support metamodule, remove built-in overlayfs mount

Co-authored-by: weishu <twsxtd@gmail.com>
Co-authored-by: YuKongA <70465933+YuKongA@users.noreply.github.com>
Co-authored-by: Ylarod <me@ylarod.cn>

userspace/ksud/src/init_event.rs

@@ -1,28 +1,14 @@
-#[cfg(target_arch = "aarch64")]
-use crate::kpm;
-use crate::utils::is_safe_mode;
-use crate::{
-    assets, defs,
-    defs::{KSU_MOUNT_SOURCE, NO_MOUNT_PATH, NO_TMPFS_PATH},
-    ksucalls,
-    module::{handle_updated_modules, prune_modules},
-    restorecon, uid_scanner, utils,
-    utils::find_tmp_path,
-};
 use anyhow::{Context, Result};
 use log::{info, warn};
-use rustix::fs::{MountFlags, mount};
 use std::path::Path;
-
-#[cfg(target_os = "android")]
-pub fn mount_modules_systemlessly() -> Result<()> {
-    crate::magic_mount::magic_mount(&find_tmp_path())
-}
-
-#[cfg(not(target_os = "android"))]
-pub fn mount_modules_systemlessly() -> Result<()> {
-    Ok(())
-}
+#[cfg(target_arch = "aarch64")]
+use crate::kpm;
+use crate::module::{handle_updated_modules, prune_modules};
+use crate::utils::is_safe_mode;
+use crate::{
+    assets, defs, ksucalls, metamodule, restorecon,
+    utils::{self},
+};
 
 pub fn on_post_data_fs() -> Result<()> {
     ksucalls::report_post_fs_data();
@@ -39,9 +25,11 @@ pub fn on_post_data_fs() -> Result<()> {
         return Ok(());
     }
 
-    let safe_mode = utils::is_safe_mode();
+    let safe_mode = crate::utils::is_safe_mode();
 
     if safe_mode {
+        // we should still ensure module directory exists in safe mode
+        // because we may need to operate the module dir in safe mode
         warn!("safe mode, skip common post-fs-data.d scripts");
     } else {
         // Then exec common post-fs-data scripts
@@ -50,18 +38,18 @@ pub fn on_post_data_fs() -> Result<()> {
         }
     }
 
+    let module_dir = defs::MODULE_DIR;
+
     assets::ensure_binaries(true).with_context(|| "Failed to extract bin assets")?;
 
     // Start UID scanner daemon with highest priority
-    uid_scanner::start_uid_scanner_daemon()?;
+    crate::uid_scanner::uid_scanner::start_uid_scanner_daemon()?;
 
     if is_safe_mode() {
         warn!("safe mode, skip load feature config");
     } else if let Err(e) = crate::umount_manager::load_and_apply_config() {
         warn!("Failed to load umount config: {e}");
     }
-    // tell kernel that we've mount the module, so that it can do some optimization
-    ksucalls::report_module_mounted();
 
     // if we are in safe mode, we should disable all modules
     if safe_mode {
@@ -72,14 +60,14 @@ pub fn on_post_data_fs() -> Result<()> {
         return Ok(());
     }
 
-    if let Err(e) = prune_modules() {
-        warn!("prune modules failed: {e}");
-    }
-
     if let Err(e) = handle_updated_modules() {
         warn!("handle updated modules failed: {e}");
     }
 
+    if let Err(e) = prune_modules() {
+        warn!("prune modules failed: {e}");
+    }
+
     if let Err(e) = restorecon::restorecon() {
         warn!("restorecon failed: {e}");
     }
@@ -110,23 +98,9 @@ pub fn on_post_data_fs() -> Result<()> {
         warn!("KPM: Failed to load KPM modules: {e}");
     }
 
-    let tmpfs_path = find_tmp_path();
-    // for compatibility
-    let no_mount = Path::new(NO_TMPFS_PATH).exists() || Path::new(NO_MOUNT_PATH).exists();
-
-    // mount temp dir
-    if !no_mount {
-        if let Err(e) = mount(
-            KSU_MOUNT_SOURCE,
-            &tmpfs_path,
-            "tmpfs",
-            MountFlags::empty(),
-            "",
-        ) {
-            warn!("do temp dir mount failed: {e}");
-        }
-    } else {
-        info!("no tmpfs requested");
+    // execute metamodule post-fs-data script first (priority)
+    if let Err(e) = metamodule::exec_stage_script("post-fs-data", true) {
+        warn!("exec metamodule post-fs-data script failed: {e}");
     }
 
     // exec modules post-fs-data scripts
@@ -140,18 +114,15 @@ pub fn on_post_data_fs() -> Result<()> {
         warn!("load system.prop failed: {e}");
     }
 
-    // mount module systemlessly by magic mount
-    #[cfg(target_os = "android")]
-    if !no_mount {
-        if let Err(e) = crate::magic_mount::magic_mount(&tmpfs_path) {
-            warn!("do systemless mount failed: {e}");
-        }
-    } else {
-        info!("no mount requested");
+    // execute metamodule mount script
+    if let Err(e) = metamodule::exec_mount_script(module_dir) {
+        warn!("execute metamodule mount failed: {e}");
     }
 
     run_stage("post-mount", true);
 
+    std::env::set_current_dir("/").with_context(|| "failed to chdir to /")?;
+
     Ok(())
 }
 
@@ -171,6 +142,13 @@ fn run_stage(stage: &str, block: bool) {
     if let Err(e) = crate::module::exec_common_scripts(&format!("{stage}.d"), block) {
         warn!("Failed to exec common {stage} scripts: {e}");
     }
+
+    // execute metamodule stage script first (priority)
+    if let Err(e) = metamodule::exec_stage_script(stage, block) {
+        warn!("Failed to exec metamodule {stage} script: {e}");
+    }
+
+    // execute regular modules stage scripts
     if let Err(e) = crate::module::exec_stage_script(stage, block) {
         warn!("Failed to exec {stage} scripts: {e}");
     }