Never allow multiple root implementation

zygiskd/src/root_impl/magisk.rs

@@ -4,12 +4,12 @@ use crate::constants::MIN_MAGISK_VERSION;
 
 pub fn is_magisk() -> Result<bool> {
     let version: Option<i32> = Command::new("magisk")
-        .arg("--version")
+        .arg("-V")
         .stdout(Stdio::piped())
         .spawn().ok()
         .and_then(|child| child.wait_with_output().ok())
         .and_then(|output| String::from_utf8(output.stdout).ok())
-        .and_then(|output| output.parse().ok());
+        .and_then(|output| output.trim().parse().ok());
     if let Some(version) = version {
         if version < MIN_MAGISK_VERSION {
             bail!("Magisk version too old: {}", version);

zygiskd/src/root_impl/mod.rs

@@ -13,6 +13,9 @@ static ROOT_IMPL: OnceCell<RootImpl> = OnceCell::new();
 
 pub fn setup() -> Result<()> {
     if kernelsu::is_kernel_su()? {
+        if let Ok(true) = magisk::is_magisk() {
+            bail!("Multiple root implementation");
+        }
         let _ = ROOT_IMPL.set(RootImpl::KernelSU);
     } else if magisk::is_magisk()? {
         let _ = ROOT_IMPL.set(RootImpl::Magisk);