Fix non-root user startup and config fallback

build.rs

@@ -1,4 +1,5 @@
 fn main() {
-    let lib_path = "./assets/libs/arm64-v8a";
-    println!("cargo::rustc-link-search={}", lib_path);
+    if std::env::var("CARGO_CFG_TARGET_OS").as_deref() == Ok("android") {
+        println!("cargo::rustc-link-search=./assets/libs/arm64-v8a");
+    }
 }

gh-pages/docs/user/2-creating-a-non-root-user.md

@@ -61,13 +61,17 @@ _(Replace `teddy` with the username you created [previously](#create-your-user))
 
 Save and exit.
 
-You can test if your new user can use `sudo` by temporarily logging in:
+You can test whether the account is resolvable and can use `sudo` by temporarily logging in:
 
 ```bash
-su teddy # Change to your username
+getent passwd teddy # Change to your username
+su - teddy
 sudo ls /root # Make sure it does not output something like: "teddy is not in the sudoers file"
+exit
 ```
 
+If `su` displays `I have no name`, close and reopen Local Desktop, then repeat the test. Local Desktop repairs the account database permissions during startup so non-root processes can resolve users and groups.
+
 ## [Important] Tell Local Desktop
 
 You must tell Local Desktop who to log in as, or it will log in as root. To (create and) edit the config file:
@@ -76,13 +80,14 @@ You must tell Local Desktop who to log in as, or it will log in as root. To (cre
 nano /etc/localdesktop/localdesktop.toml
 ```
 
-Add the following content:
+Test the new account for one launch while keeping root as the persistent fallback:
 
 ```toml title="/etc/localdesktop/localdesktop.toml"
 [user]
-username = "teddy"
+username = "root"
+try_username = "teddy"
 ```
 
 _(Replace `teddy` with the username you created [previously](#create-your-user))_
 
-The changes will take effect the next time you launch Local Desktop. If something goes wrong, you can always delete this config file and restart as root.
+The changes will take effect the next time you launch Local Desktop. After that launch, `try_username` is commented out automatically. If the desktop works, change `username = "root"` to `username = "teddy"` and remove the commented `try_username` line. If the configured account is missing, Local Desktop falls back to root so you can repair the account or config without clearing the app's storage.

src/android/proot/process.rs

@@ -1,5 +1,8 @@
 use crate::android::utils::application_context::get_application_context;
-use crate::core::config;
+use crate::core::{
+    config,
+    guest_user::{repair_account_database_permissions, GuestUser, ROOT_USERNAME},
+};
 use std::ffi::CString;
 use std::fs;
 use std::io::{BufRead, BufReader, Read};
@@ -101,7 +104,17 @@ impl ArchProcess {
 
     pub fn run(self) -> Output {
         let context = get_application_context();
-        let user = self.user.as_deref().unwrap_or("root");
+        if let Err(error) = repair_account_database_permissions(Path::new(config::ARCH_FS_ROOT)) {
+            log::warn!("Failed to repair guest account database permissions: {error}");
+        }
+
+        let requested_username = self.user.as_deref().unwrap_or(ROOT_USERNAME);
+        let user = GuestUser::resolve(Path::new(config::ARCH_FS_ROOT), requested_username);
+        if self.user.is_some() && user.username() != requested_username {
+            log::warn!(
+                "Configured guest user '{requested_username}' could not be resolved; falling back to root"
+            );
+        }
 
         let mut process = Command::new(context.native_library_dir.join("libproot.so"));
         process
@@ -153,28 +166,24 @@ impl ArchProcess {
 
         // env vars
         process.arg("/usr/bin/env").arg("-i");
-        if user == "root" {
-            process.arg("HOME=/root");
-        } else {
-            process.arg(format!("HOME=/home/{}", user));
-        }
         process
+            .arg(format!("HOME={}", user.guest_home_dir().display()))
             .arg("LANG=C.UTF-8")
             .arg("TERM=xterm-256color")
             .arg("PATH=/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin:/usr/local/games:/usr/games:/system/bin:/system/xbin")
             .arg("TMPDIR=/tmp")
-            .arg(format!("USER={}", user))
-            .arg(format!("LOGNAME={}", user));
+            .arg(format!("USER={}", user.username()))
+            .arg(format!("LOGNAME={}", user.username()));
 
         // user shell
-        if user == "root" {
+        if user.username() == ROOT_USERNAME {
             process.arg("sh");
         } else {
             process
                 .arg("runuser")
                 .arg("--pty")
                 .arg("-u")
-                .arg(user)
+                .arg(user.username())
                 .arg("--")
                 .arg("sh");
         }

src/android/proot/setup.rs

@@ -9,7 +9,10 @@ use crate::{
         utils::application_context::get_application_context,
         utils::ndk::run_in_jvm,
     },
-    core::config::{CommandConfig, ARCH_FS_ARCHIVE, ARCH_FS_ROOT, DOCS_HOME_URL, PULSE_GUEST_SERVER},
+    core::{
+        config::{CommandConfig, ARCH_FS_ARCHIVE, ARCH_FS_ROOT, DOCS_HOME_URL, PULSE_GUEST_SERVER},
+        guest_user::GuestUser,
+    },
 };
 use jni::objects::JObject;
 use jni::sys::_jobject;
@@ -19,7 +22,7 @@ use std::{
     fs::{self, File},
     io::{Read, Write},
     os::unix::fs::{symlink, PermissionsExt},
-    path::{Path, PathBuf},
+    path::Path,
     sync::{
         mpsc::{self, Sender},
         Arc, Mutex,
@@ -501,14 +504,6 @@ runpy.run_path('/usr/sbin/onboard', run_name='__main__')
     None
 }
 
-fn chroot_home_dir(fs_root: &Path, username: &str) -> PathBuf {
-    if username == "root" {
-        fs_root.join("root")
-    } else {
-        fs_root.join(format!("home/{username}"))
-    }
-}
-
 fn write_executable(path: &Path, contents: &str) {
     if let Some(parent) = path.parent() {
         let _ = fs::create_dir_all(parent);
@@ -561,8 +556,9 @@ fn android_ui_scale(density_dpi: i32) -> i32 {
 
 fn setup_xfce_wayland(options: &SetupOptions) -> StageOutput {
     let fs_root = Path::new(ARCH_FS_ROOT);
-    let username = get_application_context().local_config.user.username;
-    let home_dir = chroot_home_dir(fs_root, &username);
+    let configured_username = get_application_context().local_config.user.username;
+    let guest_user = GuestUser::resolve(fs_root, &configured_username);
+    let home_dir = guest_user.host_home_dir(fs_root);
     let labwc_dir = home_dir.join(".config/xfce4/labwc");
 
     let density_dpi = read_android_density_dpi(options.android_app.clone());
@@ -926,7 +922,7 @@ pub fn setup(android_app: AndroidApp) -> PolarBearBackend {
         Box::new(setup_onboard_signal_fix), // Step 6. Wrap Onboard to survive proot fstat/signal.set_wakeup_fd failure
         Box::new(setup_xfce_wayland),       // Step 7. Setup Xfce Wayland launch and HiDPI scaling
         Box::new(fix_xkb_symlink),          // Step 8. Fix xkb symlink
-        Box::new(setup_pulse_client_conf), // Step 9. Write PulseAudio conf (last)
+        Box::new(setup_pulse_client_conf),  // Step 9. Write PulseAudio conf (last)
     ];
 
     let handle_stage_error = |e: Box<dyn std::any::Any + Send>, sender: &Sender<SetupMessage>| {

src/core/config.rs

@@ -41,7 +41,7 @@ pub const CONFIG_FILE: &str = "/etc/localdesktop/localdesktop.toml";
 
 #[derive(Debug, Serialize, Deserialize, Default, Clone)]
 pub struct LocalConfig {
-    #[serde(default)]
+    #[serde(default, alias = "users")]
     pub user: UserConfig,
 
     /// What happens if we don't assign this `#[serde(default)]` attribute?
@@ -54,13 +54,18 @@ pub struct LocalConfig {
 
 #[derive(Debug, Serialize, Deserialize, Clone)]
 pub struct UserConfig {
+    #[serde(default = "default_username")]
     pub username: String,
 }
 
+fn default_username() -> String {
+    "root".to_string()
+}
+
 impl Default for UserConfig {
     fn default() -> Self {
         Self {
-            username: "root".to_string(),
+            username: default_username(),
         }
     }
 }
@@ -179,8 +184,7 @@ pub fn parse_config(full_config_path: String) -> LocalConfig {
         return config;
     }
     // Config malformed, use the default config and the user can modify it again
-    let default_config = LocalConfig::default();
-    default_config
+    LocalConfig::default()
 }
 
 #[cfg(test)]
@@ -244,6 +248,41 @@ mod tests {
         );
     }
 
+    #[test]
+    fn should_keep_other_sections_when_try_username_has_been_consumed() {
+        with_config_file(
+            r#"
+                [user]
+                try_username = "alice"
+
+                [command]
+                check = "custom-check"
+            "#,
+            |full_config_path| {
+                let first_launch = parse_config(full_config_path.clone());
+                assert_eq!(first_launch.user.username, "alice");
+
+                let second_launch = parse_config(full_config_path);
+                assert_eq!(second_launch.user.username, "root");
+                assert_eq!(second_launch.command.check, "custom-check");
+            },
+        );
+    }
+
+    #[test]
+    fn should_accept_the_legacy_users_section_name() {
+        with_config_file(
+            r#"
+                [users]
+                username = "alice"
+            "#,
+            |full_config_path| {
+                let config = parse_config(full_config_path);
+                assert_eq!(config.user.username, "alice");
+            },
+        );
+    }
+
     #[test]
     fn should_comment_out_try_configs() {
         with_config_file(