From 904646e93b8e365e8bb248c9d73e281a0af4eee8 Mon Sep 17 00:00:00 2001
From: Ryan Houdek <Sonicadvance1@gmail.com>
Date: Fri, 5 Apr 2024 13:02:04 -0700
Subject: [PATCH] FEXCore: Fixes priority of FEX_APP_CONFIG

This environment variable had an incorrect priority on the configuration
system. The expectation was higher priority than most other layers.

Now the only layer that has higher priority is the environment
variables.
---
 FEXCore/Source/Interface/Config/Config.cpp    |  3 +-
 FEXCore/include/FEXCore/Config/Config.h       |  1 +
 Source/Common/Config.cpp                      | 33 ++++++++++---------
 Source/Common/Config.h                        |  1 +
 .../LinuxSyscalls/FileManagement.cpp          |  6 ++++
 5 files changed, 28 insertions(+), 16 deletions(-)

diff --git a/FEXCore/Source/Interface/Config/Config.cpp b/FEXCore/Source/Interface/Config/Config.cpp
index f64136dd3a..339539951d 100644
--- a/FEXCore/Source/Interface/Config/Config.cpp
+++ b/FEXCore/Source/Interface/Config/Config.cpp
@@ -130,7 +130,7 @@ namespace DefaultValues {
   static fextl::map<FEXCore::Config::LayerType, fextl::unique_ptr<FEXCore::Config::Layer>> ConfigLayers;
   static FEXCore::Config::Layer *Meta{};
 
-  constexpr std::array<FEXCore::Config::LayerType, 9> LoadOrder = {
+  constexpr std::array<FEXCore::Config::LayerType, 10> LoadOrder = {
     FEXCore::Config::LayerType::LAYER_GLOBAL_MAIN,
     FEXCore::Config::LayerType::LAYER_MAIN,
     FEXCore::Config::LayerType::LAYER_GLOBAL_STEAM_APP,
@@ -138,6 +138,7 @@ namespace DefaultValues {
     FEXCore::Config::LayerType::LAYER_LOCAL_STEAM_APP,
     FEXCore::Config::LayerType::LAYER_LOCAL_APP,
     FEXCore::Config::LayerType::LAYER_ARGUMENTS,
+    FEXCore::Config::LayerType::LAYER_USER_OVERRIDE,
     FEXCore::Config::LayerType::LAYER_ENVIRONMENT,
     FEXCore::Config::LayerType::LAYER_TOP
   };
diff --git a/FEXCore/include/FEXCore/Config/Config.h b/FEXCore/include/FEXCore/Config/Config.h
index 9aa01f2d13..38c2aa5352 100644
--- a/FEXCore/include/FEXCore/Config/Config.h
+++ b/FEXCore/include/FEXCore/Config/Config.h
@@ -81,6 +81,7 @@ namespace Handler {
     LAYER_GLOBAL_APP,
     LAYER_LOCAL_STEAM_APP,
     LAYER_LOCAL_APP,
+    LAYER_USER_OVERRIDE,
     LAYER_ENVIRONMENT,
     LAYER_TOP,
   };
diff --git a/Source/Common/Config.cpp b/Source/Common/Config.cpp
index 5a1aaef50e..1430479ed7 100644
--- a/Source/Common/Config.cpp
+++ b/Source/Common/Config.cpp
@@ -129,6 +129,8 @@ namespace JSON {
   public:
     explicit MainLoader(FEXCore::Config::LayerType Type);
     explicit MainLoader(fextl::string ConfigFile);
+    explicit MainLoader(FEXCore::Config::LayerType Type, const char* ConfigFile);
+
     void Load() override;
 
   private:
@@ -188,6 +190,12 @@ namespace JSON {
     , Config{std::move(ConfigFile)} {
   }
 
+
+  MainLoader::MainLoader(FEXCore::Config::LayerType Type, const char* ConfigFile)
+    : OptionMapper(Type)
+    , Config{ConfigFile} {
+  }
+
   void MainLoader::Load() {
     JSON::LoadJSonConfig(Config, [this](const char *Name, const char *ConfigString) {
       MapNameToOption(Name, ConfigString);
@@ -276,6 +284,10 @@ namespace JSON {
     }
   }
 
+  fextl::unique_ptr<FEXCore::Config::Layer> CreateUserOverrideLayer(const char* AppConfig) {
+    return fextl::make_unique<MainLoader>(FEXCore::Config::LayerType::LAYER_USER_OVERRIDE, AppConfig);
+  }
+
   fextl::unique_ptr<FEXCore::Config::Layer> CreateAppLayer(const fextl::string& Filename, FEXCore::Config::LayerType Type) {
     return fextl::make_unique<AppLoader>(Filename, Type);
   }
@@ -371,6 +383,11 @@ namespace JSON {
       FEXCore::Config::AddLayer(fextl::make_unique<FEX::ArgLoader::ArgLoader>(argc, argv));
     }
 
+    const char *AppConfig = getenv("FEX_APP_CONFIG");
+    if (AppConfig && FHU::Filesystem::Exists(AppConfig)) {
+      FEXCore::Config::AddLayer(CreateUserOverrideLayer(AppConfig));
+    }
+
     FEXCore::Config::AddLayer(CreateEnvironmentLayer(envp));
     FEXCore::Config::Load();
 
@@ -529,21 +546,7 @@ namespace JSON {
   }
 
   fextl::string GetConfigFileLocation(bool Global) {
-    fextl::string ConfigFile{};
-    if (Global) {
-      ConfigFile = GetConfigDirectory(true) + "Config.json";
-    }
-    else {
-      const char *AppConfig = getenv("FEX_APP_CONFIG");
-      if (AppConfig) {
-        // App config environment variable overwrites only the config file
-        ConfigFile = AppConfig;
-      }
-      else {
-        ConfigFile = GetConfigDirectory(false) + "Config.json";
-      }
-    }
-    return ConfigFile;
+    return GetConfigDirectory(Global) + "Config.json";
   }
 
   void InitializeConfigs() {
diff --git a/Source/Common/Config.h b/Source/Common/Config.h
index 5e08d1ef7c..5e7bbeb040 100644
--- a/Source/Common/Config.h
+++ b/Source/Common/Config.h
@@ -73,6 +73,7 @@ namespace FEX::Config {
    * @return unique_ptr for that layer
    */
   fextl::unique_ptr<FEXCore::Config::Layer> CreateMainLayer(fextl::string const *File = nullptr);
+  fextl::unique_ptr<FEXCore::Config::Layer> CreateUserOverrideLayer(const char* AppConfig);
 
   /**
    * @brief Create an application configuration loader
diff --git a/Source/Tools/LinuxEmulation/LinuxSyscalls/FileManagement.cpp b/Source/Tools/LinuxEmulation/LinuxSyscalls/FileManagement.cpp
index 4fafd612c9..75941f9e3d 100644
--- a/Source/Tools/LinuxEmulation/LinuxSyscalls/FileManagement.cpp
+++ b/Source/Tools/LinuxEmulation/LinuxSyscalls/FileManagement.cpp
@@ -219,6 +219,7 @@ FileManager::FileManager(FEXCore::Context::Context *ctx)
   // - AppConfig Global
   // - Steam AppConfig Local
   // - AppConfig Local
+  // - AppConfig override
   // This doesn't support the classic thunks interface.
 
   auto AppName = AppConfigName();
@@ -245,6 +246,11 @@ FileManager::FileManager(FEXCore::Context::Context *ctx)
     ConfigPaths.emplace_back(FEXCore::Config::GetApplicationConfig(AppName, false));
   }
 
+  const char *AppConfig = getenv("FEX_APP_CONFIG");
+  if (AppConfig) {
+    ConfigPaths.emplace_back(AppConfig);
+  }
+
   if (!LDPath().empty()) {
     RootFSFD = open(LDPath().c_str(), O_DIRECTORY | O_PATH | O_CLOEXEC);
     if (RootFSFD == -1) {