Move MagiskInit::redirect_second_stage to rust

native/src/Android.mk

@@ -66,7 +66,6 @@ LOCAL_SRC_FILES := \
     init/mount.cpp \
     init/rootdir.cpp \
     init/getinfo.cpp \
-    init/twostage.cpp \
     init/selinux.cpp \
     init/init-rs.cpp
 

native/src/init/lib.rs

@@ -84,9 +84,6 @@ pub mod ffi {
         fn patch_rw_root(self: &mut MagiskInit);
         fn patch_ro_root(self: &mut MagiskInit);
 
-        // Two stage init
-        fn redirect_second_stage(self: &MagiskInit);
-
         // SELinux
         unsafe fn patch_sepolicy(self: &MagiskInit, in_: *const c_char, out: *const c_char);
         fn hijack_sepolicy(self: &mut MagiskInit) -> bool;

native/src/init/twostage.cpp

@@ -1,26 +0,0 @@
-#include <sys/mount.h>
-
-#include <consts.hpp>
-#include <base.hpp>
-#include <sys/vfs.h>
-
-#include "init.hpp"
-
-using namespace std;
-
-void MagiskInit::redirect_second_stage() const noexcept {
-    // Patch init binary
-    int src = xopen("/init", O_RDONLY);
-    int dest = xopen("/data/init", O_CREAT | O_WRONLY, 0);
-    {
-        mmap_data init("/init");
-        for (size_t off : init.patch(INIT_PATH, REDIR_PATH)) {
-            LOGD("Patch @ %08zX [" INIT_PATH "] -> [" REDIR_PATH "]\n", off);
-        }
-        write(dest, init.buf(), init.sz());
-        fclone_attr(src, dest);
-        close(dest);
-        close(src);
-    }
-    xmount("/data/init", "/init", nullptr, MS_BIND, nullptr);
-}

native/src/init/twostage.rs

@@ -1,14 +1,15 @@
 use crate::ffi::MagiskInit;
-use base::libc::{mount, MS_BIND};
+use base::libc::{mount, MS_BIND, O_WRONLY};
 use base::{
-    cstr, debug, info,
+    clone_attr, cstr, debug, error, info,
     libc::{
         fstatat, stat, statfs, umount2, AT_SYMLINK_NOFOLLOW, MNT_DETACH, O_CLOEXEC, O_CREAT,
         O_RDONLY, TMPFS_MAGIC,
     },
-    raw_cstr, FsPath, MappedFile, MutBytesExt, ResultExt,
+    raw_cstr, FsPath, LibcReturn, MappedFile, MutBytesExt, ResultExt,
 };
 use std::ffi::c_long;
+use std::io::Write;
 use std::ptr::null;
 
 impl MagiskInit {
@@ -17,7 +18,7 @@ impl MagiskInit {
         self.prepare_data();
 
         if unsafe {
-            let mut st: stat = unsafe { std::mem::zeroed() };
+            let mut st: stat = std::mem::zeroed();
             fstatat(
                 -1,
                 raw_cstr!("/sdcard"),
@@ -104,11 +105,40 @@ impl MagiskInit {
                     debug!("Patch @ {:#010X} [{}] -> [{}]", off, from, to);
                 }
             } else {
-                debug!("Failed to open /init for hexpatch");
+                error!("Failed to open /init for hexpatch");
             }
         }
     }
 
+    pub(crate) fn redirect_second_stage(&self) {
+        let src = FsPath::from(cstr!("/init"));
+        let dest = FsPath::from(cstr!("/data/init"));
+        // Patch init binary
+        if let Ok(mut map) = MappedFile::open(src) {
+            let from = "/system/bin/init";
+            let to = "/data/magiskinit";
+
+            // Redirect original init to magiskinit
+            let v = map.patch(from.as_bytes(), to.as_bytes());
+            for off in &v {
+                debug!("Patch @ {:#010X} [{}] -> [{}]", off, from, to);
+            }
+            if let Ok(mut dest) = dest.create(O_CREAT | O_WRONLY, 0) {
+                dest.write_all(map.as_ref()).log().ok();
+            } else {
+                error!("Failed to create {}", dest);
+            }
+        } else {
+            error!("Failed to open {} for hexpatch", src);
+        }
+        clone_attr(src, dest).log().ok();
+        unsafe {
+            mount(dest.as_ptr(), src.as_ptr(), null(), MS_BIND, null())
+                .as_os_err()
+                .ok();
+        }
+    }
+
     pub(crate) fn second_stage(&mut self) {
         info!("Second Stage Init");
         unsafe {