bpo-28411: Remove "modules" field from Py_InterpreterState. (#1638)

sys.modules is the one true source.

1 files changed, 168 insertions, 37 deletions

diff --git a/Python/import.c b/Python/import.c
index f27b7cb010..542a91b9e6 100644
--- a/Python/import.c
+++ b/Python/import.c
@@ -303,10 +303,115 @@ _PyImport_Fini(void)
 PyObject *
 PyImport_GetModuleDict(void)
 {
-    PyInterpreterState *interp = PyThreadState_GET()->interp;
-    if (interp->modules == NULL)
-        Py_FatalError("PyImport_GetModuleDict: no module dictionary!");
-    return interp->modules;
+    PyObject *sysdict = PyThreadState_GET()->interp->sysdict;
+    if (sysdict == NULL) {
+        Py_FatalError("PyImport_GetModuleDict: no sys module!");
+    }
+
+    _Py_IDENTIFIER(modules);
+    PyObject *modules = _PyDict_GetItemId(sysdict, &PyId_modules);
+    if (modules == NULL) {
+        Py_FatalError("lost sys.modules");
+    }
+    return modules;
+}
+
+/* In some corner cases it is important to be sure that the import
+   machinery has been initialized (or not cleaned up yet).  For
+   example, see issue #4236 and PyModule_Create2(). */
+
+int
+_PyImport_IsInitialized(PyInterpreterState *interp)
+{
+    if (interp->sysdict == NULL)
+        return 0;
+    _Py_IDENTIFIER(modules);
+    PyObject *modules = _PyDict_GetItemId(interp->sysdict, &PyId_modules);
+    if (modules == NULL)
+        return 0;
+    return 1;
+}
+
+PyObject *
+_PyImport_GetModule(PyObject *name)
+{
+    PyObject *modules = PyImport_GetModuleDict();
+    if (PyDict_CheckExact(modules)) {
+        return PyDict_GetItem(modules, name);
+    }
+
+    PyObject *mod = PyObject_GetItem(modules, name);
+    // For backward-comaptibility we copy the behavior of PyDict_GetItem().
+    if (PyErr_Occurred()) {
+        PyErr_Clear();
+    }
+    Py_XDECREF(mod);
+    return mod;
+}
+
+PyObject *
+_PyImport_GetModuleWithError(PyObject *name)
+{
+    PyObject *modules = PyImport_GetModuleDict();
+    if (PyDict_CheckExact(modules)) {
+        return PyDict_GetItemWithError(modules, name);
+    }
+
+    PyObject *mod = PyObject_GetItem(modules, name);
+    // For backward-comaptibility we copy the behavior
+    // of PyDict_GetItemWithError().
+    if (PyErr_ExceptionMatches(PyExc_KeyError)) {
+        PyErr_Clear();
+    }
+    return mod;
+}
+
+PyObject *
+_PyImport_GetModuleId(struct _Py_Identifier *nameid)
+{
+    PyObject *name = _PyUnicode_FromId(nameid); /* borrowed */
+    if (name == NULL) {
+        return NULL;
+    }
+    return _PyImport_GetModule(name);
+}
+
+int
+_PyImport_SetModule(PyObject *name, PyObject *m)
+{
+    PyObject *modules = PyImport_GetModuleDict();
+    return PyObject_SetItem(modules, name, m);
+}
+
+int
+_PyImport_SetModuleString(const char *name, PyObject *m)
+{
+    PyObject *modules = PyImport_GetModuleDict();
+    return PyMapping_SetItemString(modules, name, m);
+}
+
+PyObject *
+PyImport_GetModule(PyObject *name)
+{
+    PyObject *m;
+    PyObject *modules = PyImport_GetModuleDict();
+    if (modules == NULL) {
+        PyErr_SetString(PyExc_RuntimeError, "unable to get sys.modules");
+        return NULL;
+    }
+    Py_INCREF(modules);
+    if (PyDict_CheckExact(modules)) {
+        m = PyDict_GetItemWithError(modules, name);  /* borrowed */
+        Py_XINCREF(m);
+    }
+    else {
+        m = PyObject_GetItem(modules, name);
+        if (PyErr_ExceptionMatches(PyExc_KeyError)) {
+            PyErr_Clear();
+        }
+    }
+    Py_DECREF(modules);
+    return m;
 }
 
 
@@ -336,7 +441,7 @@ PyImport_Cleanup(void)
     Py_ssize_t pos;
     PyObject *key, *value, *dict;
     PyInterpreterState *interp = PyThreadState_GET()->interp;
-    PyObject *modules = interp->modules;
+    PyObject *modules = PyImport_GetModuleDict();
     PyObject *weaklist = NULL;
     const char * const *p;
 
@@ -398,7 +503,7 @@ PyImport_Cleanup(void)
             if (Py_VerboseFlag && PyUnicode_Check(key))
                 PySys_FormatStderr("# cleanup[2] removing %U\n", key);
             STORE_MODULE_WEAKREF(key, value);
-            PyDict_SetItem(modules, key, Py_None);
+            PyObject_SetItem(modules, key, Py_None);
         }
     }
 
@@ -465,7 +570,6 @@ PyImport_Cleanup(void)
     /* Clear and delete the modules directory.  Actual modules will
        still be there only if imported during the execution of some
        destructor. */
-    interp->modules = NULL;
     Py_DECREF(modules);
 
     /* Once more */
@@ -524,9 +628,9 @@ PyImport_GetMagicTag(void)
 
 int
 _PyImport_FixupExtensionObject(PyObject *mod, PyObject *name,
-                               PyObject *filename)
+                                 PyObject *filename, PyObject *modules)
 {
-    PyObject *modules, *dict, *key;
+    PyObject *dict, *key;
     struct PyModuleDef *def;
     int res;
     if (extensions == NULL) {
@@ -543,11 +647,10 @@ _PyImport_FixupExtensionObject(PyObject *mod, PyObject *name,
         PyErr_BadInternalCall();
         return -1;
     }
-    modules = PyImport_GetModuleDict();
-    if (PyDict_SetItem(modules, name, mod) < 0)
+    if (PyObject_SetItem(modules, name, mod) < 0)
         return -1;
     if (_PyState_AddModule(mod, def) < 0) {
-        PyDict_DelItem(modules, name);
+        PyMapping_DelItem(modules, name);
         return -1;
     }
     if (def->m_size == -1) {
@@ -575,14 +678,14 @@ _PyImport_FixupExtensionObject(PyObject *mod, PyObject *name,
 }
 
 int
-_PyImport_FixupBuiltin(PyObject *mod, const char *name)
+_PyImport_FixupBuiltin(PyObject *mod, const char *name, PyObject *modules)
 {
     int res;
     PyObject *nameobj;
     nameobj = PyUnicode_InternFromString(name);
     if (nameobj == NULL)
         return -1;
-    res = _PyImport_FixupExtensionObject(mod, nameobj, nameobj);
+    res = _PyImport_FixupExtensionObject(mod, nameobj, nameobj, modules);
     Py_DECREF(nameobj);
     return res;
 }
@@ -590,6 +693,14 @@ _PyImport_FixupBuiltin(PyObject *mod, const char *name)
 PyObject *
 _PyImport_FindExtensionObject(PyObject *name, PyObject *filename)
 {
+    PyObject *modules = PyImport_GetModuleDict();
+    return _PyImport_FindExtensionObjectEx(name, filename, modules);
+}
+
+PyObject *
+_PyImport_FindExtensionObjectEx(PyObject *name, PyObject *filename,
+                                PyObject *modules)
+{
     PyObject *mod, *mdict, *key;
     PyModuleDef* def;
     if (extensions == NULL)
@@ -605,7 +716,7 @@ _PyImport_FindExtensionObject(PyObject *name, PyObject *filename)
         /* Module does not support repeated initialization */
         if (def->m_base.m_copy == NULL)
             return NULL;
-        mod = PyImport_AddModuleObject(name);
+        mod = _PyImport_AddModuleObject(name, modules);
         if (mod == NULL)
             return NULL;
         mdict = PyModule_GetDict(mod);
@@ -620,14 +731,14 @@ _PyImport_FindExtensionObject(PyObject *name, PyObject *filename)
         mod = def->m_base.m_init();
         if (mod == NULL)
             return NULL;
-        if (PyDict_SetItem(PyImport_GetModuleDict(), name, mod) == -1) {
+        if (PyObject_SetItem(modules, name, mod) == -1) {
             Py_DECREF(mod);
             return NULL;
         }
         Py_DECREF(mod);
     }
     if (_PyState_AddModule(mod, def) < 0) {
-        PyDict_DelItem(PyImport_GetModuleDict(), name);
+        PyMapping_DelItem(modules, name);
         Py_DECREF(mod);
         return NULL;
     }
@@ -639,13 +750,13 @@ _PyImport_FindExtensionObject(PyObject *name, PyObject *filename)
 }
 
 PyObject *
-_PyImport_FindBuiltin(const char *name)
+_PyImport_FindBuiltin(const char *name, PyObject *modules)
 {
     PyObject *res, *nameobj;
     nameobj = PyUnicode_InternFromString(name);
     if (nameobj == NULL)
         return NULL;
-    res = _PyImport_FindExtensionObject(nameobj, nameobj);
+    res = _PyImport_FindExtensionObjectEx(nameobj, nameobj, modules);
     Py_DECREF(nameobj);
     return res;
 }
@@ -660,19 +771,34 @@ PyObject *
 PyImport_AddModuleObject(PyObject *name)
 {
     PyObject *modules = PyImport_GetModuleDict();
-    PyObject *m;
+    return _PyImport_AddModuleObject(name, modules);
+}
 
-    if ((m = PyDict_GetItemWithError(modules, name)) != NULL &&
-        PyModule_Check(m)) {
-        return m;
+PyObject *
+_PyImport_AddModuleObject(PyObject *name, PyObject *modules)
+{
+    PyObject *m;
+    if (PyDict_CheckExact(modules)) {
+        m = PyDict_GetItemWithError(modules, name);
+    }
+    else {
+        m = PyObject_GetItem(modules, name);
+        // For backward-comaptibility we copy the behavior
+        // of PyDict_GetItemWithError().
+        if (PyErr_ExceptionMatches(PyExc_KeyError)) {
+            PyErr_Clear();
+        }
     }
     if (PyErr_Occurred()) {
         return NULL;
     }
+    if (m != NULL && PyModule_Check(m)) {
+        return m;
+    }
     m = PyModule_NewObject(name);
     if (m == NULL)
         return NULL;
-    if (PyDict_SetItem(modules, name, m) != 0) {
+    if (PyObject_SetItem(modules, name, m) != 0) {
         Py_DECREF(m);
         return NULL;
     }
@@ -699,11 +825,13 @@ static void
 remove_module(PyObject *name)
 {
     PyObject *modules = PyImport_GetModuleDict();
-    if (PyDict_GetItem(modules, name) == NULL)
-        return;
-    if (PyDict_DelItem(modules, name) < 0)
+    if (PyMapping_DelItem(modules, name) < 0) {
+        if (!PyMapping_HasKey(modules, name)) {
+            return;
+        }
         Py_FatalError("import:  deleting existing key in"
                       "sys.modules failed");
+    }
 }
 
 
@@ -812,7 +940,6 @@ module_dict_for_exec(PyObject *name)
 static PyObject *
 exec_code_in_module(PyObject *name, PyObject *module_dict, PyObject *code_object)
 {
-    PyObject *modules = PyImport_GetModuleDict();
     PyObject *v, *m;
 
     v = PyEval_EvalCode(code_object, module_dict, module_dict);
@@ -822,7 +949,8 @@ exec_code_in_module(PyObject *name, PyObject *module_dict, PyObject *code_object
     }
     Py_DECREF(v);
 
-    if ((m = PyDict_GetItem(modules, name)) == NULL) {
+    m = _PyImport_GetModule(name);
+    if (m == NULL) {
         PyErr_Format(PyExc_ImportError,
                      "Loaded module %R not found in sys.modules",
                      name);
@@ -1055,6 +1183,7 @@ _imp_create_builtin(PyObject *module, PyObject *spec)
         return NULL;
     }
 
+    PyObject *modules = NULL;
     for (p = PyImport_Inittab; p->name != NULL; p++) {
         PyModuleDef *def;
         if (_PyUnicode_EqualToASCIIString(name, p->name)) {
@@ -1080,7 +1209,11 @@ _imp_create_builtin(PyObject *module, PyObject *spec)
                     return NULL;
                 }
                 def->m_base.m_init = p->initfunc;
-                if (_PyImport_FixupExtensionObject(mod, name, name) < 0) {
+                if (modules == NULL) {
+                    modules = PyImport_GetModuleDict();
+                }
+                if (_PyImport_FixupExtensionObject(mod, name, name,
+                                                   modules) < 0) {
                     Py_DECREF(name);
                     return NULL;
                 }
@@ -1524,7 +1657,7 @@ PyImport_ImportModuleLevelObject(PyObject *name, PyObject *globals,
         Py_INCREF(abs_name);
     }
 
-    mod = PyDict_GetItem(interp->modules, abs_name);
+    mod = _PyImport_GetModule(abs_name);
     if (mod != NULL && mod != Py_None) {
         _Py_IDENTIFIER(__spec__);
         _Py_IDENTIFIER(_initializing);
@@ -1611,7 +1744,7 @@ PyImport_ImportModuleLevelObject(PyObject *name, PyObject *globals,
                     goto error;
                 }
 
-                final_mod = PyDict_GetItem(interp->modules, to_return);
+                final_mod = _PyImport_GetModule(to_return);
                 Py_DECREF(to_return);
                 if (final_mod == NULL) {
                     PyErr_Format(PyExc_KeyError,
@@ -1664,10 +1797,10 @@ PyImport_ImportModuleLevel(const char *name, PyObject *globals, PyObject *locals
 PyObject *
 PyImport_ReloadModule(PyObject *m)
 {
+    _Py_IDENTIFIER(imp);
     _Py_IDENTIFIER(reload);
     PyObject *reloaded_module = NULL;
-    PyObject *modules = PyImport_GetModuleDict();
-    PyObject *imp = PyDict_GetItemString(modules, "imp");
+    PyObject *imp = _PyImport_GetModuleId(&PyId_imp);
     if (imp == NULL) {
         imp = PyImport_ImportModule("imp");
         if (imp == NULL) {
@@ -1702,7 +1835,6 @@ PyImport_Import(PyObject *module_name)
     PyObject *globals = NULL;
     PyObject *import = NULL;
     PyObject *builtins = NULL;
-    PyObject *modules = NULL;
     PyObject *r = NULL;
 
     /* Initialize constant string objects */
@@ -1757,8 +1889,7 @@ PyImport_Import(PyObject *module_name)
         goto err;
     Py_DECREF(r);
 
-    modules = PyImport_GetModuleDict();
-    r = PyDict_GetItemWithError(modules, module_name);
+    r = _PyImport_GetModule(module_name);
     if (r != NULL) {
         Py_INCREF(r);
     }