ksud: make tmpfs and magic mount optional

- Create /data/adb/ksu/{.notmpfs,.nomount} to disable them.

userspace/ksud/src/defs.rs

@@ -41,3 +41,6 @@ pub const VERSION_NAME: &str = include_str!(concat!(env!("OUT_DIR"), "/VERSION_N
 pub const KSU_BACKUP_DIR: &str = WORKING_DIR;
 pub const KSU_BACKUP_FILE_PREFIX: &str = "ksu_backup_";
 pub const BACKUP_FILENAME: &str = "stock_image.sha1";
+
+pub const NO_TMPFS_PATH: &str = concatcp!(WORKING_DIR, ".notmpfs");
+pub const NO_MOUNT_PATH: &str = concatcp!(WORKING_DIR, ".nomount");

userspace/ksud/src/init_event.rs

@@ -1,4 +1,4 @@
-use crate::defs::{KSU_MOUNT_SOURCE, TEMP_DIR};
+use crate::defs::{KSU_MOUNT_SOURCE, NO_MOUNT_PATH, NO_TMPFS_PATH, TEMP_DIR};
 use crate::module::{handle_updated_modules, prune_modules};
 use crate::{assets, defs, ksucalls, restorecon, utils};
 use anyhow::{Context, Result};
@@ -68,8 +68,12 @@ pub fn on_post_data_fs() -> Result<()> {
     }
 
     // mount temp dir
-    if let Err(e) = mount(KSU_MOUNT_SOURCE, TEMP_DIR, "tmpfs", MountFlags::empty(), "") {
-        warn!("do temp dir mount failed: {}", e);
+    if !Path::new(NO_TMPFS_PATH).exists() {
+        if let Err(e) = mount(KSU_MOUNT_SOURCE, TEMP_DIR, "tmpfs", MountFlags::empty(), "") {
+            warn!("do temp dir mount failed: {}", e);
+        }
+    } else {
+        info!("no tmpfs requested");
     }
 
     // exec modules post-fs-data scripts
@@ -84,8 +88,12 @@ pub fn on_post_data_fs() -> Result<()> {
     }
 
     // mount module systemlessly by magic mount
-    if let Err(e) = mount_modules_systemlessly() {
-        warn!("do systemless mount failed: {}", e);
+    if !Path::new(NO_MOUNT_PATH).exists() {
+        if let Err(e) = mount_modules_systemlessly() {
+            warn!("do systemless mount failed: {}", e);
+        }
+    } else {
+        info!("no mount requested");
     }
 
     run_stage("post-mount", true);