Luna/gui/wind/main.cpp

#include "Client.h"
#include "Keyboard.h"
#include "Layer.h"
#include "Mouse.h"
#include "Screen.h"
#include "Window.h"
#include <errno.h>
#include <moon/Keyboard.h>
#include <os/ArgumentParser.h>
#include <os/File.h>
#include <os/IPC.h>
#include <os/LocalServer.h>
#include <os/Process.h>
#include <os/Security.h>
#include <stdlib.h>
#include <string.h>
#include <sys/poll.h>
#include <sys/stat.h>
#include <time.h>
#include <unistd.h>

static constexpr uid_t WIND_USER_ID = 2;
static constexpr gid_t WIND_GROUP_ID = 2;
static constexpr gid_t WSYS_GROUP_ID = 3;

Result<int> luna_main(int argc, char** argv)
{
    srand((unsigned)time(NULL));

    TRY(os::Security::pledge("stdio rpath wpath cpath unix tty id", NULL));

    StringView socket_path = "/tmp/wind.sock";
    StringView system_socket_path = "/tmp/wsys.sock";

    os::ArgumentParser parser;
    parser.add_description("The display server for Luna's graphical user interface."_sv);
    parser.add_system_program_info("wind"_sv);
    parser.add_value_argument(socket_path, 's', "socket"_sv, "the path for the local IPC socket"_sv);
    parser.add_value_argument(system_socket_path, ' ', "system-socket"_sv,
                              "the path for the system IPC socket, for privileged clients"_sv);
    parser.parse(argc, argv);

    if (geteuid() != 0)
    {
        os::eprintln("error: wind must be run as root to initialize resources, the server will drop "
                     "privileges automatically afterwards");
        return 1;
    }

    auto mouse = TRY(os::File::open("/dev/mouse", os::File::ReadOnly));
    mouse->set_buffer(os::File::NotBuffered);
    mouse->set_close_on_exec();

    auto keyboard = TRY(os::File::open("/dev/kbd", os::File::ReadOnly));
    keyboard->set_buffer(os::File::NotBuffered);
    keyboard->set_close_on_exec();

    TRY(Screen::open());
    auto& screen = Screen::the();

    Mouse mouse_pointer { screen.canvas() };

    umask(0002);

    // Set permissions to wind:wsys temporarily, to create /tmp/wsys.sock with those privileges.
    setegid(WSYS_GROUP_ID);
    seteuid(WIND_USER_ID);

    auto system_server = TRY(os::LocalServer::create(system_socket_path, false));
    TRY(system_server->listen(20));

    seteuid(0);

    // Opened all necessary files as root, drop privileges now.
    setgid(WIND_GROUP_ID);
    setuid(WIND_USER_ID);

    auto server = TRY(os::LocalServer::create(socket_path, false));
    TRY(server->listen(20));

    int fd = open("/dev/null", O_RDONLY);
    if (fd >= 0)
    {
        dup2(fd, STDIN_FILENO);
        close(fd);
    }

    // We're ready now.
    os::IPC::notify_parent();

    ui::Color background = ui::Color::from_rgb(0x10, 0x10, 0x10);

    Vector<OwnedPtr<Client>> clients;
    Vector<struct pollfd> fds;
    TRY(fds.try_append({ .fd = mouse->fd(), .events = POLLIN, .revents = 0 }));
    TRY(fds.try_append({ .fd = keyboard->fd(), .events = POLLIN, .revents = 0 }));
    TRY(fds.try_append({ .fd = server->fd(), .events = POLLIN, .revents = 0 }));
    TRY(fds.try_append({ .fd = system_server->fd(), .events = POLLIN, .revents = 0 }));

    TRY(os::Security::pledge("stdio rpath wpath cpath unix", NULL));

    while (1)
    {
        screen.canvas().fill(background);
        Layer::draw_all_windows(screen.canvas());
        mouse_pointer.draw(screen.canvas());
        screen.sync();

        for (auto& pfd : fds) { pfd.revents = 0; }

        int rc = poll(fds.data(), fds.size(), 1000);
        if (!rc) continue;
        if (rc < 0 && errno != EINTR) { os::println("poll: error: %s", strerror(errno)); }

        if (fds[0].revents & POLLIN)
        {
            moon::MousePacket packet;
            TRY(mouse->read_typed(packet));
            mouse_pointer.update(packet);
        }
        if (fds[1].revents & POLLIN)
        {
            moon::KeyboardPacket packet;
            TRY(keyboard->read_typed(packet));
            auto request = wind::Keyboard::decode_keyboard_event((moon::KeyCode)packet.key, packet.released);
            if (auto* window = Layer::focused_window())
            {
                request.window = window->id;
                window->client->conn->send_async(request);
            }
        }
        if (fds[2].revents & POLLIN)
        {
            auto client = TRY(server->accept());
            os::println("wind: New client connected!");
            TRY(fds.try_append({ .fd = client.fd(), .events = POLLIN, .revents = 0 }));

            auto connection = TRY(os::IPC::ClientConnection::adopt_connection(move(client)));

            OwnedPtr<Client> c = TRY(adopt_owned_if_nonnull(new Client(move(connection), EMPTY_PLEDGE)));
            TRY(clients.try_append(move(c)));
        }
        if (fds[3].revents & POLLIN)
        {
            auto client = TRY(system_server->accept());
            os::println("wind: New privileged client connected!");
            TRY(fds.try_append({ .fd = client.fd(), .events = POLLIN, .revents = 0 }));

            auto connection = TRY(os::IPC::ClientConnection::adopt_connection(move(client)));

            OwnedPtr<Client> c = TRY(adopt_owned_if_nonnull(new Client(move(connection), HAS_NOT_YET_PLEDGED)));
            TRY(clients.try_append(move(c)));
        }
        for (usize i = 0; i < clients.size(); i++)
        {
            if (fds[i + 4].revents & POLLIN) clients[i]->conn->check_for_messages();
            if (fds[i + 4].revents & POLLHUP) clients[i]->should_be_disconnected = true;
            if (clients[i]->should_be_disconnected)
            {
                os::println("wind: Client %zu disconnected", i);
                fds.remove_at(i + 4);
                auto client = clients.remove_at(i);
                client->conn->disconnect();
                for (auto& window : client->windows)
                {
                    if (window)
                    {
                        window->layer->windows.remove(window);
                        mouse_pointer.window_did_close(window);
                        delete window;
                    }
                }
            }
        }
    }
}