Use Rust for formatting

The fprintf implementation included in crt0 is too rudimental

native/src/init/lib.rs

@@ -1,13 +1,26 @@
+#![feature(format_args_nl)]
+
 use logging::setup_klog;
+use rootdir::inject_magisk_rc;
 // Has to be pub so all symbols in that crate is included
 pub use magiskpolicy;
 
 mod logging;
+mod rootdir;
 
 #[cxx::bridge]
 pub mod ffi {
     #[namespace = "rust"]
     extern "Rust" {
         fn setup_klog();
+        fn inject_magisk_rc(fd: i32, tmp_dir: Utf8CStrRef);
+    }
+
+    unsafe extern "C++" {
+        include!("../base/include/base.hpp");
+
+        #[namespace = "rust"]
+        #[cxx_name = "Utf8CStr"]
+        type Utf8CStrRef<'a> = base::ffi::Utf8CStrRef<'a>;
     }
 }