bpo-34170: Rework _PyCoreConfig_Read() to avoid side effect (GH-8353)

Rework _PyCoreConfig_Read() function which *reads* core configuration
to not *modify* the path configuration.

A new _PyCoreConfig_SetPathConfig() function now recreates the path
configuration from the core configuration. This function is now
called very late in _Py_InitializeCore(), just before calling
initimport().

Changes:

* Add _PyCoreConfig.dll_path
* Py_SetPath() now fails with a fatal python error on memory
   allocation failure.
* Rename _PyPathConfig_Calculate() to _PyPathConfig_Calculate_impl()
* Replace _PyPathConfig_Init() with _PyPathConfig_Calculate(): the
  function now requires a _PyPathConfig
* Add _PyPathConfig_SetGlobal() to set the _Py_path_config global
  variable.
* Add _PyCoreConfig_InitPathConfig(): compute the path configuration
* Add _PyCoreConfig_SetPathConfig(): set path configuration from core
  configuration
* Rename wstrlist_append() to _Py_wstrlist_append()
* _Py_wstrlist_append() now handles integer overflow.

1 files changed, 7 insertions, 3 deletions

diff --git a/Include/internal/pystate.h b/Include/internal/pystate.h
index 70e0666..83fa7dc 100644
--- a/Include/internal/pystate.h
+++ b/Include/internal/pystate.h
@@ -37,7 +37,7 @@ struct _gilstate_runtime_state {
 #define _PyGILState_check_enabled _PyRuntime.gilstate.check_enabled
 
 
-typedef struct {
+typedef struct _PyPathConfig {
     /* Full path to the Python program */
     wchar_t *program_full_path;
     wchar_t *prefix;
@@ -59,11 +59,15 @@ typedef struct {
 
 PyAPI_DATA(_PyPathConfig) _Py_path_config;
 
-PyAPI_FUNC(_PyInitError) _PyPathConfig_Calculate(
+PyAPI_FUNC(_PyInitError) _PyPathConfig_Calculate_impl(
     _PyPathConfig *config,
     const _PyCoreConfig *core_config);
-PyAPI_FUNC(void) _PyPathConfig_Clear(_PyPathConfig *config);
+PyAPI_FUNC(void) _PyPathConfig_ClearGlobal(void);
 
+PyAPI_FUNC(_PyInitError) _Py_wstrlist_append(
+    int *len,
+    wchar_t ***list,
+    const wchar_t *str);
 
 /* interpreter state */