From 6031727a37c6003f78e3b0c7414a0a214855dd08 Mon Sep 17 00:00:00 2001
From: Steve Dower <steve.dower@python.org>
Date: Thu, 25 May 2023 00:16:13 +0100
Subject: gh-104820: Fixes os.stat on Windows to better handle file systems
 that do not support FileIdInformation (GH-104892)

---
 .../Windows/2023-05-24-21-00-57.gh-issue-104820.ibyrpp.rst   |  2 ++
 Modules/posixmodule.c                                        | 12 ++++++++----
 Python/fileutils.c                                           |  3 ++-
 3 files changed, 12 insertions(+), 5 deletions(-)
 create mode 100644 Misc/NEWS.d/next/Windows/2023-05-24-21-00-57.gh-issue-104820.ibyrpp.rst

diff --git a/Misc/NEWS.d/next/Windows/2023-05-24-21-00-57.gh-issue-104820.ibyrpp.rst b/Misc/NEWS.d/next/Windows/2023-05-24-21-00-57.gh-issue-104820.ibyrpp.rst
new file mode 100644
index 0000000..5bdfbab
--- /dev/null
+++ b/Misc/NEWS.d/next/Windows/2023-05-24-21-00-57.gh-issue-104820.ibyrpp.rst
@@ -0,0 +1,2 @@
+Fixes :func:`~os.stat` and related functions on file systems that do not
+support file ID requests. This includes FAT32 and exFAT.
diff --git a/Modules/posixmodule.c b/Modules/posixmodule.c
index 2fe9973..294e9a2 100644
--- a/Modules/posixmodule.c
+++ b/Modules/posixmodule.c
@@ -1864,6 +1864,7 @@ win32_xstat_slow_impl(const wchar_t *path, struct _Py_stat_struct *result,
     BY_HANDLE_FILE_INFORMATION fileInfo;
     FILE_BASIC_INFO basicInfo;
     FILE_ID_INFO idInfo;
+    FILE_ID_INFO *pIdInfo = &idInfo;
     FILE_ATTRIBUTE_TAG_INFO tagInfo = { 0 };
     DWORD fileType, error;
     BOOL isUnhandledTag = FALSE;
@@ -2000,9 +2001,7 @@ win32_xstat_slow_impl(const wchar_t *path, struct _Py_stat_struct *result,
 
         if (!GetFileInformationByHandle(hFile, &fileInfo) ||
             !GetFileInformationByHandleEx(hFile, FileBasicInfo,
-                                          &basicInfo, sizeof(basicInfo)) ||
-            !GetFileInformationByHandleEx(hFile, FileIdInfo,
-                                          &idInfo, sizeof(idInfo))) {
+                                          &basicInfo, sizeof(basicInfo))) {
             switch (GetLastError()) {
             case ERROR_INVALID_PARAMETER:
             case ERROR_INVALID_FUNCTION:
@@ -2018,7 +2017,12 @@ win32_xstat_slow_impl(const wchar_t *path, struct _Py_stat_struct *result,
         }
     }
 
-    _Py_attribute_data_to_stat(&fileInfo, tagInfo.ReparseTag, &basicInfo, &idInfo, result);
+    if (!GetFileInformationByHandleEx(hFile, FileIdInfo, &idInfo, sizeof(idInfo))) {
+        /* Failed to get FileIdInfo, so do not pass it along */
+        pIdInfo = NULL;
+    }
+
+    _Py_attribute_data_to_stat(&fileInfo, tagInfo.ReparseTag, &basicInfo, pIdInfo, result);
     update_st_mode_from_path(path, fileInfo.dwFileAttributes, result);
 
 cleanup:
diff --git a/Python/fileutils.c b/Python/fileutils.c
index 969b716..f137ee9 100644
--- a/Python/fileutils.c
+++ b/Python/fileutils.c
@@ -1132,7 +1132,8 @@ _Py_attribute_data_to_stat(BY_HANDLE_FILE_INFORMATION *info, ULONG reparse_tag,
         file_id.id = id_info->FileId;
         result->st_ino = file_id.st_ino;
         result->st_ino_high = file_id.st_ino_high;
-    } else {
+    }
+    if (!result->st_ino && !result->st_ino_high) {
         /* should only occur for DirEntry_from_find_data, in which case the
            index is likely to be zero anyway. */
         result->st_ino = (((uint64_t)info->nFileIndexHigh) << 32) + info->nFileIndexLow;
-- 
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