KeepAlive foreground service

BUILD.md

@@ -52,7 +52,7 @@ $ wget https://openssl.org/source/openssl-3.3.1.tar.gz
 ```
 Verify OpenSSL signature:
 ```
-$ https://openssl.org/source/openssl-3.3.1.tar.gz.asc
+$ wget https://openssl.org/source/openssl-3.3.1.tar.gz.asc
 $ gpg --verify openssl-3.3.1.tar.gz.asc openssl-3.3.1.tar.gz
 ```
 Continue **ONLY** if the signature is **VALID**.

TODO.md

@@ -8,7 +8,8 @@ Here's a list of features that it would be nice to have in DroidFS. As this is a
 
 ## UX
 - File associations editor
-- Optional discovery before file operations
+- Discovery before exporting
+- Making discovery before file operations optional
 - Modifiable CryFS scrypt parameters
 - Alert dialog showing details of file operations
 - Internal file browser to select volumes

app/src/main/AndroidManifest.xml

@@ -58,10 +58,11 @@
         <activity android:name=".CameraActivity" android:screenOrientation="nosensor" />
         <activity android:name=".LogcatActivity"/>
 
-        <service android:name=".WiperService" android:exported="false" android:stopWithTask="false"/>
+        <service android:name=".KeepAliveService" android:exported="false" android:foregroundServiceType="dataSync" />
+        <service android:name=".ClosingService" android:exported="false" android:stopWithTask="false"/>
         <service android:name=".file_operations.FileOperationService" android:exported="false" android:foregroundServiceType="dataSync"/>
 
-        <receiver android:name=".file_operations.NotificationBroadcastReceiver" android:exported="false">
+        <receiver android:name=".NotificationBroadcastReceiver" android:exported="false">
             <intent-filter>
                 <action android:name="file_operation_cancel"/>
             </intent-filter>

app/src/main/java/sushi/hardcore/droidfs/BaseActivity.kt

@@ -4,6 +4,7 @@ import android.content.SharedPreferences
 import android.os.Bundle
 import android.view.WindowManager
 import androidx.appcompat.app.AppCompatActivity
+import androidx.preference.PreferenceManager
 
 open class BaseActivity: AppCompatActivity() {
     protected lateinit var sharedPrefs: SharedPreferences
@@ -12,7 +13,7 @@ open class BaseActivity: AppCompatActivity() {
 
     override fun onCreate(savedInstanceState: Bundle?) {
         super.onCreate(savedInstanceState)
-        sharedPrefs = (application as VolumeManagerApp).sharedPreferences
+        sharedPrefs = PreferenceManager.getDefaultSharedPreferences(this)
         theme = Theme.fromSharedPrefs(sharedPrefs)
         if (applyCustomTheme) {
             setTheme(theme.toResourceId())

app/src/main/java/sushi/hardcore/droidfs/CameraActivity.kt

@@ -7,7 +7,10 @@ import android.os.Build
 import android.os.Bundle
 import android.text.InputType
 import android.util.Size
-import android.view.*
+import android.view.MotionEvent
+import android.view.ScaleGestureDetector
+import android.view.Surface
+import android.view.View
 import android.view.animation.Animation
 import android.view.animation.LinearInterpolator
 import android.view.animation.RotateAnimation
@@ -42,8 +45,8 @@ import kotlinx.coroutines.delay
 import kotlinx.coroutines.launch
 import sushi.hardcore.droidfs.databinding.ActivityCameraBinding
 import sushi.hardcore.droidfs.filesystems.EncryptedVolume
-import sushi.hardcore.droidfs.util.IntentUtils
 import sushi.hardcore.droidfs.util.PathUtils
+import sushi.hardcore.droidfs.util.finishOnClose
 import sushi.hardcore.droidfs.video_recording.AsynchronousSeekableWriter
 import sushi.hardcore.droidfs.video_recording.FFmpegMuxer
 import sushi.hardcore.droidfs.video_recording.SeekableWriter
@@ -52,7 +55,9 @@ import sushi.hardcore.droidfs.widgets.EditTextDialog
 import java.io.ByteArrayInputStream
 import java.io.ByteArrayOutputStream
 import java.text.SimpleDateFormat
-import java.util.*
+import java.util.Date
+import java.util.Locale
+import java.util.Random
 import java.util.concurrent.Executor
 import kotlin.math.pow
 import kotlin.math.sqrt
@@ -113,7 +118,10 @@ class CameraActivity : BaseActivity(), SensorOrientationListener.Listener {
         binding = ActivityCameraBinding.inflate(layoutInflater)
         setContentView(binding.root)
         supportActionBar?.hide()
-        encryptedVolume = IntentUtils.getParcelableExtra(intent, "volume")!!
+        encryptedVolume = (application as VolumeManagerApp).volumeManager.getVolume(
+            intent.getIntExtra("volumeId", -1)
+        )!!
+        finishOnClose(encryptedVolume)
         outputDirectory = intent.getStringExtra("path")!!
 
         if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.M) {
@@ -577,12 +585,8 @@ class CameraActivity : BaseActivity(), SensorOrientationListener.Listener {
 
     override fun onResume() {
         super.onResume()
-        if (encryptedVolume.isClosed()) {
-            finish()
-        } else {
         sensorOrientationListener.addListener(this)
     }
-    }
 
     override fun onOrientationChange(newOrientation: Int) {
         val realOrientation = when (newOrientation) {

app/src/main/java/sushi/hardcore/droidfs/ClosingService.kt

@@ -0,0 +1,20 @@
+package sushi.hardcore.droidfs
+
+import android.app.Service
+import android.content.Intent
+
+/**
+ * Dummy background service listening for application task removal in order to
+ * close all volumes still open on quit.
+ *
+ * Should only be running when usfBackground is enabled AND usfKeepOpen is disabled.
+ */
+class ClosingService : Service() {
+    override fun onBind(intent: Intent) = null
+
+    override fun onTaskRemoved(rootIntent: Intent) {
+        super.onTaskRemoved(rootIntent)
+        (application as VolumeManagerApp).volumeManager.closeAll()
+        stopSelf()
+    }
+}

app/src/main/java/sushi/hardcore/droidfs/KeepAliveService.kt

@@ -0,0 +1,120 @@
+package sushi.hardcore.droidfs
+
+import android.app.Notification
+import android.app.NotificationChannel
+import android.app.NotificationManager
+import android.app.PendingIntent
+import android.app.Service
+import android.content.Intent
+import android.content.pm.ServiceInfo
+import android.os.Build
+import android.os.Parcel
+import android.os.Parcelable
+import androidx.core.app.NotificationCompat
+import androidx.core.app.NotificationManagerCompat
+import androidx.core.app.ServiceCompat
+import androidx.core.content.IntentCompat
+
+class KeepAliveService: Service() {
+    internal class NotificationDetails(
+        val channel: String,
+        val title: String,
+        val text: String,
+        val action: NotificationAction,
+    ) : Parcelable {
+        internal class NotificationAction(
+            val icon: Int,
+            val title: String,
+            val action: String,
+        )
+
+        constructor(parcel: Parcel) : this(
+            parcel.readString()!!,
+            parcel.readString()!!,
+            parcel.readString()!!,
+            NotificationAction(
+                parcel.readInt(),
+                parcel.readString()!!,
+                parcel.readString()!!,
+            )
+        )
+
+        override fun writeToParcel(parcel: Parcel, flags: Int) {
+            with (parcel) {
+                writeString(channel)
+                writeString(title)
+                writeString(text)
+                writeInt(action.icon)
+                writeString(action.title)
+                writeString(action.action)
+            }
+        }
+
+        override fun describeContents() = 0
+
+        companion object CREATOR : Parcelable.Creator<NotificationDetails> {
+            override fun createFromParcel(parcel: Parcel) = NotificationDetails(parcel)
+            override fun newArray(size: Int) = arrayOfNulls<NotificationDetails>(size)
+        }
+
+    }
+
+    companion object {
+        const val ACTION_START = "start"
+
+        /**
+         * If [startForeground] is called before notification permission is granted,
+         * the notification won't appear.
+         *
+         * This action can be used once the permission is granted, to make the service
+         * call [startForeground] again in order to properly show the notification.
+         */
+        const val ACTION_FOREGROUND = "foreground"
+        const val NOTIFICATION_CHANNEL_ID = "KeepAlive"
+    }
+
+    private val notificationManager by lazy {
+        NotificationManagerCompat.from(this)
+    }
+    private var notification: Notification? = null
+
+    override fun onBind(intent: Intent?) = null
+
+    override fun onStartCommand(intent: Intent, flags: Int, startId: Int): Int {
+        if (intent.action == ACTION_START) {
+            val notificationDetails = IntentCompat.getParcelableExtra(intent, "notification", NotificationDetails::class.java)!!
+            if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.O) {
+                notificationManager.createNotificationChannel(
+                    NotificationChannel(
+                        NOTIFICATION_CHANNEL_ID,
+                        notificationDetails.channel,
+                        NotificationManager.IMPORTANCE_LOW
+                    )
+                )
+            }
+            notification = NotificationCompat.Builder(this, NOTIFICATION_CHANNEL_ID)
+                .setSmallIcon(R.drawable.ic_notification)
+                .setContentTitle(notificationDetails.title)
+                .setContentText(notificationDetails.text)
+                .addAction(NotificationCompat.Action(
+                    notificationDetails.action.icon,
+                    notificationDetails.action.title,
+                    PendingIntent.getBroadcast(
+                        this,
+                        0,
+                        Intent(this, NotificationBroadcastReceiver::class.java).apply {
+                            action = notificationDetails.action.action
+                        },
+                        PendingIntent.FLAG_IMMUTABLE
+                    )
+                ))
+                .build()
+        }
+        ServiceCompat.startForeground(this, startId, notification!!, if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.R) {
+            ServiceInfo.FOREGROUND_SERVICE_TYPE_DATA_SYNC // is there a better use case flag?
+        } else {
+            0
+        })
+        return START_NOT_STICKY
+    }
+}

app/src/main/java/sushi/hardcore/droidfs/MainActivity.kt

@@ -1,12 +1,8 @@
 package sushi.hardcore.droidfs
 
-import android.content.ComponentName
-import android.content.Context
 import android.content.Intent
-import android.content.ServiceConnection
 import android.net.Uri
 import android.os.Bundle
-import android.os.IBinder
 import android.view.Menu
 import android.view.MenuItem
 import android.view.View
@@ -131,7 +127,6 @@ class MainActivity : BaseActivity(), VolumeAdapter.Listener {
                 }
             }
         }
-        startService(Intent(this, WiperService::class.java))
         FileOperationService.bind(this) {
             fileOperationService = it
         }
@@ -184,9 +179,7 @@ class MainActivity : BaseActivity(), VolumeAdapter.Listener {
     }
 
     private fun unselect(position: Int) {
-        volumeAdapter.selectedItems.remove(position)
+        volumeAdapter.unselect(position)
-        volumeAdapter.onVolumeChanged(position)
-        onSelectionChanged(0) // unselect() is always called when only one element is selected
         invalidateOptionsMenu()
     }
 
@@ -285,7 +278,7 @@ class MainActivity : BaseActivity(), VolumeAdapter.Listener {
             R.id.delete_password_hash -> {
                 for (i in volumeAdapter.selectedItems) {
                     if (volumeDatabase.removeHash(volumeAdapter.volumes[i]))
-                        volumeAdapter.onVolumeChanged(i)
+                        volumeAdapter.onVolumeDataChanged(i)
                 }
                 unselectAll(false)
                 true
@@ -475,6 +468,7 @@ class MainActivity : BaseActivity(), VolumeAdapter.Listener {
             if (success) {
                 volumeDatabase.renameVolume(volume, newDBName)
                 VolumeProvider.notifyRootsChanged(this)
+                volumeAdapter.onVolumeDataChanged(position)
                 unselect(position)
                 if (volume.name == volumeOpener.defaultVolumeName) {
                     with (sharedPrefs.edit()) {

app/src/main/java/sushi/hardcore/droidfs/NotificationBroadcastReceiver.kt

@@ -0,0 +1,23 @@
+package sushi.hardcore.droidfs
+
+import android.content.BroadcastReceiver
+import android.content.Context
+import android.content.Intent
+import sushi.hardcore.droidfs.file_operations.FileOperationService
+
+class NotificationBroadcastReceiver: BroadcastReceiver() {
+    override fun onReceive(context: Context, intent: Intent) {
+        when (intent.action) {
+            FileOperationService.ACTION_CANCEL -> {
+                intent.getBundleExtra("bundle")?.let { bundle ->
+                    // TODO: use peekService instead?
+                    val binder = (bundle.getBinder("binder") as FileOperationService.LocalBinder?)
+                    binder?.getService()?.cancelOperation(bundle.getInt("taskId"))
+                }
+            }
+            VolumeManagerApp.ACTION_CLOSE_ALL_VOLUMES -> {
+                (context.applicationContext as VolumeManagerApp).volumeManager.closeAll()
+            }
+        }
+    }
+}

app/src/main/java/sushi/hardcore/droidfs/SettingsActivity.kt

@@ -8,21 +8,23 @@ import android.os.Bundle
 import android.text.InputType
 import android.view.MenuItem
 import android.widget.Toast
+import androidx.core.content.ContextCompat
 import androidx.preference.ListPreference
 import androidx.preference.Preference
 import androidx.preference.PreferenceFragmentCompat
 import androidx.preference.PreferenceManager
 import androidx.preference.SwitchPreference
 import androidx.preference.SwitchPreferenceCompat
-import sushi.hardcore.droidfs.content_providers.TemporaryFileProvider
 import sushi.hardcore.droidfs.content_providers.VolumeProvider
 import sushi.hardcore.droidfs.databinding.ActivitySettingsBinding
+import sushi.hardcore.droidfs.util.AndroidUtils
 import sushi.hardcore.droidfs.util.Compat
 import sushi.hardcore.droidfs.util.PathUtils
 import sushi.hardcore.droidfs.widgets.CustomAlertDialogBuilder
 import sushi.hardcore.droidfs.widgets.EditTextDialog
 
 class SettingsActivity : BaseActivity() {
+    private val notificationPermissionHelper = AndroidUtils.NotificationPermissionHelper(this)
 
     override fun onCreate(savedInstanceState: Bundle?) {
         super.onCreate(savedInstanceState)
@@ -169,20 +171,23 @@ class SettingsActivity : BaseActivity() {
                     true
                 }
             }
+            val switchBackground = findPreference<SwitchPreference>("usf_background")!!
             val switchKeepOpen = findPreference<SwitchPreference>("usf_keep_open")!!
             val switchExternalOpen = findPreference<SwitchPreference>("usf_open")!!
             val switchExpose = findPreference<SwitchPreference>("usf_expose")!!
             val switchSafWrite = findPreference<SwitchPreference>("usf_saf_write")!!
 
-            fun updateView(usfOpen: Boolean? = null, usfKeepOpen: Boolean? = null, usfExpose: Boolean? = null) {
+            fun updateView(usfOpen: Boolean? = null, usfBackground: Boolean? = null, usfExpose: Boolean? = null) {
-                val usfKeepOpen = usfKeepOpen ?: switchKeepOpen.isChecked
+                val usfBackground = usfBackground ?: switchBackground.isChecked
-                switchExpose.isEnabled = usfKeepOpen
+                switchKeepOpen.isEnabled = usfBackground
-                switchSafWrite.isEnabled = usfOpen ?: switchExternalOpen.isChecked || (usfKeepOpen && usfExpose ?: switchExpose.isChecked)
+                switchExpose.isEnabled = usfBackground
+                switchSafWrite.isEnabled = usfOpen ?: switchExternalOpen.isChecked || (usfBackground && usfExpose ?: switchExpose.isChecked)
             }
 
             updateView()
-            switchKeepOpen.setOnPreferenceChangeListener { _, checked ->
+            switchBackground.setOnPreferenceChangeListener { _, checked ->
-                updateView(usfKeepOpen = checked as Boolean)
+                updateView(usfBackground = checked as Boolean)
+                switchKeepOpen.isChecked = switchKeepOpen.isChecked && checked
                 true
             }
             switchExternalOpen.setOnPreferenceChangeListener { _, checked ->
@@ -190,17 +195,25 @@ class SettingsActivity : BaseActivity() {
                 true
             }
             switchExpose.setOnPreferenceChangeListener { _, checked ->
-                VolumeProvider.usfExpose = checked as Boolean
+                updateView(usfExpose = checked as Boolean)
-                updateView(usfExpose = checked)
                 VolumeProvider.notifyRootsChanged(requireContext())
                 true
             }
-            switchSafWrite.setOnPreferenceChangeListener { _, checked ->
+
-                VolumeProvider.usfSafWrite = checked as Boolean
+            switchKeepOpen.setOnPreferenceChangeListener { _, checked ->
-                TemporaryFileProvider.usfSafWrite = checked
+                if (checked as Boolean) {
+                    (requireActivity() as SettingsActivity).notificationPermissionHelper.askAndRun {
+                        requireContext().let {
+                            if (AndroidUtils.isServiceRunning(it, KeepAliveService::class.java)) {
+                                ContextCompat.startForegroundService(it, Intent(it, KeepAliveService::class.java).apply {
+                                    action = KeepAliveService.ACTION_FOREGROUND
+                                })
+                            }
+                        }
+                    }
+                }
                 true
             }
-
             findPreference<ListPreference>("export_method")!!.setOnPreferenceChangeListener { _, newValue ->
                 if (newValue as String == "memory" && !Compat.isMemFileSupported()) {
                     CustomAlertDialogBuilder(requireContext(), (requireActivity() as BaseActivity).theme)

app/src/main/java/sushi/hardcore/droidfs/VolumeManager.kt

@@ -7,8 +7,14 @@ import kotlinx.coroutines.SupervisorJob
 import kotlinx.coroutines.cancel
 import sushi.hardcore.droidfs.content_providers.VolumeProvider
 import sushi.hardcore.droidfs.filesystems.EncryptedVolume
+import sushi.hardcore.droidfs.util.Observable
+
+class VolumeManager(private val context: Context): Observable<VolumeManager.Observer>() {
+    interface Observer {
+        fun onVolumeStateChanged(volume: VolumeData) {}
+        fun onAllVolumesClosed() {}
+    }
 
-class VolumeManager(private val context: Context) {
     private var id = 0
     private val volumes = HashMap<Int, EncryptedVolume>()
     private val volumesData = HashMap<VolumeData, Int>()
@@ -17,6 +23,7 @@ class VolumeManager(private val context: Context) {
     fun insert(volume: EncryptedVolume, data: VolumeData): Int {
         volumes[id] = volume
         volumesData[data] = id
+        observers.forEach { it.onVolumeStateChanged(data) }
         VolumeProvider.notifyRootsChanged(context)
         return id++
     }
@@ -37,6 +44,8 @@ class VolumeManager(private val context: Context) {
         return volumesData.map { (data, id) -> Pair(id, data) }
     }
 
+    fun getVolumeCount() = volumes.size
+
     fun getCoroutineScope(volumeId: Int): CoroutineScope {
         return scopes[volumeId] ?: CoroutineScope(SupervisorJob() + Dispatchers.IO).also { scopes[volumeId] = it }
     }
@@ -44,9 +53,10 @@ class VolumeManager(private val context: Context) {
     fun closeVolume(id: Int) {
         volumes.remove(id)?.let { volume ->
             scopes[id]?.cancel()
-            volume.close()
+            volume.closeVolume()
-            volumesData.filter { it.value == id }.forEach {
+            volumesData.filter { it.value == id }.forEach { entry ->
-                volumesData.remove(it.key)
+                volumesData.remove(entry.key)
+                observers.forEach { it.onVolumeStateChanged(entry.key) }
             }
             VolumeProvider.notifyRootsChanged(context)
         }
@@ -55,10 +65,11 @@ class VolumeManager(private val context: Context) {
     fun closeAll() {
         volumes.forEach {
             scopes[it.key]?.cancel()
-            it.value.close()
+            it.value.closeVolume()
         }
         volumes.clear()
         volumesData.clear()
+        observers.forEach { it.onAllVolumesClosed() }
         VolumeProvider.notifyRootsChanged(context)
     }
 }

app/src/main/java/sushi/hardcore/droidfs/VolumeManagerApp.kt

@@ -1,40 +1,88 @@
 package sushi.hardcore.droidfs
 
 import android.app.Application
-import android.content.SharedPreferences
+import android.content.Intent
+import androidx.core.content.ContextCompat
 import androidx.lifecycle.DefaultLifecycleObserver
 import androidx.lifecycle.LifecycleOwner
 import androidx.lifecycle.ProcessLifecycleOwner
-import androidx.preference.PreferenceManager
 import sushi.hardcore.droidfs.content_providers.TemporaryFileProvider
+import sushi.hardcore.droidfs.util.AndroidUtils
 
 class VolumeManagerApp : Application(), DefaultLifecycleObserver {
     companion object {
-        private const val USF_KEEP_OPEN_KEY = "usf_keep_open"
+        const val ACTION_CLOSE_ALL_VOLUMES = "close_all"
     }
 
-    lateinit var sharedPreferences: SharedPreferences
+    private val closingServiceIntent by lazy {
-    private val sharedPreferencesListener = SharedPreferences.OnSharedPreferenceChangeListener { _, key ->
+        Intent(this, ClosingService::class.java)
-        if (key == USF_KEEP_OPEN_KEY) {
-            reloadUsfKeepOpen()
     }
+    private val keepAliveServiceStartIntent by lazy {
+        Intent(this, KeepAliveService::class.java).apply {
+            action = KeepAliveService.ACTION_START
+        }.putExtra(
+            "notification", KeepAliveService.NotificationDetails(
+                "KeepAlive",
+                getString(R.string.keep_alive_notification_title),
+                getString(R.string.keep_alive_notification_text),
+                KeepAliveService.NotificationDetails.NotificationAction(
+                    R.drawable.icon_lock,
+                    getString(R.string.close_all),
+                    ACTION_CLOSE_ALL_VOLUMES,
+                )
+            )
+        )
     }
-    private var usfKeepOpen = false
+    private val usfBackgroundDelegate = AndroidUtils.LiveBooleanPreference("usf_background", false) { _ ->
+        updateServicesStates()
+    }
+    private val usfBackground by usfBackgroundDelegate
+    private val usfKeepOpenDelegate = AndroidUtils.LiveBooleanPreference("usf_keep_open", false) { _ ->
+        updateServicesStates()
+    }
+    private val usfKeepOpen by usfKeepOpenDelegate
     var isExporting = false
     var isStartingExternalApp = false
-    val volumeManager = VolumeManager(this)
+    val volumeManager = VolumeManager(this).also {
+        it.observe(object : VolumeManager.Observer {
+            override fun onVolumeStateChanged(volume: VolumeData) {
+                updateServicesStates()
+            }
+
+            override fun onAllVolumesClosed() {
+                stopKeepAliveService()
+                // closingService should not be running when this callback is triggered
+            }
+        })
+    }
 
     override fun onCreate() {
         super<Application>.onCreate()
         ProcessLifecycleOwner.get().lifecycle.addObserver(this)
-        sharedPreferences = PreferenceManager.getDefaultSharedPreferences(this).apply {
+        AndroidUtils.LiveBooleanPreference.init(this, usfBackgroundDelegate, usfKeepOpenDelegate)
-            registerOnSharedPreferenceChangeListener(sharedPreferencesListener)
-        }
-        reloadUsfKeepOpen()
     }
 
-    private fun reloadUsfKeepOpen() {
+    fun updateServicesStates() {
-        usfKeepOpen = sharedPreferences.getBoolean(USF_KEEP_OPEN_KEY, false)
+        if (usfBackground && volumeManager.getVolumeCount() > 0) {
+            if (usfKeepOpen) {
+                stopService(closingServiceIntent)
+                if (!AndroidUtils.isServiceRunning(this@VolumeManagerApp, KeepAliveService::class.java)) {
+                    ContextCompat.startForegroundService(this, keepAliveServiceStartIntent)
+                }
+            } else {
+                stopKeepAliveService()
+                if (!AndroidUtils.isServiceRunning(this@VolumeManagerApp, ClosingService::class.java)) {
+                    startService(closingServiceIntent)
+                }
+            }
+        } else {
+            stopService(closingServiceIntent)
+            stopKeepAliveService()
+        }
+    }
+
+    private fun stopKeepAliveService() {
+        stopService(Intent(this, KeepAliveService::class.java))
     }
 
     override fun onResume(owner: LifecycleOwner) {
@@ -43,10 +91,10 @@ class VolumeManagerApp : Application(), DefaultLifecycleObserver {
 
     override fun onStop(owner: LifecycleOwner) {
         if (!isStartingExternalApp) {
-            if (!usfKeepOpen) {
+            if (!usfBackground) {
                 volumeManager.closeAll()
             }
-            if (!usfKeepOpen || !isExporting) {
+            if (!usfBackground || !isExporting) {
                 TemporaryFileProvider.instance.wipe()
             }
         }

app/src/main/java/sushi/hardcore/droidfs/VolumeOpener.kt

@@ -211,7 +211,7 @@ class VolumeOpener(
                         private var isClosed = false
                         override fun onFailed(pending: Boolean) {
                             if (!isClosed) {
-                                encryptedVolume.close()
+                                encryptedVolume.closeVolume()
                                 isClosed = true
                             }
                             Arrays.fill(returnedHash.value!!, 0)

app/src/main/java/sushi/hardcore/droidfs/WiperService.kt

@@ -1,17 +0,0 @@
-package sushi.hardcore.droidfs
-
-import android.app.Service
-import android.content.Intent
-import android.os.IBinder
-
-class WiperService : Service() {
-    override fun onBind(intent: Intent): IBinder? {
-        return null
-    }
-
-    override fun onTaskRemoved(rootIntent: Intent) {
-        super.onTaskRemoved(rootIntent)
-        (application as VolumeManagerApp).volumeManager.closeAll()
-        stopSelf()
-    }
-}

app/src/main/java/sushi/hardcore/droidfs/adapters/SelectableAdapter.kt

@@ -40,6 +40,12 @@ abstract class SelectableAdapter<T>(private val onSelectionChanged: (Int) -> Uni
         return true
     }
 
+    fun unselect(position: Int) {
+        selectedItems.remove(position)
+        onSelectionChanged(selectedItems.size)
+        notifyItemChanged(position)
+    }
+
     fun selectAll() {
         for (i in getItems().indices) {
             if (!selectedItems.contains(i) && isSelectable(i)) {

app/src/main/java/sushi/hardcore/droidfs/adapters/VolumeAdapter.kt

@@ -29,6 +29,16 @@ class VolumeAdapter(
 
     init {
         reloadVolumes()
+        volumeManager.observe(object : VolumeManager.Observer {
+            override fun onVolumeStateChanged(volume: VolumeData) {
+                notifyItemChanged(volumes.indexOf(volume))
+            }
+
+            @SuppressLint("NotifyDataSetChanged")
+            override fun onAllVolumesClosed() {
+                notifyDataSetChanged()
+            }
+        })
     }
 
     interface Listener {
@@ -66,7 +76,7 @@ class VolumeAdapter(
             false
     }
 
-    fun onVolumeChanged(position: Int) {
+    fun onVolumeDataChanged(position: Int) {
         reloadVolumes()
         notifyItemChanged(position)
     }

app/src/main/java/sushi/hardcore/droidfs/content_providers/TemporaryFileProvider.kt

@@ -10,7 +10,6 @@ import android.os.ParcelFileDescriptor
 import android.provider.OpenableColumns
 import android.util.Log
 import android.webkit.MimeTypeMap
-import androidx.preference.PreferenceManager
 import kotlinx.coroutines.Dispatchers
 import kotlinx.coroutines.GlobalScope
 import kotlinx.coroutines.launch
@@ -18,6 +17,7 @@ import sushi.hardcore.droidfs.BuildConfig
 import sushi.hardcore.droidfs.EncryptedFileProvider
 import sushi.hardcore.droidfs.VolumeManager
 import sushi.hardcore.droidfs.VolumeManagerApp
+import sushi.hardcore.droidfs.util.AndroidUtils
 import sushi.hardcore.droidfs.util.Wiper
 import java.io.File
 import java.util.UUID
@@ -36,9 +36,10 @@ class TemporaryFileProvider : ContentProvider() {
 
         lateinit var instance: TemporaryFileProvider
             private set
-        var usfSafWrite = false
     }
 
+    private val usfSafWriteDelegate = AndroidUtils.LiveBooleanPreference("usf_saf_write", false)
+    private val usfSafWrite by usfSafWriteDelegate
     private lateinit var volumeManager: VolumeManager
     lateinit var encryptedFileProvider: EncryptedFileProvider
     private val files = HashMap<Uri, ProvidedFile>()
@@ -46,8 +47,7 @@ class TemporaryFileProvider : ContentProvider() {
     override fun onCreate(): Boolean {
         return context?.let {
             volumeManager = (it.applicationContext as VolumeManagerApp).volumeManager
-            usfSafWrite =
+            usfSafWriteDelegate.init(it)
-                PreferenceManager.getDefaultSharedPreferences(it).getBoolean("usf_saf_write", false)
             encryptedFileProvider = EncryptedFileProvider(it)
             instance = this
             val tmpFilesDir = EncryptedFileProvider.getTmpFilesDir(it)

app/src/main/java/sushi/hardcore/droidfs/content_providers/VolumeProvider.kt

@@ -18,6 +18,7 @@ import sushi.hardcore.droidfs.VolumeManager
 import sushi.hardcore.droidfs.VolumeManagerApp
 import sushi.hardcore.droidfs.filesystems.EncryptedVolume
 import sushi.hardcore.droidfs.filesystems.Stat
+import sushi.hardcore.droidfs.util.AndroidUtils
 import sushi.hardcore.droidfs.util.PathUtils
 import java.io.File
 
@@ -40,23 +41,23 @@ class VolumeProvider: DocumentsProvider() {
             DocumentsContract.Document.COLUMN_SIZE,
             DocumentsContract.Document.COLUMN_LAST_MODIFIED,
         )
-        var usfExpose = false
-        var usfSafWrite = false
 
         fun notifyRootsChanged(context: Context) {
             context.contentResolver.notifyChange(DocumentsContract.buildRootsUri(AUTHORITY), null)
         }
     }
 
+    private val usfExposeDelegate = AndroidUtils.LiveBooleanPreference("usf_expose", false)
+    private val usfExpose by usfExposeDelegate
+    private val usfSafWriteDelegate = AndroidUtils.LiveBooleanPreference("usf_saf_write", false)
+    private val usfSafWrite by usfSafWriteDelegate
     private lateinit var volumeManager: VolumeManager
     private val volumes = HashMap<String, Pair<Int, VolumeData>>()
     private lateinit var encryptedFileProvider: EncryptedFileProvider
 
     override fun onCreate(): Boolean {
         val context = (context ?: return false)
-        val sharedPreferences = PreferenceManager.getDefaultSharedPreferences(context)
+        AndroidUtils.LiveBooleanPreference.init(context, usfExposeDelegate, usfSafWriteDelegate)
-        usfExpose = sharedPreferences.getBoolean("usf_expose", false)
-        usfSafWrite = sharedPreferences.getBoolean("usf_saf_write", false)
         volumeManager = (context.applicationContext as VolumeManagerApp).volumeManager
         encryptedFileProvider = EncryptedFileProvider(context)
         return true

app/src/main/java/sushi/hardcore/droidfs/explorers/BaseExplorerActivity.kt

@@ -1,12 +1,8 @@
 package sushi.hardcore.droidfs.explorers
 
-import android.content.ComponentName
-import android.content.Context
 import android.content.Intent
-import android.content.ServiceConnection
 import android.net.Uri
 import android.os.Bundle
-import android.os.IBinder
 import android.view.Menu
 import android.view.MenuItem
 import android.view.View
@@ -15,7 +11,6 @@ import android.widget.ProgressBar
 import android.widget.TextView
 import android.widget.Toast
 import androidx.activity.addCallback
-import androidx.core.content.ContextCompat
 import androidx.core.view.isVisible
 import androidx.lifecycle.ViewModel
 import androidx.lifecycle.ViewModelProvider
@@ -27,7 +22,6 @@ import androidx.swiperefreshlayout.widget.SwipeRefreshLayout
 import kotlinx.coroutines.Dispatchers
 import kotlinx.coroutines.Job
 import kotlinx.coroutines.MainScope
-import kotlinx.coroutines.async
 import kotlinx.coroutines.cancel
 import kotlinx.coroutines.cancelAndJoin
 import kotlinx.coroutines.launch
@@ -55,6 +49,7 @@ import sushi.hardcore.droidfs.filesystems.EncryptedVolume
 import sushi.hardcore.droidfs.filesystems.Stat
 import sushi.hardcore.droidfs.util.PathUtils
 import sushi.hardcore.droidfs.util.UIUtils
+import sushi.hardcore.droidfs.util.finishOnClose
 import sushi.hardcore.droidfs.widgets.CustomAlertDialogBuilder
 import sushi.hardcore.droidfs.widgets.EditTextDialog
 
@@ -100,7 +95,7 @@ open class BaseExplorerActivity : BaseActivity(), ExplorerElementAdapter.Listene
         usf_open = sharedPrefs.getBoolean("usf_open", false)
         volumeName = intent.getStringExtra("volumeName") ?: ""
         volumeId = intent.getIntExtra("volumeId", -1)
-        encryptedVolume = app.volumeManager.getVolume(volumeId)!!
+        encryptedVolume = app.volumeManager.getVolume(volumeId)!!.also { finishOnClose(it) }
         sortOrderEntries = resources.getStringArray(R.array.sort_orders_entries)
         sortOrderValues = resources.getStringArray(R.array.sort_orders_values)
         foldersFirst = sharedPrefs.getBoolean("folders_first", true)
@@ -199,7 +194,7 @@ open class BaseExplorerActivity : BaseActivity(), ExplorerElementAdapter.Listene
     private fun startFileViewer(cls: Class<*>, filePath: String) {
         val intent = Intent(this, cls).apply {
             putExtra("path", filePath)
-            putExtra("volume", encryptedVolume)
+            putExtra("volumeId", volumeId)
             putExtra("sortOrder", sortOrderValues[currentSortOrderIndex])
         }
         startActivity(intent)
@@ -679,10 +674,6 @@ open class BaseExplorerActivity : BaseActivity(), ExplorerElementAdapter.Listene
         if (app.isStartingExternalApp) {
             TemporaryFileProvider.instance.wipe()
         }
-        if (encryptedVolume.isClosed()) {
-            finish()
-        } else {
         setCurrentPath(currentDirectoryPath)
     }
-    }
 }

app/src/main/java/sushi/hardcore/droidfs/explorers/ExplorerActivity.kt

@@ -181,7 +181,6 @@ class ExplorerActivity : BaseExplorerActivity() {
                             "importFromOtherVolumes" -> {
                                 val intent = Intent(this, MainActivity::class.java)
                                 intent.action = "pick"
-                                intent.putExtra("volume", encryptedVolume)
                                 pickFromOtherVolumes.launch(intent)
                             }
                             "importFiles" -> {
@@ -205,7 +204,7 @@ class ExplorerActivity : BaseExplorerActivity() {
                             "camera" -> {
                                 val intent = Intent(this, CameraActivity::class.java)
                                 intent.putExtra("path", currentDirectoryPath)
-                                intent.putExtra("volume", encryptedVolume)
+                                intent.putExtra("volumeId", volumeId)
                                 startActivity(intent)
                             }
                         }

app/src/main/java/sushi/hardcore/droidfs/file_operations/FileOperationService.kt

@@ -1,7 +1,5 @@
 package sushi.hardcore.droidfs.file_operations
 
-import android.Manifest
-import android.annotation.SuppressLint
 import android.app.Notification
 import android.app.NotificationChannel
 import android.app.NotificationManager
@@ -11,7 +9,6 @@ import android.content.ComponentName
 import android.content.Context
 import android.content.Intent
 import android.content.ServiceConnection
-import android.content.pm.PackageManager
 import android.content.pm.ServiceInfo
 import android.net.Uri
 import android.os.Binder
@@ -21,7 +18,6 @@ import android.os.IBinder
 import android.provider.Settings
 import android.util.Log
 import androidx.activity.result.ActivityResultLauncher
-import androidx.activity.result.contract.ActivityResultContracts
 import androidx.core.app.NotificationCompat
 import androidx.core.app.NotificationManagerCompat
 import androidx.core.app.ServiceCompat
@@ -39,12 +35,14 @@ import kotlinx.coroutines.withContext
 import kotlinx.coroutines.yield
 import sushi.hardcore.droidfs.BaseActivity
 import sushi.hardcore.droidfs.Constants
+import sushi.hardcore.droidfs.NotificationBroadcastReceiver
 import sushi.hardcore.droidfs.R
 import sushi.hardcore.droidfs.VolumeManager
 import sushi.hardcore.droidfs.VolumeManagerApp
 import sushi.hardcore.droidfs.explorers.ExplorerElement
 import sushi.hardcore.droidfs.filesystems.EncryptedVolume
 import sushi.hardcore.droidfs.filesystems.Stat
+import sushi.hardcore.droidfs.util.AndroidUtils
 import sushi.hardcore.droidfs.util.ObjRef
 import sushi.hardcore.droidfs.util.PathUtils
 import sushi.hardcore.droidfs.util.Wiper
@@ -91,32 +89,11 @@ class FileOperationService : Service() {
          * If multiple activities bind simultaneously, only the latest one will be used by the service.
          */
         fun bind(activity: BaseActivity, onBound: (FileOperationService) -> Unit) {
-            var service: FileOperationService? = null
+            val helper = AndroidUtils.NotificationPermissionHelper(activity)
-            val launcher = activity.registerForActivityResult(ActivityResultContracts.RequestPermission()) { granted ->
-                if (granted) {
-                    service!!.processPendingTask()
-                } else {
-                    CustomAlertDialogBuilder(activity, activity.theme)
-                        .setTitle(R.string.warning)
-                        .setMessage(R.string.notification_denied_msg)
-                        .setPositiveButton(R.string.settings) { _, _ ->
-                            activity.startActivity(
-                                Intent(
-                                    Settings.ACTION_APPLICATION_DETAILS_SETTINGS,
-                                    Uri.fromParts("package", activity.packageName, null)
-                                )
-                            )
-                        }
-                        .setNegativeButton(R.string.later, null)
-                        .setOnDismissListener { service!!.processPendingTask() }
-                        .show()
-                }
-            }
             activity.bindService(Intent(activity, FileOperationService::class.java), object : ServiceConnection {
                 override fun onServiceConnected(className: ComponentName, binder: IBinder) {
                     onBound((binder as FileOperationService.LocalBinder).getService().also {
-                        it.notificationPermissionLauncher = launcher
+                        it.notificationPermissionHelper = helper
-                        service = it
                     })
                 }
                 override fun onServiceDisconnected(arg0: ComponentName) {}
@@ -128,7 +105,7 @@ class FileOperationService : Service() {
     private val binder = LocalBinder()
     private lateinit var volumeManger: VolumeManager
     private var serviceScope = MainScope()
-    private lateinit var notificationPermissionLauncher: ActivityResultLauncher<String>
+    private lateinit var notificationPermissionHelper: AndroidUtils.NotificationPermissionHelper<BaseActivity>
     private var askForNotificationPermission = true
     private lateinit var notificationManager: NotificationManagerCompat
     private val notifications = HashMap<Int, NotificationCompat.Builder>()
@@ -315,19 +292,31 @@ class FileOperationService : Service() {
                 continuation.resume(Pair(taskId, job))
             }
             pendingTask = task
-            if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.TIRAMISU) {
+            if (askForNotificationPermission) {
-                if (
+                notificationPermissionHelper.askAndRun { granted ->
-                    ContextCompat.checkSelfPermission(
+                    if (granted) {
-                        this,
+                        processPendingTask()
-                        Manifest.permission.POST_NOTIFICATIONS
+                    } else {
-                    ) != PackageManager.PERMISSION_GRANTED
+                        CustomAlertDialogBuilder(notificationPermissionHelper.activity, notificationPermissionHelper.activity.theme)
-                    && askForNotificationPermission
+                            .setTitle(R.string.warning)
-                ) {
+                            .setMessage(R.string.notification_denied_msg)
-                    notificationPermissionLauncher.launch(Manifest.permission.POST_NOTIFICATIONS)
+                            .setPositiveButton(R.string.settings) { _, _ ->
+                                (application as VolumeManagerApp).isStartingExternalApp = true
+                                notificationPermissionHelper.activity.startActivity(
+                                    Intent(
+                                        Settings.ACTION_APPLICATION_DETAILS_SETTINGS,
+                                        Uri.fromParts("package", packageName, null)
+                                    )
+                                )
+                            }
+                            .setNegativeButton(R.string.later, null)
+                            .setOnDismissListener { processPendingTask() }
+                            .show()
+                    }
+                }
                 askForNotificationPermission = false // only ask once per service instance
                 return@suspendCoroutine
             }
-            }
             processPendingTask()
         }
         return waitForTask(startedTask.first, startedTask.second, onCancelled)

app/src/main/java/sushi/hardcore/droidfs/file_operations/NotificationBroadcastReceiver.kt

@@ -1,17 +0,0 @@
-package sushi.hardcore.droidfs.file_operations
-
-import android.content.BroadcastReceiver
-import android.content.Context
-import android.content.Intent
-
-class NotificationBroadcastReceiver: BroadcastReceiver() {
-    override fun onReceive(context: Context, intent: Intent) {
-        if (intent.action == FileOperationService.ACTION_CANCEL) {
-            intent.getBundleExtra("bundle")?.let { bundle ->
-                // TODO: use peekService instead?
-                val binder = (bundle.getBinder("binder") as FileOperationService.LocalBinder?)
-                binder?.getService()?.cancelOperation(bundle.getInt("taskId"))
-            }
-        }
-    }
-}

app/src/main/java/sushi/hardcore/droidfs/file_viewers/FileViewerActivity.kt

@@ -18,10 +18,12 @@ import kotlinx.coroutines.withContext
 import sushi.hardcore.droidfs.BaseActivity
 import sushi.hardcore.droidfs.FileTypes
 import sushi.hardcore.droidfs.R
+import sushi.hardcore.droidfs.VolumeManagerApp
 import sushi.hardcore.droidfs.explorers.ExplorerElement
 import sushi.hardcore.droidfs.filesystems.EncryptedVolume
 import sushi.hardcore.droidfs.util.IntentUtils
 import sushi.hardcore.droidfs.util.PathUtils
+import sushi.hardcore.droidfs.util.finishOnClose
 import sushi.hardcore.droidfs.widgets.CustomAlertDialogBuilder
 
 abstract class FileViewerActivity: BaseActivity() {
@@ -40,7 +42,10 @@ abstract class FileViewerActivity: BaseActivity() {
         super.onCreate(savedInstanceState)
         filePath = intent.getStringExtra("path")!!
         originalParentPath = PathUtils.getParentPath(filePath)
-        encryptedVolume = IntentUtils.getParcelableExtra(intent, "volume")!!
+        encryptedVolume = (application as VolumeManagerApp).volumeManager.getVolume(
+            intent.getIntExtra("volumeId", -1)
+        )!!
+        finishOnClose(encryptedVolume)
         foldersFirst = sharedPrefs.getBoolean("folders_first", true)
         windowInsetsController = WindowInsetsControllerCompat(window, window.decorView)
         windowInsetsController.addOnControllableInsetsChangedListener { _, typeMask ->
@@ -173,11 +178,4 @@ abstract class FileViewerActivity: BaseActivity() {
     protected fun goBackToExplorer() {
         finish()
     }
-
-    override fun onResume() {
-        super.onResume()
-        if (encryptedVolume.isClosed()) {
-            finish()
-        }
-    }
 }

app/src/main/java/sushi/hardcore/droidfs/filesystems/CryfsVolume.kt

@@ -1,6 +1,5 @@
 package sushi.hardcore.droidfs.filesystems
 
-import android.os.Parcel
 import sushi.hardcore.droidfs.Constants
 import sushi.hardcore.droidfs.R
 import sushi.hardcore.droidfs.explorers.ExplorerElement
@@ -101,13 +100,6 @@ class CryfsVolume(private val fusePtr: Long): EncryptedVolume() {
         }
     }
 
-    constructor(parcel: Parcel) : this(parcel.readLong())
-
-    override fun writeToParcel(parcel: Parcel, flags: Int) = with(parcel) {
-        writeByte(CRYFS_VOLUME_TYPE)
-        writeLong(fusePtr)
-    }
-
     override fun openFileReadMode(path: String): Long {
         return nativeOpen(fusePtr, path, 0)
     }

app/src/main/java/sushi/hardcore/droidfs/filesystems/EncryptedVolume.kt

@@ -2,18 +2,21 @@ package sushi.hardcore.droidfs.filesystems
 
 import android.content.Context
 import android.net.Uri
-import android.os.Parcel
-import android.os.Parcelable
 import sushi.hardcore.droidfs.Constants
 import sushi.hardcore.droidfs.VolumeData
 import sushi.hardcore.droidfs.explorers.ExplorerElement
 import sushi.hardcore.droidfs.util.ObjRef
+import sushi.hardcore.droidfs.util.Observable
 import java.io.File
 import java.io.FileOutputStream
 import java.io.InputStream
 import java.io.OutputStream
 
-abstract class EncryptedVolume: Parcelable {
+abstract class EncryptedVolume: Observable<EncryptedVolume.Observer>() {
+
+    interface Observer {
+        fun onClose()
+    }
 
     class InitResult(
         val errorCode: Int,
@@ -35,18 +38,6 @@ abstract class EncryptedVolume: Parcelable {
         const val GOCRYPTFS_VOLUME_TYPE: Byte = 0
         const val CRYFS_VOLUME_TYPE: Byte = 1
 
-        @JvmField
-        val CREATOR = object : Parcelable.Creator<EncryptedVolume> {
-            override fun createFromParcel(parcel: Parcel): EncryptedVolume {
-                return when (parcel.readByte()) {
-                    GOCRYPTFS_VOLUME_TYPE -> GocryptfsVolume(parcel)
-                    CRYFS_VOLUME_TYPE -> CryfsVolume(parcel)
-                    else -> throw invalidVolumeType()
-                }
-            }
-            override fun newArray(size: Int) = arrayOfNulls<EncryptedVolume>(size)
-        }
-
         /**
          * Get the type of a volume.
          *
@@ -92,8 +83,6 @@ abstract class EncryptedVolume: Parcelable {
         }
     }
 
-    override fun describeContents() = 0
-
     abstract fun openFileReadMode(path: String): Long
     abstract fun openFileWriteMode(path: String): Long
     abstract fun read(fileHandle: Long, fileOffset: Long, buffer: ByteArray, dstOffset: Long, length: Long): Int
@@ -107,9 +96,14 @@ abstract class EncryptedVolume: Parcelable {
     abstract fun rmdir(path: String): Boolean
     abstract fun getAttr(path: String): Stat?
     abstract fun rename(srcPath: String, dstPath: String): Boolean
-    abstract fun close()
+    protected abstract fun close()
     abstract fun isClosed(): Boolean
 
+    fun closeVolume() {
+        observers.forEach { it.onClose() }
+        close()
+    }
+
     fun pathExists(path: String): Boolean {
         return getAttr(path) != null
     }

app/src/main/java/sushi/hardcore/droidfs/filesystems/GocryptfsVolume.kt

@@ -1,6 +1,5 @@
 package sushi.hardcore.droidfs.filesystems
 
-import android.os.Parcel
 import android.util.Log
 import sushi.hardcore.droidfs.R
 import sushi.hardcore.droidfs.explorers.ExplorerElement
@@ -100,8 +99,6 @@ class GocryptfsVolume(private val sessionID: Int): EncryptedVolume() {
         }
     }
 
-    constructor(parcel: Parcel) : this(parcel.readInt())
-
     override fun openFileReadMode(path: String): Long {
         return native_open_read_mode(sessionID, path).toLong()
     }
@@ -122,11 +119,6 @@ class GocryptfsVolume(private val sessionID: Int): EncryptedVolume() {
         return native_get_attr(sessionID, path)
     }
 
-    override fun writeToParcel(parcel: Parcel, flags: Int) = with(parcel) {
-        writeByte(GOCRYPTFS_VOLUME_TYPE)
-        writeInt(sessionID)
-    }
-
     override fun close() {
         native_close(sessionID)
     }

app/src/main/java/sushi/hardcore/droidfs/util/AndroidUtils.kt

@@ -0,0 +1,111 @@
+package sushi.hardcore.droidfs.util
+
+import android.Manifest
+import android.app.Activity
+import android.app.ActivityManager
+import android.content.Context
+import android.content.SharedPreferences
+import android.content.pm.PackageManager
+import android.os.Build
+import androidx.activity.result.ActivityResultLauncher
+import androidx.activity.result.contract.ActivityResultContracts
+import androidx.appcompat.app.AppCompatActivity
+import androidx.core.content.ContextCompat
+import androidx.preference.PreferenceManager
+import kotlin.reflect.KProperty
+
+object AndroidUtils {
+    fun isServiceRunning(context: Context, serviceClass: Class<*>): Boolean {
+        val manager = context.getSystemService(Context.ACTIVITY_SERVICE) as ActivityManager
+        @Suppress("DEPRECATION")
+        for (service in manager.getRunningServices(Int.MAX_VALUE)) {
+            if (serviceClass.name == service.service.className) {
+                return true
+            }
+        }
+        return false
+    }
+
+    /**
+     * A [Manifest.permission.POST_NOTIFICATIONS] permission helper.
+     *
+     * Must be initialized before [Activity.onCreate].
+     */
+    class NotificationPermissionHelper<A: AppCompatActivity>(val activity: A) {
+        private var listener: ((Boolean) -> Unit)? = null
+        private val launcher = activity.registerForActivityResult(ActivityResultContracts.RequestPermission()) { granted ->
+            listener?.invoke(granted)
+            listener = null
+        }
+
+        /**
+         * Ask for notification permission if required and run the provided callback.
+         *
+         * The callback is run as soon as the user dismisses the permission dialog,
+         * no matter if the permission has been granted or not.
+         *
+         * If this function is called again before the user answered the dialog from the
+         * previous call, the previous callback won't be triggered.
+         *
+         * @param onDialogDismiss argument set to `true` if the permission is granted or
+         * not required, `false` otherwise
+         */
+        fun askAndRun(onDialogDismiss: (Boolean) -> Unit) {
+            assert(listener == null)
+            if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.TIRAMISU) {
+                if (ContextCompat.checkSelfPermission(activity, Manifest.permission.POST_NOTIFICATIONS) != PackageManager.PERMISSION_GRANTED) {
+                    listener = onDialogDismiss
+                    launcher.launch(Manifest.permission.POST_NOTIFICATIONS)
+                    return
+                }
+            }
+            onDialogDismiss(true)
+        }
+    }
+
+    /**
+     * Property delegate mirroring the state of a boolean value in shared preferences.
+     *
+     * [init] **must** be called before accessing the delegated property.
+     */
+    class LiveBooleanPreference(
+        private val key: String,
+        private val defaultValue: Boolean = false,
+        private val onChange: ((value: Boolean) -> Unit)? = null
+    ) {
+        private lateinit var sharedPreferences: SharedPreferences
+        private var value = defaultValue
+        private val listener = SharedPreferences.OnSharedPreferenceChangeListener { _, key ->
+            if (key == this.key) {
+                reload()
+                onChange?.invoke(value)
+            }
+        }
+
+        fun init(context: Context) = init(PreferenceManager.getDefaultSharedPreferences(context))
+
+        fun init(sharedPreferences: SharedPreferences) {
+            this.sharedPreferences = sharedPreferences
+            reload()
+            sharedPreferences.registerOnSharedPreferenceChangeListener(listener)
+        }
+
+        private fun reload() {
+            value = sharedPreferences.getBoolean(key, defaultValue)
+        }
+
+        operator fun getValue(thisRef: Any, property: KProperty<*>) = value
+
+        companion object {
+            fun init(context: Context, vararg liveBooleanPreferences: LiveBooleanPreference) {
+                init(PreferenceManager.getDefaultSharedPreferences(context), *liveBooleanPreferences)
+            }
+
+            fun init(sharedPreferences: SharedPreferences, vararg liveBooleanPreferences: LiveBooleanPreference) {
+                for (i in liveBooleanPreferences) {
+                    i.init(sharedPreferences)
+                }
+            }
+        }
+    }
+}

app/src/main/java/sushi/hardcore/droidfs/util/Observable.kt

@@ -0,0 +1,21 @@
+package sushi.hardcore.droidfs.util
+
+import android.app.Activity
+import sushi.hardcore.droidfs.filesystems.EncryptedVolume
+
+abstract class Observable<T> {
+    protected val observers = mutableListOf<T>()
+
+    fun observe(observer: T) {
+        observers.add(observer)
+    }
+}
+
+fun Activity.finishOnClose(encryptedVolume: EncryptedVolume) {
+    encryptedVolume.observe(object : EncryptedVolume.Observer {
+        override fun onClose() {
+            finish()
+            // no need to remove observer as the EncryptedVolume will be destroyed
+        }
+    })
+}

app/src/main/res/values-ar/strings.xml

@@ -73,7 +73,6 @@
     <string name="usf_screenshot">السماح بلقطة شاشة</string>
     <string name="usf_fingerprint">السماح بحفظ تجزئة كلمة المرور باستخدام بصمة الإصبع</string>
     <string name="usf_volume_management">إدارة مجلد التشفير</string>
-    <string name="usf_keep_open">إبقاء مجلد التشفير مفتوحاً عند الخروج من التطبيق</string>
     <string name="unsafe_features">الميزات غير الآمنة</string>
     <string name="manage_unsafe_features">إدارة الميزات غير الآمنة</string>
     <string name="manage_unsafe_features_summary">تمكين / تعطيل الميزات غير الآمنة</string>

app/src/main/res/values-de/strings.xml

@@ -74,7 +74,6 @@
     <string name="usf_screenshot">Screenshots zulassen</string>
     <string name="usf_fingerprint">Kennwort-Hash mit Fingerabdruck speichern können</string>
     <string name="usf_volume_management">Volumenverwaltung</string>
-    <string name="usf_keep_open">Volumen offen halten, wenn die App in den Hintergrund geht</string>
     <string name="unsafe_features">Unsichere Funktionen</string>
     <string name="manage_unsafe_features">Sichere Funktionen verwalten</string>
     <string name="manage_unsafe_features_summary">Aktivieren/Deaktivieren unsicherer Funktionen</string>

app/src/main/res/values-es/strings.xml

@@ -74,7 +74,6 @@
     <string name="usf_screenshot">Permitir capturas de pantalla</string>
     <string name="usf_fingerprint">Permitir guardar el hash de la contraseña mediante la huella dactilar</string>
     <string name="usf_volume_management">Gestión del volumen</string>
-    <string name="usf_keep_open">Mantener el volumen abierto cuando la aplicación está en segundo plano</string>
     <string name="unsafe_features">Características inseguras</string>
     <string name="manage_unsafe_features">Gestionar las características inseguras</string>
     <string name="manage_unsafe_features_summary">Activar/desactivar funciones inseguras</string>

app/src/main/res/values-pt-rBR/strings.xml

@@ -73,7 +73,6 @@
     <string name="usf_screenshot">Permitir capturas da tela</string>
     <string name="usf_fingerprint">Permitir salvar o hash da senha usando impressão digital</string>
     <string name="usf_volume_management">Gerenciador de volumes</string>
-    <string name="usf_keep_open">Mantenha o volume aberto quando o app ficar em segundo plano</string>
     <string name="unsafe_features">Opções perigosas</string>
     <string name="manage_unsafe_features">Gerenciar opções perigosas</string>
     <string name="manage_unsafe_features_summary">Alternar opções perigosas</string>

app/src/main/res/values-ru/strings.xml

@@ -71,7 +71,6 @@
     <string name="usf_screenshot">Разрешить снимки экрана</string>
     <string name="usf_fingerprint">Разрешить сохранение хеша пароля отпечатком пальца</string>
     <string name="usf_volume_management">Управление томом</string>
-    <string name="usf_keep_open">Оставлять том открытым, когда DroidFS в фоне</string>
     <string name="unsafe_features">Небезопасные функции</string>
     <string name="manage_unsafe_features">Управление небезопасными функциями</string>
     <string name="manage_unsafe_features_summary">Включить/отключить небезопасные функции</string>

app/src/main/res/values-tr/strings.xml

@@ -74,7 +74,6 @@
     <string name="usf_screenshot">Ekran görüntüsü almaya izin ver</string>
     <string name="usf_fingerprint">Parmak izi kullanılarak şifre hash değerinin kaydedilmesine izin ver</string>
     <string name="usf_volume_management">Birim yönetimi</string>
-    <string name="usf_keep_open">Uygulama arka plana geçtiğinde birimi açık tutun</string>
     <string name="unsafe_features">Güvenli olmayan özellikler</string>
     <string name="manage_unsafe_features">Güvenli olmayan özellikleri yönetin</string>
     <string name="manage_unsafe_features_summary">Güvenli olmayan özellikleri etkinleştirme/devre dışı bırakma</string>

app/src/main/res/values-zh-rCN/strings.xml

@@ -75,7 +75,6 @@
     <string name="usf_screenshot">允许截屏</string>
     <string name="usf_fingerprint">允许通过指纹保存密码哈希</string>
     <string name="usf_volume_management">加密卷管理</string>
-    <string name="usf_keep_open">当应用切入后台时已打开的卷不再自动锁上</string>
     <string name="unsafe_features">以下功能会降低安全性</string>
     <string name="manage_unsafe_features">管理非安全功能</string>
     <string name="manage_unsafe_features_summary">打开/关闭非安全功能</string>

app/src/main/res/values/strings.xml

@@ -74,7 +74,6 @@
     <string name="usf_screenshot">Allow screenshots</string>
     <string name="usf_fingerprint">Allow saving password hash using fingerprint</string>
     <string name="usf_volume_management">Volume Management</string>
-    <string name="usf_keep_open">Keep volume open when the app goes in background</string>
     <string name="unsafe_features">Unsafe Features</string>
     <string name="manage_unsafe_features">Manage unsafe features</string>
     <string name="manage_unsafe_features_summary">Enable/Disable unsafe features</string>
@@ -281,4 +280,11 @@
     <string name="logcat_saved">Logcat saved</string>
     <string name="later">Later</string>
     <string name="notification_denied_msg">Notification permission has been denied. Background file operations won\'t be visible. You can change this in the app\'s permission settings.</string>
+    <string name="keep_alive_notification_title">Keep alive service</string>
+    <string name="keep_alive_notification_text">One or more volumes are kept open.</string>
+    <string name="close_all">Close all</string>
+    <string name="usf_background">Disable volume auto-locking</string>
+    <string name="usf_background_summary">Don\'t lock volumes when the app goes in background</string>
+    <string name="usf_keep_open">Keep volumes open</string>
+    <string name="usf_keep_open_summary">Maintain the app always running in the background to keep volumes open</string>
 </resources>

app/src/main/res/xml/unsafe_features_preferences.xml

@@ -48,11 +48,19 @@
             android:key="usf_fingerprint"
             android:title="@string/usf_fingerprint" />
 
+        <SwitchPreference
+            android:defaultValue="false"
+            android:icon="@drawable/icon_lock_open"
+            android:key="usf_background"
+            android:title="@string/usf_background"
+            android:summary="@string/usf_background_summary" />
+
         <SwitchPreference
             android:defaultValue="false"
             android:icon="@drawable/icon_lock_open"
             android:key="usf_keep_open"
-            android:title="@string/usf_keep_open" />
+            android:title="@string/usf_keep_open"
+            android:summary="@string/usf_keep_open_summary"/>
 
     </PreferenceCategory>