Move MagiskInit to rust

native/src/init/init.cpp

@@ -60,7 +60,7 @@ void restore_ramdisk_init() {
     }
 }
 
-MagiskInit::MagiskInit(char **argv) : argv(argv), config{} {
+void MagiskInit::init() noexcept {
     // Get kernel data using procfs and sysfs
     if (access("/proc/cmdline", F_OK) != 0) {
         xmkdir("/proc", 0755);
@@ -86,7 +86,7 @@ static void recovery() {
     rm_rf("/.backup");
 }
 
-void MagiskInit::legacy_system_as_root() {
+void MagiskInit::legacy_system_as_root() noexcept {
     LOGI("Legacy SAR Init\n");
     prepare_data();
     bool is_two_stage = mount_system_root();
@@ -96,7 +96,7 @@ void MagiskInit::legacy_system_as_root() {
         patch_ro_root();
 }
 
-void MagiskInit::rootfs() {
+void MagiskInit::rootfs() noexcept {
     LOGI("RootFS Init\n");
     prepare_data();
     LOGD("Restoring /init\n");
@@ -104,7 +104,7 @@ void MagiskInit::rootfs() {
     patch_rw_root();
 }
 
-void MagiskInit::start() {
+void MagiskInit::start() noexcept {
     if (argv[1] != nullptr && argv[1] == "selinux_setup"sv)
         second_stage();
     else if (config.skip_initramfs)
@@ -132,6 +132,5 @@ int main(int argc, char *argv[]) {
     if (getpid() != 1)
         return 1;
 
-    MagiskInit init(argv);
+    rust::start_magisk_init(argv);
-    init.start();
 }

native/src/init/init.hpp

@@ -12,40 +12,3 @@ bool unxz(out_stream &strm, rust::Slice<const uint8_t> bytes);
 bool check_two_stage();
 const char *backup_init();
 void restore_ramdisk_init();
-
-class MagiskInit {
-private:
-    std::string preinit_dev;
-    std::vector<std::string> mount_list;
-    char **argv;
-    BootConfig config;
-
-    // Setup mounts and environment
-    void setup_tmp(const char *path);
-    void collect_devices();
-    void mount_preinit_dir();
-    void prepare_data();
-    dev_t find_block(const char *partname);
-    bool mount_system_root();
-
-    // Setup and patch root directory
-    void parse_config_file();
-    void patch_rw_root();
-    void patch_ro_root();
-
-    // Two stage init
-    void redirect_second_stage();
-    void first_stage();
-    void second_stage();
-
-    // SELinux
-    void patch_sepolicy(const char *in, const char *out);
-    bool hijack_sepolicy();
-
-    [[noreturn]] void exec_init();
-    void legacy_system_as_root();
-    void rootfs();
-public:
-    explicit MagiskInit(char *argv[]);
-    void start();
-};

native/src/init/lib.rs

@@ -7,6 +7,7 @@ use mount::{is_device_mounted, switch_root};
 use rootdir::{collect_overlay_contexts, inject_magisk_rc, reset_overlay_contexts};
 // Has to be pub so all symbols in that crate is included
 pub use magiskpolicy;
+use crate::ffi::{BootConfig, MagiskInit};
 
 mod logging;
 mod mount;
@@ -31,6 +32,13 @@ pub mod ffi {
         partition_map: Vec<KeyValue>,
     }
 
+    struct MagiskInit {
+        preinit_dev: String,
+        mount_list: Vec<String>,
+        argv: *mut *mut c_char,
+        config: BootConfig,
+    }
+
     #[namespace = "rust"]
     extern "Rust" {
         fn setup_klog();
@@ -39,6 +47,7 @@ pub mod ffi {
         fn is_device_mounted(dev: u64, target: Pin<&mut CxxString>) -> bool;
         fn collect_overlay_contexts(src: Utf8CStrRef);
         fn reset_overlay_contexts();
+        unsafe fn start_magisk_init(argv: *mut *mut c_char);
     }
 
     unsafe extern "C++" {
@@ -51,5 +60,53 @@ pub mod ffi {
         fn print(self: &BootConfig);
         type kv_pairs;
         fn set(self: &mut BootConfig, config: &kv_pairs);
+
+        unsafe fn setup_tmp(self: &MagiskInit, path: *const c_char);
+        fn collect_devices(self: &MagiskInit);
+        fn mount_preinit_dir(self: &MagiskInit);
+        fn prepare_data(self: &MagiskInit);
+        unsafe fn find_block(self: &MagiskInit, partname: *const c_char) -> u64;
+        fn mount_system_root(self: &mut MagiskInit) -> bool;
+
+        // Setup and patch root directory
+        fn parse_config_file(self: &mut MagiskInit);
+        fn patch_rw_root(self: &mut MagiskInit);
+        fn patch_ro_root(self: &mut MagiskInit);
+
+        // Two stage init
+        fn redirect_second_stage(self: &MagiskInit);
+        fn first_stage(self: &MagiskInit);
+        fn second_stage(self: &mut MagiskInit);
+
+        // SELinux
+        unsafe fn patch_sepolicy(self: &MagiskInit, in_: *const c_char, out: *const c_char);
+        fn hijack_sepolicy(self: &mut MagiskInit) -> bool;
+        fn exec_init(self: &MagiskInit);
+        fn legacy_system_as_root(self: &mut MagiskInit);
+        fn rootfs(self: &mut MagiskInit);
+        fn start(self: &mut MagiskInit);
+        fn init(self: &mut MagiskInit);
     }
 }
+
+pub(crate) fn start_magisk_init(argv: *mut *mut std::ffi::c_char) {
+    let mut init = MagiskInit {
+        preinit_dev: String::new(),
+        mount_list: Vec::new(),
+        argv,
+        config: BootConfig {
+            skip_initramfs: false,
+            force_normal_boot: false,
+            rootwait: false,
+            emulator: false,
+            slot: [0; 3],
+            dt_dir: [0; 64],
+            fstab_suffix: [0; 32],
+            hardware: [0; 32],
+            hardware_plat: [0; 32],
+            partition_map: Vec::new(),
+        },
+    };
+    init.init();
+    init.start();
+}

native/src/init/mount.cpp

@@ -45,7 +45,7 @@ static void parse_device(devinfo *dev, const char *uevent) {
     });
 }
 
-void MagiskInit::collect_devices() {
+void MagiskInit::collect_devices() const noexcept {
     char path[PATH_MAX];
     devinfo dev{};
     if (auto dir = xopen_dir("/sys/dev/block"); dir) {
@@ -72,7 +72,7 @@ void MagiskInit::collect_devices() {
     }
 }
 
-dev_t MagiskInit::find_block(const char *partname) {
+uint64_t MagiskInit::find_block(const char *partname) const noexcept {
     if (dev_list.empty())
         collect_devices();
 
@@ -103,7 +103,7 @@ dev_t MagiskInit::find_block(const char *partname) {
     return 0;
 }
 
-void MagiskInit::mount_preinit_dir() {
+void MagiskInit::mount_preinit_dir() const noexcept {
     if (preinit_dev.empty()) return;
     auto dev = find_block(preinit_dev.data());
     if (dev == 0) {
@@ -143,7 +143,7 @@ void MagiskInit::mount_preinit_dir() {
     }
 }
 
-bool MagiskInit::mount_system_root() {
+bool MagiskInit::mount_system_root() noexcept {
     LOGD("Mounting system_root\n");
 
     // there's no /dev in stub cpio
@@ -210,9 +210,10 @@ mount_root:
     return is_two_stage;
 }
 
-void MagiskInit::exec_init() {
+void MagiskInit::exec_init() const noexcept {
     // Unmount in reverse order
-    for (auto &p : reversed(mount_list)) {
+    for (auto i = mount_list.size(); i > 0; --i) {
+        auto &p = mount_list[i - 1];
         if (xumount2(p.data(), MNT_DETACH) == 0)
             LOGD("Unmount [%s]\n", p.data());
     }
@@ -220,7 +221,7 @@ void MagiskInit::exec_init() {
     exit(1);
 }
 
-void MagiskInit::prepare_data() {
+void MagiskInit::prepare_data() const noexcept {
     LOGD("Setup data tmp\n");
     xmkdir("/data", 0755);
     xmount("magisk", "/data", "tmpfs", 0, "mode=755");
@@ -230,7 +231,7 @@ void MagiskInit::prepare_data() {
     cp_afc("/overlay.d", "/data/overlay.d");
 }
 
-void MagiskInit::setup_tmp(const char *path) {
+void MagiskInit::setup_tmp(const char *path) const noexcept {
     LOGD("Setup Magisk tmp at %s\n", path);
     chdir("/data");
 

native/src/init/rootdir.cpp

@@ -257,17 +257,17 @@ static void extract_files(bool sbin) {
     }
 }
 
-void MagiskInit::parse_config_file() {
+void MagiskInit::parse_config_file() noexcept {
     parse_prop_file("/data/.backup/.magisk", [&](auto key, auto value) -> bool {
         if (key == "PREINITDEVICE") {
-            preinit_dev = value;
+            preinit_dev = std::string(value);
             return false;
         }
         return true;
     });
 }
 
-void MagiskInit::patch_ro_root() {
+void MagiskInit::patch_ro_root() noexcept {
     mount_list.emplace_back("/data");
     parse_config_file();
 
@@ -356,7 +356,7 @@ void MagiskInit::patch_ro_root() {
 #define PRE_TMPSRC "/magisk"
 #define PRE_TMPDIR PRE_TMPSRC "/tmp"
 
-void MagiskInit::patch_rw_root() {
+void MagiskInit::patch_rw_root() noexcept {
     mount_list.emplace_back("/data");
     parse_config_file();
 

native/src/init/selinux.cpp

@@ -7,7 +7,7 @@
 
 using namespace std;
 
-void MagiskInit::patch_sepolicy(const char *in, const char *out) {
+void MagiskInit::patch_sepolicy(const char *in, const char *out) const noexcept {
     LOGD("Patching monolithic policy\n");
     auto sepol = SePolicy::from_file(in);
 
@@ -34,7 +34,7 @@ void MagiskInit::patch_sepolicy(const char *in, const char *out) {
 #define MOCK_LOAD      SELINUXMOCK "/load"
 #define MOCK_ENFORCE   SELINUXMOCK "/enforce"
 
-bool MagiskInit::hijack_sepolicy() {
+bool MagiskInit::hijack_sepolicy() noexcept {
     xmkdir(SELINUXMOCK, 0);
 
     if (access("/system/bin/init", F_OK) == 0) {
@@ -76,10 +76,12 @@ bool MagiskInit::hijack_sepolicy() {
 
         LOGD("Hijack [%s]\n", buf);
 
+        decltype(mount_list) new_mount_list;
         // Preserve sysfs and procfs for hijacking
-        mount_list.erase(std::remove_if(
+        for (const auto &s: mount_list)
-                mount_list.begin(), mount_list.end(),
+            if (s != "/proc" && s != "/sys")
-                [](const string &s) { return s == "/proc" || s == "/sys"; }), mount_list.end());
+                new_mount_list.emplace_back(s);
+        new_mount_list.swap(mount_list);
 
         mkfifo(MOCK_COMPAT, 0444);
         xmount(MOCK_COMPAT, buf, nullptr, MS_BIND, nullptr);

native/src/init/twostage.cpp

@@ -8,7 +8,7 @@
 
 using namespace std;
 
-void MagiskInit::first_stage() {
+void MagiskInit::first_stage() const noexcept {
     LOGI("First Stage Init\n");
     prepare_data();
 
@@ -45,7 +45,7 @@ void MagiskInit::first_stage() {
     }
 }
 
-void MagiskInit::redirect_second_stage() {
+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);
@@ -62,7 +62,7 @@ void MagiskInit::redirect_second_stage() {
     xmount("/data/init", "/init", nullptr, MS_BIND, nullptr);
 }
 
-void MagiskInit::second_stage() {
+void MagiskInit::second_stage() noexcept {
     LOGI("Second Stage Init\n");
     umount2("/init", MNT_DETACH);
     umount2(INIT_PATH, MNT_DETACH); // just in case