partial");
+        partial = PyImport_GetModuleAttrString("functools", "partial");
         if (!partial)
             return NULL;
 

Modules/_pickle.c

@@ -362,7 +362,7 @@ _Pickle_InitState(PickleState *st)
     }
     Py_CLEAR(compat_pickle);
 
-    st->codecs_encode = _PyImport_GetModuleAttrString("codecs", "encode");
+    st->codecs_encode = PyImport_GetModuleAttrString("codecs", "encode");
     if (st->codecs_encode == NULL) {
         goto error;
     }
@@ -373,7 +373,7 @@ _Pickle_InitState(PickleState *st)
         goto error;
     }
 
-    st->partial = _PyImport_GetModuleAttrString("functools", "partial");
+    st->partial = PyImport_GetModuleAttrString("functools", "partial");
     if (!st->partial)
         goto error;
 

Modules/_sqlite/connection.c

@@ -34,7 +34,6 @@
 #include "prepare_protocol.h"
 #include "util.h"
 
-#include "pycore_import.h"        // _PyImport_GetModuleAttrString()
 #include "pycore_modsupport.h"    // _PyArg_NoKeywords()
 #include "pycore_pyerrors.h"      // _PyErr_ChainExceptions1()
 #include "pycore_pylifecycle.h"   // _Py_IsInterpreterFinalizing()
@@ -1995,7 +1994,7 @@ pysqlite_connection_iterdump_impl(pysqlite_Connection *self,
         return NULL;
     }
 
-    PyObject *iterdump = _PyImport_GetModuleAttrString(MODULE_NAME ".dump", "_iterdump");
+    PyObject *iterdump = PyImport_GetModuleAttrString(MODULE_NAME ".dump", "_iterdump");
     if (!iterdump) {
         if (!PyErr_Occurred()) {
             PyErr_SetString(self->OperationalError,

Modules/_sqlite/module.c

@@ -33,8 +33,6 @@
 #include "row.h"
 #include "blob.h"
 
-#include "pycore_import.h"        // _PyImport_GetModuleAttrString()
-
 #if SQLITE_VERSION_NUMBER < 3015002
 #error "SQLite 3.15.2 or higher required"
 #endif
@@ -234,7 +232,7 @@ static int
 load_functools_lru_cache(PyObject *module)
 {
     pysqlite_state *state = pysqlite_get_state(module);
-    state->lru_cache = _PyImport_GetModuleAttrString("functools", "lru_cache");
+    state->lru_cache = PyImport_GetModuleAttrString("functools", "lru_cache");
     if (state->lru_cache == NULL) {
         return -1;
     }

Modules/_sre/sre.c

@@ -1169,7 +1169,7 @@ compile_template(_sremodulestate *module_state,
     /* delegate to Python code */
     PyObject *func = module_state->compile_template;
     if (func == NULL) {
-        func = _PyImport_GetModuleAttrString("re", "_compile_template");
+        func = PyImport_GetModuleAttrString("re", "_compile_template");
         if (func == NULL) {
             return NULL;
         }

Modules/_testcapi/import.c

@@ -0,0 +1,44 @@
+#include "parts.h"
+#include "util.h"
+
+// Test PyImport_GetModuleAttr()
+static PyObject *
+pyimport_getmoduleattr(PyObject *self, PyObject *args)
+{
+    PyObject *mod_name, *attr_name;
+    if (!PyArg_ParseTuple(args, "OO", &mod_name, &attr_name)) {
+        return NULL;
+    }
+    NULLABLE(mod_name);
+    NULLABLE(attr_name);
+
+    return PyImport_GetModuleAttr(mod_name, attr_name);
+}
+
+
+// Test PyImport_GetModuleAttrString()
+static PyObject *
+pyimport_getmoduleattrstring(PyObject *self, PyObject *args)
+{
+    char *mod_name, *attr_name;
+    Py_ssize_t len;
+    if (!PyArg_ParseTuple(args, "z#z#", &mod_name, &len, &attr_name, &len)) {
+        return NULL;
+    }
+
+    return PyImport_GetModuleAttrString(mod_name, attr_name);
+}
+
+
+static PyMethodDef test_methods[] = {
+    {"PyImport_GetModuleAttr", pyimport_getmoduleattr, METH_VARARGS},
+    {"PyImport_GetModuleAttrString", pyimport_getmoduleattrstring, METH_VARARGS},
+    {NULL},
+};
+
+int
+_PyTestCapi_Init_Import(PyObject *m)
+{
+    return PyModule_AddFunctions(m, test_methods);
+}
+

Modules/_testcapi/parts.h

@@ -61,5 +61,6 @@ int _PyTestCapi_Init_Time(PyObject *module);
 int _PyTestCapi_Init_Monitoring(PyObject *module);
 int _PyTestCapi_Init_Object(PyObject *module);
 int _PyTestCapi_Init_Config(PyObject *mod);
+int _PyTestCapi_Init_Import(PyObject *mod);
 
 #endif // Py_TESTCAPI_PARTS_H

Modules/_testcapimodule.c

@@ -4400,6 +4400,9 @@ PyInit__testcapi(void)
     if (_PyTestCapi_Init_Config(m) < 0) {
         return NULL;
     }
+    if (_PyTestCapi_Init_Import(m) < 0) {
+        return NULL;
+    }
 
     PyState_AddModule(m, &_testcapimodule);
     return m;