Reimplement most of the asynchronous handling

This also involves a major split of the authentication code, which allows
the fingerprint and password logins to use the same code.

res/pam.d/ly

@@ -1,5 +1,7 @@
 #%PAM-1.0
 
+auth       sufficient   pam_unix.so try_first_pass likeauth nullok # empty-password will not pass this, but will not fail causing the next line to get executed
+-auth      sufficient   pam_fprintd.so # We do not want to get errors when pam_fprintd.so is not present
 auth       include      login
 -auth      optional     pam_gnome_keyring.so
 -auth      optional     pam_kwallet5.so

src/auth.zig

@@ -13,6 +13,66 @@ const utmp = interop.utmp;
 const Utmp = utmp.utmpx;
 const SharedError = @import("SharedError.zig");
 
+// When setting the currentLogin you must deallocate the previous currentLogin first
+pub var currentLogin: ?[:0]const u8 = null;
+pub var asyncPamHandle: ?*interop.pam.pam_handle = null;
+pub var current_environment: ?Session.Environment = null;
+
+fn environment_equals(e0: Session.Environment, e1: Session.Environment) bool {
+    if (!std.mem.eql(u8, e0.cmd, e1.cmd)) {
+        return false;
+    }
+    if (!std.mem.eql(u8, e0.name, e1.name)) {
+        return false;
+    }
+    if (!std.mem.eql(u8, e0.specifier, e1.specifier)) {
+        return false;
+    }
+    if (!(e0.xdg_desktop_names == null and e1.xdg_desktop_names == null) or
+        (e0.xdg_desktop_names != null and e1.xdg_desktop_names != null and !std.mem.eql(u8, e0.xdg_desktop_names.?, e1.xdg_desktop_names.?)))
+    {
+        return false;
+    }
+    if (!(e0.xdg_session_desktop == null and e1.xdg_session_desktop == null) or
+        (e0.xdg_session_desktop != null and e1.xdg_session_desktop != null and !std.mem.eql(u8, e0.xdg_session_desktop.?, e1.xdg_session_desktop.?)))
+    {
+        return false;
+    }
+    if (e0.display_server != e1.display_server) {
+        return false;
+    }
+    return true;
+}
+
+pub fn automaticLogin(config: Config, login: [:0]const u8, environment: Session.Environment, wakesem: *std.Thread.Semaphore) !void {
+    while (asyncPamHandle == null and currentLogin != null and std.mem.eql(u8, currentLogin.?, login)) {
+        if (authenticate(config, login, "", environment)) |handle| {
+            if (currentLogin != null and !std.mem.eql(u8, currentLogin.?, login) and environment_equals(current_environment.?, environment)) {
+                return;
+            }
+            asyncPamHandle = handle;
+            wakesem.post();
+            return;
+        } else |_| {}
+    }
+}
+
+pub fn startAutomaticLogin(allocator: std.mem.Allocator, config: Config, login: Text, environment: Session.Environment, wakesem: *std.Thread.Semaphore) !void {
+    if (currentLogin) |clogin| {
+        allocator.free(clogin);
+        currentLogin = null;
+    }
+    const login_text = try allocator.dupeZ(u8, login.text.items);
+    currentLogin = login_text;
+    var handle = try std.Thread.spawn(.{}, automaticLogin, .{
+        config,
+        login_text,
+        environment,
+        wakesem,
+    });
+    handle.detach();
+}
+
 var xorg_pid: std.posix.pid_t = 0;
 pub fn xorgSignalHandler(i: c_int) callconv(.C) void {
     if (xorg_pid > 0) _ = std.c.kill(xorg_pid, i);
@@ -23,16 +83,20 @@ pub fn sessionSignalHandler(i: c_int) callconv(.C) void {
     if (child_pid > 0) _ = std.c.kill(child_pid, i);
 }
 
-pub fn authenticate(config: Config, current_environment: Session.Environment, login: [:0]const u8, password: [:0]const u8) !void {
+pub fn authenticate(
-    var tty_buffer: [3]u8 = undefined;
+    config: Config,
-    const tty_str = try std.fmt.bufPrintZ(&tty_buffer, "{d}", .{config.tty});
+    login: [:0]const u8,
-
+    password: [:0]const u8,
+    environment: Session.Environment,
+) !*interop.pam.pam_handle {
     var pam_tty_buffer: [6]u8 = undefined;
     const pam_tty_str = try std.fmt.bufPrintZ(&pam_tty_buffer, "tty{d}", .{config.tty});
+    var tty_buffer: [2]u8 = undefined;
+    const tty_str = try std.fmt.bufPrintZ(&tty_buffer, "{d}", .{config.tty});
 
     // Set the XDG environment variables
-    setXdgSessionEnv(current_environment.display_server);
+    setXdgSessionEnv(environment.display_server);
-    try setXdgEnv(tty_str, current_environment.xdg_session_desktop orelse "", current_environment.xdg_desktop_names orelse "");
+    try setXdgEnv(tty_str, environment.xdg_session_desktop orelse "", environment.xdg_desktop_names orelse "");
 
     // Open the PAM session
     var credentials = [_:null]?[*:0]const u8{ login, password };
@@ -43,15 +107,15 @@ pub fn authenticate(config: Config, current_environment: Session.Environment, lo
     };
     var handle: ?*interop.pam.pam_handle = undefined;
 
+    // Do the PAM routine
     var status = interop.pam.pam_start(config.service_name, null, &conv, &handle);
     if (status != interop.pam.PAM_SUCCESS) return pamDiagnose(status);
-    defer _ = interop.pam.pam_end(handle, status);
+    errdefer _ = interop.pam.pam_end(handle, status);
 
     // Set PAM_TTY as the current TTY. This is required in case it isn't being set by another PAM module
     status = interop.pam.pam_set_item(handle, interop.pam.PAM_TTY, pam_tty_str.ptr);
     if (status != interop.pam.PAM_SUCCESS) return pamDiagnose(status);
 
-    // Do the PAM routine
     status = interop.pam.pam_authenticate(handle, 0);
     if (status != interop.pam.PAM_SUCCESS) return pamDiagnose(status);
 
@@ -59,12 +123,21 @@ pub fn authenticate(config: Config, current_environment: Session.Environment, lo
     if (status != interop.pam.PAM_SUCCESS) return pamDiagnose(status);
 
     status = interop.pam.pam_setcred(handle, interop.pam.PAM_ESTABLISH_CRED);
+    errdefer _ = interop.pam.pam_end(handle, status);
+
     if (status != interop.pam.PAM_SUCCESS) return pamDiagnose(status);
+    return handle.?;
+}
+
+pub fn finaliseAuth(config: Config, environment: Session.Environment, handle: ?*interop.pam.pam_handle, login: [:0]const u8) !void {
+    var status: c_int = undefined;
+    defer status = interop.pam.pam_end(handle, status);
     defer status = interop.pam.pam_setcred(handle, interop.pam.PAM_DELETE_CRED);
 
+    // Open the PAM session
     status = interop.pam.pam_open_session(handle, 0);
     if (status != interop.pam.PAM_SUCCESS) return pamDiagnose(status);
-    defer status = interop.pam.pam_close_session(handle, 0);
+    defer status = interop.pam.pam_close_session(handle, status);
 
     var pwd: *interop.pwd.passwd = undefined;
     {
@@ -86,7 +159,7 @@ pub fn authenticate(config: Config, current_environment: Session.Environment, lo
 
     child_pid = try std.posix.fork();
     if (child_pid == 0) {
-        startSession(config, pwd, handle, current_environment) catch |e| {
+        startSession(config, pwd, handle, environment) catch |e| {
             shared_err.writeError(e);
             std.process.exit(1);
         };
@@ -124,7 +197,7 @@ fn startSession(
     config: Config,
     pwd: *interop.pwd.passwd,
     handle: ?*interop.pam.pam_handle,
-    current_environment: Session.Environment,
+    environment: Session.Environment,
 ) !void {
     if (builtin.os.tag == .freebsd) {
         // FreeBSD has initgroups() in unistd
@@ -156,13 +229,13 @@ fn startSession(
     std.posix.chdirZ(pwd.pw_dir.?) catch return error.ChangeDirectoryFailed;
 
     // Execute what the user requested
-    switch (current_environment.display_server) {
+    switch (environment.display_server) {
-        .wayland => try executeWaylandCmd(pwd.pw_shell.?, config, current_environment.cmd),
+        .wayland => try executeWaylandCmd(pwd.pw_shell.?, config, environment.cmd),
         .shell => try executeShellCmd(pwd.pw_shell.?, config),
         .xinitrc, .x11 => if (build_options.enable_x11_support) {
             var vt_buf: [5]u8 = undefined;
             const vt = try std.fmt.bufPrint(&vt_buf, "vt{d}", .{config.tty});
-            try executeX11Cmd(pwd.pw_shell.?, pwd.pw_dir.?, config, current_environment.cmd, vt);
+            try executeX11Cmd(pwd.pw_shell.?, pwd.pw_dir.?, config, environment.cmd, vt);
         },
     }
 }

src/main.zig

@@ -39,6 +39,16 @@ pub fn signalHandler(i: c_int) callconv(.C) void {
     std.c.exit(i);
 }
 
+fn eventThreadMain(event: *?termbox.tb_event, event_error: *c_int, timeout: *c_int, wake: *std.Thread.Semaphore, cont: *std.Thread.Semaphore) void {
+    while (true) {
+        cont.wait();
+        var e: termbox.tb_event = undefined;
+        event_error.* = termbox.tb_peek_event(&e, timeout.*);
+        event.* = e;
+        wake.post();
+    }
+}
+
 pub fn main() !void {
     var shutdown = false;
     var restart = false;
@@ -329,7 +339,11 @@ pub fn main() !void {
     const brightness_up_key = try std.fmt.parseInt(u8, config.brightness_up_key[1..], 10);
     const brightness_up_len = try utils.strWidth(lang.brightness_up);
 
-    var event: termbox.tb_event = undefined;
+    var event_timeout: c_int = std.math.maxInt(c_int);
+    var event_error: c_int = undefined;
+    var event: ?termbox.tb_event = null;
+    var wake: std.Thread.Semaphore = .{};
+    var doneEvent: std.Thread.Semaphore = .{};
     var run = true;
     var update = true;
     var resolution_changed = false;
@@ -340,6 +354,16 @@ pub fn main() !void {
         try info_line.addMessage(lang.err_console_dev, config.error_bg, config.error_fg);
     };
 
+    doneEvent.post();
+    const thandle = try std.Thread.spawn(.{}, eventThreadMain, .{ &event, &event_error, &event_timeout, &wake, &doneEvent });
+
+    thandle.detach();
+
+    {
+        const current_environment = session.label.list.items[session.label.current];
+        try auth.startAutomaticLogin(allocator, config, login, current_environment, &wake);
+    }
+    defer allocator.free(auth.currentLogin.?);
     while (run) {
         // If there's no input or there's an animation, a resolution change needs to be checked
         if (!update or config.animation != .none) {
@@ -526,9 +550,9 @@ pub fn main() !void {
             _ = termbox.tb_present();
         }
 
-        var timeout: i32 = -1;
+        var timeout: u64 = std.math.maxInt(u64);
 
-        // Calculate the maximum timeout based on current animations, or the (big) clock. If there's none, we wait for the event indefinitely instead
+        // Calculate the maximum timeout based on current animations, or the (big) clock. If there's none, we wait for 100ms instead
         if (animate and !animation_timed_out) {
             timeout = config.min_refresh_delta;
 
@@ -556,13 +580,67 @@ pub fn main() !void {
             timeout = @intCast(1000 - @divTrunc(tv.tv_usec, 1000) + 1);
         }
 
-        const event_error = if (timeout == -1) termbox.tb_poll_event(&event) else termbox.tb_peek_event(&event, timeout);
+        var skipEvent: bool = false;
+        _ = wake.timedWait(timeout) catch .{};
+        if (auth.asyncPamHandle) |handle| {
+            var shared_err = try SharedError.init();
+            defer shared_err.deinit();
 
+            {
+                const login_text = try allocator.dupeZ(u8, login.text.items);
+                defer allocator.free(login_text);
+
+                try info_line.addMessage(lang.authenticating, config.error_bg, config.error_fg);
+                InfoLine.clearRendered(allocator, buffer) catch {
+                    try info_line.addMessage(lang.err_alloc, config.error_bg, config.error_fg);
+                };
+                info_line.label.draw();
+                _ = termbox.tb_present();
+
+                session_pid = try std.posix.fork();
+                if (session_pid == 0) {
+                    const current_environment = session.label.list.items[session.label.current];
+                    auth.finaliseAuth(config, current_environment, handle, login_text) catch |err| {
+                        shared_err.writeError(err);
+                        std.process.exit(1);
+                    };
+
+                    std.process.exit(0);
+                }
+                _ = std.posix.waitpid(session_pid, 0);
+
+                session_pid = -1;
+            }
+
+            auth.asyncPamHandle = null;
+
+            const auth_err = shared_err.readError();
+            if (auth_err) |err| {
+                try info_line.addMessage(getAuthErrorMsg(err, lang), config.error_bg, config.error_fg);
+                // We don't want to start login back in instantly. The user must first edit
+                // the login/desktop in order to login. Only in case of a failed login (so not a logout)
+                // should we automatically restart it.
+                const current_environment = session.label.list.items[session.label.current];
+                try auth.startAutomaticLogin(allocator, config, login, current_environment, &wake);
+            } else {
+                try info_line.addMessage(lang.logout, config.error_bg, config.error_fg);
+            }
+
+            try std.posix.tcsetattr(std.posix.STDIN_FILENO, .FLUSH, tb_termios);
+            _ = termbox.tb_clear();
+            _ = termbox.tb_present();
+
+            update = true;
+
+            _ = termbox.tb_set_cursor(0, 0);
+            _ = termbox.tb_present();
+        } else if (event) |e| {
+            defer doneEvent.post();
             update = timeout != -1;
+            skipEvent = event_error < 0;
+            if (skipEvent or e.type != termbox.TB_EVENT_KEY) continue;
 
-        if (event_error < 0 or event.type != termbox.TB_EVENT_KEY) continue;
+            switch (e.key) {
-
-        switch (event.key) {
                 termbox.TB_KEY_ESC => {
                     if (config.vi_mode and insert_mode) {
                         insert_mode = false;
@@ -570,7 +648,7 @@ pub fn main() !void {
                     }
                 },
                 termbox.TB_KEY_F12...termbox.TB_KEY_F1 => {
-                const pressed_key = 0xFFFF - event.key + 1;
+                    const pressed_key = 0xFFFF - e.key + 1;
                     if (pressed_key == shutdown_key) {
                         shutdown = true;
                         run = false;
@@ -609,6 +687,10 @@ pub fn main() !void {
                     update = true;
                 },
                 termbox.TB_KEY_CTRL_J, termbox.TB_KEY_ARROW_DOWN => {
+                    if (active_input == .login) {
+                        const current_environment = session.label.list.items[session.label.current];
+                        try auth.startAutomaticLogin(allocator, config, login, current_environment, &wake);
+                    }
                     active_input = switch (active_input) {
                         .info_line => .session,
                         .session => .login,
@@ -617,6 +699,10 @@ pub fn main() !void {
                     update = true;
                 },
                 termbox.TB_KEY_TAB => {
+                    if (active_input == .login) {
+                        const current_environment = session.label.list.items[session.label.current];
+                        try auth.startAutomaticLogin(allocator, config, login, current_environment, &wake);
+                    }
                     active_input = switch (active_input) {
                         .info_line => .session,
                         .session => .login,
@@ -626,6 +712,10 @@ pub fn main() !void {
                     update = true;
                 },
                 termbox.TB_KEY_BACK_TAB => {
+                    if (active_input == .info_line) {
+                        const current_environment = session.label.list.items[session.label.current];
+                        try auth.startAutomaticLogin(allocator, config, login, current_environment, &wake);
+                    }
                     active_input = switch (active_input) {
                         .info_line => .password,
                         .session => .info_line,
@@ -670,16 +760,21 @@ pub fn main() !void {
                         _ = termbox.tb_shutdown();
 
                         session_pid = try std.posix.fork();
-                    if (session_pid == 0) {
                         const current_environment = session.label.list.items[session.label.current];
-                        auth.authenticate(config, current_environment, login_text, password_text) catch |err| {
+                        if (auth.authenticate(config, login_text, password_text, current_environment)) |handle| {
+                            if (session_pid == 0) {
+                                auth.finaliseAuth(config, current_environment, handle, login_text) catch |err| {
                                     shared_err.writeError(err);
                                     std.process.exit(1);
                                 };
+
                                 std.process.exit(0);
                             }
-
                             _ = std.posix.waitpid(session_pid, 0);
+                        } else |err| {
+                            shared_err.writeError(err);
+                        }
+
                         session_pid = -1;
                     }
 
@@ -714,7 +809,7 @@ pub fn main() !void {
                 },
                 else => {
                     if (!insert_mode) {
-                    switch (event.ch) {
+                        switch (e.ch) {
                             'k' => {
                                 active_input = switch (active_input) {
                                     .session, .info_line => .info_line,
@@ -725,6 +820,10 @@ pub fn main() !void {
                                 continue;
                             },
                             'j' => {
+                                if (active_input == .login) {
+                                    const current_environment = session.label.list.items[session.label.current];
+                                    try auth.startAutomaticLogin(allocator, config, login, current_environment, &wake);
+                                }
                                 active_input = switch (active_input) {
                                     .info_line => .session,
                                     .session => .login,
@@ -743,12 +842,12 @@ pub fn main() !void {
                     }
 
                     switch (active_input) {
-                    .info_line => info_line.label.handle(&event, insert_mode),
+                        .info_line => info_line.label.handle(&event.?, insert_mode),
-                    .session => session.label.handle(&event, insert_mode),
+                        .session => session.label.handle(&event.?, insert_mode),
-                    .login => login.handle(&event, insert_mode) catch {
+                        .login => login.handle(&event.?, insert_mode) catch {
                             try info_line.addMessage(lang.err_alloc, config.error_bg, config.error_fg);
                         },
-                    .password => password.handle(&event, insert_mode) catch {
+                        .password => password.handle(&event.?, insert_mode) catch {
                             try info_line.addMessage(lang.err_alloc, config.error_bg, config.error_fg);
                         },
                     }
@@ -756,6 +855,7 @@ pub fn main() !void {
                 },
             }
         }
+    }
 }
 
 fn getAuthErrorMsg(err: anyerror, lang: Lang) []const u8 {