FEXInterpreter: Support portable installs

FEXCore/Scripts/config_generator.py

@@ -217,6 +217,14 @@ def print_man_environment_tail():
     ],
     "''", True)
 
+    print_man_env_option(
+    "FEX_PORTABLE",
+    [
+    "Allows FEX to run without installation. Global locations for configuration and binfmt_misc are ignored. These files are instead read from <FEXInterpreterPath>/fex-emu/ by default.",
+    "For further customization, see FEX_APP_CONFIG_LOCATION and FEX_APP_DATA_LOCATION."
+    ],
+    "''", True)
+
 def print_man_header():
     header ='''.Dd {0}
 .Dt FEX

Source/Common/Config.cpp

@@ -338,10 +338,13 @@ fextl::string RecoverGuestProgramFilename(fextl::string Program, bool ExecFDInte
 }
 
 ApplicationNames LoadConfig(fextl::unique_ptr<FEX::ArgLoader::ArgLoader> ArgsLoader, bool LoadProgramConfig, char** const envp,
-                            bool ExecFDInterp, int ProgramFDFromEnv) {
-  FEX::Config::InitializeConfigs();
+                            bool ExecFDInterp, int ProgramFDFromEnv, const PortableInformation& PortableInfo) {
+  const bool IsPortable = PortableInfo.IsPortable;
+  FEX::Config::InitializeConfigs(PortableInfo);
   FEXCore::Config::Initialize();
-  FEXCore::Config::AddLayer(CreateGlobalMainLayer());
+  if (!IsPortable) {
+    FEXCore::Config::AddLayer(CreateGlobalMainLayer());
+  }
   FEXCore::Config::AddLayer(CreateMainLayer());
 
   auto Args = ArgsLoader->Get();
@@ -391,15 +394,19 @@ ApplicationNames LoadConfig(fextl::unique_ptr<FEX::ArgLoader::ArgLoader> ArgsLoa
       }
     }
 
-    FEXCore::Config::AddLayer(CreateAppLayer(ProgramName, FEXCore::Config::LayerType::LAYER_GLOBAL_APP));
+    if (!IsPortable) {
+      FEXCore::Config::AddLayer(CreateAppLayer(ProgramName, FEXCore::Config::LayerType::LAYER_GLOBAL_APP));
+    }
     FEXCore::Config::AddLayer(CreateAppLayer(ProgramName, FEXCore::Config::LayerType::LAYER_LOCAL_APP));
 
     auto SteamID = getenv("SteamAppId");
     if (SteamID) {
       // If a SteamID exists then let's search for Steam application configs as well.
       // We want to key off both the SteamAppId number /and/ the executable since we may not want to thunk all binaries.
       fextl::string SteamAppName = fextl::fmt::format("Steam_{}_{}", SteamID, ProgramName);
-      FEXCore::Config::AddLayer(CreateAppLayer(SteamAppName, FEXCore::Config::LayerType::LAYER_GLOBAL_STEAM_APP));
+      if (!IsPortable) {
+        FEXCore::Config::AddLayer(CreateAppLayer(SteamAppName, FEXCore::Config::LayerType::LAYER_GLOBAL_STEAM_APP));
+      }
       FEXCore::Config::AddLayer(CreateAppLayer(SteamAppName, FEXCore::Config::LayerType::LAYER_LOCAL_STEAM_APP));
     }
   }
@@ -473,12 +480,16 @@ const char* GetHomeDirectory() {
 }
 #endif
 
-fextl::string GetDataDirectory() {
-  fextl::string DataDir {};
+fextl::string GetDataDirectory(const PortableInformation& PortableInfo) {
+  const char* DataOverride = getenv("FEX_APP_DATA_LOCATION");
 
+  if (PortableInfo.IsPortable && !DataOverride) {
+    return fextl::fmt::format("{}fex-emu/", PortableInfo.InterpreterPath);
+  }
+
+  fextl::string DataDir {};
   const char* HomeDir = GetHomeDirectory();
   const char* DataXDG = getenv("XDG_DATA_HOME");
-  const char* DataOverride = getenv("FEX_APP_DATA_LOCATION");
   if (DataOverride) {
     // Data override will override the complete directory
     DataDir = DataOverride;
@@ -489,14 +500,18 @@ fextl::string GetDataDirectory() {
   return DataDir;
 }
 
-fextl::string GetConfigDirectory(bool Global) {
+fextl::string GetConfigDirectory(bool Global, const PortableInformation& PortableInfo) {
+  const char* ConfigOverride = getenv("FEX_APP_CONFIG_LOCATION");
+  if (PortableInfo.IsPortable && (Global || !ConfigOverride)) {
+    return fextl::fmt::format("{}fex-emu/", PortableInfo.InterpreterPath);
+  }
+
   fextl::string ConfigDir;
   if (Global) {
     ConfigDir = GLOBAL_DATA_DIRECTORY;
   } else {
     const char* HomeDir = GetHomeDirectory();
     const char* ConfigXDG = getenv("XDG_CONFIG_HOME");
-    const char* ConfigOverride = getenv("FEX_APP_CONFIG_LOCATION");
     if (ConfigOverride) {
       // Config override completely overrides the config directory
       ConfigDir = ConfigOverride;
@@ -515,15 +530,15 @@ fextl::string GetConfigDirectory(bool Global) {
   return ConfigDir;
 }
 
-fextl::string GetConfigFileLocation(bool Global) {
-  return GetConfigDirectory(Global) + "Config.json";
+fextl::string GetConfigFileLocation(bool Global, const PortableInformation& PortableInfo) {
+  return GetConfigDirectory(Global, PortableInfo) + "Config.json";
 }
 
-void InitializeConfigs() {
-  FEXCore::Config::SetDataDirectory(GetDataDirectory());
-  FEXCore::Config::SetConfigDirectory(GetConfigDirectory(false), false);
-  FEXCore::Config::SetConfigDirectory(GetConfigDirectory(true), true);
-  FEXCore::Config::SetConfigFileLocation(GetConfigFileLocation(false), false);
-  FEXCore::Config::SetConfigFileLocation(GetConfigFileLocation(true), true);
+void InitializeConfigs(const PortableInformation& PortableInfo) {
+  FEXCore::Config::SetDataDirectory(GetDataDirectory(PortableInfo));
+  FEXCore::Config::SetConfigDirectory(GetConfigDirectory(false, PortableInfo), false);
+  FEXCore::Config::SetConfigDirectory(GetConfigDirectory(true, PortableInfo), true);
+  FEXCore::Config::SetConfigFileLocation(GetConfigFileLocation(false, PortableInfo), false);
+  FEXCore::Config::SetConfigFileLocation(GetConfigFileLocation(true, PortableInfo), true);
 }
 } // namespace FEX::Config

Source/Common/Config.h

@@ -28,6 +28,12 @@ struct ApplicationNames {
   fextl::string ProgramName;
 };
 
+struct PortableInformation {
+  bool IsPortable;
+  // Path of folder containing FEXInterpreter (including / at the end)
+  fextl::string InterpreterPath;
+};
+
 /**
  * @brief Loads the FEX and application configurations for the application that is getting ready to run.
  *
@@ -40,15 +46,15 @@ struct ApplicationNames {
  * @return The application name and path structure
  */
 ApplicationNames LoadConfig(fextl::unique_ptr<FEX::ArgLoader::ArgLoader> ArgLoader, bool LoadProgramConfig, char** const envp,
-                            bool ExecFDInterp, int ProgramFDFromEnv);
+                            bool ExecFDInterp, int ProgramFDFromEnv, const PortableInformation& PortableInfo);
 
 const char* GetHomeDirectory();
 
-fextl::string GetDataDirectory();
-fextl::string GetConfigDirectory(bool Global);
-fextl::string GetConfigFileLocation(bool Global);
+fextl::string GetDataDirectory(const PortableInformation& PortableInfo);
+fextl::string GetConfigDirectory(bool Global, const PortableInformation& PortableInfo);
+fextl::string GetConfigFileLocation(bool Global, const PortableInformation& PortableInfo);
 
-void InitializeConfigs();
+void InitializeConfigs(const PortableInformation& PortableInfo);
 
 /**
  * @brief Loads the global FEX config

Source/Tools/FEXConfig/Main.cpp

@@ -992,7 +992,7 @@ bool DrawUI() {
 } // namespace
 
 int main(int argc, char** argv) {
-  FEX::Config::InitializeConfigs();
+  FEX::Config::InitializeConfigs(FEX::Config::PortableInformation {});
 
   fextl::string ImGUIConfig = FEXCore::Config::GetConfigDirectory(false) + "FEXConfig_imgui.ini";
   auto [window, gl_context] = FEX::GUI::SetupIMGui("#FEXConfig", ImGUIConfig);

Source/Tools/FEXLoader/FEXLoader.cpp

@@ -64,7 +64,6 @@ desc: Glues the ELF loader, FEXCore and LinuxSyscalls to launch an elf under fex
 namespace {
 static bool SilentLog;
 static int OutputFD {-1};
-static bool ExecutedWithFD {false};
 
 void MsgHandler(LogMan::DebugLevels Level, const char* Message) {
   if (SilentLog) {
@@ -194,14 +193,55 @@ void RootFSRedirect(fextl::string* Filename, const fextl::string& RootFS) {
   }
 }
 
-bool RanAsInterpreter(const char* Program) {
+FEX::Config::PortableInformation ReadPortabilityInformation() {
+  const FEX::Config::PortableInformation BadResult {false, {}};
+  const char* PortableConfig = getenv("FEX_PORTABLE");
+  if (!PortableConfig) {
+    return BadResult;
+  }
+
+  uint32_t Value {};
+  std::string_view PortableView {PortableConfig};
+
+  if (std::from_chars(PortableView.data(), PortableView.data() + PortableView.size(), Value).ec != std::errc {} || Value == 0) {
+    return BadResult;
+  }
+
+  // Read the FEXInterpreter path from `/proc/self/exe` which is always a symlink to the absolute path of the executable running.
+  // This way we can get the parent path that the application is executing from.
+  char SelfPath[PATH_MAX];
+  auto Result = readlink("/proc/self/exe", SelfPath, PATH_MAX);
+  if (Result == -1) {
+    return BadResult;
+  }
+
+  std::string_view SelfPathView {SelfPath, std::min<size_t>(PATH_MAX, Result)};
+
+  // Extract the absolute path from the FEXInterpreter path
+  return {true, fextl::string {SelfPathView.substr(0, SelfPathView.find_last_of('/') + 1)}};
+}
+
+bool RanAsInterpreter(bool ExecutedWithFD) {
   return ExecutedWithFD || FEXLOADER_AS_INTERPRETER;
 }
 
-bool IsInterpreterInstalled() {
-  // The interpreter is installed if both the binfmt_misc handlers are available
-  // Or if we were originally executed with FD. Which means the interpreter is installed
+/**
+ * @brief Queries if FEX is installed as a binfmt_misc interpreter
+ *
+ * @param ExecutedWithFD If FEXInterpreter was executed using a binfmt_misc FD handle from the kernel
+ * @param Portable Portability information about FEX being run in portable mode
+ *
+ * @return true if the binfmt_misc handlers are installed and being used
+ */
+bool QueryInterpreterInstalled(bool ExecutedWithFD, const FEX::Config::PortableInformation& Portable) {
+  if (Portable.IsPortable) {
+    // Don't use binfmt interpreter even if it's installed
+    return false;
+  }
 
+  // We know the FEX interpreter is installed through a couple paths.
+  // - If both of the binfmt_misc handlers are installed
+  // - Or if we were executed with an FD (Which can only happen from the kernel executing through binfmt_misc)
   return ExecutedWithFD || (access("/proc/sys/fs/binfmt_misc/FEX-x86", F_OK) == 0 && access("/proc/sys/fs/binfmt_misc/FEX-x86_64", F_OK) == 0);
 }
 
@@ -267,9 +307,12 @@ static int StealFEXFDFromEnv(const char* Env) {
 int main(int argc, char** argv, char** const envp) {
   auto SBRKPointer = FEXCore::Allocator::DisableSBRKAllocations();
   FEXCore::Allocator::GLIBCScopedFault GLIBFaultScope;
-  const bool IsInterpreter = RanAsInterpreter(argv[0]);
 
-  ExecutedWithFD = getauxval(AT_EXECFD) != 0;
+  const bool ExecutedWithFD = getauxval(AT_EXECFD) != 0;
+  const bool IsInterpreter = RanAsInterpreter(ExecutedWithFD);
+  const auto PortableInfo = ReadPortabilityInformation();
+  const bool InterpreterInstalled = QueryInterpreterInstalled(ExecutedWithFD, PortableInfo);
+
   int FEXFD {StealFEXFDFromEnv("FEX_EXECVEFD")};
 
   LogMan::Throw::InstallHandler(AssertHandler);
@@ -280,7 +323,7 @@ int main(int argc, char** argv, char** const envp) {
     argc, argv);
   auto Args = ArgsLoader->Get();
   auto ParsedArgs = ArgsLoader->GetParsedArgs();
-  auto Program = FEX::Config::LoadConfig(std::move(ArgsLoader), true, envp, ExecutedWithFD, FEXFD);
+  auto Program = FEX::Config::LoadConfig(std::move(ArgsLoader), true, envp, ExecutedWithFD, FEXFD, PortableInfo);
 
   if (Program.ProgramPath.empty() && FEXFD == -1) {
     // Early exit if we weren't passed an argument
@@ -290,7 +333,7 @@ int main(int argc, char** argv, char** const envp) {
   // Reload the meta layer
   FEXCore::Config::ReloadMetaLayer();
   FEXCore::Config::Set(FEXCore::Config::CONFIG_IS_INTERPRETER, IsInterpreter ? "1" : "0");
-  FEXCore::Config::Set(FEXCore::Config::CONFIG_INTERPRETER_INSTALLED, IsInterpreterInstalled() ? "1" : "0");
+  FEXCore::Config::Set(FEXCore::Config::CONFIG_INTERPRETER_INSTALLED, InterpreterInstalled ? "1" : "0");
 #ifdef VIXL_SIMULATOR
   // If running under the vixl simulator, ensure that indirect runtime calls are enabled.
   FEXCore::Config::EraseSet(FEXCore::Config::CONFIG_DISABLE_VIXL_INDIRECT_RUNTIME_CALLS, "0");

Source/Tools/FEXQonfig/Main.cpp

@@ -351,7 +351,7 @@ void ConfigRuntime::onLoad(const QUrl& Filename) {
 int main(int Argc, char** Argv) {
   QApplication App(Argc, Argv);
 
-  FEX::Config::InitializeConfigs();
+  FEX::Config::InitializeConfigs(FEX::Config::PortableInformation {});
   fextl::string ConfigFilename = Argc > 1 ? Argv[1] : FEXCore::Config::GetConfigFileLocation();
   ConfigInit(ConfigFilename);
 

Source/Tools/FEXRootFSFetcher/Main.cpp

@@ -1091,7 +1091,7 @@ bool ExtractEroFS(const fextl::string& Path, const fextl::string& RootFS, const
 
 int main(int argc, char** argv, char** const envp) {
   auto ArgsLoader = fextl::make_unique<FEX::ArgLoader::ArgLoader>(FEX::ArgLoader::ArgLoader::LoadType::WITHOUT_FEXLOADER_PARSER, argc, argv);
-  FEX::Config::LoadConfig(std::move(ArgsLoader), false, envp, false, {});
+  FEX::Config::LoadConfig(std::move(ArgsLoader), false, envp, false, false, FEX::Config::PortableInformation {});
 
   // Reload the meta layer
   FEXCore::Config::ReloadMetaLayer();

Source/Tools/FEXServer/Main.cpp

@@ -117,7 +117,7 @@ int main(int argc, char** argv, char** const envp) {
   }
 
   auto ArgsLoader = fextl::make_unique<FEX::ArgLoader::ArgLoader>(FEX::ArgLoader::ArgLoader::LoadType::WITHOUT_FEXLOADER_PARSER, argc, argv);
-  FEX::Config::LoadConfig(std::move(ArgsLoader), false, envp, false, {});
+  FEX::Config::LoadConfig(std::move(ArgsLoader), false, envp, false, false, FEX::Config::PortableInformation {});
 
   // Reload the meta layer
   FEXCore::Config::ReloadMetaLayer();

Source/Tools/TestHarnessRunner/TestHarnessRunner.cpp

@@ -199,7 +199,7 @@ int main(int argc, char** argv, char** const envp) {
   LogMan::Throw::InstallHandler(AssertHandler);
   LogMan::Msg::InstallHandler(MsgHandler);
 
-  FEX::Config::InitializeConfigs();
+  FEX::Config::InitializeConfigs(FEX::Config::PortableInformation {});
   FEXCore::Config::Initialize();
   auto ArgsLoader = fextl::make_unique<FEX::ArgLoader::ArgLoader>(FEX::ArgLoader::ArgLoader::LoadType::WITH_FEXLOADER_PARSER, argc, argv);
   auto Args = ArgsLoader->Get();

Source/Windows/ARM64EC/Module.cpp

@@ -456,7 +456,7 @@ extern "C" void SyncThreadContext(CONTEXT* Context) {
 
 NTSTATUS ProcessInit() {
   FEX::Windows::InitCRTProcess();
-  FEX::Config::InitializeConfigs();
+  FEX::Config::InitializeConfigs(FEX::Config::PortableInformation {});
   FEXCore::Config::Initialize();
   FEXCore::Config::AddLayer(FEX::Config::CreateGlobalMainLayer());
   FEXCore::Config::AddLayer(FEX::Config::CreateMainLayer());

Source/Windows/WOW64/Module.cpp

@@ -424,7 +424,7 @@ class WowSyscallHandler : public FEXCore::HLE::SyscallHandler, public FEXCore::A
 
 void BTCpuProcessInit() {
   FEX::Windows::InitCRTProcess();
-  FEX::Config::InitializeConfigs();
+  FEX::Config::InitializeConfigs(FEX::Config::PortableInformation {});
   FEXCore::Config::Initialize();
   FEXCore::Config::AddLayer(FEX::Config::CreateGlobalMainLayer());
   FEXCore::Config::AddLayer(FEX::Config::CreateMainLayer());