diff --git a/app/src/main/java/com/topjohnwu/magisk/tasks/FlashZip.kt b/app/src/main/java/com/topjohnwu/magisk/tasks/FlashZip.kt
index 0594dc2bb..0a42d1783 100644
--- a/app/src/main/java/com/topjohnwu/magisk/tasks/FlashZip.kt
+++ b/app/src/main/java/com/topjohnwu/magisk/tasks/FlashZip.kt
@@ -1,73 +1,96 @@
 package com.topjohnwu.magisk.tasks
 
 import android.net.Uri
-
+import com.skoumal.teanity.extensions.subscribeK
 import com.topjohnwu.magisk.App
 import com.topjohnwu.magisk.Const
-import com.topjohnwu.magisk.utils.*
+import com.topjohnwu.magisk.utils.fileName
+import com.topjohnwu.magisk.utils.inject
+import com.topjohnwu.magisk.utils.readUri
+import com.topjohnwu.magisk.utils.unzip
 import com.topjohnwu.superuser.Shell
-import com.topjohnwu.superuser.internal.UiThreadHandler
-
+import io.reactivex.Single
 import java.io.File
 import java.io.FileNotFoundException
 import java.io.IOException
 
-abstract class FlashZip(private val mUri: Uri,
-                        private val console: MutableList<String>,
-                        private val logs: MutableList<String>) {
+abstract class FlashZip(
+    private val mUri: Uri,
+    private val console: MutableList<String>,
+    private val logs: MutableList<String>
+) {
 
-    private val tmpFile: File = File(App.self.cacheDir, "install.zip")
+    private val app: App by inject()
+    private val tmpFile: File = File(app.cacheDir, "install.zip")
 
     @Throws(IOException::class)
     private fun unzipAndCheck(): Boolean {
-        unzip(tmpFile, tmpFile.parentFile!!, "META-INF/com/google/android", true)
-        return Shell.su("grep -q '#MAGISK' ${File(tmpFile.parentFile, "updater-script")}")
-                .exec().isSuccess
+        val parentFile = tmpFile.parentFile ?: return false
+        tmpFile.unzip(parentFile, "META-INF/com/google/android", true)
+
+        val updaterScript = File(parentFile, "updater-script")
+        return Shell
+            .su("grep -q '#MAGISK' $updaterScript")
+            .exec()
+            .isSuccess
     }
 
     @Throws(IOException::class)
     private fun flash(): Boolean {
         console.add("- Copying zip to temp directory")
-        try {
-            App.self.readUri(mUri).use { input ->
+
+        runCatching {
+            app.readUri(mUri).use { input ->
                 tmpFile.outputStream().use { out -> input.copyTo(out) }
             }
-        } catch (e: FileNotFoundException) {
-            console.add("! Invalid Uri")
-            throw e
-        } catch (e: IOException) {
-            console.add("! Cannot copy to cache")
-            throw e
+        }.getOrElse {
+            when (it) {
+                is FileNotFoundException -> console.add("! Invalid Uri")
+                is IOException -> console.add("! Cannot copy to cache")
+            }
+            throw it
         }
 
-        try {
-            if (!unzipAndCheck()) {
-                console.add("! This zip is not a Magisk Module!")
-                return false
-            }
-        } catch (e: IOException) {
+        val isMagiskModule = runCatching {
+            unzipAndCheck()
+        }.getOrElse {
             console.add("! Unzip error")
-            throw e
+            throw it
+        }
+
+        if (!isMagiskModule) {
+            console.add("! This zip is not a Magisk Module!")
+            return false
         }
 
         console.add("- Installing ${mUri.fileName}")
-        return Shell.su("cd " + tmpFile.parent!!,
-                "BOOTMODE=true sh update-binary dummy 1 $tmpFile")
-                .to(console, logs)
-                .exec().isSuccess
+
+        val parentFile = tmpFile.parent ?: return false
+
+        return Shell
+            .su(
+                "cd $parentFile",
+                "BOOTMODE=true sh update-binary dummy 1 $tmpFile"
+            )
+            .to(console, logs)
+            .exec().isSuccess
     }
 
-    fun exec() {
-        App.THREAD_POOL.execute {
-            val success = try {
+    fun exec() = Single
+        .fromCallable {
+            runCatching {
                 flash()
-            } catch (e: IOException) {
+            }.getOrElse {
+                it.printStackTrace()
                 false
+            }.apply {
+                Shell.su("cd /", "rm -rf ${tmpFile.parent} ${Const.TMP_FOLDER_PATH}")
+                    .submit()
             }
-            Shell.su("cd /", "rm -rf ${tmpFile.parent} ${Const.TMP_FOLDER_PATH}").submit()
-            UiThreadHandler.run { onResult(success) }
         }
-    }
+        .subscribeK(onError = { onResult(false) }) { onResult(it) }
+        .let { Unit } // ignores result disposable
+
 
     protected abstract fun onResult(success: Boolean)
 }
diff --git a/app/src/main/java/com/topjohnwu/magisk/utils/DownloadApp.java b/app/src/main/java/com/topjohnwu/magisk/utils/DownloadApp.java
index e10d38420..39727e52d 100644
--- a/app/src/main/java/com/topjohnwu/magisk/utils/DownloadApp.java
+++ b/app/src/main/java/com/topjohnwu/magisk/utils/DownloadApp.java
@@ -89,7 +89,7 @@ public class DownloadApp {
             // Make it world readable
             apk.setReadable(true, false);
             if (Shell.su("pm install " + apk).exec().isSuccess())
-                RootUtils.Companion.rmAndLaunch(app.getPackageName(),
+                RootUtils.rmAndLaunch(app.getPackageName(),
                         new ComponentName(BuildConfig.APPLICATION_ID,
                                 ClassMap.get(SplashActivity.class).getName()));
             progress.dismiss();
diff --git a/app/src/main/java/com/topjohnwu/magisk/utils/PatchAPK.java b/app/src/main/java/com/topjohnwu/magisk/utils/PatchAPK.java
index 95389302f..13e6f65bf 100644
--- a/app/src/main/java/com/topjohnwu/magisk/utils/PatchAPK.java
+++ b/app/src/main/java/com/topjohnwu/magisk/utils/PatchAPK.java
@@ -3,8 +3,6 @@ package com.topjohnwu.magisk.utils;
 import android.content.ComponentName;
 import android.widget.Toast;
 
-import androidx.core.app.NotificationCompat;
-
 import com.topjohnwu.magisk.App;
 import com.topjohnwu.magisk.BuildConfig;
 import com.topjohnwu.magisk.ClassMap;
@@ -29,6 +27,8 @@ import java.util.ArrayList;
 import java.util.List;
 import java.util.jar.JarEntry;
 
+import androidx.core.app.NotificationCompat;
+
 public class PatchAPK {
 
     public static final String LOWERALPHA = "abcdefghijklmnopqrstuvwxyz";
@@ -56,7 +56,7 @@ public class PatchAPK {
         return builder.toString();
     }
 
-    private static boolean findAndPatch(byte xml[], String from, String to) {
+    private static boolean findAndPatch(byte[] xml, String from, String to) {
         if (from.length() != to.length())
             return false;
         CharBuffer buf = ByteBuffer.wrap(xml).order(ByteOrder.LITTLE_ENDIAN).asCharBuffer();
@@ -83,7 +83,7 @@ public class PatchAPK {
         return true;
     }
 
-    private static boolean findAndPatch(byte xml[], int a, int b) {
+    private static boolean findAndPatch(byte[] xml, int a, int b) {
         IntBuffer buf = ByteBuffer.wrap(xml).order(ByteOrder.LITTLE_ENDIAN).asIntBuffer();
         int len = xml.length / 4;
         for (int i = 0; i < len; ++i) {
@@ -112,7 +112,7 @@ public class PatchAPK {
 
         Config.set(Config.Key.SU_MANAGER, pkg);
         Config.export();
-        RootUtils.Companion.rmAndLaunch(BuildConfig.APPLICATION_ID,
+        RootUtils.rmAndLaunch(BuildConfig.APPLICATION_ID,
                 new ComponentName(pkg, ClassMap.get(SplashActivity.class).getName()));
 
         return true;
@@ -122,7 +122,7 @@ public class PatchAPK {
         try {
             JarMap jar = new JarMap(in);
             JarEntry je = jar.getJarEntry(Const.ANDROID_MANIFEST);
-            byte xml[] = jar.getRawData(je);
+            byte[] xml = jar.getRawData(je);
 
             if (!findAndPatch(xml, BuildConfig.APPLICATION_ID, pkg) ||
                     !findAndPatch(xml, R.string.app_name, R.string.re_app_name))
diff --git a/app/src/main/java/com/topjohnwu/magisk/utils/RootUtils.kt b/app/src/main/java/com/topjohnwu/magisk/utils/RootUtils.kt
index baa9ed7dd..5a1716931 100644
--- a/app/src/main/java/com/topjohnwu/magisk/utils/RootUtils.kt
+++ b/app/src/main/java/com/topjohnwu/magisk/utils/RootUtils.kt
@@ -38,72 +38,70 @@ fun Intent.toCommand(args: MutableList<String>) {
     }
     val extras = extras
     if (extras != null) {
-        for (key in extras.keySet()) {
+        loop@ for (key in extras.keySet()) {
             val v = extras.get(key) ?: continue
             var value: Any = v
             val arg: String
-            if (v is String)
-                arg = "--es"
-            else if (v is Boolean)
-                arg = "--ez"
-            else if (v is Int)
-                arg = "--ei"
-            else if (v is Long)
-                arg = "--el"
-            else if (v is Float)
-                arg = "--ef"
-            else if (v is Uri)
-                arg = "--eu"
-            else if (v is ComponentName) {
-                arg = "--ecn"
-                value = v.flattenToString()
-            } else if (v is ArrayList<*>) {
-                if (v.size <= 0)
-                /* Impossible to know the type due to type erasure */
-                    continue
-
-                arg = if (v[0] is Int)
-                    "--eial"
-                else if (v[0] is Long)
-                    "--elal"
-                else if (v[0] is Float)
-                    "--efal"
-                else if (v[0] is String)
-                    "--esal"
-                else
-                    continue  /* Unsupported */
-
-                val sb = StringBuilder()
-                for (o in v) {
-                    sb.append(o.toString().replace(",", "\\,"))
-                    sb.append(',')
+            when {
+                v is String -> arg = "--es"
+                v is Boolean -> arg = "--ez"
+                v is Int -> arg = "--ei"
+                v is Long -> arg = "--el"
+                v is Float -> arg = "--ef"
+                v is Uri -> arg = "--eu"
+                v is ComponentName -> {
+                    arg = "--ecn"
+                    value = v.flattenToString()
                 }
-                // Remove trailing comma
-                sb.deleteCharAt(sb.length - 1)
-                value = sb
-            } else if (v.javaClass.isArray) {
-                arg = if (v is IntArray)
-                    "--eia"
-                else if (v is LongArray)
-                    "--ela"
-                else if (v is FloatArray)
-                    "--efa"
-                else if (v is Array<*> && v.isArrayOf<String>())
-                    "--esa"
-                else
-                    continue  /* Unsupported */
+                v is ArrayList<*> -> {
+                    if (v.size <= 0)
+                    /* Impossible to know the type due to type erasure */
+                        continue@loop
 
-                val sb = StringBuilder()
-                val len = RArray.getLength(v)
-                for (i in 0 until len) {
-                    sb.append(RArray.get(v, i)!!.toString().replace(",", "\\,"))
-                    sb.append(',')
+                    arg = if (v[0] is Int)
+                        "--eial"
+                    else if (v[0] is Long)
+                        "--elal"
+                    else if (v[0] is Float)
+                        "--efal"
+                    else if (v[0] is String)
+                        "--esal"
+                    else
+                        continue@loop  /* Unsupported */
+
+                    val sb = StringBuilder()
+                    for (o in v) {
+                        sb.append(o.toString().replace(",", "\\,"))
+                        sb.append(',')
+                    }
+                    // Remove trailing comma
+                    sb.deleteCharAt(sb.length - 1)
+                    value = sb
                 }
-                // Remove trailing comma
-                sb.deleteCharAt(sb.length - 1)
-                value = sb
-            } else
-                continue  /* Unsupported */
+                v.javaClass.isArray -> {
+                    arg = if (v is IntArray)
+                        "--eia"
+                    else if (v is LongArray)
+                        "--ela"
+                    else if (v is FloatArray)
+                        "--efa"
+                    else if (v is Array<*> && v.isArrayOf<String>())
+                        "--esa"
+                    else
+                        continue@loop  /* Unsupported */
+
+                    val sb = StringBuilder()
+                    val len = RArray.getLength(v)
+                    for (i in 0 until len) {
+                        sb.append(RArray.get(v, i)!!.toString().replace(",", "\\,"))
+                        sb.append(',')
+                    }
+                    // Remove trailing comma
+                    sb.deleteCharAt(sb.length - 1)
+                    value = sb
+                }
+                else -> continue@loop
+            }  /* Unsupported */
 
             args.add(arg)
             args.add(key)
@@ -153,10 +151,12 @@ class RootUtils : Shell.Initializer() {
 
     companion object {
 
+        @JvmStatic
         fun rmAndLaunch(rm: String, component: ComponentName) {
             Shell.su("(rm_launch $rm ${component.flattenToString()})").exec()
         }
 
+        @JvmStatic
         fun reboot() {
             Shell.su("/system/bin/reboot ${if (Config.recovery) "recovery" else ""}").submit()
         }
diff --git a/app/src/main/java/com/topjohnwu/magisk/utils/ZipUtils.kt b/app/src/main/java/com/topjohnwu/magisk/utils/ZipUtils.kt
index 80a90a13a..322750717 100644
--- a/app/src/main/java/com/topjohnwu/magisk/utils/ZipUtils.kt
+++ b/app/src/main/java/com/topjohnwu/magisk/utils/ZipUtils.kt
@@ -9,16 +9,16 @@ import java.util.zip.ZipEntry
 import java.util.zip.ZipInputStream
 
 @Throws(IOException::class)
-fun unzip(zip: File, folder: File, path: String = "", junkPath: Boolean = false) {
-    zip.inputStream().buffered().use {
-        unzip(it, folder, path, junkPath)
+fun File.unzip(folder: File, path: String = "", junkPath: Boolean = false) {
+    inputStream().buffered().use {
+        it.unzip(folder, path, junkPath)
     }
 }
 
 @Throws(IOException::class)
-fun unzip(zip: InputStream, folder: File, path: String, junkPath: Boolean) {
+fun InputStream.unzip(folder: File, path: String, junkPath: Boolean) {
     try {
-        val zin = ZipInputStream(zip)
+        val zin = ZipInputStream(this)
         var entry: ZipEntry
         while (true) {
             entry = zin.nextEntry ?: break
diff --git a/app/src/main/java/com/topjohnwu/magisk/view/dialogs/EnvFixDialog.java b/app/src/main/java/com/topjohnwu/magisk/view/dialogs/EnvFixDialog.java
index aff566fb3..95e1364b6 100644
--- a/app/src/main/java/com/topjohnwu/magisk/view/dialogs/EnvFixDialog.java
+++ b/app/src/main/java/com/topjohnwu/magisk/view/dialogs/EnvFixDialog.java
@@ -4,8 +4,6 @@ import android.app.Activity;
 import android.app.ProgressDialog;
 import android.widget.Toast;
 
-import androidx.annotation.NonNull;
-
 import com.topjohnwu.magisk.R;
 import com.topjohnwu.magisk.tasks.MagiskInstaller;
 import com.topjohnwu.magisk.utils.RootUtils;
@@ -14,6 +12,8 @@ import com.topjohnwu.superuser.Shell;
 import com.topjohnwu.superuser.internal.UiThreadHandler;
 import com.topjohnwu.superuser.io.SuFile;
 
+import androidx.annotation.NonNull;
+
 public class EnvFixDialog extends CustomAlertDialog {
 
     public EnvFixDialog(@NonNull Activity activity) {
@@ -38,7 +38,7 @@ public class EnvFixDialog extends CustomAlertDialog {
                     pd.dismiss();
                     Utils.toast(success ? R.string.reboot_delay_toast : R.string.setup_fail, Toast.LENGTH_LONG);
                     if (success)
-                        UiThreadHandler.handler.postDelayed(RootUtils.Companion::reboot, 5000);
+                        UiThreadHandler.handler.postDelayed(RootUtils::reboot, 5000);
                 }
             }.exec();
         });