gui: Add a login UI and support the os::IPC::Notifier API

README.md

@@ -40,6 +40,12 @@ Additionally, the build process needs some extra dependencies to run: `cmake`, `
 
 If you have no toolchain set up, `run.sh` will build it automatically, which means that you don't necessarily have to run `setup.sh` manually since `run.sh` does it for you.
 
+## Login UI
+
+For development convenience, the system automatically starts a GUI session as the default user, without prompting for a password.
+
+Despite this, Luna does have a login window built-in. If you'd like to try this feature out or start a GUI session as a different user, you'll need to edit [base/etc/init/99-login](base/etc/init/99-login) and change the line that says `Command=/usr/bin/loginui --autologin=selene` to `Command=/usr/bin/loginui`.
+
 ## Prebuilt images
 
 Prebuilt ISO images for every release version can be found at [pub.cloudapio.eu](https://pub.cloudapio.eu/luna/releases).

base/etc/init/99-login

@@ -1,6 +1,6 @@
 Name=login
 Description=Start a graphical user session.
-Command=/usr/bin/startui --user=selene
+Command=/usr/bin/loginui --autologin=selene
 StandardOutput=/dev/uart0
 StandardError=/dev/uart0
 Restart=true

gui/CMakeLists.txt

@@ -13,3 +13,5 @@ add_subdirectory(apps)
 
 luna_service(launch.cpp launch)
 luna_service(run.cpp run)
+luna_service(loginui.cpp loginui)
+target_link_libraries(loginui PRIVATE ui)

gui/launch.cpp

@@ -10,6 +10,7 @@
 #include <errno.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>
@@ -66,6 +67,9 @@ Result<int> luna_main(int argc, char** argv)
     auto server = TRY(os::LocalServer::create(socket_path, false));
     TRY(server->listen(20));
 
+    // We're ready now.
+    os::IPC::notify_parent();
+
     Vector<OwnedPtr<os::IPC::ClientConnection>> clients;
     Vector<struct pollfd> fds;
     TRY(fds.try_append({ .fd = server->fd(), .events = POLLIN, .revents = 0 }));

gui/loginui.cpp

@@ -0,0 +1,171 @@
+/**
+ * @file loginui.cpp
+ * @author apio (cloudapio.eu)
+ * @brief Graphical login prompt.
+ *
+ * @copyright Copyright (c) 2024, the Luna authors.
+ *
+ */
+
+#include <luna/String.h>
+#include <os/ArgumentParser.h>
+#include <os/File.h>
+#include <os/FileSystem.h>
+#include <os/IPC.h>
+#include <os/Process.h>
+#include <pwd.h>
+#include <shadow.h>
+#include <sys/stat.h>
+#include <ui/App.h>
+#include <ui/Button.h>
+#include <ui/InputField.h>
+#include <ui/Label.h>
+#include <ui/Layout.h>
+#include <unistd.h>
+
+enum Stage
+{
+    UsernameInput,
+    PasswordInput,
+};
+
+static constexpr ui::Color BACKGROUND_COLOR = ui::Color::from_rgb(89, 89, 89);
+
+Result<int> luna_main(int argc, char** argv)
+{
+    StringView username;
+
+    os::ArgumentParser parser;
+    parser.add_description("Login prompt for a graphical UI session.");
+    parser.add_system_program_info("loginui"_sv);
+    // FIXME: Make this a config option instead of a switch.
+    // Also, calling "loginui --autologin=user" is functionally identical to calling "startui --user=user", the only
+    // difference is that it makes the init config easier to change (only adding or removing the autologin flag, instead
+    // of changing the program to use)
+    parser.add_value_argument(username, ' ', "autologin", "login as a specific user without prompting");
+    parser.parse(argc, argv);
+
+    if (geteuid() != 0)
+    {
+        os::eprintln("error: %s can only be started as root.", argv[0]);
+        return 1;
+    }
+
+    setsid();
+
+    bool success = os::IPC::Notifier::run_and_wait(
+        [&] {
+            StringView wind_command[] = { "/usr/bin/wind" };
+            os::Process::spawn(wind_command[0], Slice<StringView>(wind_command, 1));
+        },
+        1000);
+
+    if (!success)
+    {
+        os::eprintln("loginui: failed to start wind, timed out");
+        return 1;
+    }
+
+    if (!username.is_empty())
+    {
+        auto flag = String::format("--user=%s"_sv, username.chars()).release_value();
+
+        StringView startui_command[] = { "/usr/bin/startui", flag.view() };
+        os::Process::exec(startui_command[0], Slice<StringView>(startui_command, 2));
+        unreachable();
+    }
+
+    ui::App app;
+    TRY(app.init());
+
+    auto* window = TRY(ui::Window::create(ui::Rect { 300, 300, 400, 300 }));
+    app.set_main_window(window);
+
+    window->set_title("Log in");
+    window->set_background(BACKGROUND_COLOR);
+
+    ui::VerticalLayout main_layout;
+    window->set_main_widget(main_layout);
+
+    ui::Label label("Username:");
+    main_layout.add_widget(label);
+
+    ui::InputField input(ui::Font::default_font());
+    main_layout.add_widget(input);
+
+    ui::Label error("");
+    error.set_font(ui::Font::default_bold_font());
+    error.set_color(ui::RED);
+    main_layout.add_widget(error);
+
+    Stage stage = Stage::UsernameInput;
+    struct passwd* pw;
+
+    input.on_submit([&](StringView data) {
+        error.set_text("");
+        if (stage == Stage::UsernameInput)
+        {
+            struct passwd* entry = getpwnam(data.chars());
+            if (!entry)
+            {
+                error.set_text("User not found.");
+                input.clear();
+                return;
+            }
+
+            pw = entry;
+            stage = Stage::PasswordInput;
+            label.set_text("Password:");
+
+            String title = String::format("Log in: %s"_sv, data.chars()).release_value();
+            window->set_title(title.view());
+
+            input.clear();
+
+            return;
+        }
+        else
+        {
+            const char* passwd = pw->pw_passwd;
+
+            // If the user's password entry is 'x', read their password from the shadow file instead.
+            if (!strcmp(pw->pw_passwd, "x"))
+            {
+                struct spwd* sp = getspnam(pw->pw_name);
+
+                if (!sp)
+                {
+                    error.set_text("User not found in shadow file.");
+                    input.clear();
+                    return;
+                }
+
+                endspent();
+
+                passwd = sp->sp_pwdp;
+            }
+
+            if (!strcmp(passwd, "!"))
+            {
+                error.set_text("User's password is disabled.");
+                input.clear();
+                return;
+            }
+
+            if (strcmp(data.chars(), passwd))
+            {
+                error.set_text("Incorrect password.");
+                input.clear();
+                return;
+            }
+
+            auto flag = String::format("--user=%s"_sv, pw->pw_name).release_value();
+
+            StringView startui_command[] = { "/usr/bin/startui", flag.view() };
+            os::Process::exec(startui_command[0], Slice<StringView>(startui_command, 2));
+            unreachable();
+        }
+    });
+
+    return app.run();
+}

gui/wind/main.cpp

@@ -8,6 +8,7 @@
 #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>
@@ -115,6 +116,9 @@ Result<int> luna_main(int argc, char** argv)
         close(fd);
     }
 
+    // We're ready now.
+    os::IPC::notify_parent();
+
     ui::Color background = ui::Color::from_rgb(0x10, 0x10, 0x10);
 
     Vector<OwnedPtr<Client>> clients;

system/startui.cpp

@@ -11,6 +11,8 @@
 #include <grp.h>
 #include <os/ArgumentParser.h>
 #include <os/File.h>
+#include <os/FileSystem.h>
+#include <os/IPC.h>
 #include <os/Main.h>
 #include <os/Process.h>
 #include <pwd.h>
@@ -18,19 +20,6 @@
 #include <sys/stat.h>
 #include <unistd.h>
 
-// Timeout should be provided in milliseconds.
-Result<void> wait_until_file_created(StringView path, int timeout)
-{
-    struct stat st;
-    while (stat(path.chars(), &st) < 0)
-    {
-        if (timeout <= 0) return err(ETIMEDOUT);
-        usleep(100000); // FIXME: Implement something like inotify or use signals to avoid polling.
-        timeout -= 100;
-    }
-    return {};
-}
-
 Result<Vector<gid_t>> read_supplementary_groups(const char* name)
 {
     Vector<gid_t> extra_groups;
@@ -70,12 +59,6 @@ Result<void> spawn_process_as_user(Slice<StringView> arguments, uid_t user, gid_
 
 Result<int> luna_main(int argc, char** argv)
 {
-    if (geteuid() != 0)
-    {
-        os::eprintln("error: %s can only be started as root.", argv[0]);
-        return 1;
-    }
-
     StringView username;
 
     os::ArgumentParser parser;
@@ -84,6 +67,12 @@ Result<int> luna_main(int argc, char** argv)
     parser.add_value_argument(username, 'u', "user", "the user to start the UI session as");
     parser.parse(argc, argv);
 
+    if (geteuid() != 0)
+    {
+        os::eprintln("error: %s can only be started as root.", argv[0]);
+        return 1;
+    }
+
     if (username.is_empty())
     {
         os::eprintln("error: startui needs a --user parameter to run.");
@@ -105,9 +94,22 @@ Result<int> luna_main(int argc, char** argv)
 
     setsid();
 
-    // First of all, start the display server.
+    // First of all, start the display server, in case we haven't been started by loginui.
+    if (!os::FileSystem::exists("/tmp/wind.sock"))
+    {
+        // We need to wait for this one, since its sockets are required later.
+        bool success = os::IPC::Notifier::run_and_wait(
+            [&] {
                 StringView wind_command[] = { "/usr/bin/wind" };
-    TRY(os::Process::spawn(wind_command[0], Slice<StringView>(wind_command, 1)));
+                os::Process::spawn(wind_command[0], Slice<StringView>(wind_command, 1));
+            },
+            1000);
+        if (!success)
+        {
+            os::eprintln("startui: failed to start wind, timed out");
+            return 1;
+        }
+    }
 
     clearenv();
     chdir(pw->pw_dir);
@@ -116,18 +118,22 @@ Result<int> luna_main(int argc, char** argv)
     setenv("HOME", pw->pw_dir, 1);
     setenv("SHELL", pw->pw_shell, 1);
 
-    // Next, start the required UI components.
+    // We also need to wait for this one, since taskbar requires launch.sock.
+    bool success = os::IPC::Notifier::run_and_wait(
+        [&] {
             StringView launch_command[] = { "/usr/bin/launch" };
-    TRY(spawn_process_as_user(Slice<StringView>(launch_command, 1), pw->pw_uid, pw->pw_gid, groups.slice()));
-
-    TRY(wait_until_file_created("/tmp/wsys.sock", 10000));
-    TRY(wait_until_file_created("/tmp/launch.sock", 10000));
+            spawn_process_as_user(Slice<StringView>(launch_command, 1), pw->pw_uid, pw->pw_gid, groups.slice());
+        },
+        1000);
+    if (!success)
+    {
+        os::eprintln("startui: failed to start launch server, timed out");
+        return 1;
+    }
 
     StringView taskbar_command[] = { "/usr/bin/taskbar" };
     TRY(spawn_process_as_user(Slice<StringView>(taskbar_command, 1), pw->pw_uid, pw->pw_gid, system_groups.slice()));
 
-    TRY(wait_until_file_created("/tmp/wind.sock", 10000));
-
     // Finally, start init in user mode to manage all configured optional services.
     StringView init_command[] = { "/usr/bin/init", "--user" };
     TRY(spawn_process_as_user(Slice<StringView>(init_command, 2), pw->pw_uid, pw->pw_gid, groups.slice()));