gKeyMapper/daemon/ipc_dbus.cpp

// gKeyMapper daemon - D-Bus service for the GUI (control plane only).

#include "ipc_dbus.h"

#include <cstdio>

#include "ipc_ids.h"
#include "mapping.h"

namespace gkeymapper::daemon {

namespace {

// Index convention: 0 = G1 ... 8 = G9, the same as the internal mapping vector
// and the KeyPressed signal, so GUI and CLI agree on one numbering.
const char kIntrospectionXml[] =
    "<node>"
    "  <interface name='dev.rager.gkeymapper.Daemon'>"
    "    <method name='Reload'/>"
    "    <method name='GetStatus'>"
    "      <arg type='s' name='version' direction='out'/>"
    "      <arg type='b' name='running' direction='out'/>"
    "      <arg type='s' name='device' direction='out'/>"
    "      <arg type='s' name='configPath' direction='out'/>"
    "    </method>"
    "    <method name='TestMapping'>"
    "      <arg type='u' name='index' direction='in'/>"
    "    </method>"
    "    <signal name='KeyPressed'>"
    "      <arg type='u' name='index'/>"
    "      <arg type='s' name='action'/>"
    "    </signal>"
    "    <signal name='ConfigReloaded'>"
    "      <arg type='b' name='ok'/>"
    "    </signal>"
    "    <signal name='DeviceChanged'>"
    "      <arg type='b' name='present'/>"
    "      <arg type='s' name='device'/>"
    "    </signal>"
    "  </interface>"
    "</node>";

} // namespace

DaemonService::~DaemonService() {
    if (owner_ != 0) {
        g_bus_unown_name(owner_);
    }
    if (registration_ != 0 && connection_ != nullptr) {
        g_dbus_connection_unregister_object(connection_, registration_);
    }
    if (connection_ != nullptr) {
        g_object_unref(connection_);
    }
}

StartResult DaemonService::start(std::string configPath) {
    configPath_ = std::move(configPath);

    GError* error = nullptr;
    connection_ = g_bus_get_sync(G_BUS_TYPE_SESSION, nullptr, &error);
    if (connection_ == nullptr) {
        std::fprintf(stderr,
                     "gkeymapper-daemon: no session bus (%s); running without "
                     "the GUI channel\n",
                     error != nullptr ? error->message : "unknown");
        g_clear_error(&error);
        return StartResult::NoBus;
    }

    GDBusNodeInfo* info = g_dbus_node_info_new_for_xml(kIntrospectionXml, &error);
    if (info == nullptr) {
        std::fprintf(stderr, "gkeymapper-daemon: bad D-Bus introspection: %s\n",
                     error->message);
        g_clear_error(&error);
        return StartResult::NoBus;
    }

    GDBusInterfaceVTable vtable{};
    vtable.method_call = &DaemonService::handle_method_call;

    registration_ = g_dbus_connection_register_object(
        connection_, gkeymapper::ipc::kObjectPath, info->interfaces[0], &vtable, this,
        nullptr, &error);
    g_dbus_node_info_unref(info);
    if (registration_ == 0) {
        std::fprintf(stderr, "gkeymapper-daemon: cannot register object: %s\n",
                     error->message);
        g_clear_error(&error);
        return StartResult::NoBus;
    }

    // DO_NOT_QUEUE: if the name is taken, fail instead of waiting. Two daemons
    // would fight over the keyboard and create two virtual keyboards.
    owner_ = g_bus_own_name_on_connection(
        connection_, gkeymapper::ipc::kBusName,
        G_BUS_NAME_OWNER_FLAGS_DO_NOT_QUEUE,
        [](GDBusConnection*, const gchar*, gpointer userData) {
            static_cast<DaemonService*>(userData)->name_owned_ = true;
        },
        [](GDBusConnection*, const gchar* name, gpointer userData) {
            auto* self = static_cast<DaemonService*>(userData);
            self->name_lost_ = true;
            std::fprintf(stderr, "gkeymapper-daemon: bus name %s is taken\n", name);
        },
        this, nullptr);

    // Let the name request complete before deciding.
    for (int i = 0; i < 100 && !name_owned_ && !name_lost_; ++i) {
        g_main_context_iteration(nullptr, FALSE);
        g_usleep(10 * 1000);
    }

    if (!name_owned_ && name_lost_) {
        return StartResult::AlreadyRunning;
    }

    std::fprintf(stderr, "gkeymapper-daemon: listening on %s (%s)\n",
                 gkeymapper::ipc::kBusName, gkeymapper::ipc::kObjectPath);
    return StartResult::Ok;
}

void DaemonService::pump() {
    if (connection_ == nullptr) {
        return;
    }
    while (g_main_context_iteration(nullptr, FALSE)) {
        // Drain everything that is ready; nothing else uses this context.
    }
}

void DaemonService::handle_method_call(GDBusConnection* /*connection*/, const gchar* /*sender*/,
                                       const gchar* /*objectPath*/, const gchar* /*interfaceName*/,
                                       const gchar* methodName, GVariant* parameters,
                                       GDBusMethodInvocation* invocation, gpointer userData) {
    auto* self = static_cast<DaemonService*>(userData);

    if (g_strcmp0(methodName, "Reload") == 0) {
        if (self->reload_) {
            self->reload_();
        }
        g_dbus_method_invocation_return_value(invocation, nullptr);
        return;
    }

    if (g_strcmp0(methodName, "GetStatus") == 0) {
        const std::string device = self->device_ ? self->device_() : std::string();
        g_dbus_method_invocation_return_value(
            invocation, g_variant_new("(sbss)", gkeymapper::ipc::kVersion, TRUE,
                                      device.c_str(), self->configPath_.c_str()));
        return;
    }

    if (g_strcmp0(methodName, "TestMapping") == 0) {
        guint32 index = 0;
        g_variant_get(parameters, "(u)", &index);
        if (index >= static_cast<guint32>(gkeymapper::kNumKeys)) {
            g_dbus_method_invocation_return_error(
                invocation, G_IO_ERROR, G_IO_ERROR_INVALID_ARGUMENT,
                "no G%u (index 0..%d)", index + 1, gkeymapper::kNumKeys - 1);
            return;
        }
        std::string action;
        if (!self->test_ || !self->test_(static_cast<int>(index), action)) {
            g_dbus_method_invocation_return_error(invocation, G_IO_ERROR, G_IO_ERROR_FAILED,
                                                  "G%u has no usable mapping", index + 1);
            return;
        }
        g_dbus_method_invocation_return_value(invocation, nullptr);
        self->notify_key_pressed(static_cast<int>(index), action);
        return;
    }

    g_dbus_method_invocation_return_error(invocation, G_IO_ERROR, G_IO_ERROR_NOT_SUPPORTED,
                                          "unknown method %s", methodName);
}

void DaemonService::notify_key_pressed(int index, const std::string& action) {
    if (connection_ == nullptr) {
        return;
    }
    GError* error = nullptr;
    g_dbus_connection_emit_signal(
        connection_, nullptr, gkeymapper::ipc::kObjectPath, gkeymapper::ipc::kInterface,
        "KeyPressed",
        g_variant_new("(us)", static_cast<guint32>(index), action.c_str()), &error);
    if (error != nullptr) {
        g_clear_error(&error);
    }
}

void DaemonService::notify_config_reloaded(bool ok) {
    if (connection_ == nullptr) {
        return;
    }
    GError* error = nullptr;
    g_dbus_connection_emit_signal(connection_, nullptr, gkeymapper::ipc::kObjectPath,
                                  gkeymapper::ipc::kInterface, "ConfigReloaded",
                                  g_variant_new("(b)", ok ? TRUE : FALSE), &error);
    if (error != nullptr) {
        g_clear_error(&error);
    }
}

void DaemonService::notify_device_changed(bool present, const std::string& device) {
    if (connection_ == nullptr) {
        return;
    }
    GError* error = nullptr;
    g_dbus_connection_emit_signal(
        connection_, nullptr, gkeymapper::ipc::kObjectPath, gkeymapper::ipc::kInterface,
        "DeviceChanged", g_variant_new("(bs)", present ? TRUE : FALSE, device.c_str()),
        &error);
    if (error != nullptr) {
        g_clear_error(&error);
    }
}

} // namespace gkeymapper::daemon