From 1d4e32ba82829038b58c0b01904eb5ab6ad331df Mon Sep 17 00:00:00 2001
From: AnErrupTion <anerruption@disroot.org>
Date: Thu, 10 Jul 2025 10:06:19 +0200
Subject: [PATCH] List all users in the system (fixes #373)

Signed-off-by: AnErrupTion <anerruption@disroot.org>
---
 res/config.ini                  |   3 +
 res/lang/ar.ini                 |   1 +
 res/lang/cat.ini                |   1 +
 res/lang/cs.ini                 |   1 +
 res/lang/de.ini                 |   1 +
 res/lang/en.ini                 |   1 +
 res/lang/es.ini                 |   1 +
 res/lang/fr.ini                 |   1 +
 res/lang/it.ini                 |   1 +
 res/lang/pl.ini                 |   1 +
 res/lang/pt.ini                 |   1 +
 res/lang/pt_BR.ini              |   1 +
 res/lang/ro.ini                 |   1 +
 res/lang/ru.ini                 |   1 +
 res/lang/sr.ini                 |   1 +
 res/lang/sv.ini                 |   1 +
 res/lang/tr.ini                 |   1 +
 res/lang/uk.ini                 |   1 +
 res/lang/zh_CN.ini              |   1 +
 src/UidRange.zig                |   6 ++
 src/config/Config.zig           |   1 +
 src/config/Lang.zig             |   1 +
 src/main.zig                    | 124 ++++++++++++++++++++++++++------
 src/tui/components/UserList.zig |  45 ++++++++++++
 24 files changed, 176 insertions(+), 22 deletions(-)
 create mode 100644 src/UidRange.zig
 create mode 100644 src/tui/components/UserList.zig

diff --git a/res/config.ini b/res/config.ini
index 8b4a4f9..866b6b2 100644
--- a/res/config.ini
+++ b/res/config.ini
@@ -184,6 +184,9 @@ load = true
 # You can also set environment variables in there, they'll persist until logout
 login_cmd = null
 
+# Path for login.defs file (used for listing all local users on the system)
+login_defs_path = /etc/login.defs
+
 # Command executed when logging out
 # If null, no command will be executed
 # Important: the session will already be terminated when this command is executed, so
diff --git a/res/lang/ar.ini b/res/lang/ar.ini
index 9c2f9be..b06f253 100644
--- a/res/lang/ar.ini
+++ b/res/lang/ar.ini
@@ -41,6 +41,7 @@ err_pwnam = فشل في جلب معلومات المستخدم
 err_sleep = فشل في تنفيذ أمر sleep
 
 err_tty_ctrl = فشل في نقل تحكم الطرفية (TTY)
+
 err_user_gid = فشل في تعيين معرّف المجموعة (GID) للمستخدم
 err_user_init = فشل في تهيئة بيانات المستخدم
 err_user_uid = فشل في تعيين معرّف المستخدم (UID)
diff --git a/res/lang/cat.ini b/res/lang/cat.ini
index 7aa4261..d0ce33e 100644
--- a/res/lang/cat.ini
+++ b/res/lang/cat.ini
@@ -41,6 +41,7 @@ err_pwnam = error en obtenir la informació de l'usuari
 
 
 
+
 err_user_gid = error en establir el GID de l'usuari
 err_user_init = error en inicialitzar usuari
 err_user_uid = error en establir l'UID de l'usuari
diff --git a/res/lang/cs.ini b/res/lang/cs.ini
index cca457a..7c87ea6 100644
--- a/res/lang/cs.ini
+++ b/res/lang/cs.ini
@@ -41,6 +41,7 @@ err_pwnam = nelze získat informace o uživateli
 
 
 
+
 err_user_gid = nastavení GID uživatele selhalo
 err_user_init = inicializace uživatele selhala
 err_user_uid = nastavení UID uživateli selhalo
diff --git a/res/lang/de.ini b/res/lang/de.ini
index 32e00a6..44bbc53 100644
--- a/res/lang/de.ini
+++ b/res/lang/de.ini
@@ -41,6 +41,7 @@ err_pwnam = Abrufen der Benutzerinformationen fehlgeschlagen
 err_sleep = Sleep-Befehl fehlgeschlagen
 
 err_tty_ctrl = Fehler bei der TTY-Uebergabe
+
 err_user_gid = Fehler beim Setzen der Gruppen-ID
 err_user_init = Nutzer-Initialisierung fehlgeschlagen
 err_user_uid = Setzen der Benutzer-ID fehlgeschlagen
diff --git a/res/lang/en.ini b/res/lang/en.ini
index d7076db..9554658 100644
--- a/res/lang/en.ini
+++ b/res/lang/en.ini
@@ -41,6 +41,7 @@ err_pwnam = failed to get user info
 err_sleep = failed to execute sleep command
 err_switch_tty = failed to switch tty
 err_tty_ctrl = tty control transfer failed
+err_no_users = no users found
 err_user_gid = failed to set user GID
 err_user_init = failed to initialize user
 err_user_uid = failed to set user UID
diff --git a/res/lang/es.ini b/res/lang/es.ini
index fe3e6d9..2bd51a7 100644
--- a/res/lang/es.ini
+++ b/res/lang/es.ini
@@ -41,6 +41,7 @@ err_pwnam = error al obtener la información del usuario
 
 
 
+
 err_user_gid = error al establecer el GID del usuario
 err_user_init = error al inicializar usuario
 err_user_uid = error al establecer el UID del usuario
diff --git a/res/lang/fr.ini b/res/lang/fr.ini
index 6d46a1d..e024820 100644
--- a/res/lang/fr.ini
+++ b/res/lang/fr.ini
@@ -41,6 +41,7 @@ err_pwnam = échec de lecture des infos utilisateur
 err_sleep = échec de l'exécution de la commande de veille
 err_switch_tty = échec du changement de terminal
 err_tty_ctrl = échec du transfert de contrôle du terminal
+err_no_users = aucun utilisateur trouvé
 err_user_gid = échec de modification du GID
 err_user_init = échec d'initialisation de l'utilisateur
 err_user_uid = échec de modification du UID
diff --git a/res/lang/it.ini b/res/lang/it.ini
index 4bff87e..3a7f5a8 100644
--- a/res/lang/it.ini
+++ b/res/lang/it.ini
@@ -41,6 +41,7 @@ err_pwnam = impossibile ottenere dati utente
 
 
 
+
 err_user_gid = impossibile impostare GID utente
 err_user_init = impossibile inizializzare utente
 err_user_uid = impossible impostare UID utente
diff --git a/res/lang/pl.ini b/res/lang/pl.ini
index cfc5722..b3eee3d 100644
--- a/res/lang/pl.ini
+++ b/res/lang/pl.ini
@@ -41,6 +41,7 @@ err_pwnam = nie udało się uzyskać informacji o użytkowniku
 err_sleep = nie udało się wykonać polecenia sleep
 
 err_tty_ctrl = nie udało się przekazać kontroli tty
+
 err_user_gid = nie udało się ustawić GID użytkownika
 err_user_init = nie udało się zainicjalizować użytkownika
 err_user_uid = nie udało się ustawić UID użytkownika
diff --git a/res/lang/pt.ini b/res/lang/pt.ini
index df1db13..587d3b4 100644
--- a/res/lang/pt.ini
+++ b/res/lang/pt.ini
@@ -41,6 +41,7 @@ err_pwnam = erro ao obter informação do utilizador
 
 
 
+
 err_user_gid = erro ao definir o GID do utilizador
 err_user_init = erro ao iniciar o utilizador
 err_user_uid = erro ao definir o UID do utilizador
diff --git a/res/lang/pt_BR.ini b/res/lang/pt_BR.ini
index a7cee7b..2485522 100644
--- a/res/lang/pt_BR.ini
+++ b/res/lang/pt_BR.ini
@@ -41,6 +41,7 @@ err_pwnam = não foi possível obter informações do usuário
 
 
 
+
 err_user_gid = não foi possível definir o GID do usuário
 err_user_init = não foi possível iniciar o usuário
 err_user_uid = não foi possível definir o UID do usuário
diff --git a/res/lang/ro.ini b/res/lang/ro.ini
index 4289b7f..74c0461 100644
--- a/res/lang/ro.ini
+++ b/res/lang/ro.ini
@@ -49,6 +49,7 @@ err_perm_user = nu s-a putut face downgrade permisiunilor de utilizator
 
 
 
+
 login = utilizator
 logout = opreşte sesiunea
 
diff --git a/res/lang/ru.ini b/res/lang/ru.ini
index b9cfb1a..103f135 100644
--- a/res/lang/ru.ini
+++ b/res/lang/ru.ini
@@ -41,6 +41,7 @@ err_pwnam = не удалось получить информацию о пол
 
 
 
+
 err_user_gid = не удалось установить GID пользователя
 err_user_init = не удалось инициализировать пользователя
 err_user_uid = не удалось установить UID пользователя
diff --git a/res/lang/sr.ini b/res/lang/sr.ini
index 61ec4c0..c63fe28 100644
--- a/res/lang/sr.ini
+++ b/res/lang/sr.ini
@@ -41,6 +41,7 @@ err_pwnam = neuspijesno skupljanje informacija o korisniku
 
 
 
+
 err_user_gid = neuspijesno postavljanje korisničkog GID-a
 err_user_init = neuspijensa inicijalizacija korisnika
 err_user_uid = neuspijesno postavljanje UID-a korisnika
diff --git a/res/lang/sv.ini b/res/lang/sv.ini
index 9ccd0f3..17359cc 100644
--- a/res/lang/sv.ini
+++ b/res/lang/sv.ini
@@ -41,6 +41,7 @@ err_pwnam = misslyckades att hämta användarinfo
 
 
 
+
 err_user_gid = misslyckades att ställa in användar-GID
 err_user_init = misslyckades att initialisera användaren
 err_user_uid = misslyckades att ställa in användar-UID
diff --git a/res/lang/tr.ini b/res/lang/tr.ini
index d553495..535015c 100644
--- a/res/lang/tr.ini
+++ b/res/lang/tr.ini
@@ -41,6 +41,7 @@ err_pwnam = kullanici bilgileri alinamadi
 
 
 
+
 err_user_gid = kullanici icin GID ayarlanamadi
 err_user_init = kullanici oturumu baslatilamadi
 err_user_uid = kullanici icin UID ayarlanamadi
diff --git a/res/lang/uk.ini b/res/lang/uk.ini
index ffae75c..9e6de2d 100644
--- a/res/lang/uk.ini
+++ b/res/lang/uk.ini
@@ -41,6 +41,7 @@ err_pwnam = не вдалося отримати дані користувача
 
 
 
+
 err_user_gid = не вдалося змінити GID користувача
 err_user_init = не вдалося ініціалізувати користувача
 err_user_uid = не вдалося змінити UID користувача
diff --git a/res/lang/zh_CN.ini b/res/lang/zh_CN.ini
index 6f7ba41..9afdc66 100644
--- a/res/lang/zh_CN.ini
+++ b/res/lang/zh_CN.ini
@@ -41,6 +41,7 @@ err_pwnam = 获取用户信息失败
 
 
 
+
 err_user_gid = 设置用户GID失败
 err_user_init = 初始化用户失败
 err_user_uid = 设置用户UID失败
diff --git a/src/UidRange.zig b/src/UidRange.zig
new file mode 100644
index 0000000..13eb979
--- /dev/null
+++ b/src/UidRange.zig
@@ -0,0 +1,6 @@
+const std = @import("std");
+
+// We set both values to 0 by default so that, in case they aren't present in
+// the login.defs for some reason, then only the root username will be shown
+uid_min: std.c.uid_t = 0,
+uid_max: std.c.uid_t = 0,
diff --git a/src/config/Config.zig b/src/config/Config.zig
index 4a95b40..92e0552 100644
--- a/src/config/Config.zig
+++ b/src/config/Config.zig
@@ -50,6 +50,7 @@ input_len: u8 = 34,
 lang: []const u8 = "en",
 load: bool = true,
 login_cmd: ?[]const u8 = null,
+login_defs_path: []const u8 = "/etc/login.defs",
 logout_cmd: ?[]const u8 = null,
 margin_box_h: u8 = 2,
 margin_box_v: u8 = 1,
diff --git a/src/config/Lang.zig b/src/config/Lang.zig
index 3761fa7..7175e0f 100644
--- a/src/config/Lang.zig
+++ b/src/config/Lang.zig
@@ -46,6 +46,7 @@ err_pwnam: []const u8 = "failed to get user info",
 err_sleep: []const u8 = "failed to execute sleep command",
 err_switch_tty: []const u8 = "failed to switch tty",
 err_tty_ctrl: []const u8 = "tty control transfer failed",
+err_no_users: []const u8 = "no users found",
 err_user_gid: []const u8 = "failed to set user GID",
 err_user_init: []const u8 = "failed to initialize user",
 err_user_uid: []const u8 = "failed to set user UID",
diff --git a/src/main.zig b/src/main.zig
index b52e779..0cc2c6e 100644
--- a/src/main.zig
+++ b/src/main.zig
@@ -18,12 +18,15 @@ const TerminalBuffer = @import("tui/TerminalBuffer.zig");
 const Session = @import("tui/components/Session.zig");
 const Text = @import("tui/components/Text.zig");
 const InfoLine = @import("tui/components/InfoLine.zig");
+const UserList = @import("tui/components/UserList.zig");
 const Config = @import("config/Config.zig");
 const Lang = @import("config/Lang.zig");
 const Save = @import("config/Save.zig");
 const migrator = @import("config/migrator.zig");
 const SharedError = @import("SharedError.zig");
+const UidRange = @import("UidRange.zig");
 
+const StringList = std.ArrayListUnmanaged([]const u8);
 const Ini = ini.Ini;
 const DisplayServer = enums.DisplayServer;
 const Entry = Environment.Entry;
@@ -308,7 +311,21 @@ pub fn main() !void {
         try crawl(&session, lang, dir, .custom);
     }
 
-    var login = Text.init(allocator, &buffer, false, null);
+    var usernames = try getAllUsernames(allocator, config.login_defs_path);
+    defer {
+        for (usernames.items) |username| allocator.free(username);
+        usernames.deinit(allocator);
+    }
+
+    if (usernames.items.len == 0) {
+        // If we have no usernames, simply add an error to the info line.
+        // This effectively means you can't login, since there would be no local
+        // accounts *and* no root account...but at this point, if that's the
+        // case, you have bigger problems to deal with in the first place. :D
+        try info_line.addMessage(lang.err_no_users, config.error_bg, config.error_fg);
+    }
+
+    var login = try UserList.init(allocator, &buffer, usernames);
     defer login.deinit();
 
     var password = Text.init(allocator, &buffer, true, config.asterisk);
@@ -320,9 +337,17 @@ pub fn main() !void {
     // Load last saved username and desktop selection, if any
     if (config.load) {
         if (save.user) |user| {
-            try login.text.appendSlice(login.allocator, user);
-            login.end = user.len;
-            login.cursor = login.end;
+            // Find user with saved name, and switch over to it
+            // If it doesn't exist (anymore), we don't change the value
+            // Note that we could instead save the username index, but migrating
+            // from the raw username to an index is non-trivial and I'm lazy :P
+            for (usernames.items, 0..) |username, i| {
+                if (std.mem.eql(u8, username, user)) {
+                    login.label.current = i;
+                    break;
+                }
+            }
+
             active_input = .password;
         }
 
@@ -338,15 +363,13 @@ pub fn main() !void {
         const coordinates = buffer.calculateComponentCoordinates();
         info_line.label.position(coordinates.start_x, coordinates.y, coordinates.full_visible_length, null);
         session.label.position(coordinates.x, coordinates.y + 2, coordinates.visible_length, config.text_in_center);
-        login.position(coordinates.x, coordinates.y + 4, coordinates.visible_length);
+        login.label.position(coordinates.x, coordinates.y + 4, coordinates.visible_length, config.text_in_center);
         password.position(coordinates.x, coordinates.y + 6, coordinates.visible_length);
 
         switch (active_input) {
             .info_line => info_line.label.handle(null, insert_mode),
             .session => session.label.handle(null, insert_mode),
-            .login => login.handle(null, insert_mode) catch {
-                try info_line.addMessage(lang.err_alloc, config.error_bg, config.error_fg);
-            },
+            .login => login.label.handle(null, insert_mode),
             .password => password.handle(null, insert_mode) catch {
                 try info_line.addMessage(lang.err_alloc, config.error_bg, config.error_fg);
             },
@@ -464,7 +487,7 @@ pub fn main() !void {
                     const coordinates = buffer.calculateComponentCoordinates();
                     info_line.label.position(coordinates.start_x, coordinates.y, coordinates.full_visible_length, null);
                     session.label.position(coordinates.x, coordinates.y + 2, coordinates.visible_length, config.text_in_center);
-                    login.position(coordinates.x, coordinates.y + 4, coordinates.visible_length);
+                    login.label.position(coordinates.x, coordinates.y + 4, coordinates.visible_length, config.text_in_center);
                     password.position(coordinates.x, coordinates.y + 6, coordinates.visible_length);
 
                     resolution_changed = false;
@@ -473,9 +496,7 @@ pub fn main() !void {
                 switch (active_input) {
                     .info_line => info_line.label.handle(null, insert_mode),
                     .session => session.label.handle(null, insert_mode),
-                    .login => login.handle(null, insert_mode) catch {
-                        try info_line.addMessage(lang.err_alloc, config.error_bg, config.error_fg);
-                    },
+                    .login => login.label.handle(null, insert_mode),
                     .password => password.handle(null, insert_mode) catch {
                         try info_line.addMessage(lang.err_alloc, config.error_bg, config.error_fg);
                     },
@@ -571,7 +592,7 @@ pub fn main() !void {
                 }
 
                 session.label.draw();
-                login.draw();
+                login.label.draw();
                 password.draw();
             } else {
                 std.Thread.sleep(std.time.ns_per_ms * 10);
@@ -660,10 +681,7 @@ pub fn main() !void {
             },
             termbox.TB_KEY_CTRL_C => run = false,
             termbox.TB_KEY_CTRL_U => {
-                if (active_input == .login) {
-                    login.clear();
-                    update = true;
-                } else if (active_input == .password) {
+                if (active_input == .password) {
                     password.clear();
                     update = true;
                 }
@@ -726,7 +744,7 @@ pub fn main() !void {
                     defer file.close();
 
                     const save_data = Save{
-                        .user = login.text.items,
+                        .user = login.getCurrentUser(),
                         .session_index = session.label.current,
                     };
                     ini.writeFromStruct(save_data, file.writer(), null, .{}) catch break :save_last_settings;
@@ -739,7 +757,7 @@ pub fn main() !void {
                 defer shared_err.deinit();
 
                 {
-                    const login_text = try allocator.dupeZ(u8, login.text.items);
+                    const login_text = try allocator.dupeZ(u8, login.getCurrentUser());
                     defer allocator.free(login_text);
                     const password_text = try allocator.dupeZ(u8, password.text.items);
                     defer allocator.free(password_text);
@@ -845,9 +863,7 @@ pub fn main() !void {
                 switch (active_input) {
                     .info_line => info_line.label.handle(&event, insert_mode),
                     .session => session.label.handle(&event, insert_mode),
-                    .login => login.handle(&event, insert_mode) catch {
-                        try info_line.addMessage(lang.err_alloc, config.error_bg, config.error_fg);
-                    },
+                    .login => login.label.handle(&event, insert_mode),
                     .password => password.handle(&event, insert_mode) catch {
                         try info_line.addMessage(lang.err_alloc, config.error_bg, config.error_fg);
                     },
@@ -934,6 +950,70 @@ fn crawl(session: *Session, lang: Lang, path: []const u8, display_server: Displa
     }
 }
 
+fn getAllUsernames(allocator: std.mem.Allocator, login_defs_path: []const u8) !StringList {
+    const uid_range = try getUserIdRange(allocator, login_defs_path);
+
+    var usernames: StringList = .empty;
+    var maybe_entry = interop.pwd.getpwent();
+
+    while (maybe_entry != null) {
+        const entry = maybe_entry.*;
+
+        // We check if the UID is equal to 0 because we always want to add root
+        // as a username (even if you can't log into it)
+        if (entry.pw_uid >= uid_range.uid_min and entry.pw_uid <= uid_range.uid_max or entry.pw_uid == 0) {
+            const pw_name_slice = entry.pw_name[0..std.mem.len(entry.pw_name)];
+            const username = try allocator.dupe(u8, pw_name_slice);
+
+            try usernames.append(allocator, username);
+        }
+
+        maybe_entry = interop.pwd.getpwent();
+    }
+
+    interop.pwd.endpwent();
+    return usernames;
+}
+
+// This is very bad parsing, but we only need to get 2 values... and the format
+// of the file doesn't seem to be standard? So this should be fine...
+fn getUserIdRange(allocator: std.mem.Allocator, login_defs_path: []const u8) !UidRange {
+    const login_defs_file = try std.fs.cwd().openFile(login_defs_path, .{});
+    defer login_defs_file.close();
+
+    const login_defs_buffer = try login_defs_file.readToEndAlloc(allocator, std.math.maxInt(u16));
+    defer allocator.free(login_defs_buffer);
+
+    var iterator = std.mem.splitScalar(u8, login_defs_buffer, '\n');
+    var uid_range = UidRange{};
+
+    while (iterator.next()) |line| {
+        const trimmed_line = std.mem.trim(u8, line, " \n\r\t");
+
+        if (std.mem.startsWith(u8, trimmed_line, "UID_MIN")) {
+            uid_range.uid_min = try parseValue(std.c.uid_t, "UID_MIN", trimmed_line);
+        } else if (std.mem.startsWith(u8, trimmed_line, "UID_MAX")) {
+            uid_range.uid_max = try parseValue(std.c.uid_t, "UID_MAX", trimmed_line);
+        }
+    }
+
+    return uid_range;
+}
+
+fn parseValue(comptime T: type, name: []const u8, buffer: []const u8) !T {
+    var iterator = std.mem.splitAny(u8, buffer, " \t");
+    var maybe_value: ?T = null;
+
+    while (iterator.next()) |slice| {
+        // Skip the slice if it's empty (whitespace) or is the name of the
+        // property (e.g. UID_MIN or UID_MAX)
+        if (slice.len == 0 or std.mem.eql(u8, slice, name)) continue;
+        maybe_value = std.fmt.parseInt(T, slice, 10) catch continue;
+    }
+
+    return maybe_value orelse error.ValueNotFound;
+}
+
 fn adjustBrightness(allocator: std.mem.Allocator, cmd: []const u8) !void {
     var brightness = std.process.Child.init(&[_][]const u8{ "/bin/sh", "-c", cmd }, allocator);
     brightness.stdout_behavior = .Ignore;
diff --git a/src/tui/components/UserList.zig b/src/tui/components/UserList.zig
new file mode 100644
index 0000000..41eff39
--- /dev/null
+++ b/src/tui/components/UserList.zig
@@ -0,0 +1,45 @@
+const std = @import("std");
+const TerminalBuffer = @import("../TerminalBuffer.zig");
+const generic = @import("generic.zig");
+
+const StringList = std.ArrayListUnmanaged([]const u8);
+const Allocator = std.mem.Allocator;
+
+const UsernameText = generic.CyclableLabel([]const u8);
+
+const UserList = @This();
+
+label: UsernameText,
+
+pub fn init(allocator: Allocator, buffer: *TerminalBuffer, usernames: StringList) !UserList {
+    var userList = UserList{
+        .label = UsernameText.init(allocator, buffer, drawItem),
+    };
+
+    for (usernames.items) |username| {
+        if (username.len == 0) continue;
+
+        try userList.label.addItem(username);
+    }
+
+    return userList;
+}
+
+pub fn deinit(self: *UserList) void {
+    self.label.deinit();
+}
+
+pub fn getCurrentUser(self: UserList) []const u8 {
+    return self.label.list.items[self.label.current];
+}
+
+fn drawItem(label: *UsernameText, username: []const u8, _: usize, _: usize) bool {
+    const length = @min(username.len, label.visible_length - 3);
+    if (length == 0) return false;
+
+    const x = if (label.text_in_center) (label.x + (label.visible_length - username.len) / 2) else (label.x + 2);
+    label.first_char_x = x + username.len;
+
+    label.buffer.drawLabel(username, x, label.y);
+    return true;
+}