From a621fdf857460d0cb4cb493fd5dc4f3b69d37295 Mon Sep 17 00:00:00 2001
From: "Admiral H. Curtiss" <pikachu025@gmail.com>
Date: Thu, 16 Jun 2022 03:59:14 +0200
Subject: [PATCH] Core: In deterministic mode, build SD cards with a consistent
 filename order and dummy timestamps.

---
 Source/Core/Common/FatFsUtil.cpp | 22 ++++++++++++++++++++--
 Source/Core/Common/FatFsUtil.h   |  2 +-
 Source/Core/Core/Core.cpp        |  2 +-
 3 files changed, 22 insertions(+), 4 deletions(-)

diff --git a/Source/Core/Common/FatFsUtil.cpp b/Source/Core/Common/FatFsUtil.cpp
index ffd42e68ab..7e0c2e2a21 100644
--- a/Source/Core/Common/FatFsUtil.cpp
+++ b/Source/Core/Common/FatFsUtil.cpp
@@ -30,6 +30,7 @@ enum : u32
 
 static std::mutex s_fatfs_mutex;
 static File::IOFile s_image;
+static bool s_deterministic;
 
 extern "C" DSTATUS disk_status(BYTE pdrv)
 {
@@ -96,6 +97,9 @@ extern "C" DRESULT disk_ioctl(BYTE pdrv, BYTE cmd, void* buff)
 
 extern "C" DWORD get_fattime(void)
 {
+  if (s_deterministic)
+    return 0;
+
   const std::time_t time = std::time(nullptr);
   std::tm tm;
 #ifdef _WIN32
@@ -286,13 +290,26 @@ static bool Pack(const File::FSTEntry& entry, bool is_root, std::vector<u8>& tmp
   return true;
 }
 
-bool SyncSDFolderToSDImage()
+static void SortFST(File::FSTEntry* root)
 {
+  std::sort(root->children.begin(), root->children.end(),
+            [](const File::FSTEntry& lhs, const File::FSTEntry& rhs) {
+              return lhs.virtualName < rhs.virtualName;
+            });
+  for (auto& child : root->children)
+    SortFST(&child);
+}
+
+bool SyncSDFolderToSDImage(bool deterministic)
+{
+  deterministic = true;
   const std::string root_path = File::GetUserPath(D_WIISDCARDSYNCFOLDER_IDX);
   if (!File::IsDirectory(root_path))
     return false;
 
-  const File::FSTEntry root = File::ScanDirectoryTree(root_path, true);
+  File::FSTEntry root = File::ScanDirectoryTree(root_path, true);
+  if (deterministic)
+    SortFST(&root);
   if (!CheckIfFATCompatible(root))
     return false;
 
@@ -302,6 +319,7 @@ bool SyncSDFolderToSDImage()
   size = AlignUp(size, MAX_CLUSTER_SIZE);
 
   std::lock_guard lk(s_fatfs_mutex);
+  s_deterministic = deterministic;
 
   const std::string image_path = File::GetUserPath(F_WIISDCARDIMAGE_IDX);
   const std::string temp_image_path = File::GetTempFilenameForAtomicWrite(image_path);
diff --git a/Source/Core/Common/FatFsUtil.h b/Source/Core/Common/FatFsUtil.h
index bb981e2267..91f28330fb 100644
--- a/Source/Core/Common/FatFsUtil.h
+++ b/Source/Core/Common/FatFsUtil.h
@@ -7,6 +7,6 @@
 
 namespace Common
 {
-bool SyncSDFolderToSDImage();
+bool SyncSDFolderToSDImage(bool deterministic);
 bool SyncSDImageToSDFolder();
 }  // namespace Common
diff --git a/Source/Core/Core/Core.cpp b/Source/Core/Core/Core.cpp
index 79ac6a2ae6..f2a9ec334d 100644
--- a/Source/Core/Core/Core.cpp
+++ b/Source/Core/Core/Core.cpp
@@ -499,7 +499,7 @@ static void EmuThread(std::unique_ptr<BootParameters> boot, WindowSystemInfo wsi
   bool sync_sd_folder = core_parameter.bWii && Config::Get(Config::MAIN_WII_SD_CARD) &&
                         Config::Get(Config::MAIN_WII_SD_CARD_ENABLE_FOLDER_SYNC);
   if (sync_sd_folder)
-    sync_sd_folder = Common::SyncSDFolderToSDImage();
+    sync_sd_folder = Common::SyncSDFolderToSDImage(Core::WantsDeterminism());
 
   Common::ScopeGuard sd_folder_sync_guard{[sync_sd_folder] {
     if (sync_sd_folder && Config::Get(Config::MAIN_ALLOW_SD_WRITES))