bpo-32030: Split Py_Main() into subfunctions (#4399)

* Don't use "Python runtime" anymore to parse command line options or
  to get environment variables: pymain_init() is now a strict
  separation.
* Use an error message rather than "crashing" directly with
  Py_FatalError(). Limit the number of calls to Py_FatalError(). It
  prepares the code to handle errors more nicely later.
* Warnings options (-W, PYTHONWARNINGS) and "XOptions" (-X) are now
  only added to the sys module once Python core is properly
  initialized.
* _PyMain is now the well identified owner of some important strings
  like: warnings options, XOptions, and the "program name". The
  program name string is now properly freed at exit.
  pymain_free() is now responsible to free the "command" string.
* Rename most methods in Modules/main.c to use a "pymain_" prefix to
  avoid conflits and ease debug.
* Replace _Py_CommandLineDetails_INIT with memset(0)
* Reorder a lot of code to fix the initialization ordering. For
  example, initializing standard streams now comes before parsing
  PYTHONWARNINGS.
* Py_Main() now handles errors when adding warnings options and
  XOptions.
* Add _PyMem_GetDefaultRawAllocator() private function.
* Cleanup _PyMem_Initialize(): remove useless global constants: move
  them into _PyMem_Initialize().
* Call _PyRuntime_Initialize() as soon as possible:
  _PyRuntime_Initialize() now returns an error message on failure.
* Add _PyInitError structure and following macros:

  * _Py_INIT_OK()
  * _Py_INIT_ERR(msg)
  * _Py_INIT_USER_ERR(msg): "user" error, don't abort() in that case
  * _Py_INIT_FAILED(err)

2 files changed, 15 insertions, 4 deletions

diff --git a/Programs/_freeze_importlib.c b/Programs/_freeze_importlib.c
index 1069966a18..b8b630cfed 100644
--- a/Programs/_freeze_importlib.c
+++ b/Programs/_freeze_importlib.c
@@ -81,7 +81,10 @@ main(int argc, char *argv[])
 
     Py_SetProgramName(L"./_freeze_importlib");
     /* Don't install importlib, since it could execute outdated bytecode. */
-    _Py_InitializeEx_Private(1, 0);
+    _PyInitError err = _Py_InitializeEx_Private(1, 0);
+    if (_Py_INIT_FAILED(err)) {
+        _Py_FatalInitError(err);
+    }
 
     if (strstr(inpath, "_external") != NULL) {
         is_bootstrap = 0;
diff --git a/Programs/python.c b/Programs/python.c
index 270a11babb..707e38f257 100644
--- a/Programs/python.c
+++ b/Programs/python.c
@@ -1,6 +1,7 @@
 /* Minimal main program -- everything is loaded from the library */
 
 #include "Python.h"
+#include "internal/pystate.h"
 #include <locale.h>
 
 #ifdef __FreeBSD__
@@ -22,9 +23,16 @@ main(int argc, char **argv)
     wchar_t **argv_copy;
     /* We need a second copy, as Python might modify the first one. */
     wchar_t **argv_copy2;
-    int i, res;
+    int i, status;
     char *oldloc;
 
+    _PyInitError err = _PyRuntime_Initialize();
+    if (_Py_INIT_FAILED(err)) {
+        fprintf(stderr, "Fatal Python error: %s\n", err.msg);
+        fflush(stderr);
+        exit(1);
+    }
+
     /* Force malloc() allocator to bootstrap Python */
 #ifdef Py_DEBUG
     (void)_PyMem_SetupAllocators("malloc_debug");
@@ -88,7 +96,7 @@ main(int argc, char **argv)
     setlocale(LC_ALL, oldloc);
     PyMem_RawFree(oldloc);
 
-    res = Py_Main(argc, argv_copy);
+    status = Py_Main(argc, argv_copy);
 
     /* Force again malloc() allocator to release memory blocks allocated
        before Py_Main() */
@@ -103,6 +111,6 @@ main(int argc, char **argv)
     }
     PyMem_RawFree(argv_copy);
     PyMem_RawFree(argv_copy2);
-    return res;
+    return status;
 }
 #endif