Remove usage of magisk.img

Mounting ext4 images causes tons of issues, such as unmountable with broken F2FS drivers.
Resizing is also very complicated and does not work properly on all devices.
Each step in either measuring free space, resizing, and shrinking the image is a
point of failure, and either step's failure could cause the module system completely broken.

The new method is to directly store modules into /data/adb/modules, and for module installation
on boot /data/adb/modules_update. Several compatibility layers has been done: the new path is
bind mounted to the old path (/sbin/.magisk/img), and the helper functions in util_functions.sh
will now transparently make existing modules install to the new location without any changes.

MagiskHide is also updated to unmount module files stored in this new location.

native/jni/core/bootstages.cpp

@@ -19,12 +19,11 @@
 #include <magisk.h>
 #include <db.h>
 #include <utils.h>
-#include <img.h>
 #include <daemon.h>
 #include <resetprop.h>
 #include <selinux.h>
-#include <flags.h>
 #include <logcat.h>
+#include <flags.h>
 
 using namespace std;
 
@@ -32,7 +31,7 @@ static char buf[PATH_MAX], buf2[PATH_MAX];
 static vector<string> module_list;
 static bool seperate_vendor;
 
-char *system_block, *vendor_block, *magiskloop;
+char *system_block, *vendor_block, *data_block;
 
 static int bind_mount(const char *from, const char *to);
 extern void auto_start_magiskhide();
@@ -135,7 +134,7 @@ void node_entry::create_module_tree(const char *module) {
 	struct dirent *entry;
 
 	auto full_path = get_path();
-	snprintf(buf, PATH_MAX, "%s/%s%s", MOUNTPOINT, module, full_path.c_str());
+	snprintf(buf, PATH_MAX, "%s/%s%s", MODULEROOT, module, full_path.c_str());
 
 	if (!(dir = xopendir(buf)))
 		return;
@@ -169,7 +168,7 @@ void node_entry::create_module_tree(const char *module) {
 			node->status = IS_MODULE;
 		} else if (IS_DIR(node)) {
 			// Check if marked as replace
-			snprintf(buf2, PATH_MAX, "%s/%s%s/.replace", MOUNTPOINT, module, buf);
+			snprintf(buf2, PATH_MAX, "%s/%s%s/.replace", MODULEROOT, module, buf);
 			if (access(buf2, F_OK) == 0) {
 				// Replace everything, mark as leaf
 				node->status = IS_MODULE;
@@ -236,7 +235,7 @@ void node_entry::clone_skeleton() {
 			continue;
 		} else if (child->status & IS_MODULE) {
 			// Mount from module file to dummy file
-			snprintf(buf2, PATH_MAX, "%s/%s%s/%s", MOUNTPOINT,
+			snprintf(buf2, PATH_MAX, "%s/%s%s/%s", MODULEROOT,
 					 child->module, full_path.c_str(), child->name.c_str());
 		} else if (child->status & (IS_SKEL | IS_INTER)) {
 			// It's an intermediate folder, recursive clone
@@ -262,7 +261,7 @@ void node_entry::magic_mount() {
 	if (status & IS_MODULE) {
 		// Mount module item
 		auto real_path = get_path();
-		snprintf(buf, PATH_MAX, "%s/%s%s", MOUNTPOINT, module, real_path.c_str());
+		snprintf(buf, PATH_MAX, "%s/%s%s", MODULEROOT, module, real_path.c_str());
 		bind_mount(buf, real_path.c_str());
 	} else if (status & IS_SKEL) {
 		// The node is labeled to be cloned with skeleton, lets do it
@@ -338,7 +337,7 @@ static void exec_common_script(const char* stage) {
 static void exec_module_script(const char* stage) {
 	for (const auto &m : module_list) {
 		const auto module = m.c_str();
-		snprintf(buf2, PATH_MAX, "%s/%s/%s.sh", MOUNTPOINT, module, stage);
+		snprintf(buf2, PATH_MAX, "%s/%s/%s.sh", MODULEROOT, module, stage);
 		if (access(buf2, F_OK) == -1)
 			continue;
 		LOGI("%s: exec [%s.sh]\n", module, stage);
@@ -418,18 +417,21 @@ static bool magisk_env() {
 	// Remove legacy stuffs
 	unlink("/data/magisk.img");
 	unlink("/data/magisk_debug.log");
+	unlink(SECURE_DIR "/magisk.img");
+	unlink(SECURE_DIR "/magisk_merge.img");
 
-	// Symlink for legacy path users
+	// Legacy support
 	symlink(MAGISKTMP, "/sbin/.core");
+	xmkdir(MAGISKTMP "/img", 0755);
 
 	// Create directories in tmpfs overlay
 	xmkdirs(MIRRDIR "/system", 0755);
 	xmkdir(MIRRDIR "/bin", 0755);
 	xmkdir(BBPATH, 0755);
-	xmkdir(MOUNTPOINT, 0755);
 	xmkdir(BLOCKDIR, 0755);
 
-	// Boot script directories
+	// /data/adb directories
+	xmkdir(MODULEROOT, 0755);
 	xmkdir(SECURE_DIR "/post-fs-data.d", 0755);
 	xmkdir(SECURE_DIR "/service.d", 0755);
 
@@ -454,6 +456,9 @@ static bool magisk_env() {
 			xmkdir(MIRRDIR "/vendor", 0755);
 			xmount(vendor_block, MIRRDIR "/vendor", buf2, MS_RDONLY, nullptr);
 			VLOGI("mount", vendor_block, MIRRDIR "/vendor");
+		} else if (str_contains(line, " /data ")) {
+			sscanf(line.c_str(), "%s", buf);
+			data_block = strdup(buf);
 		} else if (SDK_INT >= 24 &&
 		str_contains(line, " /proc ") && !str_contains(line, "hidepid=2")) {
 			// Enforce hidepid
@@ -482,16 +487,43 @@ static bool magisk_env() {
 	return true;
 }
 
+static void upgrade_modules() {
+	DIR *dir;
+	struct dirent *entry;
+	if ((dir = opendir(MODULEUPGRADE))) {
+		while ((entry = xreaddir(dir))) {
+			if (entry->d_type == DT_DIR) {
+				if (strcmp(entry->d_name, ".") == 0 || strcmp(entry->d_name, "..") == 0)
+					continue;
+				// Cleanup old module if exists
+				snprintf(buf, sizeof(buf), "%s/%s", MODULEROOT, entry->d_name);
+				if (access(buf, F_OK) == 0)
+					rm_rf(buf);
+				LOGI("Upgrade / New module: %s\n", entry->d_name);
+				snprintf(buf2, sizeof(buf2), "%s/%s", MODULEUPGRADE, entry->d_name);
+				rename(buf2, buf);
+			}
+		}
+		closedir(dir);
+		rm_rf(MODULEUPGRADE);
+	}
+	// Legacy support
+	bind_mount(MODULEROOT, MAGISKTMP "/img");
+	xmkdir(LEGACYCORE, 0755);
+	symlink(SECURE_DIR "/post-fs-data.d", LEGACYCORE "/post-fs-data.d");
+	symlink(SECURE_DIR "/service.d", LEGACYCORE "/service.d");
+}
+
 static void collect_modules() {
-	chdir(MOUNTPOINT);
+	chdir(MODULEROOT);
+	rm_rf("lost+found");
 	DIR *dir = xopendir(".");
 	struct dirent *entry;
 	while ((entry = xreaddir(dir))) {
 		if (entry->d_type == DT_DIR) {
 			if (strcmp(entry->d_name, ".") == 0 ||
 				strcmp(entry->d_name, "..") == 0 ||
-				strcmp(entry->d_name, ".core") == 0 ||
+				strcmp(entry->d_name, ".core") == 0)
-				strcmp(entry->d_name, "lost+found") == 0)
 				continue;
 			chdir(entry->d_name);
 			if (access("remove", F_OK) == 0) {
@@ -510,47 +542,6 @@ static void collect_modules() {
 	chdir("/");
 }
 
-static bool prepare_img() {
-	const char *alt_img[] =
-			{ "/cache/magisk.img", "/data/magisk_merge.img", "/data/adb/magisk_merge.img" };
-
-	for (auto &alt : alt_img) {
-		if (merge_img(alt, MAINIMG)) {
-			LOGE("Image merge %s -> " MAINIMG " failed!\n", alt);
-			return false;
-		}
-	}
-
-	if (access(MAINIMG, F_OK) == -1) {
-		if (create_img(MAINIMG, 64))
-			return false;
-	}
-
-	LOGI("* Mounting " MAINIMG "\n");
-	magiskloop = mount_image(MAINIMG, MOUNTPOINT);
-	if (magiskloop == nullptr)
-		return false;
-
-	// Migrate legacy boot scripts
-	struct stat st;
-	if (lstat(LEGACY_CORE "/post-fs-data.d", &st) == 0 && S_ISDIR(st.st_mode)) {
-		cp_afc(LEGACY_CORE "/post-fs-data.d", SECURE_DIR "/post-fs-data.d");
-		rm_rf(LEGACY_CORE "/post-fs-data.d");
-	}
-	if (lstat(LEGACY_CORE "/service.d", &st) == 0 && S_ISDIR(st.st_mode)) {
-		cp_afc(LEGACY_CORE "/service.d", SECURE_DIR "/service.d");
-		rm_rf(LEGACY_CORE "/service.d");
-	}
-
-	// Links for legacy paths
-	xmkdir(LEGACY_CORE, 0755);
-	symlink(SECURE_DIR "/post-fs-data.d", LEGACY_CORE "/post-fs-data.d");
-	symlink(SECURE_DIR "/service.d", LEGACY_CORE "/service.d");
-
-	collect_modules();
-	return trim_img(MAINIMG, MOUNTPOINT, magiskloop) == 0;
-}
-
 static void install_apk(const char *apk) {
 	setfilecon(apk, "u:object_r:" SEPOL_FILE_DOMAIN ":s0");
 	while (true) {
@@ -688,24 +679,20 @@ void post_fs_data(int client) {
 
 	start_logcat();
 
-	// Run common scripts
 	LOGI("* Running post-fs-data.d scripts\n");
 	exec_common_script("post-fs-data");
 
+	upgrade_modules();
+
 	// Core only mode
 	if (access(DISABLEFILE, F_OK) == 0)
 		core_only();
 
-	if (!prepare_img()) {
-		LOGE("* Magisk image mount failed, switch to core-only mode\n");
-		free(magiskloop);
-		magiskloop = nullptr;
-		creat(DISABLEFILE, 0644);
-	}
-
 	restorecon();
 	chmod(SECURE_DIR, 0700);
 
+	collect_modules();
+
 	// Execute module scripts
 	LOGI("* Running module post-fs-data scripts\n");
 	exec_module_script("post-fs-data");
@@ -726,17 +713,17 @@ void post_fs_data(int client) {
 	for (const auto &m : module_list) {
 		const auto module = m.c_str();
 		// Read props
-		snprintf(buf, PATH_MAX, "%s/%s/system.prop", MOUNTPOINT, module);
+		snprintf(buf, PATH_MAX, "%s/%s/system.prop", MODULEROOT, module);
 		if (access(buf, F_OK) == 0) {
 			LOGI("%s: loading [system.prop]\n", module);
 			load_prop_file(buf, false);
 		}
 		// Check whether enable auto_mount
-		snprintf(buf, PATH_MAX, "%s/%s/auto_mount", MOUNTPOINT, module);
+		snprintf(buf, PATH_MAX, "%s/%s/auto_mount", MODULEROOT, module);
 		if (access(buf, F_OK) == -1)
 			continue;
 		// Double check whether the system folder exists
-		snprintf(buf, PATH_MAX, "%s/%s/system", MOUNTPOINT, module);
+		snprintf(buf, PATH_MAX, "%s/%s/system", MODULEROOT, module);
 		if (access(buf, F_OK) == -1)
 			continue;
 
@@ -744,9 +731,9 @@ void post_fs_data(int client) {
 		has_modules = true;
 		LOGI("%s: constructing magic mount structure\n", module);
 		// If /system/vendor exists in module, create a link outside
-		snprintf(buf, PATH_MAX, "%s/%s/system/vendor", MOUNTPOINT, module);
+		snprintf(buf, PATH_MAX, "%s/%s/system/vendor", MODULEROOT, module);
 		if (access(buf, F_OK) == 0) {
-			snprintf(buf2, PATH_MAX, "%s/%s/vendor", MOUNTPOINT, module);
+			snprintf(buf2, PATH_MAX, "%s/%s/vendor", MODULEROOT, module);
 			unlink(buf2);
 			xsymlink(buf, buf2);
 		}

native/jni/include/magisk.h

@@ -18,16 +18,18 @@
 #define BLOCKDIR        MAGISKTMP "/block"
 #define MIRRDIR         MAGISKTMP "/mirror"
 #define BBPATH          MAGISKTMP "/busybox"
-#define MOUNTPOINT      MAGISKTMP "/img"
-#define LEGACY_CORE     MOUNTPOINT "/.core"
 #define SECURE_DIR      "/data/adb"
-#define MAINIMG         SECURE_DIR "/magisk.img"
+#define MODULEROOT      SECURE_DIR "/modules"
+#define MODULEUPGRADE   SECURE_DIR "/modules_update"
 #define DATABIN         SECURE_DIR "/magisk"
 #define MAGISKDB        SECURE_DIR "/magisk.db"
 #define SIMPLEMOUNT     SECURE_DIR "/magisk_simple"
 #define BOOTCOUNT       SECURE_DIR "/.boot_count"
 #define MANAGERAPK      DATABIN "/magisk.apk"
 
+// Legacy crap
+#define LEGACYCORE     MODULEROOT "/.core"
+
 // selinux consts
 #define SELINUX_PATH        "/sys/fs/selinux"
 #define SELINUX_ENFORCE     SELINUX_PATH "/enforce"

native/jni/magiskhide/hide_utils.cpp

@@ -233,7 +233,7 @@ int rm_list(int client) {
 	return ret;
 }
 
-#define LEGACY_LIST MOUNTPOINT "/.core/hidelist"
+#define LEGACY_LIST MODULEROOT "/.core/hidelist"
 
 static int collect_list(void *, int, char **data, char**) {
 	LOGI("hide_list: [%s]\n", data[0]);

native/jni/magiskhide/proc_monitor.cpp

@@ -26,7 +26,7 @@
 
 using namespace std;
 
-extern char *system_block, *vendor_block, *magiskloop;
+extern char *system_block, *vendor_block, *data_block;
 
 // Workaround for the lack of pthread_cancel
 static void term_thread(int) {
@@ -91,10 +91,10 @@ static void hide_daemon(int pid) {
 	// Re-read mount infos
 	mounts = file_to_vector("mounts");
 
-	// Unmount everything under /system, /vendor, and loop mounts
+	// Unmount everything under /system, /vendor, and data mounts
 	for (auto &s : mounts) {
 		if ((str_contains(s, " /system/") || str_contains(s, " /vendor/")) &&
-			(str_contains(s, system_block) || str_contains(s, vendor_block) || str_contains(s, magiskloop))) {
+			(str_contains(s, system_block) || str_contains(s, vendor_block) || str_contains(s, data_block))) {
 			sscanf(s.c_str(), "%*s %4096s", buffer);
 			lazy_unmount(buffer);
 		}

native/jni/utils/selinux.cpp

@@ -162,7 +162,8 @@ void restorecon() {
 	if (write(fd, ADB_CON, sizeof(ADB_CON)) >= 0)
 		lsetfilecon(SECURE_DIR, ADB_CON);
 	close(fd);
-	fd = xopen(MOUNTPOINT, O_RDONLY | O_CLOEXEC);
+	lsetfilecon(MODULEROOT, MAGISK_CON);
+	fd = xopen(MODULEROOT, O_RDONLY | O_CLOEXEC);
 	restore_syscon(fd);
 	close(fd);
 	fd = xopen(DATABIN, O_RDONLY | O_CLOEXEC);

scripts/util_functions.sh

@@ -52,7 +52,8 @@ abort() {
 
 resolve_vars() {
   MAGISKBIN=$NVBASE/magisk
-  IMG=$NVBASE/magisk.img
+  POSTFSDATAD=$NVBASE/post-fs-data.d
+  SERVICED=$NVBASE/service.d
 }
 
 ######################
@@ -351,7 +352,9 @@ find_manager_apk() {
 set_perm() {
   chown $2:$3 $1 || return 1
   chmod $4 $1 || return 1
-  [ -z $5 ] && chcon 'u:object_r:system_file:s0' $1 || chcon $5 $1 || return 1
+  CON=$5
+  [ -z $CON ] && CON=u:object_r:system_file:s0
+  chcon $CON $1 || return 1
 }
 
 set_perm_recursive() {
@@ -370,64 +373,30 @@ mktouch() {
 }
 
 request_size_check() {
-  reqSizeM=`du -ms $1 | cut -f1`
+  reqSizeM=`du -ms "$1" | cut -f1`
 }
 
 request_zip_size_check() {
   reqSizeM=`unzip -l "$1" | tail -n 1 | awk '{ print int(($1 - 1) / 1048576 + 1) }'`
 }
 
-check_filesystem() {
-  curSizeM=`wc -c < $1`
-  curSizeM=$((curSizeM / 1048576))
-  local DF=`df -Pk $2 | grep $2`
-  curUsedM=`echo $DF | awk '{ print int($3 / 1024) }'`
-  curFreeM=`echo $DF | awk '{ print int($4 / 1024) }'`
-}
-
-mount_snippet() {
-  MAGISKLOOP=`$MAGISKBIN/magisk imgtool mount $IMG $MOUNTPATH`
-  is_mounted $MOUNTPATH || abort "! $IMG mount failed..."
-}
-
-mount_magisk_img() {
-  [ -z $reqSizeM ] && reqSizeM=0
-  mkdir -p $MOUNTPATH 2>/dev/null
-  if [ -f "$IMG" ]; then
-    ui_print "- Found $IMG"
-    mount_snippet
-    check_filesystem $IMG $MOUNTPATH
-    if [ $reqSizeM -gt $curFreeM ]; then
-      newSizeM=$(((curSizeM + reqSizeM - curFreeM) / 32 * 32 + 64))
-      ui_print "- Resizing $IMG to ${newSizeM}M"
-      $MAGISKBIN/magisk imgtool umount $MOUNTPATH $MAGISKLOOP
-      $MAGISKBIN/magisk imgtool resize $IMG $newSizeM >&2
-      mount_snippet
-    fi
-    ui_print "- Mount $IMG to $MOUNTPATH"
-  else
-    newSizeM=$((reqSizeM / 32 * 32 + 64))
-    ui_print "- Creating $IMG with size ${newSizeM}M"
-    $MAGISKBIN/magisk imgtool create $IMG $newSizeM >&2
-    mount_snippet
-  fi
-}
-
-unmount_magisk_img() {
-  check_filesystem $IMG $MOUNTPATH
-  newSizeM=$((curUsedM / 32 * 32 + 64))
-  $MAGISKBIN/magisk imgtool umount $MOUNTPATH $MAGISKLOOP
-  if [ $curSizeM -gt $newSizeM ]; then
-    ui_print "- Shrinking $IMG to ${newSizeM}M"
-    $MAGISKBIN/magisk imgtool resize $IMG $newSizeM >&2
-  fi
-}
-
 ##################################
 # Backwards Compatibile Functions
 ##################################
+
 get_outfd() { setup_flashable; }
 
+mount_magisk_img() {
+  $BOOTMODE && MODULE_BASE=modules_update || MODULE_BASE=modules
+  MODULEPATH=$NVBASE/$MODULE_BASE
+  mkdir -p $MODULEPATH 2>/dev/null
+  ln -s $MODULEPATH $MOUNTPATH
+}
+
+unmount_magisk_img() {
+  rm -f $MODULEPATH 2>/dev/null
+}
+
 #######
 # main
 #######