Separate SAR and legacy implementation

native/jni/init/early_mount.cpp

@@ -5,6 +5,7 @@
 
 #include <utils.h>
 #include <logging.h>
+#include <selinux.h>
 
 #include "init.h"
 
@@ -73,7 +74,7 @@ static void setup_block(const char *partname, char *block_dev) {
 	}
 }
 
-bool MagiskInit::read_dt_fstab(const char *name, char *partname, char *fstype) {
+bool BaseInit::read_dt_fstab(const char *name, char *partname, char *fstype) {
 	char path[128];
 	int fd;
 	sprintf(path, "%s/fstab/%s/dev", cmd->dt_dir, name);
@@ -106,38 +107,57 @@ if (!is_lnk("/" #name) && read_dt_fstab(#name, partname, fstype)) { \
 	mnt_##name = true; \
 }
 
-void MagiskInit::early_mount() {
+void LegacyInit::early_mount() {
 	char partname[32];
 	char fstype[32];
 	char block_dev[64];
 
-	if (cmd->system_as_root) {
-		LOGD("Early mount system_root\n");
-		sprintf(partname, "system%s", cmd->slot);
-		setup_block(partname, block_dev);
-		xmkdir("/system_root", 0755);
-		if (xmount(block_dev, "/system_root", "ext4", MS_RDONLY, nullptr))
-			xmount(block_dev, "/system_root", "erofs", MS_RDONLY, nullptr);
-		xmkdir("/system", 0755);
-		xmount("/system_root/system", "/system", nullptr, MS_BIND, nullptr);
-
-		// Android Q
-		if (is_lnk("/system_root/init"))
-			load_sepol = true;
-
-		// System-as-root with monolithic sepolicy
-		if (access("/system_root/sepolicy", F_OK) == 0)
-			cp_afc("/system_root/sepolicy", "/sepolicy");
-
-		// Copy if these partitions are symlinks
-		link_root("/vendor");
-		link_root("/product");
-		link_root("/odm");
-	} else {
-		mount_root(system);
-	}
-
+	mount_root(system);
 	mount_root(vendor);
 	mount_root(product);
 	mount_root(odm);
 }
+
+void SARInit::early_mount() {
+	char partname[32];
+	char fstype[32];
+	char block_dev[64];
+
+	LOGD("Early mount system_root\n");
+	sprintf(partname, "system%s", cmd->slot);
+	setup_block(partname, block_dev);
+	xmkdir("/system_root", 0755);
+	if (xmount(block_dev, "/system_root", "ext4", MS_RDONLY, nullptr))
+		xmount(block_dev, "/system_root", "erofs", MS_RDONLY, nullptr);
+	xmkdir("/system", 0755);
+	xmount("/system_root/system", "/system", nullptr, MS_BIND, nullptr);
+
+	// Android Q
+	if (is_lnk("/system_root/init"))
+		load_sepol = true;
+
+	// System-as-root with monolithic sepolicy
+	if (access("/system_root/sepolicy", F_OK) == 0)
+		cp_afc("/system_root/sepolicy", "/sepolicy");
+
+	link_root("/vendor");
+	link_root("/product");
+	link_root("/odm");
+	mount_root(vendor);
+	mount_root(product);
+	mount_root(odm);
+}
+
+#define umount_root(name) \
+if (mnt_##name) \
+	umount("/" #name);
+
+void BaseInit::cleanup() {
+	umount(SELINUX_MNT);
+	umount("/sys");
+	umount("/proc");
+	umount_root(system);
+	umount_root(vendor);
+	umount_root(product);
+	umount_root(odm);
+}

native/jni/init/init.cpp

@@ -6,13 +6,11 @@
 #include <stdlib.h>
 #include <unistd.h>
 #include <string.h>
-#include <dirent.h>
 #include <fcntl.h>
 #include <libgen.h>
 
 #include <xz.h>
 #include <magisk.h>
-#include <selinux.h>
 #include <cpio.h>
 #include <utils.h>
 #include <flags.h>
@@ -48,12 +46,10 @@ static void setup_klog() {
 #define setup_klog(...)
 #endif
 
-static int test_main(int argc, char *argv[]);
-
 constexpr const char *init_applet[] =
-		{ "magiskpolicy", "supolicy", "init_test", nullptr };
+		{ "magiskpolicy", "supolicy", nullptr };
 constexpr int (*init_applet_main[])(int, char *[]) =
-		{ magiskpolicy_main, magiskpolicy_main, test_main, nullptr };
+		{ magiskpolicy_main, magiskpolicy_main, nullptr };
 
 static bool unxz(int fd, const uint8_t *buf, size_t size) {
 	uint8_t out[8192];
@@ -117,50 +113,27 @@ static int dump_manager(const char *path, mode_t mode) {
 	return 0;
 }
 
-void MagiskInit::preset() {
-	root = open("/", O_RDONLY | O_CLOEXEC);
-
-	if (cmd->system_as_root) {
-		// Clear rootfs
-		LOGD("Cleaning rootfs\n");
-		frm_rf(root, { "overlay", "proc", "sys" });
-	} else {
-		decompress_ramdisk();
-
-		// Revert original init binary
-		rename("/.backup/init", "/init");
-		rm_rf("/.backup");
-
-		// Do not go further if device is booting into recovery
-		if (access("/sbin/recovery", F_OK) == 0) {
-			LOGD("Ramdisk is recovery, abort\n");
-			re_exec_init();
-		}
-	}
-}
-
-#define umount_root(name) \
-if (mnt_##name) \
-	umount("/" #name);
-
-void MagiskInit::cleanup() {
-	umount(SELINUX_MNT);
-	umount("/sys");
-	umount("/proc");
-	umount_root(system);
-	umount_root(vendor);
-	umount_root(product);
-	umount_root(odm);
-}
-
-void MagiskInit::re_exec_init() {
+void BaseInit::re_exec_init() {
 	LOGD("Re-exec /init\n");
 	cleanup();
 	execv("/init", argv);
 	exit(1);
 }
 
-void MagiskInit::start() {
+void LegacyInit::preset() {
+	LOGD("Reverting /init\n");
+	root = open("/", O_RDONLY | O_CLOEXEC);
+	rename("/.backup/init", "/init");
+	rm_rf("/.backup");
+}
+
+void SARInit::preset() {
+	LOGD("Cleaning rootfs\n");
+	root = open("/", O_RDONLY | O_CLOEXEC);
+	frm_rf(root, { "overlay", "proc", "sys" });
+}
+
+void BaseInit::start() {
 	// Prevent file descriptor confusion
 	mknod("/null", S_IFCHR | 0666, makedev(1, 3));
 	int null = open("/null", O_RDWR | O_CLOEXEC);
@@ -180,27 +153,27 @@ void MagiskInit::start() {
 	re_exec_init();
 }
 
-void MagiskInit::test() {
-	cmdline_logging();
-	log_cb.ex = nop_ex;
+class RecoveryInit : public BaseInit {
+public:
+	RecoveryInit(char *argv[], cmdline *cmd) : BaseInit(argv, cmd) {};
+	void start() override {
+		LOGD("Ramdisk is recovery, abort\n");
+		rename("/.backup/init", "/init");
+		rm_rf("/.backup");
+		re_exec_init();
+	}
+};
 
-	chdir(dirname(argv[0]));
-	chroot(".");
-	chdir("/");
-
-	preset();
-	early_mount();
-	setup_rootfs();
-	cleanup();
-}
-
-static int test_main(int, char *argv[]) {
-	cmdline cmd{};
-	load_kernel_info(&cmd);
-	MagiskInit init(argv, &cmd);
-	init.test();
-	return 0;
-}
+class TestInit : public SARInit {
+public:
+	TestInit(char *argv[], cmdline *cmd) : SARInit(argv, cmd) {};
+	void start() override {
+		preset();
+		early_mount();
+		setup_rootfs();
+		cleanup();
+	}
+};
 
 int main(int argc, char *argv[]) {
 	umask(0);
@@ -217,16 +190,40 @@ int main(int argc, char *argv[]) {
 			return dump_manager(argv[3], 0644);
 	}
 
-	if (getpid() != 1)
-		return 1;
+#ifdef MAGISK_DEBUG
+	bool run_test = getenv("INIT_TEST") != nullptr;
+#else
+	constexpr bool run_test = false;
+#endif
 
-	setup_klog();
+	if (run_test) {
+		chdir(dirname(argv[0]));
+		chroot(".");
+		chdir("/");
+		cmdline_logging();
+		log_cb.ex = nop_ex;
+	} else {
+		if (getpid() != 1)
+			return 1;
+		setup_klog();
+	}
 
 	cmdline cmd{};
 	load_kernel_info(&cmd);
 
-	MagiskInit init(argv, &cmd);
+	unique_ptr<BaseInit> init;
+	if (run_test) {
+		init = make_unique<TestInit>(argv, &cmd);
+	} else if (cmd.system_as_root) {
+		init = make_unique<SARInit>(argv, &cmd);
+	} else {
+		decompress_ramdisk();
+		if (access("/sbin/recovery", F_OK) == 0)
+			init = make_unique<RecoveryInit>(argv, &cmd);
+		else
+			init = make_unique<LegacyInit>(argv, &cmd);
+	}
 
 	// Run the main routine
-	init.start();
+	init->start();
 }

native/jni/init/init.h

@@ -11,21 +11,21 @@ struct raw_data {
 	size_t sz;
 };
 
-class MagiskInit {
-private:
+class BaseInit {
+protected:
 	cmdline *cmd;
 	raw_data self{};
 	raw_data config{};
-	int root = -1;
 	char **argv;
+	int root = -1;
 	bool load_sepol = false;
 	bool mnt_system = false;
 	bool mnt_vendor = false;
 	bool mnt_product = false;
 	bool mnt_odm = false;
 
-	void preset();
-	void early_mount();
+	virtual void preset() {};
+	virtual void early_mount() {}
 	void setup_rootfs();
 	bool read_dt_fstab(const char *name, char *partname, char *fstype);
 	bool patch_sepolicy();
@@ -33,9 +33,25 @@ private:
 	void re_exec_init();
 
 public:
-	explicit MagiskInit(char *argv[], cmdline *cmd) : cmd(cmd), argv(argv) {}
-	void start();
-	void test();
+	BaseInit(char *argv[], cmdline *cmd) : cmd(cmd), argv(argv) {}
+	virtual ~BaseInit() = default;
+	virtual void start();
+};
+
+class LegacyInit : public BaseInit {
+protected:
+	void preset() override;
+	void early_mount() override;
+public:
+	LegacyInit(char *argv[], cmdline *cmd) : BaseInit(argv, cmd) {};
+};
+
+class SARInit : public BaseInit {
+protected:
+	void preset() override;
+	void early_mount() override;
+public:
+	SARInit(char *argv[], cmdline *cmd) : BaseInit(argv, cmd) {};
 };
 
 static inline bool is_lnk(const char *name) {

native/jni/init/rootfs.cpp

@@ -37,7 +37,7 @@ constexpr const char wrapper[] =
 "exec /sbin/magisk.bin \"$0\" \"$@\"\n"
 ;
 
-void MagiskInit::setup_rootfs() {
+void BaseInit::setup_rootfs() {
 	bool patch_init = patch_sepolicy();
 
 	if (cmd->system_as_root) {
@@ -173,7 +173,7 @@ void MagiskInit::setup_rootfs() {
 	close(sbin);
 }
 
-bool MagiskInit::patch_sepolicy() {
+bool BaseInit::patch_sepolicy() {
 	bool patch_init = false;
 
 	if (access(SPLIT_PLAT_CIL, R_OK) == 0) {