Upgrade Lua service intercepts (#775)

Co-authored-by: Théo B. <16072534+LiquidFenrir@users.noreply.github.com>

CMakeLists.txt

@@ -416,7 +416,7 @@ set(HEADER_FILES include/emulator.hpp include/helpers.hpp include/termcolor.hpp
                  include/fs/archive_twl_sound.hpp include/fs/archive_card_spi.hpp include/services/ns.hpp include/audio/audio_device.hpp
                  include/audio/audio_device_interface.hpp include/audio/libretro_audio_device.hpp include/services/ir/ir_types.hpp
                  include/services/ir/ir_device.hpp include/services/ir/circlepad_pro.hpp include/services/service_intercept.hpp
-                 include/screen_layout.hpp
+                 include/screen_layout.hpp include/services/service_map.hpp
 )
 
 if(IOS)

include/lua_manager.hpp

@@ -48,7 +48,8 @@ class LuaManager {
 		}
 	}
 
-	bool signalInterceptedService(const std::string& service, u32 function, u32 messagePointer);
+	bool signalInterceptedService(const std::string& service, u32 function, u32 messagePointer, int callbackRef);
+	void removeInterceptedService(const std::string& service, u32 function, int callbackRef);
 };
 
 #else  // Lua not enabled, Lua manager does nothing
@@ -62,6 +63,7 @@ class LuaManager {
 	void loadString(const std::string& code) {}
 	void reset() {}
 	void signalEvent(LuaEvent e) {}
-	bool signalInterceptedService(const std::string& service, u32 function, u32 messagePointer) { return false; }
+	bool signalInterceptedService(const std::string& service, u32 function, u32 messagePointer, int callbackRef) { return false; }
+	void removeInterceptedService(const std::string& service, u32 function, int callbackRef) {}
 };
 #endif

include/services/service_manager.hpp

@@ -3,7 +3,7 @@
 #include <optional>
 #include <span>
 #include <string>
-#include <unordered_set>
+#include <unordered_map>
 
 #include "kernel_types.hpp"
 #include "logger.hpp"
@@ -94,8 +94,10 @@ class ServiceManager {
 	// For example, if we want to intercept dsp::DSP ReadPipe (Header: 0x000E00C0), the "serviceName" field would be "dsp::DSP"
 	// and the "function" field would be 0x000E00C0
 	LuaManager& lua;
-	std::unordered_set<InterceptedService> interceptedServices = {};
-	// Calling std::unordered_set<T>::size() compiles to a fairly non-trivial function call on Clang, so we store this
+
+	// Map from service intercept entries to their corresponding Lua callbacks
+	std::unordered_map<InterceptedService, int> interceptedServices = {};
+	// Calling std::unordered_map<T>::size() compiles to a non-trivial function call on Clang, so we store this
 	// separately and check it on service calls, for performance reasons
 	bool haveServiceIntercepts = false;
 
@@ -134,12 +136,23 @@ class ServiceManager {
 	Y2RService& getY2R() { return y2r; }
 	IRUserService& getIRUser() { return ir_user; }
 
-	void addServiceIntercept(const std::string& service, u32 function) {
-		interceptedServices.insert(InterceptedService(service, function));
+	void addServiceIntercept(const std::string& service, u32 function, int callbackRef) {
+		auto success = interceptedServices.try_emplace(InterceptedService(service, function), callbackRef);
+		if (!success.second) {
+			// An intercept for this service function already exists
+			// Remove the old callback and set the new one
+			lua.removeInterceptedService(service, function, success.first->second);
+			success.first->second = callbackRef;
+		}
+
 		haveServiceIntercepts = true;
 	}
 
 	void clearServiceIntercepts() {
+		for (const auto& [interceptedService, callbackRef] : interceptedServices) {
+			lua.removeInterceptedService(interceptedService.serviceName, interceptedService.function, callbackRef);
+		}
+
 		interceptedServices.clear();
 		haveServiceIntercepts = false;
 	}

include/services/service_map.hpp

@@ -0,0 +1,29 @@
+#pragma once
+#include <string>
+#include <type_traits>
+#include <utility>
+
+#include "handles.hpp"
+
+// Helpers for constructing std::maps to look up OS services.
+// We want to be able to map both service names -> services (Used for OS emulation)
+// And service handles -> services (For Lua service call intercepts)
+using ServiceMapEntry = std::pair<std::string, HorizonHandle>;
+
+// Comparator for constructing a name->handle service map
+struct ServiceMapByNameComparator {
+	// The comparators must be transparent, as our search key is different from our set key
+	// Our set key is a ServiceMapEntry, while the comparator each time is either the name or the service handle
+	using is_transparent = std::true_type;
+	bool operator()(const ServiceMapEntry& lhs, std::string_view rhs) const { return lhs.first < rhs; }
+	bool operator()(std::string_view lhs, const ServiceMapEntry& rhs) const { return lhs < rhs.first; }
+	bool operator()(const ServiceMapEntry& lhs, const ServiceMapEntry& rhs) const { return lhs.first < rhs.first; }
+};
+
+// Comparator for constructing a handle->name service map
+struct ServiceMapByHandleComparator {
+	using is_transparent = std::true_type;
+	bool operator()(const ServiceMapEntry& lhs, HorizonHandle rhs) const { return lhs.second < rhs; }
+	bool operator()(HorizonHandle lhs, const ServiceMapEntry& rhs) const { return lhs < rhs.second; }
+	bool operator()(const ServiceMapEntry& lhs, const ServiceMapEntry& rhs) const { return lhs.second < rhs.second; }
+};

src/core/services/service_manager.cpp

@@ -1,9 +1,10 @@
 #include "services/service_manager.hpp"
 
-#include <map>
+#include <set>
 
 #include "ipc.hpp"
 #include "kernel.hpp"
+#include "services/service_map.hpp"
 
 ServiceManager::ServiceManager(
 	std::span<u32, 16> regs, Memory& mem, GPU& gpu, u32& currentPID, Kernel& kernel, const EmulatorConfig& config, LuaManager& lua
@@ -98,7 +99,7 @@ void ServiceManager::registerClient(u32 messagePointer) {
 }
 
 // clang-format off
-static std::map<std::string, HorizonHandle> serviceMap = {
+static const ServiceMapEntry serviceMapArray[] = {
 	{ "ac:u", KernelHandles::AC },
 	{ "ac:i", KernelHandles::AC },
 	{ "act:a", KernelHandles::ACT },
@@ -148,6 +149,9 @@ static std::map<std::string, HorizonHandle> serviceMap = {
 };
 // clang-format on
 
+static std::set<ServiceMapEntry, ServiceMapByNameComparator> serviceMapByName{std::begin(serviceMapArray), std::end(serviceMapArray)};
+static std::set<ServiceMapEntry, ServiceMapByHandleComparator> serviceMapByHandle{std::begin(serviceMapArray), std::end(serviceMapArray)};
+
 // https://www.3dbrew.org/wiki/SRV:GetServiceHandle
 void ServiceManager::getServiceHandle(u32 messagePointer) {
 	u32 nameLength = mem.read32(messagePointer + 12);
@@ -158,7 +162,7 @@ void ServiceManager::getServiceHandle(u32 messagePointer) {
 	log("srv::getServiceHandle (Service: %s, nameLength: %d, flags: %d)\n", service.c_str(), nameLength, flags);
 
 	// Look up service handle in map, panic if it does not exist
-	if (auto search = serviceMap.find(service); search != serviceMap.end())
+	if (auto search = serviceMapByName.find(service); search != serviceMapByName.end())
 		handle = search->second;
 	else
 		Helpers::panic("srv: GetServiceHandle with unknown service %s", service.c_str());
@@ -271,16 +275,13 @@ bool ServiceManager::checkForIntercept(u32 messagePointer, Handle handle) {
 	// Check if there's a Lua handler for this function and call it
 	const u32 function = mem.read32(messagePointer);
 
-	for (auto [serviceName, serviceHandle] : serviceMap) {
-		if (serviceHandle == handle) {
-			auto intercept = InterceptedService(std::string(serviceName), function);
-			if (interceptedServices.contains(intercept)) {
-				// If the Lua handler returns true, it means the service is handled entirely
-				// From Lua, and we shouldn't do anything else here.
-				return lua.signalInterceptedService(intercept.serviceName, function, messagePointer);
-			}
+	if (auto service_it = serviceMapByHandle.find(handle); service_it != serviceMapByHandle.end()) {
+		auto intercept = InterceptedService(service_it->first, function);
 
-			break;
+		if (auto intercept_it = interceptedServices.find(intercept); intercept_it != interceptedServices.end()) {
+			// If the Lua handler returns true, it means the service is handled entirely
+			// From Lua, and we shouldn't do anything else here.
+			return lua.signalInterceptedService(intercept.serviceName, function, messagePointer, intercept_it->second);
 		}
 	}
 

src/lua.cpp

@@ -101,14 +101,14 @@ void LuaManager::signalEventInternal(LuaEvent e) {
 	lua_pcall(L, 1, 0, 0);
 }
 
-// Calls the "interceptService" function, if it exists, when a service call is intercepted
+// Calls the callback passed to the addServiceIntercept function when a service call is intercepted
 // It passes the service name, the function header, and a pointer to the call's TLS buffer as parameters
-// interceptService is expected to return a bool, which indicates whether the C++ code should proceed to handle the service call
+// The callback is expected to return a bool, indicating whether the C++ code should proceed to handle the service call
 // or if the Lua code handles it entirely.
-// If the bool is true, the Lua code handles the service call entirely and the C++ code doesn't do anything extra
-// Otherwise, then the C++ code calls its service call handling code as usual.
-bool LuaManager::signalInterceptedService(const std::string& service, u32 function, u32 messagePointer) {
-	lua_getglobal(L, "interceptService");
+// If the bool is true, the Lua code handles the service call entirely and the C++ side doesn't do anything extra
+// Otherwise, the C++ side calls its service call handling code as usual.
+bool LuaManager::signalInterceptedService(const std::string& service, u32 function, u32 messagePointer, int callbackRef) {
+	lua_rawgeti(L, LUA_REGISTRYINDEX, callbackRef);
 	lua_pushstring(L, service.c_str());  // Push service name
 	lua_pushinteger(L, function);        // Push function header
 	lua_pushinteger(L, messagePointer);  // Push pointer to TLS buffer
@@ -129,6 +129,12 @@ bool LuaManager::signalInterceptedService(const std::string& service, u32 functi
 	return ret;
 }
 
+// Removes a reference from the callback value in the registry
+// Prevents memory leaks, otherwise the function object would stay forever
+void LuaManager::removeInterceptedService(const std::string& service, u32 function, int callbackRef) {
+	luaL_unref(L, LUA_REGISTRYINDEX, callbackRef);
+}
+
 void LuaManager::reset() {
 	// Reset scripts
 	haveScript = false;
@@ -238,15 +244,20 @@ static int loadROMThunk(lua_State* L) {
 static int addServiceInterceptThunk(lua_State* L) {
 	// Service name argument is invalid, report that loading failed and exit
 	if (lua_type(L, 1) != LUA_TSTRING) {
-		lua_pushboolean(L, 0);
-		lua_error(L);
-		return 2;
+		return luaL_error(L, "Argument 1 (service name) is not a string");
 	}
 
 	if (lua_type(L, 2) != LUA_TNUMBER) {
-		lua_pushboolean(L, 0);
-		lua_error(L);
-		return 2;
+		return luaL_error(L, "Argument 2 (function id) is not a number");
+	}
+
+	// Callback is not a function object directly, fail and exit
+	// Objects with a __call metamethod are not allowed (tables, userdata)
+	// Good: addServiceIntercept(serviceName, func, myLuaFunction)
+	// Good: addServiceIntercept(serviceName, func, function (service, func, buffer) ... end)
+	// Bad:  addServiceIntercept(serviceName, func, obj:method)
+	if (lua_type(L, 3) != LUA_TFUNCTION) {
+		return luaL_error(L, "Argument 3 (callback) is not a function");
 	}
 
 	// Get the name of the service we want to intercept, as well as the header of the function to intercept
@@ -254,8 +265,13 @@ static int addServiceInterceptThunk(lua_State* L) {
 	const char* const str = lua_tolstring(L, 1, &nameLength);
 	const u32 function = (u32)lua_tointeger(L, 2);
 	const auto serviceName = std::string(str, nameLength);
-	LuaManager::g_emulator->getServiceManager().addServiceIntercept(serviceName, function);
-	return 2;
+
+	// Stores a reference to the callback function object in the registry for later use
+	// Must be freed with lua_unref later, in order to avoid memory leaks
+	lua_pushvalue(L, 3);
+	const int callbackRef = luaL_ref(L, LUA_REGISTRYINDEX);
+	LuaManager::g_emulator->getServiceManager().addServiceIntercept(serviceName, function, callbackRef);
+	return 0;
 }
 
 static int clearServiceInterceptsThunk(lua_State* L) {
@@ -391,7 +407,7 @@ void LuaManager::initializeThunks() {
 
 		disassembleARM = function(pc, instruction) return GLOBALS.__disassembleARM(pc, instruction) end,
 		disassembleTeak = function(opcode, exp) return GLOBALS.__disassembleTeak(opcode, exp or 0) end,
-		addServiceIntercept = function(service, func) return GLOBALS.__addServiceIntercept(service, func) end,
+		addServiceIntercept = function(service, func, cb) return GLOBALS.__addServiceIntercept(service, func, cb) end,
 		clearServiceIntercepts = function() return GLOBALS.__clearServiceIntercepts() end,
 
 		Frame = __Frame,