bpo-36763: Add _PyPreConfig._config_init (GH-13481)

* _PyPreConfig_GetGlobalConfig() and  _PyCoreConfig_GetGlobalConfig()
  now do nothing if the configuration was not initialized with
  _PyPreConfig_InitCompatConfig() and _PyCoreConfig_InitCompatConfig()
* Remove utf8_mode=-2 special case: use utf8_mode=-1 instead.
* Fix _PyPreConfig_InitPythonConfig():

  * isolated = 0 instead of -1
  * use_environment = 1 instead of -1

* Rename _PyConfig_INIT to  _PyConfig_INIT_COMPAT
* Rename _PyPreConfig_Init() to _PyPreConfig_InitCompatConfig()
* Rename _PyCoreConfig_Init() to _PyCoreConfig_InitCompatConfig()
* PyInterpreterState_New() now uses _PyCoreConfig_InitPythonConfig()
  as default configuration, but it's very quickly overriden anyway.
* _freeze_importlib.c uses _PyCoreConfig_SetString() to set
  program_name.
* Cleanup preconfig_init_utf8_mode(): cmdline is always non-NULL.

6 files changed, 53 insertions, 33 deletions

diff --git a/Python/coreconfig.c b/Python/coreconfig.c
index 958845e..40dba4e 100644
--- a/Python/coreconfig.c
+++ b/Python/coreconfig.c
@@ -109,7 +109,7 @@ static const char usage_6[] =
 /* UTF-8 mode (PEP 540): if equals to 1, use the UTF-8 encoding, and change
    stdin and stdout error handler to "surrogateescape". It is equal to
    -1 by default: unknown, will be set by Py_Main() */
-int Py_UTF8Mode = 0;
+int Py_UTF8Mode = -1;
 int Py_DebugFlag = 0; /* Needed by parser.c */
 int Py_VerboseFlag = 0; /* Needed by import.c */
 int Py_QuietFlag = 0; /* Needed by sysmodule.c */
@@ -546,12 +546,12 @@ _PyCoreConfig_Clear(_PyCoreConfig *config)
 
 
 void
-_PyCoreConfig_Init(_PyCoreConfig *config)
+_PyCoreConfig_InitCompatConfig(_PyCoreConfig *config)
 {
     memset(config, 0, sizeof(*config));
 
     config->_config_version = _Py_CONFIG_VERSION;
-    config->_config_init = (int)_PyCoreConfig_INIT;
+    config->_config_init = (int)_PyConfig_INIT_COMPAT;
     config->isolated = -1;
     config->use_environment = -1;
     config->dev_mode = -1;
@@ -586,7 +586,7 @@ _PyCoreConfig_Init(_PyCoreConfig *config)
 static void
 _PyCoreConfig_InitDefaults(_PyCoreConfig *config)
 {
-    _PyCoreConfig_Init(config);
+    _PyCoreConfig_InitCompatConfig(config);
 
     config->isolated = 0;
     config->use_environment = 1;
@@ -613,7 +613,7 @@ _PyCoreConfig_InitPythonConfig(_PyCoreConfig *config)
 {
     _PyCoreConfig_InitDefaults(config);
 
-    config->_config_init = (int)_PyCoreConfig_INIT_PYTHON;
+    config->_config_init = (int)_PyConfig_INIT_PYTHON;
     config->configure_c_stdio = 1;
     config->parse_argv = 1;
 
@@ -626,7 +626,7 @@ _PyCoreConfig_InitIsolatedConfig(_PyCoreConfig *config)
 {
     _PyCoreConfig_InitDefaults(config);
 
-    config->_config_init = (int)_PyCoreConfig_INIT_ISOLATED;
+    config->_config_init = (int)_PyConfig_INIT_ISOLATED;
     config->isolated = 1;
     config->use_environment = 0;
     config->user_site_directory = 0;
@@ -962,6 +962,11 @@ _PyCoreConfig_GetEnvDup(_PyCoreConfig *config,
 static void
 _PyCoreConfig_GetGlobalConfig(_PyCoreConfig *config)
 {
+    if (config->_config_init != _PyConfig_INIT_COMPAT) {
+        /* Python and Isolated configuration ignore global variables */
+        return;
+    }
+
 #define COPY_FLAG(ATTR, VALUE) \
         if (config->ATTR == -1) { \
             config->ATTR = VALUE; \
diff --git a/Python/frozenmain.c b/Python/frozenmain.c
index a51fb58..c3af080 100644
--- a/Python/frozenmain.c
+++ b/Python/frozenmain.c
@@ -40,7 +40,11 @@ Py_FrozenMain(int argc, char **argv)
     }
 
     _PyCoreConfig config;
-    _PyCoreConfig_InitPythonConfig(&config);
+    err = _PyCoreConfig_InitPythonConfig(&config);
+    if (_PyInitError_Failed(err)) {
+        _PyCoreConfig_Clear(&config);
+        _Py_ExitInitError(err);
+    }
     config.pathconfig_warnings = 0;   /* Suppress errors from getpath.c */
 
     if ((p = Py_GETENV("PYTHONINSPECT")) && *p != '\0')
@@ -82,8 +86,7 @@ Py_FrozenMain(int argc, char **argv)
         Py_SetProgramName(argv_copy[0]);
 
     err = _Py_InitializeFromConfig(&config);
-    /* No need to call _PyCoreConfig_Clear() since we didn't allocate any
-       memory: program_name is a constant string. */
+    _PyCoreConfig_Clear(&config);
     if (_PyInitError_Failed(err)) {
         _Py_ExitInitError(err);
     }
diff --git a/Python/pathconfig.c b/Python/pathconfig.c
index 3d9d3b1..bbf29b2 100644
--- a/Python/pathconfig.c
+++ b/Python/pathconfig.c
@@ -383,7 +383,7 @@ pathconfig_global_init(void)
 
     _PyInitError err;
     _PyCoreConfig config;
-    _PyCoreConfig_Init(&config);
+    _PyCoreConfig_InitCompatConfig(&config);
 
     err = _PyCoreConfig_Read(&config);
     if (_Py_INIT_FAILED(err)) {
diff --git a/Python/preconfig.c b/Python/preconfig.c
index 4df6208..392324f 100644
--- a/Python/preconfig.c
+++ b/Python/preconfig.c
@@ -262,16 +262,17 @@ _PyPreCmdline_Read(_PyPreCmdline *cmdline, const _PyPreConfig *preconfig)
 
 
 void
-_PyPreConfig_Init(_PyPreConfig *config)
+_PyPreConfig_InitCompatConfig(_PyPreConfig *config)
 {
     memset(config, 0, sizeof(*config));
 
     config->_config_version = _Py_CONFIG_VERSION;
+    config->_config_init = (int)_PyConfig_INIT_COMPAT;
     config->parse_argv = 0;
     config->isolated = -1;
     config->use_environment = -1;
     config->configure_locale = 1;
-    config->utf8_mode = -2;
+    config->utf8_mode = -1;
     config->dev_mode = -1;
     config->allocator = PYMEM_ALLOCATOR_NOT_SET;
 #ifdef MS_WINDOWS
@@ -283,23 +284,30 @@ _PyPreConfig_Init(_PyPreConfig *config)
 void
 _PyPreConfig_InitPythonConfig(_PyPreConfig *config)
 {
-    _PyPreConfig_Init(config);
+    _PyPreConfig_InitCompatConfig(config);
 
+    config->_config_init = (int)_PyConfig_INIT_PYTHON;
+    config->isolated = 0;
     config->parse_argv = 1;
+    config->use_environment = 1;
     /* Set to -1 to enable C locale coercion (PEP 538) and UTF-8 Mode (PEP 540)
        depending on the LC_CTYPE locale, PYTHONUTF8 and PYTHONCOERCECLOCALE
        environment variables. */
     config->coerce_c_locale = -1;
     config->coerce_c_locale_warn = -1;
     config->utf8_mode = -1;
+#ifdef MS_WINDOWS
+    config->legacy_windows_fs_encoding = 0;
+#endif
 }
 
 
 void
 _PyPreConfig_InitIsolatedConfig(_PyPreConfig *config)
 {
-    _PyPreConfig_Init(config);
+    _PyPreConfig_InitCompatConfig(config);
 
+    config->_config_init = (int)_PyConfig_INIT_ISOLATED;
     config->configure_locale = 0;
     config->isolated = 1;
     config->use_environment = 0;
@@ -315,7 +323,7 @@ void
 _PyPreConfig_InitFromPreConfig(_PyPreConfig *config,
                                const _PyPreConfig *config2)
 {
-    _PyPreConfig_Init(config);
+    _PyPreConfig_InitCompatConfig(config);
     _PyPreConfig_Copy(config, config2);
 }
 
@@ -324,17 +332,17 @@ void
 _PyPreConfig_InitFromCoreConfig(_PyPreConfig *config,
                                 const _PyCoreConfig *coreconfig)
 {
-    _PyCoreConfigInitEnum config_init = (_PyCoreConfigInitEnum)coreconfig->_config_init;
+    _PyConfigInitEnum config_init = (_PyConfigInitEnum)coreconfig->_config_init;
     switch (config_init) {
-    case _PyCoreConfig_INIT_PYTHON:
+    case _PyConfig_INIT_PYTHON:
         _PyPreConfig_InitPythonConfig(config);
         break;
-    case _PyCoreConfig_INIT_ISOLATED:
+    case _PyConfig_INIT_ISOLATED:
         _PyPreConfig_InitIsolatedConfig(config);
         break;
-    case _PyCoreConfig_INIT:
+    case _PyConfig_INIT_COMPAT:
     default:
-        _PyPreConfig_Init(config);
+        _PyPreConfig_InitCompatConfig(config);
     }
     _PyPreConfig_GetCoreConfig(config, coreconfig);
 }
@@ -428,6 +436,11 @@ _PyPreConfig_GetCoreConfig(_PyPreConfig *config,
 static void
 _PyPreConfig_GetGlobalConfig(_PyPreConfig *config)
 {
+    if (config->_config_init != _PyConfig_INIT_COMPAT) {
+        /* Python and Isolated configuration ignore global variables */
+        return;
+    }
+
 #define COPY_FLAG(ATTR, VALUE) \
     if (config->ATTR < 0) { \
         config->ATTR = VALUE; \
@@ -439,12 +452,10 @@ _PyPreConfig_GetGlobalConfig(_PyPreConfig *config)
 
     COPY_FLAG(isolated, Py_IsolatedFlag);
     COPY_NOT_FLAG(use_environment, Py_IgnoreEnvironmentFlag);
+    COPY_FLAG(utf8_mode, Py_UTF8Mode);
 #ifdef MS_WINDOWS
     COPY_FLAG(legacy_windows_fs_encoding, Py_LegacyWindowsFSEncodingFlag);
 #endif
-    if (config->utf8_mode == -2) {
-        config->utf8_mode = Py_UTF8Mode;
-    }
 
 #undef COPY_FLAG
 #undef COPY_NOT_FLAG
@@ -565,12 +576,7 @@ preconfig_init_utf8_mode(_PyPreConfig *config, const _PyPreCmdline *cmdline)
     }
 
     const wchar_t *xopt;
-    if (cmdline) {
-        xopt = _Py_get_xoption(&cmdline->xoptions, L"utf8");
-    }
-    else {
-        xopt = NULL;
-    }
+    xopt = _Py_get_xoption(&cmdline->xoptions, L"utf8");
     if (xopt) {
         wchar_t *sep = wcschr(xopt, L'=');
         if (sep) {
diff --git a/Python/pylifecycle.c b/Python/pylifecycle.c
index 6dc684b..21c386b 100644
--- a/Python/pylifecycle.c
+++ b/Python/pylifecycle.c
@@ -867,7 +867,7 @@ _Py_InitializeCore(_PyRuntimeState *runtime,
     }
 
     _PyCoreConfig local_config;
-    _PyCoreConfig_Init(&local_config);
+    _PyCoreConfig_InitCompatConfig(&local_config);
     err = pyinit_coreconfig(runtime, &local_config, src_config, args, interp_p);
     _PyCoreConfig_Clear(&local_config);
     return err;
@@ -1096,7 +1096,7 @@ Py_InitializeEx(int install_sigs)
     }
 
     _PyCoreConfig config;
-    _PyCoreConfig_Init(&config);
+    _PyCoreConfig_InitCompatConfig(&config);
     config.install_signal_handlers = install_sigs;
 
     err = _Py_InitializeFromConfig(&config);
diff --git a/Python/pystate.c b/Python/pystate.c
index 2f80aa2..879a5a9 100644
--- a/Python/pystate.c
+++ b/Python/pystate.c
@@ -49,7 +49,7 @@ _PyRuntimeState_Init_impl(_PyRuntimeState *runtime)
 
     _PyGC_Initialize(&runtime->gc);
     _PyEval_Initialize(&runtime->ceval);
-    _PyPreConfig_Init(&runtime->preconfig);
+    _PyPreConfig_InitPythonConfig(&runtime->preconfig);
 
     runtime->gilstate.check_enabled = 1;
 
@@ -189,7 +189,13 @@ PyInterpreterState_New(void)
     memset(interp, 0, sizeof(*interp));
     interp->id_refcount = -1;
     interp->check_interval = 100;
-    _PyCoreConfig_Init(&interp->core_config);
+
+    _PyInitError err = _PyCoreConfig_InitPythonConfig(&interp->core_config);
+    if (_Py_INIT_FAILED(err)) {
+        PyMem_RawFree(interp);
+        return NULL;
+    }
+
     interp->eval_frame = _PyEval_EvalFrameDefault;
 #ifdef HAVE_DLOPEN
 #if HAVE_DECL_RTLD_NOW