A bit of a redesign.

Sessions and Ports are now detached from each other.
HLE services are handled by means of a SessionRequestHandler class, Interface now inherits from this class.
The File and Directory classes are no longer kernel objects, but SessionRequestHandlers instead, bound to a ServerSession when requested.
File::OpenLinkFile now creates a new session pair and binds the File instance to it.

src/core/hle/kernel/client_port.cpp

@@ -14,21 +14,7 @@ namespace Kernel {
 ClientPort::ClientPort() {}
 ClientPort::~ClientPort() {}
 
-Kernel::SharedPtr<ClientPort> ClientPort::CreateForHLE(u32 max_sessions, std::shared_ptr<Service::Interface> hle_interface) {
-    SharedPtr<ClientPort> client_port(new ClientPort);
-    client_port->max_sessions = max_sessions;
-    client_port->active_sessions = 0;
-    client_port->name = hle_interface->GetPortName();
-    client_port->hle_interface = std::move(hle_interface);
-
-    return client_port;
-}
-
 void ClientPort::AddWaitingSession(SharedPtr<ServerSession> server_session) {
-    // A port that has an associated HLE interface doesn't have a server port.
-    if (hle_interface != nullptr)
-        return;
-
     server_port->pending_sessions.push_back(server_session);
     // Wake the threads waiting on the ServerPort
     server_port->WakeupAllWaitingThreads();

src/core/hle/kernel/client_port.h

@@ -22,14 +22,6 @@ class ClientPort final : public Object {
 public:
     friend class ServerPort;
 
-    /**
-     * Creates a serverless ClientPort that represents a bridge between the HLE implementation of a service/port and the emulated application.
-     * @param max_sessions Maximum number of sessions that this port is able to handle concurrently.
-     * @param hle_interface Interface object that implements the commands of the service.
-     * @returns ClientPort for the given HLE interface.
-     */
-    static Kernel::SharedPtr<ClientPort> CreateForHLE(u32 max_sessions, std::shared_ptr<Service::Interface> hle_interface);
-
     /**
      * Adds the specified server session to the queue of pending sessions of the associated ServerPort
      * @param server_session Server session to add to the queue
@@ -44,12 +36,10 @@ public:
         return HANDLE_TYPE;
     }
 
-    SharedPtr<ServerPort> server_port = nullptr;                 ///< ServerPort associated with this client port.
+    SharedPtr<ServerPort> server_port;                           ///< ServerPort associated with this client port.
     u32 max_sessions;                                            ///< Maximum number of simultaneous sessions the port can have
     u32 active_sessions;                                         ///< Number of currently open sessions to this port
     std::string name;                                            ///< Name of client port (optional)
-    std::shared_ptr<Service::Interface> hle_interface = nullptr; ///< HLE implementation of this port's request handler
-
 private:
     ClientPort();
     ~ClientPort() override;

src/core/hle/kernel/client_session.cpp

@@ -15,29 +15,17 @@ namespace Kernel {
 ClientSession::ClientSession() {}
 ClientSession::~ClientSession() {}
 
-ResultVal<SharedPtr<ClientSession>> ClientSession::Create(SharedPtr<ServerSession> server_session, SharedPtr<ClientPort> client_port, std::string name) {
+ResultVal<SharedPtr<ClientSession>> ClientSession::Create(SharedPtr<ServerSession> server_session, std::string name) {
     SharedPtr<ClientSession> client_session(new ClientSession);
 
     client_session->name = std::move(name);
     client_session->server_session = server_session;
-    client_session->client_port = client_port;
-    client_session->hle_helper = client_port->hle_interface;
-
     return MakeResult<SharedPtr<ClientSession>>(std::move(client_session));
 }
 
 ResultCode ClientSession::HandleSyncRequest() {
     // Signal the server session that new data is available
-    ResultCode result = server_session->HandleSyncRequest();
-
-    if (result.IsError())
-        return result;
-
-    // If this ClientSession has an associated HLE helper, forward the request to it.
-    if (hle_helper != nullptr)
-        result = hle_helper->HandleSyncRequest(server_session);
-
-    return result;
+    return server_session->HandleSyncRequest();
 }
 
 } // namespace

src/core/hle/kernel/client_session.h

@@ -25,11 +25,10 @@ public:
     /**
      * Creates a client session.
      * @param server_session The server session associated with this client session
-     * @param client_port The client port which this session is connected to
      * @param name Optional name of client session
      * @return The created client session
      */
-    static ResultVal<SharedPtr<ClientSession>> Create(SharedPtr<ServerSession> server_session, SharedPtr<ClientPort> client_port, std::string name = "Unknown");
+    static ResultVal<SharedPtr<ClientSession>> Create(SharedPtr<ServerSession> server_session, std::string name = "Unknown");
 
     std::string GetTypeName() const override { return "ClientSession"; }
     std::string GetName() const override { return name; }
@@ -45,8 +44,6 @@ public:
 
     std::string name;                           ///< Name of client port (optional)
     SharedPtr<ServerSession> server_session;    ///< The server session associated with this client session.
-    SharedPtr<ClientPort> client_port;          ///< The client port which this session is connected to.
-    std::shared_ptr<Service::Interface> hle_helper = nullptr; ///< HLE implementation of this port's request handler
 
 private:
     ClientSession();

src/core/hle/kernel/server_session.cpp

@@ -14,11 +14,12 @@ namespace Kernel {
 ServerSession::ServerSession() {}
 ServerSession::~ServerSession() {}
 
-ResultVal<SharedPtr<ServerSession>> ServerSession::Create(std::string name) {
+ResultVal<SharedPtr<ServerSession>> ServerSession::Create(std::string name, std::shared_ptr<Service::SessionRequestHandler> hle_handler) {
     SharedPtr<ServerSession> server_session(new ServerSession);
 
     server_session->name = std::move(name);
     server_session->signaled = false;
+    server_session->hle_handler = hle_handler;
 
     return MakeResult<SharedPtr<ServerSession>>(std::move(server_session));
 }
@@ -34,23 +35,21 @@ void ServerSession::Acquire() {
 
 ResultCode ServerSession::HandleSyncRequest() {
     // The ServerSession received a sync request, this means that there's new data available
-    // from one of its ClientSessions, so wake up any threads that may be waiting on a svcReplyAndReceive or similar.
+    // from its ClientSession, so wake up any threads that may be waiting on a svcReplyAndReceive or similar.
+
+    // If this ServerSession has an associated HLE handler, forward the request to it.
+    if (hle_handler != nullptr)
+        return hle_handler->HandleSyncRequest(SharedPtr<ServerSession>(this));
+
+    // If this ServerSession does not have an HLE implementation, just wake up the threads waiting on it.
     signaled = true;
     WakeupAllWaitingThreads();
     return RESULT_SUCCESS;
 }
 
-SharedPtr<ClientSession> ServerSession::CreateClientSession() {
-    // In Citra, some types of ServerSessions (File and Directory sessions) are not created as a pair of Server-Client sessions,
-    // but are instead created as a single ServerSession, which then hands over a ClientSession on demand (When opening the File or Directory).
-    // The real kernel (Or more specifically, the real FS service) does create the pair of Sessions at the same time (via svcCreateSession), and simply
-    // stores the ClientSession until it is needed.
-    return ClientSession::Create(SharedPtr<ServerSession>(this), nullptr, name + "Client").MoveFrom();
-}
-
-std::tuple<SharedPtr<ServerSession>, SharedPtr<ClientSession>> ServerSession::CreateSessionPair(SharedPtr<ClientPort> client_port, const std::string& name) {
-    auto server_session = ServerSession::Create(name + "Server").MoveFrom();
-    auto client_session = ClientSession::Create(server_session, client_port, name + "Client").MoveFrom();
+std::tuple<SharedPtr<ServerSession>, SharedPtr<ClientSession>> ServerSession::CreateSessionPair(const std::string& name, std::shared_ptr<Service::SessionRequestHandler> hle_handler) {
+    auto server_session = ServerSession::Create(name + "Server", hle_handler).MoveFrom();
+    auto client_session = ClientSession::Create(server_session, name + "Client").MoveFrom();
 
     return std::make_tuple(server_session, client_session);
 }

src/core/hle/kernel/server_session.h

@@ -10,158 +10,11 @@
 #include "core/hle/kernel/kernel.h"
 #include "core/hle/kernel/thread.h"
 #include "core/hle/result.h"
+#include "core/hle/service/service.h"
 #include "core/memory.h"
 
-namespace IPC {
-
-enum DescriptorType : u32 {
-    // Buffer related desciptors types (mask : 0x0F)
-    StaticBuffer = 0x02,
-    PXIBuffer = 0x04,
-    MappedBuffer = 0x08,
-    // Handle related descriptors types (mask : 0x30, but need to check for buffer related
-    // descriptors first )
-    CopyHandle = 0x00,
-    MoveHandle = 0x10,
-    CallingPid = 0x20,
-};
-
-/**
- * @brief Creates a command header to be used for IPC
- * @param command_id            ID of the command to create a header for.
- * @param normal_params         Size of the normal parameters in words. Up to 63.
- * @param translate_params_size Size of the translate parameters in words. Up to 63.
- * @return The created IPC header.
- *
- * Normal parameters are sent directly to the process while the translate parameters might go
- * through modifications and checks by the kernel.
- * The translate parameters are described by headers generated with the IPC::*Desc functions.
- *
- * @note While #normal_params is equivalent to the number of normal parameters,
- * #translate_params_size includes the size occupied by the translate parameters headers.
- */
-constexpr u32 MakeHeader(u16 command_id, unsigned int normal_params,
-                         unsigned int translate_params_size) {
-    return (u32(command_id) << 16) | ((u32(normal_params) & 0x3F) << 6) |
-           (u32(translate_params_size) & 0x3F);
-}
-
-union Header {
-    u32 raw;
-    BitField<0, 6, u32> translate_params_size;
-    BitField<6, 6, u32> normal_params;
-    BitField<16, 16, u32> command_id;
-};
-
-inline Header ParseHeader(u32 header) {
-    return {header};
-}
-
-constexpr u32 MoveHandleDesc(u32 num_handles = 1) {
-    return MoveHandle | ((num_handles - 1) << 26);
-}
-
-constexpr u32 CopyHandleDesc(u32 num_handles = 1) {
-    return CopyHandle | ((num_handles - 1) << 26);
-}
-
-constexpr u32 CallingPidDesc() {
-    return CallingPid;
-}
-
-constexpr bool isHandleDescriptor(u32 descriptor) {
-    return (descriptor & 0xF) == 0x0;
-}
-
-constexpr u32 HandleNumberFromDesc(u32 handle_descriptor) {
-    return (handle_descriptor >> 26) + 1;
-}
-
-constexpr u32 StaticBufferDesc(u32 size, u8 buffer_id) {
-    return StaticBuffer | (size << 14) | ((buffer_id & 0xF) << 10);
-}
-
-union StaticBufferDescInfo {
-    u32 raw;
-    BitField<10, 4, u32> buffer_id;
-    BitField<14, 18, u32> size;
-};
-
-inline StaticBufferDescInfo ParseStaticBufferDesc(const u32 desc) {
-    return {desc};
-}
-
-/**
- * @brief Creates a header describing a buffer to be sent over PXI.
- * @param size         Size of the buffer. Max 0x00FFFFFF.
- * @param buffer_id    The Id of the buffer. Max 0xF.
- * @param is_read_only true if the buffer is read-only. If false, the buffer is considered to have
- * read-write access.
- * @return The created PXI buffer header.
- *
- * The next value is a phys-address of a table located in the BASE memregion.
- */
-inline u32 PXIBufferDesc(u32 size, unsigned buffer_id, bool is_read_only) {
-    u32 type = PXIBuffer;
-    if (is_read_only)
-        type |= 0x2;
-    return type | (size << 8) | ((buffer_id & 0xF) << 4);
-}
-
-enum MappedBufferPermissions {
-    R = 1,
-    W = 2,
-    RW = R | W,
-};
-
-constexpr u32 MappedBufferDesc(u32 size, MappedBufferPermissions perms) {
-    return MappedBuffer | (size << 4) | (u32(perms) << 1);
-}
-
-union MappedBufferDescInfo {
-    u32 raw;
-    BitField<4, 28, u32> size;
-    BitField<1, 2, MappedBufferPermissions> perms;
-};
-
-inline MappedBufferDescInfo ParseMappedBufferDesc(const u32 desc) {
-    return {desc};
-}
-
-inline DescriptorType GetDescriptorType(u32 descriptor) {
-    // Note: Those checks must be done in this order
-    if (isHandleDescriptor(descriptor))
-        return (DescriptorType)(descriptor & 0x30);
-
-    // handle the fact that the following descriptors can have rights
-    if (descriptor & MappedBuffer)
-        return MappedBuffer;
-
-    if (descriptor & PXIBuffer)
-        return PXIBuffer;
-
-    return StaticBuffer;
-}
-
-} // namespace IPC
-
 namespace Kernel {
 
-static const int kCommandHeaderOffset = 0x80; ///< Offset into command buffer of header
-
-/**
- * Returns a pointer to the command buffer in the current thread's TLS
- * TODO(Subv): This is not entirely correct, the command buffer should be copied from
- * the thread's TLS to an intermediate buffer in kernel memory, and then copied again to
- * the service handler process' memory.
- * @param offset Optional offset into command buffer
- * @return Pointer to command buffer
- */
-inline u32* GetCommandBuffer(const int offset = 0) {
-    return (u32*)Memory::GetPointer(GetCurrentThread()->GetTLSAddress() + kCommandHeaderOffset +
-                                    offset);
-}
-
 class ClientSession;
 class ClientPort;
 
@@ -183,11 +36,13 @@ public:
     ~ServerSession() override;
 
     /**
-     * Creates a server session.
-     * @param name Optional name of the server session
+     * Creates a server session. The server session can have an optional HLE handler,
+     * which will be invoked to handle the IPC requests that this session receives.
+     * @param name Optional name of the server session.
+     * @param hle_handler Optional HLE handler for this server session.
      * @return The created server session
      */
-    static ResultVal<SharedPtr<ServerSession>> Create(std::string name = "Unknown");
+    static ResultVal<SharedPtr<ServerSession>> Create(std::string name = "Unknown", std::shared_ptr<Service::SessionRequestHandler> hle_handler = nullptr);
 
     std::string GetTypeName() const override { return "ServerSession"; }
 
@@ -196,17 +51,10 @@ public:
 
     /**
      * Creates a pair of ServerSession and an associated ClientSession.
-     * @param client_port ClientPort to which the sessions are connected
      * @param name Optional name of the ports
      * @return The created session tuple
      */
-    static std::tuple<SharedPtr<ServerSession>, SharedPtr<ClientSession>> CreateSessionPair(SharedPtr<ClientPort> client_port, const std::string& name = "Unknown");
-
-    /**
-     * Creates a portless ClientSession and associates it with this ServerSession.
-     * @returns ClientSession The newly created ClientSession.
-     */
-    SharedPtr<ClientSession> CreateClientSession();
+    static std::tuple<SharedPtr<ServerSession>, SharedPtr<ClientSession>> CreateSessionPair(const std::string& name = "Unknown", std::shared_ptr<Service::SessionRequestHandler> hle_handler = nullptr);
 
     /**
      * Handle a sync request from the emulated application.
@@ -221,5 +69,6 @@ public:
 
     std::string name; ///< The name of this session (optional)
     bool signaled;    ///< Whether there's new data available to this ServerSession
+    std::shared_ptr<Service::SessionRequestHandler> hle_handler; ///< This session's HLE request handler (optional)
 };
 }

src/core/hle/service/fs/archive.cpp

@@ -23,10 +23,11 @@
 #include "core/file_sys/directory_backend.h"
 #include "core/file_sys/file_backend.h"
 #include "core/hle/hle.h"
+#include "core/hle/kernel/client_session.h"
 #include "core/hle/result.h"
+#include "core/hle/service/service.h"
 #include "core/hle/service/fs/archive.h"
 #include "core/hle/service/fs/fs_user.h"
-#include "core/hle/service/service.h"
 #include "core/memory.h"
 
 // Specializes std::hash for ArchiveIdCode, so that we can use it in std::unordered_map.
@@ -92,11 +93,10 @@ File::File(std::unique_ptr<FileSys::FileBackend>&& backend, const FileSys::Path&
 
 File::~File() {}
 
-ResultCode File::HandleSyncRequest() {
+ResultCode File::HandleSyncRequest(Kernel::SharedPtr<Kernel::ServerSession> server_session) {
     u32* cmd_buff = Kernel::GetCommandBuffer();
     FileCommand cmd = static_cast<FileCommand>(cmd_buff[0]);
     switch (cmd) {
-
     // Read from file...
     case FileCommand::Read: {
         u64 offset = cmd_buff[1] | ((u64)cmd_buff[2]) << 32;
@@ -170,9 +170,11 @@ ResultCode File::HandleSyncRequest() {
         break;
     }
 
-    case FileCommand::OpenLinkFile: {
+    case FileCommand::OpenLinkFile:
+    {
         LOG_WARNING(Service_FS, "(STUBBED) File command OpenLinkFile %s", GetName().c_str());
-        cmd_buff[3] = Kernel::g_handle_table.Create(this).ValueOr(INVALID_HANDLE);
+        auto sessions = Kernel::ServerSession::CreateSessionPair(GetName(), shared_from_this());
+        cmd_buff[3] = Kernel::g_handle_table.Create(std::get<Kernel::SharedPtr<Kernel::ClientSession>>(sessions)).ValueOr(INVALID_HANDLE);
         break;
     }
 
@@ -193,10 +195,10 @@ ResultCode File::HandleSyncRequest() {
         LOG_ERROR(Service_FS, "Unknown command=0x%08X!", cmd);
         ResultCode error = UnimplementedFunction(ErrorModule::FS);
         cmd_buff[1] = error.raw; // TODO(Link Mauve): use the correct error code for that.
-        return ServerSession::HandleSyncRequest();
+        return RESULT_SUCCESS;
     }
     cmd_buff[1] = RESULT_SUCCESS.raw; // No error
-    return ServerSession::HandleSyncRequest();
+    return RESULT_SUCCESS;
 }
 
 Directory::Directory(std::unique_ptr<FileSys::DirectoryBackend>&& backend,
@@ -205,11 +207,10 @@ Directory::Directory(std::unique_ptr<FileSys::DirectoryBackend>&& backend,
 
 Directory::~Directory() {}
 
-ResultCode Directory::HandleSyncRequest() {
+ResultCode Directory::HandleSyncRequest(Kernel::SharedPtr<Kernel::ServerSession> server_session) {
     u32* cmd_buff = Kernel::GetCommandBuffer();
     DirectoryCommand cmd = static_cast<DirectoryCommand>(cmd_buff[0]);
     switch (cmd) {
-
     // Read from directory...
     case DirectoryCommand::Read: {
         u32 count = cmd_buff[1];
@@ -236,10 +237,10 @@ ResultCode Directory::HandleSyncRequest() {
         LOG_ERROR(Service_FS, "Unknown command=0x%08X!", cmd);
         ResultCode error = UnimplementedFunction(ErrorModule::FS);
         cmd_buff[1] = error.raw; // TODO(Link Mauve): use the correct error code for that.
-        return ServerSession::HandleSyncRequest();
+        return RESULT_SUCCESS;
     }
     cmd_buff[1] = RESULT_SUCCESS.raw; // No error
-    return ServerSession::HandleSyncRequest();
+    return RESULT_SUCCESS;
 }
 
 ////////////////////////////////////////////////////////////////////////////////////////////////////
@@ -306,7 +307,7 @@ ResultCode RegisterArchiveType(std::unique_ptr<FileSys::ArchiveFactory>&& factor
     return RESULT_SUCCESS;
 }
 
-ResultVal<Kernel::SharedPtr<File>> OpenFileFromArchive(ArchiveHandle archive_handle,
+ResultVal<std::shared_ptr<File>> OpenFileFromArchive(ArchiveHandle archive_handle,
                                                        const FileSys::Path& path,
                                                        const FileSys::Mode mode) {
     ArchiveBackend* archive = GetArchive(archive_handle);
@@ -317,8 +318,8 @@ ResultVal<Kernel::SharedPtr<File>> OpenFileFromArchive(ArchiveHandle archive_han
     if (backend.Failed())
         return backend.Code();
 
-    auto file = Kernel::SharedPtr<File>(new File(backend.MoveFrom(), path));
-    return MakeResult<Kernel::SharedPtr<File>>(std::move(file));
+    auto file = std::shared_ptr<File>(new File(backend.MoveFrom(), path));
+    return MakeResult<std::shared_ptr<File>>(std::move(file));
 }
 
 ResultCode DeleteFileFromArchive(ArchiveHandle archive_handle, const FileSys::Path& path) {
@@ -397,7 +398,7 @@ ResultCode RenameDirectoryBetweenArchives(ArchiveHandle src_archive_handle,
     }
 }
 
-ResultVal<Kernel::SharedPtr<Directory>> OpenDirectoryFromArchive(ArchiveHandle archive_handle,
+ResultVal<std::shared_ptr<Directory>> OpenDirectoryFromArchive(ArchiveHandle archive_handle,
                                                                  const FileSys::Path& path) {
     ArchiveBackend* archive = GetArchive(archive_handle);
     if (archive == nullptr)
@@ -407,8 +408,8 @@ ResultVal<Kernel::SharedPtr<Directory>> OpenDirectoryFromArchive(ArchiveHandle a
     if (backend.Failed())
         return backend.Code();
 
-    auto directory = Kernel::SharedPtr<Directory>(new Directory(backend.MoveFrom(), path));
-    return MakeResult<Kernel::SharedPtr<Directory>>(std::move(directory));
+    auto directory = std::shared_ptr<Directory>(new Directory(backend.MoveFrom(), path));
+    return MakeResult<std::shared_ptr<Directory>>(std::move(directory));
 }
 
 ResultVal<u64> GetFreeBytesInArchive(ArchiveHandle archive_handle) {

src/core/hle/service/fs/archive.h

@@ -41,32 +41,32 @@ enum class MediaType : u32 { NAND = 0, SDMC = 1 };
 
 typedef u64 ArchiveHandle;
 
-class File : public Kernel::ServerSession {
+class File : public SessionRequestHandler, public std::enable_shared_from_this<File> {
 public:
     File(std::unique_ptr<FileSys::FileBackend>&& backend, const FileSys::Path& path);
     ~File();
 
-    std::string GetName() const override {
+    std::string GetName() const {
         return "Path: " + path.DebugStr();
     }
 
-    ResultCode HandleSyncRequest() override;
+    ResultCode HandleSyncRequest(Kernel::SharedPtr<Kernel::ServerSession> server_session) override;
 
     FileSys::Path path; ///< Path of the file
     u32 priority;       ///< Priority of the file. TODO(Subv): Find out what this means
     std::unique_ptr<FileSys::FileBackend> backend; ///< File backend interface
 };
 
-class Directory : public Kernel::ServerSession {
+class Directory : public SessionRequestHandler {
 public:
     Directory(std::unique_ptr<FileSys::DirectoryBackend>&& backend, const FileSys::Path& path);
     ~Directory();
 
-    std::string GetName() const override {
+    std::string GetName() const {
         return "Directory: " + path.DebugStr();
     }
 
-    ResultCode HandleSyncRequest() override;
+    ResultCode HandleSyncRequest(Kernel::SharedPtr<Kernel::ServerSession> server_session) override;
 
     FileSys::Path path;                                 ///< Path of the directory
     std::unique_ptr<FileSys::DirectoryBackend> backend; ///< File backend interface
@@ -99,9 +99,9 @@ ResultCode RegisterArchiveType(std::unique_ptr<FileSys::ArchiveFactory>&& factor
  * @param archive_handle Handle to an open Archive object
  * @param path Path to the File inside of the Archive
  * @param mode Mode under which to open the File
- * @return The opened File object as a Session
+ * @return The opened File object
  */
-ResultVal<Kernel::SharedPtr<File>> OpenFileFromArchive(ArchiveHandle archive_handle,
+ResultVal<std::shared_ptr<File>> OpenFileFromArchive(ArchiveHandle archive_handle,
                                                        const FileSys::Path& path,
                                                        const FileSys::Mode mode);
 
@@ -178,9 +178,9 @@ ResultCode RenameDirectoryBetweenArchives(ArchiveHandle src_archive_handle,
  * Open a Directory from an Archive
  * @param archive_handle Handle to an open Archive object
  * @param path Path to the Directory inside of the Archive
- * @return The opened Directory object as a Session
+ * @return The opened Directory object
  */
-ResultVal<Kernel::SharedPtr<Directory>> OpenDirectoryFromArchive(ArchiveHandle archive_handle,
+ResultVal<std::shared_ptr<Directory>> OpenDirectoryFromArchive(ArchiveHandle archive_handle,
                                                                  const FileSys::Path& path);
 
 /**

src/core/hle/service/fs/fs_user.cpp

@@ -68,10 +68,12 @@ static void OpenFile(Service::Interface* self) {
     LOG_DEBUG(Service_FS, "path=%s, mode=%u attrs=%u", file_path.DebugStr().c_str(), mode.hex,
               attributes);
 
-    ResultVal<SharedPtr<File>> file_res = OpenFileFromArchive(archive_handle, file_path, mode);
+    ResultVal<std::shared_ptr<File>> file_res = OpenFileFromArchive(archive_handle, file_path, mode);
     cmd_buff[1] = file_res.Code().raw;
     if (file_res.Succeeded()) {
-        cmd_buff[3] = Kernel::g_handle_table.Create((*file_res)->CreateClientSession()).MoveFrom();
+        std::shared_ptr<File> file = *file_res;
+        auto sessions = ServerSession::CreateSessionPair(file->GetName(), file);
+        cmd_buff[3] = Kernel::g_handle_table.Create(std::get<Kernel::SharedPtr<Kernel::ClientSession>>(sessions)).MoveFrom();
     } else {
         cmd_buff[3] = 0;
         LOG_ERROR(Service_FS, "failed to get a handle for file %s", file_path.DebugStr().c_str());
@@ -128,10 +130,12 @@ static void OpenFileDirectly(Service::Interface* self) {
     }
     SCOPE_EXIT({ CloseArchive(*archive_handle); });
 
-    ResultVal<SharedPtr<File>> file_res = OpenFileFromArchive(*archive_handle, file_path, mode);
+    ResultVal<std::shared_ptr<File>> file_res = OpenFileFromArchive(*archive_handle, file_path, mode);
     cmd_buff[1] = file_res.Code().raw;
     if (file_res.Succeeded()) {
-        cmd_buff[3] = Kernel::g_handle_table.Create((*file_res)->CreateClientSession()).MoveFrom();
+        std::shared_ptr<File> file = *file_res;
+        auto sessions = ServerSession::CreateSessionPair(file->GetName(), file);
+        cmd_buff[3] = Kernel::g_handle_table.Create(std::get<Kernel::SharedPtr<Kernel::ClientSession>>(sessions)).MoveFrom();
     } else {
         cmd_buff[3] = 0;
         LOG_ERROR(Service_FS, "failed to get a handle for file %s mode=%u attributes=%u",
@@ -389,10 +393,12 @@ static void OpenDirectory(Service::Interface* self) {
     LOG_DEBUG(Service_FS, "type=%u size=%u data=%s", static_cast<u32>(dirname_type), dirname_size,
               dir_path.DebugStr().c_str());
 
-    ResultVal<SharedPtr<Directory>> dir_res = OpenDirectoryFromArchive(archive_handle, dir_path);
+    ResultVal<std::shared_ptr<Directory>> dir_res = OpenDirectoryFromArchive(archive_handle, dir_path);
     cmd_buff[1] = dir_res.Code().raw;
     if (dir_res.Succeeded()) {
-        cmd_buff[3] = Kernel::g_handle_table.Create((*dir_res)->CreateClientSession()).MoveFrom();
+        std::shared_ptr<Directory> directory = *dir_res;
+        auto sessions = ServerSession::CreateSessionPair(directory->GetName(), directory);
+        cmd_buff[3] = Kernel::g_handle_table.Create(std::get<Kernel::SharedPtr<Kernel::ClientSession>>(sessions)).MoveFrom();
     } else {
         LOG_ERROR(Service_FS, "failed to get a handle for directory type=%d size=%d data=%s",
                   dirname_type, dirname_size, dir_path.DebugStr().c_str());

src/core/hle/service/service.cpp

@@ -4,6 +4,9 @@
 
 #include "common/logging/log.h"
 #include "common/string_util.h"
+
+#include "core/hle/kernel/server_port.h"
+#include "core/hle/service/service.h"
 #include "core/hle/service/ac_u.h"
 #include "core/hle/service/act_a.h"
 #include "core/hle/service/act_u.h"
@@ -41,8 +44,8 @@
 
 namespace Service {
 
-std::unordered_map<std::string, Kernel::SharedPtr<Kernel::ClientPort>> g_kernel_named_ports;
-std::unordered_map<std::string, Kernel::SharedPtr<Kernel::ClientPort>> g_srv_services;
+std::unordered_map<std::string, std::tuple<Kernel::SharedPtr<Kernel::ClientPort>, std::shared_ptr<Interface>>> g_kernel_named_ports;
+std::unordered_map<std::string, std::tuple<Kernel::SharedPtr<Kernel::ClientPort>, std::shared_ptr<Interface>>> g_srv_services;
 
 /**
  * Creates a function string for logging, complete with the name (or header code, depending
@@ -99,13 +102,15 @@ void Interface::Register(const FunctionInfo* functions, size_t n) {
 // Module interface
 
 static void AddNamedPort(Interface* interface_) {
-    auto client_port = Kernel::ClientPort::CreateForHLE(interface_->GetMaxSessions(), std::shared_ptr<Interface>(interface_));
-    g_kernel_named_ports.emplace(interface_->GetPortName(), client_port);
+    auto ports = Kernel::ServerPort::CreatePortPair(interface_->GetMaxSessions(), interface_->GetPortName());
+    auto client_port = std::get<Kernel::SharedPtr<Kernel::ClientPort>>(ports);
+    g_kernel_named_ports.emplace(interface_->GetPortName(), std::make_tuple(client_port, std::shared_ptr<Interface>(interface_)));
 }
 
 void AddService(Interface* interface_) {
-    auto client_port = Kernel::ClientPort::CreateForHLE(interface_->GetMaxSessions(), std::shared_ptr<Interface>(interface_));
-    g_srv_services.emplace(interface_->GetPortName(), client_port);
+    auto ports = Kernel::ServerPort::CreatePortPair(interface_->GetMaxSessions(), interface_->GetPortName());
+    auto client_port = std::get<Kernel::SharedPtr<Kernel::ClientPort>>(ports);
+    g_srv_services.emplace(interface_->GetPortName(), std::make_tuple(client_port, std::shared_ptr<Interface>(interface_)));
 }
 
 /// Initialize ServiceManager

src/core/hle/service/service.h

@@ -10,8 +10,163 @@
 #include <boost/container/flat_map.hpp>
 #include "common/common_types.h"
 #include "core/hle/kernel/client_port.h"
-#include "core/hle/kernel/server_session.h"
+#include "core/hle/kernel/thread.h"
 #include "core/hle/result.h"
+#include "core/memory.h"
+
+namespace Kernel {
+class ServerSession;
+
+// TODO(Subv): Move these declarations out of here
+static const int kCommandHeaderOffset = 0x80; ///< Offset into command buffer of header
+
+/**
+ * Returns a pointer to the command buffer in the current thread's TLS
+ * TODO(Subv): This is not entirely correct, the command buffer should be copied from
+ * the thread's TLS to an intermediate buffer in kernel memory, and then copied again to
+ * the service handler process' memory.
+ * @param offset Optional offset into command buffer
+ * @return Pointer to command buffer
+ */
+inline u32* GetCommandBuffer(const int offset = 0) {
+    return (u32*)Memory::GetPointer(GetCurrentThread()->GetTLSAddress() + kCommandHeaderOffset +
+                                    offset);
+}
+}
+
+// TODO(Subv): Move this namespace out of here
+namespace IPC {
+
+enum DescriptorType : u32 {
+    // Buffer related desciptors types (mask : 0x0F)
+    StaticBuffer = 0x02,
+    PXIBuffer = 0x04,
+    MappedBuffer = 0x08,
+    // Handle related descriptors types (mask : 0x30, but need to check for buffer related
+    // descriptors first )
+    CopyHandle = 0x00,
+    MoveHandle = 0x10,
+    CallingPid = 0x20,
+};
+
+/**
+* @brief Creates a command header to be used for IPC
+* @param command_id            ID of the command to create a header for.
+* @param normal_params         Size of the normal parameters in words. Up to 63.
+* @param translate_params_size Size of the translate parameters in words. Up to 63.
+* @return The created IPC header.
+*
+* Normal parameters are sent directly to the process while the translate parameters might go
+* through modifications and checks by the kernel.
+* The translate parameters are described by headers generated with the IPC::*Desc functions.
+*
+* @note While #normal_params is equivalent to the number of normal parameters,
+* #translate_params_size includes the size occupied by the translate parameters headers.
+*/
+constexpr u32 MakeHeader(u16 command_id, unsigned int normal_params,
+                         unsigned int translate_params_size) {
+    return (u32(command_id) << 16) | ((u32(normal_params) & 0x3F) << 6) |
+        (u32(translate_params_size) & 0x3F);
+}
+
+union Header {
+    u32 raw;
+    BitField<0, 6, u32> translate_params_size;
+    BitField<6, 6, u32> normal_params;
+    BitField<16, 16, u32> command_id;
+};
+
+inline Header ParseHeader(u32 header) {
+    return{ header };
+}
+
+constexpr u32 MoveHandleDesc(u32 num_handles = 1) {
+    return MoveHandle | ((num_handles - 1) << 26);
+}
+
+constexpr u32 CopyHandleDesc(u32 num_handles = 1) {
+    return CopyHandle | ((num_handles - 1) << 26);
+}
+
+constexpr u32 CallingPidDesc() {
+    return CallingPid;
+}
+
+constexpr bool isHandleDescriptor(u32 descriptor) {
+    return (descriptor & 0xF) == 0x0;
+}
+
+constexpr u32 HandleNumberFromDesc(u32 handle_descriptor) {
+    return (handle_descriptor >> 26) + 1;
+}
+
+constexpr u32 StaticBufferDesc(u32 size, u8 buffer_id) {
+    return StaticBuffer | (size << 14) | ((buffer_id & 0xF) << 10);
+}
+
+union StaticBufferDescInfo {
+    u32 raw;
+    BitField<10, 4, u32> buffer_id;
+    BitField<14, 18, u32> size;
+};
+
+inline StaticBufferDescInfo ParseStaticBufferDesc(const u32 desc) {
+    return{ desc };
+}
+
+/**
+* @brief Creates a header describing a buffer to be sent over PXI.
+* @param size         Size of the buffer. Max 0x00FFFFFF.
+* @param buffer_id    The Id of the buffer. Max 0xF.
+* @param is_read_only true if the buffer is read-only. If false, the buffer is considered to have
+* read-write access.
+* @return The created PXI buffer header.
+*
+* The next value is a phys-address of a table located in the BASE memregion.
+*/
+inline u32 PXIBufferDesc(u32 size, unsigned buffer_id, bool is_read_only) {
+    u32 type = PXIBuffer;
+    if (is_read_only)
+        type |= 0x2;
+    return type | (size << 8) | ((buffer_id & 0xF) << 4);
+}
+
+enum MappedBufferPermissions {
+    R = 1,
+    W = 2,
+    RW = R | W,
+};
+
+constexpr u32 MappedBufferDesc(u32 size, MappedBufferPermissions perms) {
+    return MappedBuffer | (size << 4) | (u32(perms) << 1);
+}
+
+union MappedBufferDescInfo {
+    u32 raw;
+    BitField<4, 28, u32> size;
+    BitField<1, 2, MappedBufferPermissions> perms;
+};
+
+inline MappedBufferDescInfo ParseMappedBufferDesc(const u32 desc) {
+    return{ desc };
+}
+
+inline DescriptorType GetDescriptorType(u32 descriptor) {
+    // Note: Those checks must be done in this order
+    if (isHandleDescriptor(descriptor))
+        return (DescriptorType)(descriptor & 0x30);
+
+    // handle the fact that the following descriptors can have rights
+    if (descriptor & MappedBuffer)
+        return MappedBuffer;
+
+    if (descriptor & PXIBuffer)
+        return PXIBuffer;
+
+    return StaticBuffer;
+}
+
+} // namespace IPC
 
 ////////////////////////////////////////////////////////////////////////////////////////////////////
 // Namespace Service
@@ -21,8 +176,22 @@ namespace Service {
 static const int kMaxPortSize = 8; ///< Maximum size of a port name (8 characters)
 static const u32 DefaultMaxSessions = 10; ///< Arbitrary default number of maximum connections to an HLE port
 
+/// TODO(Subv): Write documentation for this class
+class SessionRequestHandler {
+public:
+    /**
+     * Dispatches and handles a sync request from the emulated application.
+     * @param server_session The ServerSession that was triggered for this sync request,
+     * it should be used to differentiate which client (As in ClientSession) we're answering to.
+     * TODO(Subv): Make a HandleSyncRequestParent function that is called from the outside and does { ReturnIfError(Translate()); HandleSyncRequest(); }
+     * The Translate() function would copy the command buffer from the ServerSession thread's TLS into a temporary buffer, and pass it to HandleSyncRequest.
+     * TODO(Subv): HandleSyncRequest's return type should be void.
+     */
+    virtual ResultCode HandleSyncRequest(Kernel::SharedPtr<Kernel::ServerSession> server_session) = 0;
+};
+
 /// Interface to a CTROS service
-class Interface {
+class Interface : public SessionRequestHandler {
 public:
     std::string GetName() const {
         return GetPortName();
@@ -56,7 +225,7 @@ public:
         return "[UNKNOWN SERVICE PORT]";
     }
 
-    ResultCode HandleSyncRequest(Kernel::SharedPtr<Kernel::ServerSession> server_session);
+    ResultCode HandleSyncRequest(Kernel::SharedPtr<Kernel::ServerSession> server_session) override;
 
 protected:
     /**
@@ -88,9 +257,9 @@ void Init();
 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;
+extern std::unordered_map<std::string, std::tuple<Kernel::SharedPtr<Kernel::ClientPort>, std::shared_ptr<Interface>>> g_kernel_named_ports;
 /// Map of services registered with the "srv:" service, retrieved using GetServiceHandle.
-extern std::unordered_map<std::string, Kernel::SharedPtr<Kernel::ClientPort>> g_srv_services;
+extern std::unordered_map<std::string, std::tuple<Kernel::SharedPtr<Kernel::ClientPort>, std::shared_ptr<Interface>>> g_srv_services;
 
 /// Adds a service to the services table
 void AddService(Interface* interface_);

src/core/hle/service/srv.cpp

@@ -10,6 +10,7 @@
 #include "core/hle/kernel/client_session.h"
 #include "core/hle/kernel/event.h"
 #include "core/hle/service/srv.h"
+#include "core/hle/kernel/server_session.h"
 
 ////////////////////////////////////////////////////////////////////////////////////////////////////
 // Namespace SRV
@@ -85,13 +86,18 @@ static void GetServiceHandle(Service::Interface* self) {
     auto it = Service::g_srv_services.find(port_name);
 
     if (it != Service::g_srv_services.end()) {
-        auto client_port = it->second;
+        auto client_port = std::get<Kernel::SharedPtr<Kernel::ClientPort>>(it->second);
+        // The hle_handler will be nullptr if this port was registered by the emulated
+        // application by means of srv:RegisterService.
+        auto hle_handler = std::get<std::shared_ptr<Service::Interface>>(it->second);
 
         // Create a new session pair
-        auto sessions = Kernel::ServerSession::CreateSessionPair(client_port, port_name);
+        auto sessions = Kernel::ServerSession::CreateSessionPair(port_name, hle_handler);
         auto client_session = std::get<Kernel::SharedPtr<Kernel::ClientSession>>(sessions);
         auto server_session = std::get<Kernel::SharedPtr<Kernel::ServerSession>>(sessions);
 
+        // TODO(Subv): Wait the current thread until the ServerPort calls AcceptSession.
+
         // Add the server session to the port's queue
         client_port->AddWaitingSession(server_session);
 

src/core/hle/svc.cpp

@@ -21,6 +21,7 @@
 #include "core/hle/kernel/resource_limit.h"
 #include "core/hle/kernel/semaphore.h"
 #include "core/hle/kernel/server_port.h"
+#include "core/hle/kernel/server_session.h"
 #include "core/hle/kernel/shared_memory.h"
 #include "core/hle/kernel/thread.h"
 #include "core/hle/kernel/timer.h"
@@ -223,13 +224,18 @@ static ResultCode ConnectToPort(Handle* out_handle, const char* port_name) {
         return ERR_NOT_FOUND;
     }
 
-    auto client_port = it->second;
+    auto client_port = std::get<Kernel::SharedPtr<Kernel::ClientPort>>(it->second);
+    // The hle_handler will be nullptr if this port was registered by the emulated
+    // application by means of svcCreatePort with a defined name.
+    auto hle_handler = std::get<std::shared_ptr<Service::Interface>>(it->second);
 
     // Create a new session pair
-    auto sessions = Kernel::ServerSession::CreateSessionPair(client_port, port_name);
+    auto sessions = Kernel::ServerSession::CreateSessionPair(port_name, hle_handler);
     auto client_session = std::get<Kernel::SharedPtr<Kernel::ClientSession>>(sessions);
     auto server_session = std::get<Kernel::SharedPtr<Kernel::ServerSession>>(sessions);
 
+    // TODO(Subv): Wait the current thread until the ServerPort calls AcceptSession.
+
     // Add the server session to the port's queue
     client_port->AddWaitingSession(server_session);
 
@@ -247,6 +253,7 @@ static ResultCode SendSyncRequest(Handle handle) {
 
     LOG_TRACE(Kernel_SVC, "called handle=0x%08X(%s)", handle, session->GetName().c_str());
 
+    // TODO(Subv): Wait the current thread and reschedule if this request is not going to be handled by HLE code.
     return session->HandleSyncRequest();
 }