bpo-42260: Add _PyInterpreterState_SetConfig() (GH-23158)

* Inline _PyInterpreterState_SetConfig(): replace it with _PyConfig_Copy(). * Add _PyErr_SetFromPyStatus() * Add _PyInterpreterState_GetConfigCopy() * Add a new _PyInterpreterState_SetConfig() function. * Add an unit which gets, modifies, and sets the config.

Author: vstinner

Doc/c-api/init_config.rst

@@ -128,6 +128,8 @@ PyStatus
 
  Initialization error with a message.
 
+ *err_msg* must not be ``NULL``.
+
  .. c:function:: PyStatus PyStatus_NoMemory(void)
 
  Memory allocation failure (out of memory).

Include/cpython/pystate.h

@@ -193,6 +193,36 @@ PyAPI_FUNC(void) _PyInterpreterState_SetEvalFrameFunc(
 
 PyAPI_FUNC(const PyConfig*) _PyInterpreterState_GetConfig(PyInterpreterState *interp);
 
+/* Get a copy of the current interpreter configuration.
+
+ Return 0 on success. Raise an exception and return -1 on error.
+
+ The caller must initialize 'config', using PyConfig_InitPythonConfig()
+ for example.
+
+ Python must be preinitialized to call this method.
+ The caller must hold the GIL. */
+PyAPI_FUNC(int) _PyInterpreterState_GetConfigCopy(
+ struct PyConfig *config);
+
+/* Set the configuration of the current interpreter.
+
+ This function should be called during or just after the Python
+ initialization.
+
+ Update the sys module with the new configuration. If the sys module was
+ modified directly after the Python initialization, these changes are lost.
+
+ Some configuration like faulthandler or warnoptions can be updated in the
+ configuration, but don't reconfigure Python (don't enable/disable
+ faulthandler and don't reconfigure warnings filters).
+
+ Return 0 on success. Raise an exception and return -1 on error.
+
+ The configuration should come from _PyInterpreterState_GetConfigCopy(). */
+PyAPI_FUNC(int) _PyInterpreterState_SetConfig(
+ const struct PyConfig *config);
+
 // Get the configuration of the currrent interpreter.
 // The caller must hold the GIL.
 PyAPI_FUNC(const PyConfig*) _Py_GetConfig(void);

Include/internal/pycore_initconfig.h

@@ -44,6 +44,8 @@ struct pyruntimestate;
 #define _PyStatus_UPDATE_FUNC(err) \
  do { err.func = _PyStatus_GET_FUNC(); } while (0)
 
+PyObject* _PyErr_SetFromPyStatus(PyStatus status);
+
 /* --- PyWideStringList ------------------------------------------------ */
 
 #define _PyWideStringList_INIT (PyWideStringList){.length = 0, .items = NULL}

Include/internal/pycore_interp.h

@@ -263,13 +263,7 @@ struct _is {
  struct ast_state ast;
 };
 
-/* Used by _PyImport_Cleanup() */
 extern void _PyInterpreterState_ClearModules(PyInterpreterState *interp);
-
-extern PyStatus _PyInterpreterState_SetConfig(
- PyInterpreterState *interp,
- const PyConfig *config);
-
 extern void _PyInterpreterState_Clear(PyThreadState *tstate);
 
 

Lib/test/test_embed.py

@@ -1394,6 +1394,15 @@ def test_init_warnoptions(self):
  self.check_all_configs("test_init_warnoptions", config, preconfig,
  api=API_PYTHON)
 
+ def test_init_set_config(self):
+ config = {
+ '_init_main': 0,
+ 'bytes_warning': 2,
+ 'warnoptions': ['error::BytesWarning'],
+ }
+ self.check_all_configs("test_init_set_config", config,
+ api=API_ISOLATED)
+
  def test_get_argc_argv(self):
  self.run_embedded_interpreter("test_get_argc_argv")
  # ignore output

Programs/_testembed.c

@@ -1526,6 +1526,55 @@ static int test_init_warnoptions(void)
 }
 
 
+static int tune_config(void)
+{
+ PyConfig config;
+ PyConfig_InitPythonConfig(&config);
+ if (_PyInterpreterState_GetConfigCopy(&config) < 0) {
+ PyConfig_Clear(&config);
+ PyErr_Print();
+ return -1;
+ }
+
+ config.bytes_warning = 2;
+
+ if (_PyInterpreterState_SetConfig(&config) < 0) {
+ PyConfig_Clear(&config);
+ return -1;
+ }
+ PyConfig_Clear(&config);
+ return 0;
+}
+
+
+static int test_set_config(void)
+{
+ // Initialize core
+ PyConfig config;
+ PyConfig_InitIsolatedConfig(&config);
+ config_set_string(&config, &config.program_name, PROGRAM_NAME);
+ config._init_main = 0;
+ config.bytes_warning = 0;
+ init_from_config_clear(&config);
+
+ // Tune the configuration using _PyInterpreterState_SetConfig()
+ if (tune_config() < 0) {
+ PyErr_Print();
+ return 1;
+ }
+
+ // Finish initialization: main part
+ PyStatus status = _Py_InitializeMain();
+ if (PyStatus_Exception(status)) {
+ Py_ExitStatusException(status);
+ }
+
+ dump_config();
+ Py_Finalize();
+ return 0;
+}
+
+
 static void configure_init_main(PyConfig *config)
 {
  wchar_t* argv[] = {
@@ -1693,6 +1742,7 @@ static struct TestCase TestCases[] = {
  {"test_init_setpath_config", test_init_setpath_config},
  {"test_init_setpythonhome", test_init_setpythonhome},
  {"test_init_warnoptions", test_init_warnoptions},
+ {"test_init_set_config", test_set_config},
  {"test_run_main", test_run_main},
  {"test_get_argc_argv", test_get_argc_argv},
 

Python/initconfig.c

@@ -242,8 +242,9 @@ PyStatus PyStatus_Ok(void)
 
 PyStatus PyStatus_Error(const char *err_msg)
 {
+ assert(err_msg != NULL);
  return (PyStatus){._type = _PyStatus_TYPE_ERROR,
-  .err_msg = err_msg};
+ .err_msg = err_msg};
 }
 
 PyStatus PyStatus_NoMemory(void)
@@ -262,6 +263,23 @@ int PyStatus_IsExit(PyStatus status)
 int PyStatus_Exception(PyStatus status)
 { return _PyStatus_EXCEPTION(status); }
 
+PyObject*
+_PyErr_SetFromPyStatus(PyStatus status)
+{
+ if (!_PyStatus_IS_ERROR(status)) {
+ PyErr_Format(PyExc_SystemError,
+ "%s() expects an error PyStatus",
+ _PyStatus_GET_FUNC());
+ }
+ else if (status.func) {
+ PyErr_Format(PyExc_ValueError, "%s: %s", status.func, status.err_msg);
+ }
+ else {
+ PyErr_Format(PyExc_ValueError, "%s", status.err_msg);
+ }
+ return NULL;
+}
+
 
 /* --- PyWideStringList ------------------------------------------------ */
 

Python/pylifecycle.c

@@ -428,6 +428,67 @@ _Py_SetLocaleFromEnv(int category)
 }
 
 
+static int
+interpreter_set_config(const PyConfig *config)
+{
+ PyThreadState *tstate = PyThreadState_Get();
+
+ PyStatus status = _PyConfig_Write(config, tstate->interp->runtime);
+ if (_PyStatus_EXCEPTION(status)) {
+ _PyErr_SetFromPyStatus(status);
+ return -1;
+ }
+
+ status = _PyConfig_Copy(&tstate->interp->config, config);
+ if (_PyStatus_EXCEPTION(status)) {
+ _PyErr_SetFromPyStatus(status);
+ return -1;
+ }
+ config = &tstate->interp->config;
+
+ if (config->_install_importlib && _Py_IsMainInterpreter(tstate)) {
+ status = _PyConfig_WritePathConfig(config);
+ if (_PyStatus_EXCEPTION(status)) {
+ _PyErr_SetFromPyStatus(status);
+ return -1;
+ }
+ }
+
+ // Update the sys module for the new configuration
+ if (_PySys_UpdateConfig(tstate) < 0) {
+ return -1;
+ }
+ return 0;
+}
+
+
+int
+_PyInterpreterState_SetConfig(const PyConfig *src_config)
+{
+ int res = -1;
+
+ PyConfig config;
+ PyConfig_InitPythonConfig(&config);
+ PyStatus status = _PyConfig_Copy(&config, src_config);
+ if (_PyStatus_EXCEPTION(status)) {
+ _PyErr_SetFromPyStatus(status);
+ goto done;
+ }
+
+ status = PyConfig_Read(&config);
+ if (_PyStatus_EXCEPTION(status)) {
+ _PyErr_SetFromPyStatus(status);
+ goto done;
+ }
+
+ res = interpreter_set_config(&config);
+
+done:
+ PyConfig_Clear(&config);
+ return res;
+}
+
+
 /* Global initializations. Can be undone by Py_Finalize(). Don't
  call this twice without an intervening Py_Finalize() call.
 
@@ -462,7 +523,7 @@ pyinit_core_reconfigure(_PyRuntimeState *runtime,
  return status;
  }
 
- status = _PyInterpreterState_SetConfig(interp, config);
+ status = _PyConfig_Copy(&interp->config, config);
  if (_PyStatus_EXCEPTION(status)) {
  return status;
  }
@@ -550,7 +611,7 @@ pycore_create_interpreter(_PyRuntimeState *runtime,
  return _PyStatus_ERR("can't make main interpreter");
  }
 
- PyStatus status = _PyInterpreterState_SetConfig(interp, config);
+ PyStatus status = _PyConfig_Copy(&interp->config, config);
  if (_PyStatus_EXCEPTION(status)) {
  return status;
  }
@@ -917,7 +978,7 @@ pyinit_core(_PyRuntimeState *runtime,
  }
 
  PyConfig config;
- _PyConfig_InitCompatConfig(&config);
+ PyConfig_InitPythonConfig(&config);
 
  status = _PyConfig_Copy(&config, src_config);
  if (_PyStatus_EXCEPTION(status)) {
@@ -1835,7 +1896,8 @@ new_interpreter(PyThreadState **tstate_p, int isolated_subinterpreter)
  config = _PyInterpreterState_GetConfig(main_interp);
  }
 
- status = _PyInterpreterState_SetConfig(interp, config);
+
+ status = _PyConfig_Copy(&interp->config, config);
  if (_PyStatus_EXCEPTION(status)) {
  goto error;
  }

Python/pystate.c

@@ -778,7 +778,7 @@ PyState_RemoveModule(struct PyModuleDef* def)
  return PyList_SetItem(interp->modules_by_index, index, Py_None);
 }
 
-/* Used by PyImport_Cleanup() */
+// Used by finalize_modules()
 void
 _PyInterpreterState_ClearModules(PyInterpreterState *interp)
 {
@@ -1920,11 +1920,17 @@ _PyInterpreterState_GetConfig(PyInterpreterState *interp)
 }
 
 
-PyStatus
-_PyInterpreterState_SetConfig(PyInterpreterState *interp,
- const PyConfig *config)
+int
+_PyInterpreterState_GetConfigCopy(PyConfig *config)
 {
- return _PyConfig_Copy(&interp->config, config);
+ PyInterpreterState *interp = PyInterpreterState_Get();
+
+ PyStatus status = _PyConfig_Copy(config, &interp->config);
+ if (PyStatus_Exception(status)) {
+ _PyErr_SetFromPyStatus(status);
+ return -1;
+ }
+ return 0;
 }