Service: Add new ServiceFramework framework for writing HLE services

The old "Interface" class had a few problems such as using free
functions (Which didn't allow you to write the service handler as if it
were a regular class.) which weren't very extensible. (Only received one
parameter with a pointer to the Interface object.)

The new ServiceFramework aims to solve these problems by working with
member functions and passing a generic context struct as parameter. This
struct can be extended in the future without having to update all
existing service implementations.

src/core/hle/service/service.h

@@ -18,11 +18,16 @@
 
 namespace Kernel {
 class ClientPort;
+class ServerPort;
 class ServerSession;
 }
 
 namespace Service {
 
+namespace SM {
+class ServiceManager;
+}
+
 static const int kMaxPortSize = 8; ///< Maximum size of a port name (8 characters)
 /// Arbitrary default number of maximum connections to an HLE service.
 static const u32 DefaultMaxSessions = 10;
@@ -30,6 +35,9 @@ static const u32 DefaultMaxSessions = 10;
 /**
  * Framework for implementing HLE service handlers which dispatch incoming SyncRequests based on a
  * table mapping header ids to handler functions.
+ *
+ * @deprecated Use ServiceFramework for new services instead. It allows services to be stateful and
+ *     is more extensible going forward.
  */
 class Interface : public Kernel::SessionRequestHandler {
 public:
@@ -101,6 +109,146 @@ private:
     boost::container::flat_map<u32, FunctionInfo> m_functions;
 };
 
+/**
+ * This is an non-templated base of ServiceFramework to reduce code bloat and compilation times, it
+ * is not meant to be used directly.
+ *
+ * @see ServiceFramework
+ */
+class ServiceFrameworkBase : public Kernel::SessionRequestHandler {
+public:
+    /// Returns the string identifier used to connect to the service.
+    std::string GetServiceName() const {
+        return service_name;
+    }
+
+    /**
+     * Returns the maximum number of sessions that can be connected to this service at the same
+     * time.
+     */
+    u32 GetMaxSessions() const {
+        return max_sessions;
+    }
+
+    /// Creates a port pair and registers this service with the given ServiceManager.
+    void InstallAsService(SM::ServiceManager& service_manager);
+    /// Creates a port pair and registers it on the kernel's global port registry.
+    void InstallAsNamedPort();
+
+    void HandleSyncRequest(Kernel::SharedPtr<Kernel::ServerSession> server_session) override;
+
+protected:
+    /// Member-function pointer type of SyncRequest handlers.
+    template <typename Self>
+    using HandlerFnP = void (Self::*)(Kernel::HLERequestContext&);
+
+private:
+    template <typename T>
+    friend class ServiceFramework;
+
+    struct FunctionInfoBase {
+        u32 expected_header;
+        HandlerFnP<ServiceFrameworkBase> handler_callback;
+        const char* name;
+    };
+
+    using InvokerFn = void(ServiceFrameworkBase* object, HandlerFnP<ServiceFrameworkBase> member,
+                           Kernel::HLERequestContext& ctx);
+
+    ServiceFrameworkBase(const char* service_name, u32 max_sessions, InvokerFn* handler_invoker);
+    ~ServiceFrameworkBase();
+
+    void RegisterHandlersBase(const FunctionInfoBase* functions, size_t n);
+    void ReportUnimplementedFunction(u32* cmd_buf, const FunctionInfoBase* info);
+
+    /// Identifier string used to connect to the service.
+    std::string service_name;
+    /// Maximum number of concurrent sessions that this service can handle.
+    u32 max_sessions;
+
+    /**
+     * Port where incoming connections will be received. Only created when InstallAsService() or
+     * InstallAsNamedPort() are called.
+     */
+    Kernel::SharedPtr<Kernel::ServerPort> port;
+
+    /// Function used to safely up-cast pointers to the derived class before invoking a handler.
+    InvokerFn* handler_invoker;
+    boost::container::flat_map<u32, FunctionInfoBase> handlers;
+};
+
+/**
+ * Framework for implementing HLE services. Dispatches on the header id of incoming SyncRequests
+ * based on a table mapping header ids to handler functions. Service implementations should inherit
+ * from ServiceFramework using the CRTP (`class Foo : public ServiceFramework<Foo> { ... };`) and
+ * populate it with handlers by calling #RegisterHandlers.
+ *
+ * In order to avoid duplicating code in the binary and exposing too many implementation details in
+ * the header, this class is split into a non-templated base (ServiceFrameworkBase) and a template
+ * deriving from it (ServiceFramework). The functions in this class will mostly only erase the type
+ * of the passed in function pointers and then delegate the actual work to the implementation in the
+ * base class.
+ */
+template <typename Self>
+class ServiceFramework : public ServiceFrameworkBase {
+protected:
+    /// Contains information about a request type which is handled by the service.
+    struct FunctionInfo : FunctionInfoBase {
+        // TODO(yuriks): This function could be constexpr, but clang is the only compiler that
+        // doesn't emit an ICE or a wrong diagnostic because of the static_cast.
+
+        /**
+         * Constructs a FunctionInfo for a function.
+         *
+         * @param expected_header request header in the command buffer which will trigger dispatch
+         *     to this handler
+         * @param handler_callback member function in this service which will be called to handle
+         *     the request
+         * @param name human-friendly name for the request. Used mostly for logging purposes.
+         */
+        FunctionInfo(u32 expected_header, HandlerFnP<Self> handler_callback, const char* name)
+            : FunctionInfoBase{
+                  expected_header,
+                  // Type-erase member function pointer by casting it down to the base class.
+                  static_cast<HandlerFnP<ServiceFrameworkBase>>(handler_callback), name} {}
+    };
+
+    /**
+     * Initializes the handler with no functions installed.
+     * @param max_sessions Maximum number of sessions that can be
+     * connected to this service at the same time.
+     */
+    ServiceFramework(const char* service_name, u32 max_sessions = DefaultMaxSessions)
+        : ServiceFrameworkBase(service_name, max_sessions, Invoker) {}
+
+    /// Registers handlers in the service.
+    template <size_t N>
+    void RegisterHandlers(const FunctionInfo (&functions)[N]) {
+        RegisterHandlers(functions, N);
+    }
+
+    /**
+     * Registers handlers in the service. Usually prefer using the other RegisterHandlers
+     * overload in order to avoid needing to specify the array size.
+     */
+    void RegisterHandlers(const FunctionInfo* functions, size_t n) {
+        RegisterHandlersBase(functions, n);
+    }
+
+private:
+    /**
+     * This function is used to allow invocation of pointers to handlers stored in the base class
+     * without needing to expose the type of this derived class. Pointers-to-member may require a
+     * fixup when being up or downcast, and thus code that does that needs to know the concrete type
+     * of the derived class in order to invoke one of it's functions through a pointer.
+     */
+    static void Invoker(ServiceFrameworkBase* object, HandlerFnP<ServiceFrameworkBase> member,
+                        Kernel::HLERequestContext& ctx) {
+        // Cast back up to our original types and call the member function
+        (static_cast<Self*>(object)->*static_cast<HandlerFnP<Self>>(member))(ctx);
+    }
+};
+
 /// Initialize ServiceManager
 void Init();
 
@@ -110,6 +258,8 @@ void Shutdown();
 /// Map of named ports managed by the kernel, which can be retrieved using the ConnectToPort SVC.
 extern std::unordered_map<std::string, Kernel::SharedPtr<Kernel::ClientPort>> g_kernel_named_ports;
 
+/// Adds a port to the named port table
+void AddNamedPort(std::string name, Kernel::SharedPtr<Kernel::ClientPort> port);
 /// Adds a service to the services table
 void AddService(Interface* interface_);