From 21220bbe65108f5a763ead24a6b572f80d84c9e2 Mon Sep 17 00:00:00 2001
From: Victor Stinner <vstinner@redhat.com>
Date: Tue, 30 Oct 2018 12:59:20 +0100
Subject: bpo-34403: Fix initfsencoding() for ASCII (GH-10233)

* Add _Py_GetForceASCII(): check if Python forces the usage of ASCII
  in Py_DecodeLocale() and Py_EncodeLocale().
* initfsencoding() now uses ASCII if _Py_GetForceASCII() is true.
---
 Include/fileutils.h  |  4 ++++
 Python/fileutils.c   | 12 ++++++++++++
 Python/pylifecycle.c |  4 ++++
 3 files changed, 20 insertions(+)

diff --git a/Include/fileutils.h b/Include/fileutils.h
index c05ff43..d75189a 100644
--- a/Include/fileutils.h
+++ b/Include/fileutils.h
@@ -183,6 +183,10 @@ PyAPI_FUNC(int) _Py_GetLocaleconvNumeric(
 
 #endif   /* Py_LIMITED_API */
 
+#ifdef Py_BUILD_CORE
+PyAPI_FUNC(int) _Py_GetForceASCII(void);
+#endif
+
 #ifdef __cplusplus
 }
 #endif
diff --git a/Python/fileutils.c b/Python/fileutils.c
index e72ce54..1b7e669 100644
--- a/Python/fileutils.c
+++ b/Python/fileutils.c
@@ -180,6 +180,18 @@ error:
     return 1;
 }
 
+
+int
+_Py_GetForceASCII(void)
+{
+    if (force_ascii == -1) {
+        force_ascii = check_force_ascii();
+    }
+    return force_ascii;
+}
+
+
+
 static int
 encode_ascii(const wchar_t *text, char **str,
              size_t *error_pos, const char **reason,
diff --git a/Python/pylifecycle.c b/Python/pylifecycle.c
index ba4b548..c01b21f 100644
--- a/Python/pylifecycle.c
+++ b/Python/pylifecycle.c
@@ -1615,6 +1615,10 @@ initfsencoding(PyInterpreterState *interp)
         Py_FileSystemDefaultEncoding = "utf-8";
         Py_HasFileSystemDefaultEncoding = 1;
     }
+    else if (_Py_GetForceASCII()) {
+        Py_FileSystemDefaultEncoding = "ascii";
+        Py_HasFileSystemDefaultEncoding = 1;
+    }
     else if (Py_FileSystemDefaultEncoding == NULL) {
         Py_FileSystemDefaultEncoding = get_locale_encoding();
         if (Py_FileSystemDefaultEncoding == NULL) {
-- 
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