bpo-28411: Support other mappings in PyInterpreterState.modules. (#3593)

The concrete PyDict_* API is used to interact with PyInterpreterState.modules in a number of places. This isn't compatible with all dict subclasses, nor with other Mapping implementations. This patch switches the concrete API usage to the corresponding abstract API calls.

We also add a PyImport_GetModule() function (and some other helpers) to reduce a bunch of code duplication.

1 files changed, 3 insertions, 8 deletions

diff --git a/Python/pylifecycle.c b/Python/pylifecycle.c
index 5c8cf5b9bd..7adbc29406 100644
--- a/Python/pylifecycle.c
+++ b/Python/pylifecycle.c
@@ -42,6 +42,7 @@ _Py_IDENTIFIER(name);
 _Py_IDENTIFIER(stdin);
 _Py_IDENTIFIER(stdout);
 _Py_IDENTIFIER(stderr);
+_Py_IDENTIFIER(threading);
 
 #ifdef __cplusplus
 extern "C" {
@@ -283,7 +284,6 @@ initimport(PyInterpreterState *interp, PyObject *sysmod)
 {
     PyObject *importlib;
     PyObject *impmod;
-    PyObject *sys_modules;
     PyObject *value;
 
     /* Import _importlib through its frozen version, _frozen_importlib. */
@@ -314,11 +314,7 @@ initimport(PyInterpreterState *interp, PyObject *sysmod)
     else if (Py_VerboseFlag) {
         PySys_FormatStderr("import _imp # builtin\n");
     }
-    sys_modules = PyImport_GetModuleDict();
-    if (Py_VerboseFlag) {
-        PySys_FormatStderr("import sys # builtin\n");
-    }
-    if (PyDict_SetItemString(sys_modules, "_imp", impmod) < 0) {
+    if (_PyImport_SetModuleString("_imp", impmod) < 0) {
         Py_FatalError("Py_Initialize: can't save _imp to sys.modules");
     }
 
@@ -1916,8 +1912,7 @@ wait_for_thread_shutdown(void)
 {
     _Py_IDENTIFIER(_shutdown);
     PyObject *result;
-    PyObject *modules = PyImport_GetModuleDict();
-    PyObject *threading = PyMapping_GetItemString(modules, "threading");
+    PyObject *threading = _PyImport_GetModuleId(&PyId_threading);
     if (threading == NULL) {
         /* threading not imported */
         PyErr_Clear();