Revert "Drop some legacy codes (tiann#1981)"

This reverts commit fd09ccf.

userspace/ksud/src/defs.rs

@@ -29,6 +29,8 @@ pub const MODULE_UPDATE_TMP_DIR: &str = concatcp!(ADB_DIR, "modules_update/");
 pub const SYSTEM_RW_DIR: &str = concatcp!(MODULE_DIR, ".rw/");
 
 pub const TEMP_DIR: &str = "/debug_ramdisk";
+pub const TEMP_DIR_LEGACY: &str = "/sbin";
+
 pub const MODULE_WEB_DIR: &str = "webroot";
 pub const DISABLE_FILE_NAME: &str = "disable";
 pub const UPDATE_FILE_NAME: &str = "update";

userspace/ksud/src/init_event.rs

@@ -191,7 +191,7 @@ pub fn on_post_data_fs() -> Result<()> {
     }
 
     // mount temp dir
-    if let Err(e) = mount::mount_tmpfs(defs::TEMP_DIR) {
+    if let Err(e) = mount::mount_tmpfs(utils::get_tmp_path()) {
         warn!("do temp dir mount failed: {}", e);
     }
 

userspace/ksud/src/mount.rs

@@ -63,18 +63,21 @@ pub fn mount_ext4(source: impl AsRef<Path>, target: impl AsRef<Path>) -> Result<
         .attach(source)
         .with_context(|| "Failed to attach loop")?;
     let lo = new_loopback.path().ok_or(anyhow!("no loop"))?;
-    let fs = fsopen("ext4", FsOpenFlags::FSOPEN_CLOEXEC)?;
-    let fs = fs.as_fd();
-    fsconfig_set_string(fs, "source", lo)?;
-    fsconfig_create(fs)?;
-    let mount = fsmount(fs, FsMountFlags::FSMOUNT_CLOEXEC, MountAttrFlags::empty())?;
-    move_mount(
-        mount.as_fd(),
-        "",
-        CWD,
-        target.as_ref(),
-        MoveMountFlags::MOVE_MOUNT_F_EMPTY_PATH,
-    )?;
+    if let Result::Ok(fs) = fsopen("ext4", FsOpenFlags::FSOPEN_CLOEXEC) {
+        let fs = fs.as_fd();
+        fsconfig_set_string(fs, "source", lo)?;
+        fsconfig_create(fs)?;
+        let mount = fsmount(fs, FsMountFlags::FSMOUNT_CLOEXEC, MountAttrFlags::empty())?;
+        move_mount(
+            mount.as_fd(),
+            "",
+            CWD,
+            target.as_ref(),
+            MoveMountFlags::MOVE_MOUNT_F_EMPTY_PATH,
+        )?;
+    } else {
+        mount(lo, target.as_ref(), "ext4", MountFlags::empty(), "")?;
+    }
     Ok(())
 }
 
@@ -154,18 +157,27 @@ pub fn mount_overlayfs(
 #[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());
-    let fs = fsopen("tmpfs", FsOpenFlags::FSOPEN_CLOEXEC)?;
-    let fs = fs.as_fd();
-    fsconfig_set_string(fs, "source", KSU_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,
-    )?;
+    if let Result::Ok(fs) = fsopen("tmpfs", FsOpenFlags::FSOPEN_CLOEXEC) {
+        let fs = fs.as_fd();
+        fsconfig_set_string(fs, "source", KSU_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(
+            KSU_OVERLAY_SOURCE,
+            dest.as_ref(),
+            "tmpfs",
+            MountFlags::empty(),
+            "",
+        )?;
+    }
     Ok(())
 }
 
@@ -176,20 +188,29 @@ pub fn bind_mount(from: impl AsRef<Path>, to: impl AsRef<Path>) -> Result<()> {
         from.as_ref().display(),
         to.as_ref().display()
     );
-    let tree = open_tree(
+    if let Result::Ok(tree) = open_tree(
         CWD,
         from.as_ref(),
         OpenTreeFlags::OPEN_TREE_CLOEXEC
             | OpenTreeFlags::OPEN_TREE_CLONE
             | OpenTreeFlags::AT_RECURSIVE,
-    )?;
-    move_mount(
-        tree.as_fd(),
-        "",
-        CWD,
-        to.as_ref(),
-        MoveMountFlags::MOVE_MOUNT_F_EMPTY_PATH,
-    )?;
+    ) {
+        move_mount(
+            tree.as_fd(),
+            "",
+            CWD,
+            to.as_ref(),
+            MoveMountFlags::MOVE_MOUNT_F_EMPTY_PATH,
+        )?;
+    } else {
+        mount(
+            from.as_ref(),
+            to.as_ref(),
+            "",
+            MountFlags::BIND | MountFlags::REC,
+            "",
+        )?;
+    }
     Ok(())
 }
 

userspace/ksud/src/utils.rs

@@ -1,15 +1,17 @@
 use anyhow::{bail, Context, Error, Ok, Result};
 use std::{
-    fs::{create_dir_all, remove_file, write, File, OpenOptions},
+    fs::{self, create_dir_all, remove_file, write, File, OpenOptions},
     io::{
         ErrorKind::{AlreadyExists, NotFound},
         Write,
     },
     path::Path,
     process::Command,
+    sync::OnceLock,
 };
 
 use crate::{assets, boot_patch, defs, ksucalls, module, restorecon};
+use std::fs::metadata;
 #[allow(unused_imports)]
 use std::fs::{set_permissions, Permissions};
 #[cfg(unix)]
@@ -187,6 +189,68 @@ pub fn has_magisk() -> bool {
     which::which("magisk").is_ok()
 }
 
+fn is_ok_empty(dir: &str) -> bool {
+    use std::result::Result::Ok;
+
+    match fs::read_dir(dir) {
+        Ok(mut entries) => entries.next().is_none(),
+        Err(_) => false,
+    }
+}
+
+fn find_temp_path() -> String {
+    use std::result::Result::Ok;
+
+    if is_ok_empty(defs::TEMP_DIR) {
+        return defs::TEMP_DIR.to_string();
+    }
+
+    // Try to create a random directory in /dev/
+    let r = tempfile::tempdir_in("/dev/");
+    match r {
+        Ok(tmp_dir) => {
+            if let Some(path) = tmp_dir.into_path().to_str() {
+                return path.to_string();
+            }
+        }
+        Err(_e) => {}
+    }
+
+    let dirs = [
+        defs::TEMP_DIR,
+        "/patch_hw",
+        "/oem",
+        "/root",
+        defs::TEMP_DIR_LEGACY,
+    ];
+
+    // find empty directory
+    for dir in dirs {
+        if is_ok_empty(dir) {
+            return dir.to_string();
+        }
+    }
+
+    // Fallback to non-empty directory
+    for dir in dirs {
+        if metadata(dir).is_ok() {
+            return dir.to_string();
+        }
+    }
+
+    "".to_string()
+}
+
+pub fn get_tmp_path() -> &'static str {
+    static CHOSEN_TMP_PATH: OnceLock<String> = OnceLock::new();
+
+    CHOSEN_TMP_PATH.get_or_init(|| {
+        let r = find_temp_path();
+        log::info!("Chosen temp_path: {}", r);
+        r
+    })
+}
+
 #[cfg(target_os = "android")]
 fn link_ksud_to_bin() -> Result<()> {
     let ksu_bin = PathBuf::from(defs::DAEMON_PATH);