bpo-36763: _PyInitError always use int for exitcode (GH-13360)

We cannot use "unsigned int" for exitcode on Windows, since
Py_Main() and _Py_RunMain() always return an "int".

Changes:

* _PyPathConfig_ComputeSysPath0() now returns -1 if an exception is
  raised.
* pymain_run_python() no longer uses _PyInitError but display the
  exception and set exitcode to 1 in case of error.
* Fix _Py_RunMain(): return an exitcode rather than calling
  exit() on pymain_run_python() failure.
* _Py_ExitInitError() no longer uses ExitProcess() on Windows, use
  exit() on all platforms.
* _Py_ExitInitError() now fails with a fatal error if 'err' is not an
  error not an exit.

Include/cpython/coreconfig.h

@@ -15,11 +15,7 @@ typedef struct {
     } _type;
     const char *_func;
     const char *err_msg;
-#ifdef MS_WINDOWS
-    unsigned int exitcode;
-#else
     int exitcode;
-#endif
 } _PyInitError;
 
 /* Almost all errors causing Python initialization to fail */

Modules/main.c

@@ -130,7 +130,7 @@ pymain_sys_path_add_path0(PyInterpreterState *interp, PyObject *path0)
     if (sysdict != NULL) {
         sys_path = _PyDict_GetItemIdWithError(sysdict, &PyId_path);
         if (sys_path == NULL && PyErr_Occurred()) {
-            goto error;
+            return -1;
         }
     }
     else {
@@ -138,17 +138,13 @@ pymain_sys_path_add_path0(PyInterpreterState *interp, PyObject *path0)
     }
     if (sys_path == NULL) {
         PyErr_SetString(PyExc_RuntimeError, "unable to get sys.path");
-        goto error;
+        return -1;
     }
 
     if (PyList_Insert(sys_path, 0, path0)) {
-        goto error;
+        return -1;
     }
     return 0;
-
-error:
-    PyErr_Print();
-    return -1;
 }
 
 
@@ -443,11 +439,9 @@ pymain_repl(_PyCoreConfig *config, PyCompilerFlags *cf, int *exitcode)
 }
 
 
-static _PyInitError
+static void
 pymain_run_python(int *exitcode)
 {
-    _PyInitError err;
-
     PyInterpreterState *interp = _PyInterpreterState_GET_UNSAFE();
     /* pymain_run_stdin() modify the config */
     _PyCoreConfig *config = &interp->core_config;
@@ -464,22 +458,20 @@ pymain_run_python(int *exitcode)
 
     if (main_importer_path != NULL) {
         if (pymain_sys_path_add_path0(interp, main_importer_path) < 0) {
-            err = _Py_INIT_EXIT(1);
-            goto done;
+            goto error;
         }
     }
     else if (!config->isolated) {
         PyObject *path0 = NULL;
-        if (_PyPathConfig_ComputeSysPath0(&config->argv, &path0)) {
-            if (path0 == NULL) {
-                err = _Py_INIT_NO_MEMORY();
-                goto done;
+        int res = _PyPathConfig_ComputeSysPath0(&config->argv, &path0);
+        if (res < 0) {
+            goto error;
         }
 
+        if (res > 0) {
             if (pymain_sys_path_add_path0(interp, path0) < 0) {
                 Py_DECREF(path0);
-                err = _Py_INIT_EXIT(1);
-                goto done;
+                goto error;
             }
             Py_DECREF(path0);
         }
@@ -508,11 +500,14 @@ pymain_run_python(int *exitcode)
     }
 
     pymain_repl(config, &cf, exitcode);
-    err = _Py_INIT_OK();
+    goto done;
+
+error:
+    PyErr_Print();
+    *exitcode = 1;
 
 done:
     Py_XDECREF(main_importer_path);
-    return err;
 }
 
 
@@ -578,17 +573,14 @@ _Py_RunMain(void)
 {
     int exitcode = 0;
 
-    _PyInitError err = pymain_run_python(&exitcode);
-    if (_Py_INIT_FAILED(err)) {
-        pymain_exit_error(err);
-    }
-
+    pymain_run_python(&exitcode);
     if (Py_FinalizeEx() < 0) {
         /* Value unlikely to be confused with a non-error exit status or
            other special meaning */
         exitcode = 120;
     }
 
+done:
     pymain_free();
 
     if (_Py_UnhandledKeyboardInterrupt) {
@@ -603,6 +595,10 @@ static int
 pymain_main(_PyArgv *args)
 {
     _PyInitError err = pymain_init(args);
+    if (_Py_INIT_IS_EXIT(err)) {
+        pymain_free();
+        return err.exitcode;
+    }
     if (_Py_INIT_FAILED(err)) {
         pymain_exit_error(err);
     }

Python/pathconfig.c

@@ -570,18 +570,17 @@ Py_GetProgramName(void)
    directory ("-m module" case) which will be prepended to sys.argv:
    sys.path[0].
 
-   Return 1 if the path is correctly resolved, but *path0_p can be NULL
-   if the Unicode object fail to be created.
+   Return 1 if the path is correctly resolved and written into *path0_p.
 
-   Return 0 if it fails to resolve the full path (and *path0_p will be NULL).
-   For example, return 0 if the current working directory has been removed
-   (bpo-36236) or if argv is empty.
+   Return 0 if it fails to resolve the full path. For example, return 0 if the
+   current working directory has been removed (bpo-36236) or if argv is empty.
+
+   Raise an exception and return -1 on error.
    */
 int
 _PyPathConfig_ComputeSysPath0(const _PyWstrList *argv, PyObject **path0_p)
 {
     assert(_PyWstrList_CheckConsistency(argv));
-    assert(*path0_p == NULL);
 
     if (argv->length == 0) {
         /* Leave sys.path unchanged if sys.argv is empty */
@@ -697,7 +696,12 @@ _PyPathConfig_ComputeSysPath0(const _PyWstrList *argv, PyObject **path0_p)
     }
 #endif /* All others */
 
-    *path0_p = PyUnicode_FromWideChar(path0, n);
+    PyObject *path0_obj = PyUnicode_FromWideChar(path0, n);
+    if (path0_obj == NULL) {
+        return -1;
+    }
+
+    *path0_p = path0_obj;
     return 1;
 }
 

Python/pylifecycle.c

@@ -2124,17 +2124,14 @@ Py_FatalError(const char *msg)
 void _Py_NO_RETURN
 _Py_ExitInitError(_PyInitError err)
 {
-    assert(_Py_INIT_FAILED(err));
     if (_Py_INIT_IS_EXIT(err)) {
-#ifdef MS_WINDOWS
-        ExitProcess(err.exitcode);
-#else
         exit(err.exitcode);
-#endif
+    }
+    else if (_Py_INIT_IS_ERROR(err)) {
+        fatal_error(err._func, err.err_msg, 1);
     }
     else {
-        assert(_Py_INIT_IS_ERROR(err));
-        fatal_error(err._func, err.err_msg, 1);
+        Py_FatalError("_Py_ExitInitError() must not be called on success");
     }
 }