From 2820158534e96b0a26890a408a9e27c33be55daa Mon Sep 17 00:00:00 2001
From: AXON <aminurfisa3@gmail.com>
Date: Thu, 21 Jan 2021 01:21:13 +0600
Subject: [PATCH] refactor: bind-mount pre-existing su bins instead of wiping
 them out completely

---
 src/main.rs    | 20 ++++++++++++++++----
 src/utils.rs   | 22 ----------------------
 vendorsetup.sh |  7 +++++++
 3 files changed, 23 insertions(+), 26 deletions(-)
 create mode 100644 vendorsetup.sh

diff --git a/src/main.rs b/src/main.rs
index 4d397f0..c6a8921 100755
--- a/src/main.rs
+++ b/src/main.rs
@@ -5,7 +5,7 @@ use std::{env, fs, os::unix::fs::symlink, path::Path, process::Command};
 use sys_mount::{Mount, MountFlags};
 use utils::{
     chmod, clone_perms, dir_is_empty, early_mode, extract_file, load_modfile, remount_root,
-    switch_init, wipe_old_su, KernelFsMount,
+    switch_init, KernelFsMount,
 };
 
 pub fn job() {
@@ -119,7 +119,6 @@ pub fn job() {
             .mount()
             {
                 Ok(_) => {
-                    wipe_old_su();
                     extract_file("/dev/chmod", include_bytes!("asset/chmod"), 777);
                     for dir in ["/system/bin"].iter() {
                         match Command::new("/dev/chmod").args(&["755", dir]).status() {
@@ -304,8 +303,21 @@ pub fn job() {
         }
     }
 
-    // Wipe old su binaries
-    wipe_old_su();
+    // Own pre-existing su binaries
+    if bin_dir == "/sbin" {
+        for su_bin in ["/system/bin/su", "/system/xbin/su"].iter() {
+            if Path::new(su_bin).exists() {
+                if let Err(why) =
+                    libmount::BindMount::new(format!("{}/{}", bin_dir, "su"), su_bin).mount()
+                {
+                    println!(
+                        "rusty-magisk: Failed to bind mount {} into {}: {}",
+                        bin_dir, su_bin, why
+                    );
+                }
+            }
+        }
+    }
 
     // Ensure /sbin is accessible globally
     if bin_dir == "/sbin" {
diff --git a/src/utils.rs b/src/utils.rs
index 02e626c..749457c 100644
--- a/src/utils.rs
+++ b/src/utils.rs
@@ -124,28 +124,6 @@ pub fn clone_perms(source: &str, target: &str) -> std::io::Result<()> {
     Ok(())
 }
 
-pub fn wipe_old_su() {
-    for su_bin in ["/system/bin/su", "/system/xbin/su"].iter() {
-        if Path::new(su_bin).exists() {
-            if let Err(why) = fs::remove_file(su_bin) {
-                println!(
-                    "rusty-magisk: Failed to remove existing {} binary: {}",
-                    su_bin, why
-                );
-            }
-        }
-
-        /*
-        match symlink("/sbin/su", su_bin) {
-            Ok(_) => {}
-            Err(why) => {
-                println!("rusty-magisk: Failed to symlink for {}: {}", su_bin, why);
-            }
-        }
-        */
-    }
-}
-
 pub fn early_mode() -> bool {
     if env::var("ANDROID_BOOTLOGO").is_err() || !Path::new("/etc").exists() {
         true
diff --git a/vendorsetup.sh b/vendorsetup.sh
new file mode 100644
index 0000000..1e612ad
--- /dev/null
+++ b/vendorsetup.sh
@@ -0,0 +1,7 @@
+### Incomplete
+
+# Define vars
+aosp_root="$(pwd)"
+project_root="${aosp_root}/vendor/rusty-magisk"
+
+# Patch files