[loader] Add nxlink log server mode

src/common/settings.h

@@ -840,6 +840,9 @@ struct Values {
     Setting<bool> gpu_log_driver_debug{linkage, true, "gpu_log_driver_debug", Category::Debugging};
     Setting<s32> gpu_log_ring_buffer_size{linkage, 512, "gpu_log_ring_buffer_size",
                                            Category::Debugging};
+    Setting<HomebrewNxlinkServerMode> homebrew_nxlink_server_mode{
+        linkage, HomebrewNxlinkServerMode::Disabled, "homebrew_nxlink_server_mode",
+        Category::Debugging};
 
     SwitchableSetting<u16, true> debug_knobs{linkage,
                                            0,

src/common/settings_enums.h

@@ -159,6 +159,7 @@ ENUM(GpuUnswizzleChunk, VeryLow, Low, Normal, Medium, High)
 ENUM(TemperatureUnits, Celsius, Fahrenheit)
 ENUM(ExtendedDynamicState, Disabled, EDS1, EDS2, EDS3);
 ENUM(GpuLogLevel, Off, Errors, Standard, Verbose, All)
+ENUM(HomebrewNxlinkServerMode, Disabled, EdenLog, HostStdout, File)
 ENUM(GameListMode, TreeView, GridView, CarouselView);
 ENUM(SpeedMode, Standard, Turbo, Slow);
 

src/core/core.cpp

@@ -52,6 +52,7 @@
 #include "core/hle/service/set/system_settings_server.h"
 #include "core/hle/service/sm/sm.h"
 #include "core/internal_network/network.h"
+#include "core/loader/homebrew_nxlink.h"
 #include "core/loader/loader.h"
 #include "core/memory.h"
 #include "core/memory/cheat_engine.h"
@@ -397,6 +398,7 @@ struct System::Impl {
 
         stop_event.request_stop();
         core_timing.SyncPause(false);
+        Loader::HomebrewNxlink::StopServer();
         Network::CancelPendingSocketOperations();
         kernel.SuspendEmulation(true);
         kernel.CloseServices();

src/core/loader/homebrew_nxlink.cpp

@@ -3,11 +3,48 @@
 
 #include "core/loader/homebrew_nxlink.h"
 
+#include <array>
 #include <cctype>
+#include <memory>
+#include <mutex>
+#include <optional>
+#include <stop_token>
+#include <utility>
+
+#include <boost/asio.hpp>
+
+#include "common/logging.h"
+#include "common/polyfill_thread.h"
+#include "common/thread.h"
 
 namespace Loader::HomebrewNxlink {
 namespace {
 
+using boost::asio::ip::tcp;
+
+constexpr u16 NxlinkClientPort = 28771;
+constexpr size_t ReceiveBufferSize = 1024;
+constexpr size_t MaxLogLineSize = 16 * 1024;
+
+struct LogConnection {
+    explicit LogConnection(boost::asio::io_context& io_context_) : socket{io_context_} {}
+
+    tcp::socket socket;
+    std::array<char, ReceiveBufferSize> buffer{};
+    std::string line;
+};
+
+struct LogServerState {
+    LogServerState() : acceptor{io_context} {}
+
+    boost::asio::io_context io_context;
+    tcp::acceptor acceptor;
+};
+
+std::mutex server_mutex;
+std::shared_ptr<LogServerState> server_state;
+std::optional<std::jthread> server_thread;
+
 std::optional<std::string> GetLastArgvToken(std::string_view argv_string) {
     while (!argv_string.empty() && argv_string.back() == '\0') {
         argv_string.remove_suffix(1);
@@ -72,6 +109,102 @@ void AppendArgvToken(std::string& argv_string, std::string_view token) {
     argv_string.append(token);
 }
 
+void FlushLogLine(std::string& line) {
+    if (!line.empty() && line.back() == '\r') {
+        line.pop_back();
+    }
+    if (!line.empty()) {
+        LOG_INFO(Loader, "{}", line);
+        line.clear();
+    }
+}
+
+void ConsumeLogBytes(LogConnection& connection, std::string_view bytes) {
+    for (const char byte : bytes) {
+        if (byte == '\n') {
+            FlushLogLine(connection.line);
+            continue;
+        }
+
+        connection.line.push_back(byte);
+        if (connection.line.size() >= MaxLogLineSize) {
+            FlushLogLine(connection.line);
+        }
+    }
+}
+
+void StartRead(std::shared_ptr<LogConnection> connection) {
+    connection->socket.async_read_some(
+        boost::asio::buffer(connection->buffer),
+        [connection](const boost::system::error_code& error, size_t bytes_read) {
+            if (error.failed()) {
+                FlushLogLine(connection->line);
+                return;
+            }
+
+            ConsumeLogBytes(*connection, {connection->buffer.data(), bytes_read});
+            StartRead(connection);
+        });
+}
+
+void StartAccept(std::shared_ptr<LogServerState> state) {
+    auto connection = std::make_shared<LogConnection>(state->io_context);
+    state->acceptor.async_accept(
+        connection->socket,
+        [state, connection](const boost::system::error_code& error) {
+            if (!error.failed()) {
+                LOG_INFO(Loader, "Homebrew nxlink log client connected");
+                StartRead(connection);
+            }
+            if (state->acceptor.is_open()) {
+                StartAccept(state);
+            }
+        });
+}
+
+void StartLogServer() {
+    std::scoped_lock lock{server_mutex};
+    if (server_thread) {
+        return;
+    }
+
+    auto state = std::make_shared<LogServerState>();
+    const tcp::endpoint endpoint{boost::asio::ip::address_v4::loopback(), NxlinkClientPort};
+
+    boost::system::error_code error;
+    state->acceptor.open(endpoint.protocol(), error);
+    if (!error.failed()) {
+        state->acceptor.set_option(tcp::acceptor::reuse_address(true), error);
+    }
+    if (!error.failed()) {
+        state->acceptor.bind(endpoint, error);
+    }
+    if (!error.failed()) {
+        state->acceptor.listen(boost::asio::socket_base::max_listen_connections, error);
+    }
+    if (error.failed()) {
+        LOG_WARNING(Loader, "Homebrew nxlink log server could not listen on 127.0.0.1:{}: {}",
+                    NxlinkClientPort, error.message());
+        return;
+    }
+
+    StartAccept(state);
+    server_state = state;
+    server_thread.emplace([state](std::stop_token stop_token) {
+        Common::SetCurrentThreadName("HomebrewNxlink");
+        std::stop_callback stop_callback{stop_token, [state] {
+            boost::system::error_code ignored;
+            state->acceptor.close(ignored);
+            state->io_context.stop();
+        }};
+
+        LOG_INFO(Loader, "Homebrew nxlink log server listening on 127.0.0.1:{}",
+                 NxlinkClientPort);
+        state->io_context.run();
+        LOG_INFO(Loader, "Homebrew nxlink log server stopped");
+    });
+}
+
 } // namespace
 
 bool IsArgvMarker(std::string_view token) {
@@ -88,6 +221,20 @@ bool IsArgvMarker(std::string_view token) {
     return true;
 }
 
+bool IsLoopbackArgvMarker(std::string_view token) {
+    if (!IsArgvMarker(token)) {
+        return false;
+    }
+
+    for (size_t i = 0; i < 8; i++) {
+        if (std::tolower(static_cast<unsigned char>(token[i])) !=
+            std::tolower(static_cast<unsigned char>(LoopbackArgvMarker[i]))) {
+            return false;
+        }
+    }
+    return true;
+}
+
 std::optional<std::string> GetArgvMarker(std::string_view argv_string) {
     auto last_token = GetLastArgvToken(argv_string);
     if (!last_token || !IsArgvMarker(*last_token)) {
@@ -97,13 +244,68 @@ std::optional<std::string> GetArgvMarker(std::string_view argv_string) {
 }
 
 std::optional<std::string> PrepareArgv(std::string& argv_string,
-                                       std::string_view inherited_marker) {
+                                       std::string_view inherited_marker,
+                                       bool append_loopback_marker) {
     auto marker = GetArgvMarker(argv_string);
     if (!marker && IsArgvMarker(inherited_marker)) {
         AppendArgvToken(argv_string, inherited_marker);
         marker = std::string{inherited_marker};
     }
+    if (!marker && append_loopback_marker) {
+        AppendArgvToken(argv_string, LoopbackArgvMarker);
+        marker = std::string{LoopbackArgvMarker};
+    }
     return marker;
 }
 
+void ApplyServerMode(Settings::HomebrewNxlinkServerMode mode,
+                     const std::optional<std::string>& active_marker) {
+    switch (mode) {
+    case Settings::HomebrewNxlinkServerMode::Disabled:
+        StopServer();
+        return;
+    case Settings::HomebrewNxlinkServerMode::EdenLog:
+        if (active_marker && IsLoopbackArgvMarker(*active_marker)) {
+            StartLogServer();
+            return;
+        }
+        StopServer();
+        if (active_marker) {
+            LOG_INFO(Loader,
+                     "Homebrew nxlink server mode overridden by argv marker '{}'; not starting "
+                     "local nxlink log server",
+                     *active_marker);
+        } else {
+            LOG_WARNING(Loader,
+                        "Homebrew nxlink log server requested, but no argv marker is active");
+        }
+        return;
+    case Settings::HomebrewNxlinkServerMode::HostStdout:
+    case Settings::HomebrewNxlinkServerMode::File:
+        StopServer();
+        LOG_WARNING(Loader, "Homebrew nxlink server mode {} is not implemented",
+                    static_cast<int>(mode));
+        return;
+    }
+}
+
+void StopServer() {
+    std::shared_ptr<LogServerState> state;
+    std::optional<std::jthread> thread;
+    {
+        std::scoped_lock lock{server_mutex};
+        state = std::move(server_state);
+        thread = std::move(server_thread);
+    }
+
+    if (state) {
+        boost::system::error_code ignored;
+        state->acceptor.close(ignored);
+        state->io_context.stop();
+    }
+    if (thread) {
+        thread->request_stop();
+    }
+}
+
 } // namespace Loader::HomebrewNxlink

src/core/loader/homebrew_nxlink.h

@@ -8,16 +8,23 @@
 #include <string>
 #include <string_view>
 
+#include "common/settings_enums.h"
+
 namespace Loader::HomebrewNxlink {
 
 constexpr size_t ArgvMarkerSize = 16;
 constexpr std::string_view ArgvMarkerSuffix = "_NXLINK_";
+constexpr std::string_view LoopbackArgvMarker = "0100007F_NXLINK_";
 
-// This module handles only the libnx argv marker. Client stream handling should be an
-// explicit byte-sink API; the marker alone must not imply logging.
 bool IsArgvMarker(std::string_view token);
+bool IsLoopbackArgvMarker(std::string_view token);
 std::optional<std::string> GetArgvMarker(std::string_view argv_string);
 std::optional<std::string> PrepareArgv(std::string& argv_string,
-                                       std::string_view inherited_marker);
+                                       std::string_view inherited_marker,
+                                       bool append_loopback_marker = false);
+
+void ApplyServerMode(Settings::HomebrewNxlinkServerMode mode,
+                     const std::optional<std::string>& active_marker);
+void StopServer();
 
 } // namespace Loader::HomebrewNxlink

src/core/loader/nro.cpp

@@ -343,7 +343,8 @@ static std::optional<HomebrewNroImage> BuildHomebrewNroImage(const std::vector<u
                                                              std::string nro_path,
                                                              std::string file_name,
                                                              std::string launch_argv,
-                                                             std::string_view inherited_marker) {
+                                                             std::string_view inherited_marker,
+                                                             bool append_loopback_nxlink_marker) {
     if (data.size() < sizeof(NroHeader)) {
         return std::nullopt;
     }
@@ -388,7 +389,8 @@ static std::optional<HomebrewNroImage> BuildHomebrewNroImage(const std::vector<u
     } else {
         image.argv_string = QuoteHomebrewArgvComponent(argv0);
     }
-    image.nxlink_argv_marker = HomebrewNxlink::PrepareArgv(image.argv_string, inherited_marker);
+    image.nxlink_argv_marker = HomebrewNxlink::PrepareArgv(
+        image.argv_string, inherited_marker, append_loopback_nxlink_marker);
     if (image.argv_string.empty() || image.argv_string.back() != '\0') {
         image.argv_string.push_back('\0');
     }
@@ -451,8 +453,12 @@ bool LoadNroInPlace(Core::System& system, Kernel::KProcess& process, Kernel::KTh
         return false;
     }
 
-    auto image = BuildHomebrewNroImage(nro_file->ReadAllBytes(), nro_path, nro_file->GetName(),
-                                       launch_argv, process.GetHomebrewNxlinkArgvMarker());
+    const auto nxlink_server_mode = Settings::values.homebrew_nxlink_server_mode.GetValue();
+    const bool append_loopback_nxlink_marker =
+        nxlink_server_mode != Settings::HomebrewNxlinkServerMode::Disabled;
+    auto image = BuildHomebrewNroImage(
+        nro_file->ReadAllBytes(), nro_path, nro_file->GetName(), launch_argv,
+        process.GetHomebrewNxlinkArgvMarker(), append_loopback_nxlink_marker);
     if (!image) {
         LOG_WARNING(Loader, "NextLoad: in-place handoff failed because '{}' is invalid",
                     nro_path);
@@ -547,6 +553,7 @@ bool LoadNroInPlace(Core::System& system, Kernel::KProcess& process, Kernel::KTh
     } else {
         process.ClearHomebrewNxlinkArgvMarker();
     }
+    HomebrewNxlink::ApplyServerMode(nxlink_server_mode, image->nxlink_argv_marker);
     system.GetFileSystemController().RegisterProcess(
         process.GetProcessId(), program_id,
         std::make_unique<FileSys::RomFSFactory>(loader, system.GetContentProvider(),
@@ -628,7 +635,11 @@ static bool LoadNroImpl(Core::System& system, Kernel::KProcess& process,
         argv_string.push_back(' ');
         argv_string += program_args;
     }
-    const auto nxlink_argv_marker = HomebrewNxlink::PrepareArgv(argv_string, {});
+    const auto nxlink_server_mode = Settings::values.homebrew_nxlink_server_mode.GetValue();
+    const bool append_loopback_nxlink_marker =
+        nxlink_server_mode != Settings::HomebrewNxlinkServerMode::Disabled;
+    const auto nxlink_argv_marker =
+        HomebrewNxlink::PrepareArgv(argv_string, {}, append_loopback_nxlink_marker);
     if (argv_string.empty() || argv_string.back() != '\0') {
         argv_string.push_back('\0');
     }
@@ -727,6 +738,7 @@ static bool LoadNroImpl(Core::System& system, Kernel::KProcess& process,
     } else {
         process.ClearHomebrewNxlinkArgvMarker();
     }
+    HomebrewNxlink::ApplyServerMode(nxlink_server_mode, nxlink_argv_marker);
     {
         const u64 base = GetInteger(process.GetEntryPoint());
         const u64 config_addr = base + args_offset_in_image;