Minor code cleanups

native/jni/init/init.cpp

@@ -24,6 +24,61 @@ using namespace std;
 constexpr int (*init_applet_main[])(int, char *[]) =
 		{ magiskpolicy_main, magiskpolicy_main, nullptr };
 
+int data_holder::patch(str_pairs list) {
+	int count = 0;
+	for (uint8_t *p = buf, *eof = buf + sz; p < eof; ++p) {
+		for (auto [from, to] : list) {
+			if (memcmp(p, from.data(), from.length() + 1) == 0) {
+				LOGD("Replace [%s] -> [%s]\n", from.data(), to.data());
+				memset(p, 0, from.length());
+				memcpy(p, to.data(), to.length());
+				++count;
+				p += from.length();
+			}
+		}
+	}
+	return count;
+}
+
+void data_holder::consume(data_holder &other) {
+	buf = other.buf;
+	sz = other.sz;
+	other.buf = nullptr;
+	other.sz = 0;
+}
+
+template <>
+auto_data<MMAP>::~auto_data<MMAP>() {
+	if (buf) munmap(buf, sz);
+}
+
+template <>
+auto_data<HEAP>::~auto_data<HEAP>() {
+	free(buf);
+}
+
+auto_data<HEAP> raw_data::read(int fd) {
+	auto_data<HEAP> data;
+	fd_full_read(fd, data.buf, data.sz);
+	return data;
+}
+
+auto_data<HEAP> raw_data::read(const char *name) {
+	auto_data<HEAP> data;
+	full_read(name, data.buf, data.sz);
+	return data;
+}
+
+auto_data<MMAP> raw_data::mmap_rw(const char *name) {
+	auto_data<MMAP> data;
+	::mmap_rw(name, data.buf, data.sz);
+	return data;
+}
+
+// Explicit instantiation
+template struct auto_data<HEAP>;
+template struct auto_data<MMAP>;
+
 static bool unxz(int fd, const uint8_t *buf, size_t size) {
 	uint8_t out[8192];
 	xz_crc32_init();

native/jni/init/init.hpp

@@ -16,23 +16,32 @@ struct cmdline {
 	char hardware_plat[32];
 };
 
-struct raw_data {
+struct data_holder {
 	uint8_t *buf = nullptr;
 	size_t sz = 0;
-
+	using str_pairs = std::initializer_list<std::pair<std::string_view, std::string_view>>;
-	raw_data() = default;
+	int patch(str_pairs list);
-	raw_data(const raw_data&) = delete;
+protected:
-	raw_data(raw_data &&d) {
+	void consume(data_holder &other);
-		buf = d.buf;
-		sz = d.sz;
-		d.buf = nullptr;
-		d.sz = 0;
-	}
-	~raw_data() {
-		free(buf);
-	}
 };
 
+enum data_type { HEAP, MMAP };
+
+template <data_type T>
+struct auto_data : public data_holder {
+	auto_data<T>() = default;
+	auto_data<T>(const auto_data&) = delete;
+	auto_data<T>(auto_data<T> &&other) { consume(other); }
+	~auto_data<T>() {}
+	auto_data<T>& operator=(auto_data<T> &&other) { consume(other); return *this; }
+};
+
+namespace raw_data {
+	auto_data<HEAP> read(const char *name);
+	auto_data<HEAP> read(int fd);
+	auto_data<MMAP> mmap_rw(const char *name);
+}
+
 struct fstab_entry {
 	std::string dev;
 	std::string mnt_point;
@@ -41,7 +50,7 @@ struct fstab_entry {
 	std::string fsmgr_flags;
 
 	fstab_entry() = default;
-	fstab_entry(const fstab_entry &o) = delete;
+	fstab_entry(const fstab_entry &) = delete;
 	fstab_entry(fstab_entry &&o) = default;
 	void to_file(FILE *fp);
 };
@@ -53,10 +62,7 @@ void load_kernel_info(cmdline *cmd);
 int dump_magisk(const char *path, mode_t mode);
 int magisk_proxy_main(int argc, char *argv[]);
 void setup_klog();
-void setup_tmp(const char *path, const raw_data &self, const raw_data &config);
+void setup_tmp(const char *path, const data_holder &self, const data_holder &config);
-
-using str_pairs = std::initializer_list<std::pair<std::string_view, std::string_view>>;
-int raw_data_patch(void *addr, size_t sz, str_pairs list);
 
 /***************
  * Base classes
@@ -85,7 +91,7 @@ public:
 
 class MagiskInit : public BaseInit {
 protected:
-	raw_data self;
+	auto_data<HEAP> self;
 	std::string persist_dir;
 
 	virtual void early_mount() = 0;
@@ -96,7 +102,7 @@ public:
 
 class SARBase : public MagiskInit {
 protected:
-	raw_data config;
+	auto_data<HEAP> config;
 	std::vector<raw_file> overlays;
 
 	void backup_files();

native/jni/init/mount.cpp

@@ -219,7 +219,7 @@ static void mount_persist(const char *dev_base, const char *mnt_base) {
 }
 
 void RootFSInit::early_mount() {
-	full_read("/init", self.buf, self.sz);
+	self = raw_data::read("/init");
 
 	LOGD("Restoring /init\n");
 	rename("/.backup/init", "/init");
@@ -236,9 +236,9 @@ void SARBase::backup_files() {
 	if (access("/overlay.d", F_OK) == 0)
 		backup_folder("/overlay.d", overlays);
 
-	full_read("/proc/self/exe", self.buf, self.sz);
+	self = raw_data::read("/proc/self/exe");
 	if (access("/.backup/.magisk", R_OK) == 0)
-		full_read("/.backup/.magisk", config.buf, config.sz);
+		config = raw_data::read("/.backup/.magisk");
 }
 
 void SARBase::mount_system_root() {
@@ -304,14 +304,11 @@ void BaseInit::cleanup() {
 static void patch_socket_name(const char *path) {
 	char rstr[16];
 	gen_rand_str(rstr, sizeof(rstr));
-	char *buf;
+	auto bin = raw_data::mmap_rw(path);
-	size_t size;
+	bin.patch({ make_pair(MAIN_SOCKET, rstr) });
-	mmap_rw(path, buf, size);
-	raw_data_patch(buf, size, { make_pair(MAIN_SOCKET, rstr) });
-	munmap(buf, size);
 }
 
-void setup_tmp(const char *path, const raw_data &self, const raw_data &config) {
+void setup_tmp(const char *path, const data_holder &self, const data_holder &config) {
 	LOGD("Setup Magisk tmp at %s\n", path);
 	xmount("tmpfs", path, "tmpfs", 0, "mode=755");
 

native/jni/init/rootdir.cpp

@@ -81,29 +81,10 @@ static void load_overlay_rc(const char *overlay) {
 	}
 }
 
-int raw_data_patch(void *addr, size_t sz, str_pairs list) {
-	int count = 0;
-	for (uint8_t *p = (uint8_t *)addr, *eof = (uint8_t *)addr + sz; p < eof; ++p) {
-		for (auto &[from, to] : list) {
-			if (memcmp(p, from.data(), from.length() + 1) == 0) {
-				LOGD("Replace [%s] -> [%s]\n", from.data(), to.data());
-				memset(p, 0, from.length());
-				memcpy(p, to.data(), to.length());
-				++count;
-				p += from.length();
-			}
-		}
-	}
-	return count;
-}
-
 void RootFSInit::setup_rootfs() {
 	if (patch_sepolicy("/sepolicy")) {
-		char *addr;
+		auto init = raw_data::mmap_rw("/init");
-		size_t size;
+		init.patch({ make_pair(SPLIT_PLAT_CIL, "xxx") });
-		mmap_rw("/init", addr, size);
-		raw_data_patch(addr, size, {make_pair(SPLIT_PLAT_CIL, "xxx")});
-		munmap(addr, size);
 	}
 
 	// Handle overlays
@@ -267,10 +248,9 @@ void SARBase::patch_rootdir() {
 		recreate_sbin(ROOTMIR "/sbin", true);
 
 	// Patch init
-	raw_data init;
 	int src = xopen("/init", O_RDONLY | O_CLOEXEC);
-	fd_full_read(src, init.buf, init.sz);
+	auto init = raw_data::read(src);
-	int patch_count = raw_data_patch(init.buf, init.sz, {
+	int patch_count = init.patch({
 		make_pair(SPLIT_PLAT_CIL, "xxx"), /* Force loading monolithic sepolicy */
 		make_pair(MONOPOLICY, sepol)      /* Redirect /sepolicy to custom path */
 	});
@@ -283,9 +263,8 @@ void SARBase::patch_rootdir() {
 
 	if (patch_count != 2 && access(LIBSELINUX, F_OK) == 0) {
 		// init is dynamically linked, need to patch libselinux
-		raw_data lib;
+		auto lib = raw_data::read(LIBSELINUX);
-		full_read(LIBSELINUX, lib.buf, lib.sz);
+		lib.patch({make_pair(MONOPOLICY, sepol)});
-		raw_data_patch(lib.buf, lib.sz, {make_pair(MONOPOLICY, sepol)});
 		xmkdirs(dirname(ROOTOVL LIBSELINUX), 0755);
 		dest = xopen(ROOTOVL LIBSELINUX, O_CREAT | O_WRONLY | O_CLOEXEC, 0);
 		xwrite(dest, lib.buf, lib.sz);
@@ -341,11 +320,8 @@ void SARBase::patch_rootdir() {
 int magisk_proxy_main(int argc, char *argv[]) {
 	setup_klog();
 
-	raw_data config;
+	auto config = raw_data::read("/sbin/magisk");
-	raw_data self;
+	auto self = raw_data::read("/.backup/.magisk");
-
-	full_read("/sbin/magisk", self.buf, self.sz);
-	full_read("/.backup/.magisk", config.buf, config.sz);
 
 	xmount(nullptr, "/", nullptr, MS_REMOUNT, nullptr);
 

native/jni/init/twostage.cpp

@@ -108,14 +108,9 @@ void FirstStageInit::prepare() {
 			sprintf(fstab_file, "fstab.%s", hw);
 		}
 
-		// Patch init to force ignore dt fstab
+		// Patch init to force IsDtFstabCompatible() return false
-		uint8_t *addr;
+		auto init = raw_data::mmap_rw("/init");
-		size_t sz;
+		init.patch({ make_pair("android,fstab", "xxx") });
-		mmap_rw("/init", addr, sz);
-		raw_data_patch(addr, sz, {
-			make_pair("android,fstab", "xxx")  /* Force IsDtFstabCompatible() to return false */
-		});
-		munmap(addr, sz);
 	}
 
 	{
@@ -150,9 +145,8 @@ void SARFirstStageInit::prepare() {
 	int src = xopen("/init", O_RDONLY);
 	int dest = xopen("/dev/init", O_CREAT | O_WRONLY, 0);
 	{
-		raw_data init;
+		auto init = raw_data::read(dest);
-		fd_full_read(src, init.buf, init.sz);
+		init.patch({ make_pair(INIT_PATH, REDIR_PATH) });
-		raw_data_patch(init.buf, init.sz, { make_pair(INIT_PATH, REDIR_PATH) });
 		write(dest, init.buf, init.sz);
 		fclone_attr(src, dest);
 		close(dest);