Stop using polymorphism in magiskinit

native/src/init/getinfo.cpp

@@ -11,8 +11,6 @@
 
 using namespace std;
 
-vector<string> mount_list;
-
 template<char... cs> using chars = integer_sequence<char, cs...>;
 
 // If quoted, parsing ends when we find char in [breaks]
@@ -180,22 +178,7 @@ if (access(file_name, R_OK) == 0) {                                 \
     }                                                               \
 }
 
-BootConfig::BootConfig() {
-    // Get kernel data using procfs and sysfs
-    if (access("/proc/cmdline", F_OK) != 0) {
-        xmkdir("/proc", 0755);
-        xmount("proc", "/proc", "proc", 0, nullptr);
-        mount_list.emplace_back("/proc");
-    }
-    if (access("/sys/block", F_OK) != 0) {
-        xmkdir("/sys", 0755);
-        xmount("sysfs", "/sys", "sysfs", 0, nullptr);
-        mount_list.emplace_back("/sys");
-    }
-
-    // Log to kernel
-    rust::setup_klog();
-
+void BootConfig::init() {
     set(parse_cmdline(full_read("/proc/cmdline")));
     set(parse_bootconfig(full_read("/proc/bootconfig")));
 
@@ -234,7 +217,7 @@ bool check_two_stage() {
     return init.contains("selinux_setup");
 }
 
-void unxz_init(const char *init_xz, const char *init) {
+static void unxz_init(const char *init_xz, const char *init) {
     LOGD("unxz %s -> %s\n", init_xz, init);
     int fd = xopen(init, O_WRONLY | O_CREAT, 0777);
     fd_stream ch(fd);

native/src/init/init.cpp

@@ -60,16 +60,67 @@ void restore_ramdisk_init() {
     }
 }
 
-class RecoveryInit : public BaseInit {
-public:
-    using BaseInit::BaseInit;
-    void start() override {
-        LOGD("Ramdisk is recovery, abort\n");
-        restore_ramdisk_init();
-        rm_rf("/.backup");
-        exec_init();
+MagiskInit::MagiskInit(char **argv) : argv(argv), config{} {
+    // Get kernel data using procfs and sysfs
+    if (access("/proc/cmdline", F_OK) != 0) {
+        xmkdir("/proc", 0755);
+        xmount("proc", "/proc", "proc", 0, nullptr);
+        mount_list.emplace_back("/proc");
     }
-};
+    if (access("/sys/block", F_OK) != 0) {
+        xmkdir("/sys", 0755);
+        xmount("sysfs", "/sys", "sysfs", 0, nullptr);
+        mount_list.emplace_back("/sys");
+    }
+
+    // Log to kernel
+    rust::setup_klog();
+
+    // Load kernel configs
+    config.init();
+}
+
+static void recovery() {
+    LOGI("Ramdisk is recovery, abort\n");
+    restore_ramdisk_init();
+    rm_rf("/.backup");
+}
+
+void MagiskInit::legacy_system_as_root() {
+    LOGI("Legacy SAR Init\n");
+    prepare_data();
+    bool is_two_stage = mount_system_root();
+    if (is_two_stage)
+        redirect_second_stage();
+    else
+        patch_ro_root();
+}
+
+void MagiskInit::rootfs() {
+    LOGI("RootFS Init\n");
+    prepare_data();
+    LOGD("Restoring /init\n");
+    rename(backup_init(), "/init");
+    patch_rw_root();
+}
+
+void MagiskInit::start() {
+    if (argv[1] != nullptr && argv[1] == "selinux_setup"sv)
+        second_stage();
+    else if (config.skip_initramfs)
+        legacy_system_as_root();
+    else if (config.force_normal_boot)
+        first_stage();
+    else if (access("/sbin/recovery", F_OK) == 0 || access("/system/bin/recovery", F_OK) == 0)
+        recovery();
+    else if (check_two_stage())
+        first_stage();
+    else
+        rootfs();
+
+    // Finally execute the original init
+    exec_init();
+}
 
 int main(int argc, char *argv[]) {
     umask(0);
@@ -81,23 +132,6 @@ int main(int argc, char *argv[]) {
     if (getpid() != 1)
         return 1;
 
-    BaseInit *init;
-    BootConfig config;
-
-    if (argc > 1 && argv[1] == "selinux_setup"sv)
-        init = new SecondStageInit(argv, &config);
-    else if (config.skip_initramfs)
-        init = new LegacySARInit(argv, &config);
-    else if (config.force_normal_boot)
-        init = new FirstStageInit(argv, &config);
-    else if (access("/sbin/recovery", F_OK) == 0 || access("/system/bin/recovery", F_OK) == 0)
-        init = new RecoveryInit(argv, &config);
-    else if (check_two_stage())
-        init = new FirstStageInit(argv, &config);
-    else
-        init = new RootFSInit(argv, &config);
-
-    // Run the main routine
-    init->start();
-    exit(1);
+    MagiskInit init(argv);
+    init.start();
 }

native/src/init/init.hpp

@@ -6,18 +6,18 @@
 using kv_pairs = std::vector<std::pair<std::string, std::string>>;
 
 struct BootConfig {
-    bool skip_initramfs = false;
-    bool force_normal_boot = false;
-    bool rootwait = false;
-    bool emulator = false;
-    char slot[3]{};
-    char dt_dir[64]{};
-    char fstab_suffix[32]{};
-    char hardware[32]{};
-    char hardware_plat[32]{};
+    bool skip_initramfs;
+    bool force_normal_boot;
+    bool rootwait;
+    bool emulator;
+    char slot[3];
+    char dt_dir[64];
+    char fstab_suffix[32];
+    char hardware[32];
+    char hardware_plat[32];
     kv_pairs partition_map;
 
-    BootConfig();
+    void init();
 private:
     void set(const kv_pairs &);
     void print();
@@ -27,121 +27,45 @@ private:
 #define INIT_PATH  "/system/bin/init"
 #define REDIR_PATH "/data/magiskinit"
 
-extern std::vector<std::string> mount_list;
-
 int magisk_proxy_main(int argc, char *argv[]);
 bool unxz(out_stream &strm, rust::Slice<const uint8_t> bytes);
 bool check_two_stage();
 const char *backup_init();
 void restore_ramdisk_init();
 
-/***************
- * Base classes
- ***************/
-
-class BaseInit {
-protected:
-    BootConfig *config;
-    char **argv;
-
-    [[noreturn]] void exec_init();
-    void prepare_data();
-    dev_t find_block(const char *partname);
-    void collect_devices();
-public:
-    BaseInit(char *argv[], BootConfig *config) : config(config), argv(argv) {}
-    virtual ~BaseInit() = default;
-    virtual void start() = 0;
-};
-
-class MagiskInit : public BaseInit {
+class MagiskInit {
 private:
     std::string preinit_dev;
+    std::vector<std::string> mount_list;
+    char **argv;
+    BootConfig config;
 
-    void parse_config_file();
-    void patch_sepolicy(const char *in, const char *out);
-    bool hijack_sepolicy();
+    // Setup mounts and environment
     void setup_tmp(const char *path);
+    void collect_devices();
     void mount_preinit_dir();
-protected:
+    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:
-    using BaseInit::BaseInit;
-};
-
-/***************
- * 2 Stage Init
- ***************/
-
-class FirstStageInit : public BaseInit {
-private:
-    void prepare();
-public:
-    FirstStageInit(char *argv[], BootConfig *config) : BaseInit(argv, config) {
-        LOGD("%s\n", __FUNCTION__);
-    };
-    void start() override {
-        prepare();
-        exec_init();
-    }
-};
-
-class SecondStageInit : public MagiskInit {
-private:
-    bool prepare();
-public:
-    SecondStageInit(char *argv[], BootConfig *config) : MagiskInit(argv, config) {
-        LOGD("%s\n", __FUNCTION__);
-    };
-
-    void start() override {
-        bool is_rootfs = prepare();
-        if (is_rootfs)
-            patch_rw_root();
-        else
-            patch_ro_root();
-        exec_init();
-    }
-};
-
-/*************
- * Legacy SAR
- *************/
-
-class LegacySARInit : public MagiskInit {
-private:
-    bool mount_system_root();
-    void first_stage_prep();
-public:
-    LegacySARInit(char *argv[], BootConfig *config) : MagiskInit(argv, config) {
-        LOGD("%s\n", __FUNCTION__);
-    };
-    void start() override {
-        prepare_data();
-        bool is_two_stage = mount_system_root();
-        if (is_two_stage)
-            first_stage_prep();
-        else
-            patch_ro_root();
-        exec_init();
-    }
-};
-
-/************
- * Initramfs
- ************/
-
-class RootFSInit : public MagiskInit {
-private:
-    void prepare();
-public:
-    RootFSInit(char *argv[], BootConfig *config) : MagiskInit(argv, config) {
-        LOGD("%s\n", __FUNCTION__);
-    }
-    void start() override {
-        prepare();
-        patch_rw_root();
-        exec_init();
-    }
+    explicit MagiskInit(char *argv[]);
+    void start();
 };

native/src/init/mount.cpp

@@ -45,7 +45,7 @@ static void parse_device(devinfo *dev, const char *uevent) {
     });
 }
 
-void BaseInit::collect_devices() {
+void MagiskInit::collect_devices() {
     char path[PATH_MAX];
     devinfo dev{};
     if (auto dir = xopen_dir("/sys/dev/block"); dir) {
@@ -59,9 +59,9 @@ void BaseInit::collect_devices() {
                 auto name = rtrim(full_read(path));
                 strscpy(dev.dmname, name.data(), sizeof(dev.dmname));
             }
-            if (auto it = std::ranges::find_if(config->partition_map, [&](const auto &i) {
+            if (auto it = std::ranges::find_if(config.partition_map, [&](const auto &i) {
                 return i.first == dev.devname;
-            }); dev.partname[0] == '\0' && it != config->partition_map.end()) {
+            }); dev.partname[0] == '\0' && it != config.partition_map.end()) {
                 // use androidboot.partition_map as partname fallback.
                 strscpy(dev.partname, it->second.data(), sizeof(dev.partname));
             }
@@ -72,7 +72,7 @@ void BaseInit::collect_devices() {
     }
 }
 
-dev_t BaseInit::find_block(const char *partname) {
+dev_t MagiskInit::find_block(const char *partname) {
     if (dev_list.empty())
         collect_devices();
 
@@ -143,7 +143,7 @@ void MagiskInit::mount_preinit_dir() {
     }
 }
 
-bool LegacySARInit::mount_system_root() {
+bool MagiskInit::mount_system_root() {
     LOGD("Mounting system_root\n");
 
     // there's no /dev in stub cpio
@@ -163,13 +163,13 @@ bool LegacySARInit::mount_system_root() {
 
         // Try normal partname
         char sys_part[32];
-        sprintf(sys_part, "system%s", config->slot);
+        sprintf(sys_part, "system%s", config.slot);
         dev = find_block(sys_part);
         if (dev > 0)
             goto mount_root;
 
         // Poll forever if rootwait was given in cmdline
-    } while (config->rootwait);
+    } while (config.rootwait);
 
     // We don't really know what to do at this point...
     LOGE("Cannot find root partition, abort\n");
@@ -198,7 +198,7 @@ mount_root:
 
     // For API 28 AVD, it uses legacy SAR setup that requires
     // special hacks in magiskinit to work properly.
-    if (!is_two_stage && config->emulator) {
+    if (!is_two_stage && config.emulator) {
         avd_hack = true;
         // These values are hardcoded for API 28 AVD
         auto vendor_dev = find_block("vendor");
@@ -210,7 +210,7 @@ mount_root:
     return is_two_stage;
 }
 
-void BaseInit::exec_init() {
+void MagiskInit::exec_init() {
     // Unmount in reverse order
     for (auto &p : reversed(mount_list)) {
         if (xumount2(p.data(), MNT_DETACH) == 0)
@@ -220,12 +220,12 @@ void BaseInit::exec_init() {
     exit(1);
 }
 
-void BaseInit::prepare_data() {
+void MagiskInit::prepare_data() {
     LOGD("Setup data tmp\n");
     xmkdir("/data", 0755);
     xmount("magisk", "/data", "tmpfs", 0, "mode=755");
 
-    cp_afc("/init", "/data/magiskinit");
+    cp_afc("/init", REDIR_PATH);
     cp_afc("/.backup", "/data/.backup");
     cp_afc("/overlay.d", "/data/overlay.d");
 }

native/src/init/rootdir.cpp

@@ -347,12 +347,6 @@ void MagiskInit::patch_ro_root() {
     chdir("/");
 }
 
-void RootFSInit::prepare() {
-    prepare_data();
-    LOGD("Restoring /init\n");
-    rename(backup_init(), "/init");
-}
-
 #define PRE_TMPSRC "/magisk"
 #define PRE_TMPDIR PRE_TMPSRC "/tmp"
 

native/src/init/selinux.cpp

@@ -64,7 +64,7 @@ bool MagiskInit::hijack_sepolicy() {
         // This only happens on Android 8.0 - 9.0
 
         char buf[4096];
-        ssprintf(buf, sizeof(buf), "%s/fstab/compatible", config->dt_dir);
+        ssprintf(buf, sizeof(buf), "%s/fstab/compatible", config.dt_dir);
         dt_compat = full_read(buf);
         if (dt_compat.empty()) {
             // Device does not do early mount and uses monolithic policy
@@ -106,7 +106,7 @@ bool MagiskInit::hijack_sepolicy() {
         int fd = xopen(MOCK_COMPAT, O_WRONLY);
 
         char buf[4096];
-        ssprintf(buf, sizeof(buf), "%s/fstab/compatible", config->dt_dir);
+        ssprintf(buf, sizeof(buf), "%s/fstab/compatible", config.dt_dir);
         xumount2(buf, MNT_DETACH);
 
         hijack();

native/src/init/twostage.cpp

@@ -8,12 +8,13 @@
 
 using namespace std;
 
-void FirstStageInit::prepare() {
+void MagiskInit::first_stage() {
+    LOGI("First Stage Init\n");
     prepare_data();
 
     if (struct stat st{}; fstatat(-1, "/sdcard", &st, AT_SYMLINK_NOFOLLOW) != 0 &&
         fstatat(-1, "/first_stage_ramdisk/sdcard", &st, AT_SYMLINK_NOFOLLOW) != 0) {
-        if (config->force_normal_boot) {
+        if (config.force_normal_boot) {
             xmkdirs("/first_stage_ramdisk/storage/self", 0755);
             xsymlink("/system/system/bin/init", "/first_stage_ramdisk/storage/self/primary");
             LOGD("Symlink /first_stage_ramdisk/storage/self/primary -> /system/system/bin/init\n");
@@ -29,8 +30,8 @@ void FirstStageInit::prepare() {
             LOGD("Bind mount /sdcard -> /sdcard\n");
         } else {
             // rootfs before 3.12
-            xmount("/data/magiskinit", "/sdcard", nullptr, MS_BIND, nullptr);
-            LOGD("Bind mount /sdcard -> /data/magiskinit\n");
+            xmount(REDIR_PATH, "/sdcard", nullptr, MS_BIND, nullptr);
+            LOGD("Bind mount " REDIR_PATH " -> /sdcard\n");
         }
         restore_ramdisk_init();
     } else {
@@ -44,7 +45,7 @@ void FirstStageInit::prepare() {
     }
 }
 
-void LegacySARInit::first_stage_prep() {
+void MagiskInit::redirect_second_stage() {
     // Patch init binary
     int src = xopen("/init", O_RDONLY);
     int dest = xopen("/data/init", O_CREAT | O_WRONLY, 0);
@@ -61,7 +62,8 @@ void LegacySARInit::first_stage_prep() {
     xmount("/data/init", "/init", nullptr, MS_BIND, nullptr);
 }
 
-bool SecondStageInit::prepare() {
+void MagiskInit::second_stage() {
+    LOGI("Second Stage Init\n");
     umount2("/init", MNT_DETACH);
     umount2(INIT_PATH, MNT_DETACH); // just in case
     unlink("/data/init");
@@ -76,7 +78,8 @@ bool SecondStageInit::prepare() {
         // We are still on rootfs, so make sure we will execute the init of the 2nd stage
         unlink("/init");
         xsymlink(INIT_PATH, "/init");
-        return true;
+        patch_rw_root();
+    } else {
+        patch_ro_root();
     }
-    return false;
 }