temp_mount

apd/Cargo.toml

@@ -34,9 +34,12 @@ rust-embed = { version = "8.0.0", features = [
 which = "5"
 getopts = "0.2"
 sha256 = "1"
+tempdir = "0.3"
+chrono = "0.4"
 
 [target.'cfg(any(target_os = "android", target_os = "linux"))'.dependencies]
 sys-mount = { git = "https://github.com/tiann/sys-mount", branch = "loopfix" }
+rustix = { git = "https://github.com/Kernel-SU/rustix.git", branch = "main", features = ["all-apis"] }
 # some android specific dependencies which compiles under unix are also listed here for convenience of coding
 android-properties = { version = "0.2.2", features = ["bionic-deprecated"] }
 procfs = "0.16"

apd/src/defs.rs

@@ -22,6 +22,9 @@ pub const MODULE_UPDATE_TMP_IMG: &str = concatcp!(WORKING_DIR, "update_tmp.img")
 // warning: this directory should not change, or you need to change the code in module_installer.sh!!!
 pub const MODULE_UPDATE_TMP_DIR: &str = concatcp!(ADB_DIR, "modules_update/");
 
+pub const TEMP_DIR: &str = "/debug_ramdisk";
+pub const TEMP_DIR_LEGACY: &str = "/sbin";
+
 pub const DISABLE_FILE_NAME: &str = "disable";
 pub const UPDATE_FILE_NAME: &str = "update";
 pub const REMOVE_FILE_NAME: &str = "remove";

apd/src/event.rs

@@ -192,6 +192,10 @@ pub fn on_post_data_fs() -> Result<()> {
     if crate::module::load_sepolicy_rule().is_err() {
         warn!("load sepolicy.rule failed");
     }
+
+    if let Err(e) = mount::mount_tmpfs(utils::get_tmp_path()) {
+        warn!("do temp dir mount failed: {}", e);
+    }
 
     // exec modules post-fs-data scripts
     // TODO: Add timeout

apd/src/mount.rs

@@ -6,6 +6,8 @@ use anyhow::Context;
 use retry::delay::NoDelay;
 #[cfg(any(target_os = "linux", target_os = "android"))]
 use sys_mount::{unmount, FilesystemType, Mount, MountFlags, Unmount, UnmountFlags};
+#[cfg(any(target_os = "linux", target_os = "android"))]
+use rustix::{fd::AsFd, fs::CWD, mount::*};
 
 use crate::defs::AP_OVERLAY_SOURCE;
 use log::{info, warn};
@@ -161,6 +163,34 @@ fn mount_overlayfs(
     Ok(())
 }
 
+#[cfg(any(target_os = "linux", target_os = "android"))]
+pub fn mount_tmpfs(dest: impl AsRef<Path>) -> Result<()> {
+    info!("mount tmpfs on {}", dest.as_ref().display());
+    if let Result::Ok(fs) = fsopen("tmpfs", FsOpenFlags::FSOPEN_CLOEXEC) {
+        let fs = fs.as_fd();
+        fsconfig_set_string(fs, "source", AP_OVERLAY_SOURCE)?;
+        fsconfig_create(fs)?;
+        let mount = fsmount(fs, FsMountFlags::FSMOUNT_CLOEXEC, MountAttrFlags::empty())?;
+        move_mount(
+            mount.as_fd(),
+            "",
+            CWD,
+            dest.as_ref(),
+            MoveMountFlags::MOVE_MOUNT_F_EMPTY_PATH,
+        )?;
+    } else {
+        mount(
+            AP_OVERLAY_SOURCE,
+            dest.as_ref(),
+            "tmpfs",
+            rustix::fs::MountFlags::empty(),
+            "",
+        )?;
+    }
+    Ok(())
+}
+
+
 #[cfg(any(target_os = "linux", target_os = "android"))]
 fn bind_mount(from: impl AsRef<Path>, to: impl AsRef<Path>) -> Result<()> {
     info!(

apd/src/utils.rs

@@ -11,6 +11,7 @@ use std::fs::{set_permissions, Permissions};
 use std::os::unix::prelude::PermissionsExt;
 
 use crate::defs;
+use std::fs::metadata;
 
 pub fn ensure_clean_dir(dir: &str) -> Result<()> {
     let path = Path::new(dir);
@@ -161,3 +162,12 @@ pub fn umask(_mask: u32) {
 pub fn has_magisk() -> bool {
     which::which("magisk").is_ok()
 }
+pub fn get_tmp_path() -> &'static str {
+    if metadata(defs::TEMP_DIR_LEGACY).is_ok() {
+        return defs::TEMP_DIR_LEGACY;
+    }
+    if metadata(defs::TEMP_DIR).is_ok() {
+        return defs::TEMP_DIR;
+    }
+    ""
+}