From 213ca72fa172ef2b46addc923eea911d89a63272 Mon Sep 17 00:00:00 2001
From: Stephen Miller <56742918+StevenMiller123@users.noreply.github.com>
Date: Sun, 15 Jun 2025 14:43:39 -0500
Subject: [PATCH] Filesystem: Fixes for posix_rename and write (#3099)

* Fix rename

We shouldn't be leaving a copy of the original filename laying around.
This fixes one of a few broken savedata checks in DRAGON BALL XENOVERSE (CUSA01341)

* sceKernelWrite hack

Seems like std::fwrite has some weird edge cases we aren't handling properly.
Until we get to the bottom of this issue, here's a hack that bypasses it.
This fixes saves in DRAGON BALL XENOVERSE (CUSA01341)

* hack fix

* Improved "hack"

* Fix rename for Windows users

Turns out, we're using copy instead of rename for a reason, and that same reason came up when adding the remove call.
Also adds a log for the sceKernelWrite issue, since that's definitely a hack that needs to be debugged.

* A real fix for the sceKernelWrite issue

Turns out, some data was just buffered.
Running Flush fixes that problem.

* Move fflush call to WriteRaw

To prevent future cases of this issue.
---
 src/common/io_file.h                      |  4 +++-
 src/core/libraries/kernel/file_system.cpp | 18 ++++++++++++++++++
 2 files changed, 21 insertions(+), 1 deletion(-)

diff --git a/src/common/io_file.h b/src/common/io_file.h
index 45787a092..cb01e154a 100644
--- a/src/common/io_file.h
+++ b/src/common/io_file.h
@@ -186,7 +186,9 @@ public:
 
     template <typename T>
     size_t WriteRaw(const void* data, size_t size) const {
-        return std::fwrite(data, sizeof(T), size, file);
+        auto bytes = std::fwrite(data, sizeof(T), size, file);
+        std::fflush(file);
+        return bytes;
     }
 
     template <typename T>
diff --git a/src/core/libraries/kernel/file_system.cpp b/src/core/libraries/kernel/file_system.cpp
index fecc606fd..76d1a3339 100644
--- a/src/core/libraries/kernel/file_system.cpp
+++ b/src/core/libraries/kernel/file_system.cpp
@@ -293,6 +293,7 @@ s64 PS4_SYSV_ABI write(s32 fd, const void* buf, size_t nbytes) {
         }
         return result;
     }
+
     return file->f.WriteRaw<u8>(buf, nbytes);
 }
 
@@ -750,7 +751,24 @@ s32 PS4_SYSV_ABI posix_rename(const char* from, const char* to) {
         *__Error() = POSIX_ENOTEMPTY;
         return -1;
     }
+
+    // On Windows, std::filesystem::rename will error if the file has been opened before.
     std::filesystem::copy(src_path, dst_path, std::filesystem::copy_options::overwrite_existing);
+    auto* h = Common::Singleton<Core::FileSys::HandleTable>::Instance();
+    auto file = h->GetFile(src_path);
+    if (file) {
+        // We need to force ReadWrite if the file had Write access before
+        // Otherwise f.Open will clear the file contents.
+        auto access_mode = file->f.GetAccessMode() == Common::FS::FileAccessMode::Write
+                               ? Common::FS::FileAccessMode::ReadWrite
+                               : file->f.GetAccessMode();
+        file->f.Close();
+        std::filesystem::remove(src_path);
+        file->f.Open(dst_path, access_mode);
+    } else {
+        std::filesystem::remove(src_path);
+    }
+
     return ORBIS_OK;
 }