Add storage library (and demo app)

and use for periodic files backup

.gitignore

@@ -6,7 +6,7 @@ hs_err_pid*
 
 ## Intellij
 out/
-lib/
+/lib/
 .idea/*
 !.idea/runConfigurations*
 !.idea/inspectionProfiles*
@@ -33,7 +33,8 @@ local.properties
 
 ## NetBeans
 **/nbproject/private/
-build/
+/build/
+/app/build/
 nbbuild/
 dist/
 nbdist/
@@ -50,6 +51,3 @@ gradle-app.setting
 
 ## Android
 gen/
-
-## Prebuilt
-Backup.apk

.idea/runConfigurations/All_unit_tests.xml

@@ -0,0 +1,8 @@
+<component name="ProjectRunConfigurationManager">
+  <configuration default="false" name="All unit tests" type="CompoundRunConfigurationType">
+    <toRun name="Unit tests: storage/lib" type="AndroidJUnit" />
+    <toRun name="Unit tests: app" type="AndroidJUnit" />
+    <toRun name="Unit tests: contactsbackup" type="AndroidJUnit" />
+    <method v="2" />
+  </configuration>
+</component>

.idea/runConfigurations/Instrumentation_tests__app.xml

@@ -1,5 +1,5 @@
 <component name="ProjectRunConfigurationManager">
-  <configuration default="false" name="Instrumentation Tests" type="AndroidTestRunConfigurationType" factoryName="Android Instrumented Tests" singleton="true">
+  <configuration default="false" name="Instrumentation tests: app" type="AndroidTestRunConfigurationType" factoryName="Android Instrumented Tests" singleton="true">
     <module name="seedvault.app" />
     <option name="TESTING_TYPE" value="0" />
     <option name="METHOD_NAME" value="" />

.idea/runConfigurations/Unit_tests__app.xml

@@ -1,5 +1,5 @@
 <component name="ProjectRunConfigurationManager">
-  <configuration default="false" name="Unit Tests" type="AndroidJUnit" factoryName="Android JUnit">
+  <configuration default="false" name="Unit tests: app" type="AndroidJUnit" factoryName="Android JUnit">
     <module name="seedvault.app" />
     <useClassPathOnly />
     <option name="ALTERNATIVE_JRE_PATH_ENABLED" value="true" />

.idea/runConfigurations/Unit_tests__contactsbackup.xml

@@ -0,0 +1,15 @@
+<component name="ProjectRunConfigurationManager">
+  <configuration default="false" name="Unit tests: contactsbackup" type="AndroidJUnit" factoryName="Android JUnit">
+    <module name="seedvault.contactsbackup" />
+    <useClassPathOnly />
+    <option name="MAIN_CLASS_NAME" value="" />
+    <option name="METHOD_NAME" value="" />
+    <option name="TEST_OBJECT" value="directory" />
+    <option name="PARAMETERS" value="" />
+    <option name="WORKING_DIRECTORY" value="$MODULE_DIR$" />
+    <dir value="$PROJECT_DIR$/contactsbackup/src/test/java" />
+    <method v="2">
+      <option name="Android.Gradle.BeforeRunTask" enabled="true" />
+    </method>
+  </configuration>
+</component>

.idea/runConfigurations/Unit_tests__storage_lib.xml

@@ -0,0 +1,15 @@
+<component name="ProjectRunConfigurationManager">
+  <configuration default="false" name="Unit tests: storage/lib" type="AndroidJUnit" factoryName="Android JUnit">
+    <module name="seedvault.storage.lib" />
+    <useClassPathOnly />
+    <option name="MAIN_CLASS_NAME" value="" />
+    <option name="METHOD_NAME" value="" />
+    <option name="TEST_OBJECT" value="directory" />
+    <option name="PARAMETERS" value="" />
+    <option name="WORKING_DIRECTORY" value="$MODULE_DIR$" />
+    <dir value="$PROJECT_DIR$/storage/lib/src/test/java" />
+    <method v="2">
+      <option name="Android.Gradle.BeforeRunTask" enabled="true" />
+    </method>
+  </configuration>
+</component>

.idea/runConfigurations/seedvault_storage_lib__assembleRelease_.xml

@@ -0,0 +1,21 @@
+<component name="ProjectRunConfigurationManager">
+  <configuration default="false" name="seedvault:storage:lib [assembleRelease]" type="GradleRunConfiguration" factoryName="Gradle">
+    <ExternalSystemSettings>
+      <option name="executionName" />
+      <option name="externalProjectPath" value="$PROJECT_DIR$/storage/lib" />
+      <option name="externalSystemIdString" value="GRADLE" />
+      <option name="scriptParameters" value="" />
+      <option name="taskDescriptions">
+        <list />
+      </option>
+      <option name="taskNames">
+        <list>
+          <option value="assembleRelease" />
+        </list>
+      </option>
+      <option name="vmOptions" value="" />
+    </ExternalSystemSettings>
+    <GradleScriptDebugEnabled>true</GradleScriptDebugEnabled>
+    <method v="2" />
+  </configuration>
+</component>

Android.bp

@@ -31,9 +31,16 @@ android_app {
         "androidx.lifecycle_lifecycle-livedata-ktx",
         "androidx-constraintlayout_constraintlayout",
         "com.google.android.material_material",
+        // storage
+        "seedvault-lib-storage", // did not manage to add this as transitive dependency
+        "seedvault-lib-tink-android",
+        "androidx.room_room-runtime",
+        "libprotobuf-java-lite",
+        // koin
         "seedvault-lib-koin-core", // did not manage to add this as transitive dependency
         "seedvault-lib-koin-android",
         "seedvault-lib-koin-androidx-viewmodel",
+        // bip39
         "seedvault-lib-novacrypto-bip39",
     ],
     manifest: "app/src/main/AndroidManifest.xml",

README.md

@@ -30,6 +30,9 @@ It uses the same internal APIs as `adb backup` which is deprecated and thus need
 * `android.permission.WRITE_SECURE_SETTINGS` to change system backup settings and enable call log backup.
 * `android.permission.QUERY_ALL_PACKAGES` to get information about all installed apps for backup.
 * `android.permission.INSTALL_PACKAGES` to re-install apps when restoring from backup.
+* `android.permission.MANAGE_EXTERNAL_STORAGE` to backup and restore files from device storage.
+* `android.permission.ACCESS_MEDIA_LOCATION` to backup original media files e.g. without stripped EXIF metadata.
+* `android.permission.FOREGROUND_SERVICE` to do periodic storage backups without interruption.
 * `android.permission.MANAGE_DOCUMENTS` to retrieve the available storage roots (optional) for better UX.
 
 ## Contributing

app/build.gradle

@@ -16,13 +16,12 @@ def gitDescribe = { ->
 }
 
 android {
-
+    compileSdkVersion rootProject.ext.compileSdkVersion
-    compileSdkVersion 30
+    buildToolsVersion rootProject.ext.buildToolsVersion
-    buildToolsVersion '30.0.2'
 
     defaultConfig {
         minSdkVersion 29 // leave at 29 for robolectric tests
-        targetSdkVersion 30
+        targetSdkVersion rootProject.ext.targetSdkVersion
         versionNameSuffix "-$gitDescribe"
         testInstrumentationRunner "androidx.test.runner.AndroidJUnitRunner"
         testInstrumentationRunnerArguments disableAnalytics: 'true'
@@ -44,6 +43,7 @@ android {
     }
     kotlinOptions {
         jvmTarget = JavaVersion.VERSION_1_8.toString()
+        languageVersion = "1.3"
     }
     testOptions {
         unitTests.all {
@@ -81,7 +81,72 @@ android {
     buildTypes.debug.signingConfig = signingConfigs.aosp
 }
 
-apply from: '../gradle/dependencies.gradle'
+dependencies {
+    compileOnly rootProject.ext.aosp_libs
+
+    /**
+     * Dependencies in AOSP
+     *
+     * We try to keep the dependencies in sync with what AOSP ships as Seedvault is meant to be built
+     * with the AOSP build system and gradle builds are just for more pleasant development.
+     * Using the AOSP versions in gradle builds allows us to spot issues early on.
+     */
+    implementation rootProject.ext.kotlin_libs.std
+    // These coroutine libraries get upgraded otherwise to versions incompatible with kotlin version
+    implementation rootProject.ext.kotlin_libs.coroutines
+
+    implementation rootProject.ext.std_libs.androidx_core
+    // A newer version gets pulled in with AOSP via core, so we include fragment here explicitly
+    implementation rootProject.ext.std_libs.androidx_fragment
+    implementation rootProject.ext.std_libs.androidx_preference
+    implementation rootProject.ext.std_libs.androidx_lifecycle_viewmodel_ktx
+    implementation rootProject.ext.std_libs.androidx_lifecycle_livedata_ktx
+    implementation rootProject.ext.std_libs.androidx_constraintlayout
+    implementation rootProject.ext.std_libs.androidx_documentfile
+    implementation rootProject.ext.std_libs.com_google_android_material
+
+    /**
+     * Storage Dependencies
+     */
+    implementation project(':storage:lib')
+//    implementation fileTree(include: ['storage.aar'], dir: "${rootProject.rootDir}/storage/lib/libs")
+
+    /**
+     * External Dependencies
+     *
+     * If the dependencies below are updated,
+     * please make sure to update the prebuilt libraries and the Android.bp files
+     * in the top-level `libs` folder to reflect that.
+     * You can copy these libraries from ~/.gradle/caches/modules-2
+     */
+    // later versions than 2.1.1 require newer kotlin version
+    implementation fileTree(include: ['*.jar'], dir: "${rootProject.rootDir}/libs/koin-android")
+    implementation fileTree(include: ['*.aar'], dir: "${rootProject.rootDir}/libs/koin-android")
+
+    implementation fileTree(include: ['*.jar'], dir: "${rootProject.rootDir}/libs/novacrypto-bip39")
+
+    /**
+     * Test Dependencies (do not concern the AOSP build)
+     */
+    lintChecks rootProject.ext.lint_libs.exceptions
+
+    // anything less than 'implementation' fails tests run with gradlew
+    testImplementation rootProject.ext.aosp_libs
+    testImplementation 'androidx.test.ext:junit:1.1.2'
+    testImplementation('org.robolectric:robolectric:4.3.1') { // 4.4 has issue with non-idle Looper
+        // https://github.com/robolectric/robolectric/issues/5245
+        exclude group: "com.google.auto.service", module: "auto-service"
+    }
+    testImplementation "org.junit.jupiter:junit-jupiter-api:$junit5_version"
+    testImplementation "io.mockk:mockk:$mockk_version"
+    testRuntimeOnly "org.junit.jupiter:junit-jupiter-engine:$junit5_version"
+    testRuntimeOnly "org.junit.vintage:junit-vintage-engine:$junit5_version"
+
+    androidTestImplementation 'androidx.test:runner:1.3.0'
+    androidTestImplementation 'androidx.test:rules:1.3.0'
+    androidTestImplementation 'androidx.test.ext:junit:1.1.2'
+    androidTestImplementation "io.mockk:mockk-android:$mockk_version"
+}
 
 ktlint {
     version = "0.36.0" // https://github.com/pinterest/ktlint/issues/764

app/src/main/AndroidManifest.xml

@@ -113,5 +113,18 @@
             </intent-filter>
         </receiver>
 
+        <!-- Used to start actual BackupService depending on scheduling criteria -->
+        <service
+            android:name=".storage.StorageBackupJobService"
+            android:exported="false"
+            android:label="BackupJobService"
+            android:permission="android.permission.BIND_JOB_SERVICE" />
+        <!-- Does the actual backup work as a foreground service -->
+        <service
+            android:name=".storage.StorageBackupService"
+            android:exported="false"
+            android:foregroundServiceType="dataSync"
+            android:label="BackupService" />
+
     </application>
 </manifest>

app/src/main/java/com/stevesoltys/seedvault/App.kt

@@ -17,8 +17,10 @@ import com.stevesoltys.seedvault.restore.install.installModule
 import com.stevesoltys.seedvault.settings.AppListRetriever
 import com.stevesoltys.seedvault.settings.SettingsManager
 import com.stevesoltys.seedvault.settings.SettingsViewModel
+import com.stevesoltys.seedvault.storage.storageModule
 import com.stevesoltys.seedvault.transport.backup.backupModule
 import com.stevesoltys.seedvault.transport.restore.restoreModule
+import com.stevesoltys.seedvault.ui.files.FileSelectionViewModel
 import com.stevesoltys.seedvault.ui.notification.BackupNotificationManager
 import com.stevesoltys.seedvault.ui.recoverycode.RecoveryCodeViewModel
 import com.stevesoltys.seedvault.ui.storage.BackupStorageViewModel
@@ -43,11 +45,12 @@ open class App : Application() {
         factory<IBackupManager> { IBackupManager.Stub.asInterface(getService(BACKUP_SERVICE)) }
         factory { AppListRetriever(this@App, get(), get(), get()) }
 
-        viewModel { SettingsViewModel(this@App, get(), get(), get(), get(), get()) }
+        viewModel { SettingsViewModel(this@App, get(), get(), get(), get(), get(), get()) }
         viewModel { RecoveryCodeViewModel(this@App, get(), get(), get()) }
         viewModel { BackupStorageViewModel(this@App, get(), get(), get()) }
         viewModel { RestoreStorageViewModel(this@App, get(), get()) }
         viewModel { RestoreViewModel(this@App, get(), get(), get(), get(), get()) }
+        viewModel { FileSelectionViewModel(this@App, get()) }
     }
 
     override fun onCreate() {
@@ -85,6 +88,7 @@ open class App : Application() {
                 backupModule,
                 restoreModule,
                 installModule,
+                storageModule,
                 appModule
             )
         )

app/src/main/java/com/stevesoltys/seedvault/settings/AppStatusFragment.kt

@@ -36,7 +36,7 @@ class AppStatusFragment : Fragment(), AppStatusToggleListener {
         inflater: LayoutInflater,
         container: ViewGroup?,
         savedInstanceState: Bundle?
-    ): View? {
+    ): View {
         setHasOptionsMenu(true)
         val v: View = inflater.inflate(R.layout.fragment_app_status, container, false)
 

app/src/main/java/com/stevesoltys/seedvault/settings/SettingsFragment.kt

@@ -1,12 +1,11 @@
 package com.stevesoltys.seedvault.settings
 
 import android.app.backup.IBackupManager
-import android.content.Context.BACKUP_SERVICE // ktlint-disable no-unused-imports
 import android.content.Intent
 import android.os.Bundle
 import android.os.RemoteException
 import android.provider.Settings
-import android.provider.Settings.Secure.BACKUP_AUTO_RESTORE // ktlint-disable no-unused-imports
+import android.provider.Settings.Secure.BACKUP_AUTO_RESTORE
 import android.util.Log
 import android.view.Menu
 import android.view.MenuInflater
@@ -38,6 +37,8 @@ class SettingsFragment : PreferenceFragmentCompat() {
     private lateinit var apkBackup: TwoStatePreference
     private lateinit var backupLocation: Preference
     private lateinit var backupStatus: Preference
+    private lateinit var backupStorage: TwoStatePreference
+    private lateinit var backupRecoveryCode: Preference
 
     private var menuBackupNow: MenuItem? = null
     private var menuRestore: MenuItem? = null
@@ -102,6 +103,19 @@ class SettingsFragment : PreferenceFragmentCompat() {
             return@OnPreferenceChangeListener false
         }
         backupStatus = findPreference("backup_status")!!
+
+        backupStorage = findPreference("backup_storage")!!
+        backupStorage.onPreferenceChangeListener = OnPreferenceChangeListener { _, newValue ->
+            val disable = !(newValue as Boolean)
+            if (disable) {
+                viewModel.disableStorageBackup()
+                return@OnPreferenceChangeListener true
+            }
+            onEnablingStorageBackup()
+            return@OnPreferenceChangeListener false
+        }
+
+        backupRecoveryCode = findPreference("backup_recovery_code")!!
     }
 
     override fun onViewCreated(view: View, savedInstanceState: Bundle?) {
@@ -110,6 +124,11 @@ class SettingsFragment : PreferenceFragmentCompat() {
         viewModel.lastBackupTime.observe(viewLifecycleOwner, Observer { time ->
             setAppBackupStatusSummary(time)
         })
+
+        val backupFiles: Preference = findPreference("backup_files")!!
+        viewModel.filesSummary.observe(viewLifecycleOwner, Observer { summary ->
+            backupFiles.summary = summary
+        })
     }
 
     override fun onStart() {
@@ -190,4 +209,40 @@ class SettingsFragment : PreferenceFragmentCompat() {
         backupStatus.summary = getString(R.string.settings_backup_status_summary, lastBackup)
     }
 
+    private fun onEnablingStorageBackup() {
+        AlertDialog.Builder(requireContext())
+            .setIcon(R.drawable.ic_warning)
+            .setTitle(R.string.settings_backup_storage_dialog_title)
+            .setMessage(R.string.settings_backup_storage_dialog_message)
+            .setPositiveButton(R.string.settings_backup_storage_dialog_ok) { dialog, _ ->
+                if (viewModel.hasMainKey()) {
+                    viewModel.enableStorageBackup()
+                    backupStorage.isChecked = true
+                } else {
+                    showCodeVerificationNeededDialog()
+                }
+                dialog.dismiss()
+            }
+            .setNegativeButton(R.string.settings_backup_apk_dialog_cancel) { dialog, _ ->
+                dialog.dismiss()
+            }
+            .show()
+    }
+
+    private fun showCodeVerificationNeededDialog() {
+        AlertDialog.Builder(requireContext())
+            .setIcon(R.drawable.ic_vpn_key)
+            .setTitle(R.string.settings_backup_storage_code_dialog_title)
+            .setMessage(R.string.settings_backup_storage_code_dialog_message)
+            .setPositiveButton(R.string.settings_backup_storage_code_dialog_ok) { dialog, _ ->
+                val callback = (requireActivity() as OnPreferenceStartFragmentCallback)
+                callback.onPreferenceStartFragment(this, backupRecoveryCode)
+                dialog.dismiss()
+            }
+            .setNegativeButton(R.string.settings_backup_apk_dialog_cancel) { dialog, _ ->
+                dialog.dismiss()
+            }
+            .show()
+    }
+
 }

app/src/main/java/com/stevesoltys/seedvault/settings/SettingsViewModel.kt

@@ -1,6 +1,7 @@
 package com.stevesoltys.seedvault.settings
 
 import android.app.Application
+import android.app.job.JobInfo.NETWORK_TYPE_UNMETERED
 import android.database.ContentObserver
 import android.net.ConnectivityManager
 import android.net.Network
@@ -22,11 +23,15 @@ import com.stevesoltys.seedvault.R
 import com.stevesoltys.seedvault.crypto.KeyManager
 import com.stevesoltys.seedvault.metadata.MetadataManager
 import com.stevesoltys.seedvault.permitDiskReads
+import com.stevesoltys.seedvault.storage.StorageBackupJobService
 import com.stevesoltys.seedvault.transport.requestBackup
 import com.stevesoltys.seedvault.ui.RequireProvisioningViewModel
 import com.stevesoltys.seedvault.ui.notification.BackupNotificationManager
 import kotlinx.coroutines.Dispatchers
 import kotlinx.coroutines.launch
+import org.calyxos.backup.storage.api.StorageBackup
+import org.calyxos.backup.storage.backup.BackupJobService
+import java.util.concurrent.TimeUnit.HOURS
 
 private const val TAG = "SettingsViewModel"
 private const val USER_FULL_DATA_BACKUP_AWARE = "user_full_data_backup_aware"
@@ -37,7 +42,8 @@ internal class SettingsViewModel(
     keyManager: KeyManager,
     private val notificationManager: BackupNotificationManager,
     private val metadataManager: MetadataManager,
-    private val appListRetriever: AppListRetriever
+    private val appListRetriever: AppListRetriever,
+    private val storageBackup: StorageBackup
 ) : RequireProvisioningViewModel(app, settingsManager, keyManager) {
 
     private val contentResolver = app.contentResolver
@@ -59,6 +65,9 @@ internal class SettingsViewModel(
     private val mAppEditMode = MutableLiveData<Boolean>()
     internal val appEditMode: LiveData<Boolean> = mAppEditMode
 
+    private val _filesSummary = MutableLiveData<String>()
+    internal val filesSummary: LiveData<String> = _filesSummary
+
     private val storageObserver = object : ContentObserver(null) {
         override fun onChange(selfChange: Boolean, uris: MutableCollection<Uri>, flags: Int) {
             onStorageLocationChanged()
@@ -89,6 +98,7 @@ internal class SettingsViewModel(
             metadataManager.getLastBackupTime()
         }
         onStorageLocationChanged()
+        loadFilesSummary()
     }
 
     override fun onStorageLocationChanged() {
@@ -134,8 +144,8 @@ internal class SettingsViewModel(
         // maybe replace the check below with one that checks if our transport service is running
         if (notificationManager.hasActiveBackupNotifications()) {
             Toast.makeText(app, R.string.notification_backup_already_running, LENGTH_LONG).show()
-        } else {
+        } else viewModelScope.launch(Dispatchers.IO) {
-            Thread { requestBackup(app) }.start()
+            requestBackup(app)
         }
     }
 
@@ -156,6 +166,14 @@ internal class SettingsViewModel(
         settingsManager.onAppBackupStatusChanged(status)
     }
 
+    @UiThread
+    fun loadFilesSummary() = viewModelScope.launch {
+        val uriSummary = storageBackup.getUriSummaryString()
+        _filesSummary.value = if (uriSummary.isEmpty()) {
+            app.getString(R.string.settings_backup_files_summary)
+        } else uriSummary
+    }
+
     /**
      * Ensures that the call log will be included in backups.
      *
@@ -170,4 +188,21 @@ internal class SettingsViewModel(
         }
     }
 
+    fun hasMainKey(): Boolean {
+        return keyManager.hasMainKey()
+    }
+
+    fun enableStorageBackup() = BackupJobService.scheduleJob(
+        context = app,
+        jobServiceClass = StorageBackupJobService::class.java,
+        periodMillis = HOURS.toMillis(24),
+        networkType = NETWORK_TYPE_UNMETERED,
+        deviceIdle = false,
+        charging = true
+    )
+
+    fun disableStorageBackup() {
+        BackupJobService.cancelJob(app)
+    }
+
 }

app/src/main/java/com/stevesoltys/seedvault/storage/SeedvaultStoragePlugin.kt

@@ -0,0 +1,20 @@
+package com.stevesoltys.seedvault.storage
+
+import android.content.Context
+import androidx.documentfile.provider.DocumentFile
+import com.stevesoltys.seedvault.crypto.KeyManager
+import com.stevesoltys.seedvault.plugins.saf.DocumentsStorage
+import org.calyxos.backup.storage.plugin.saf.SafStoragePlugin
+import javax.crypto.SecretKey
+
+internal class SeedvaultStoragePlugin(
+    context: Context,
+    private val storage: DocumentsStorage,
+    private val keyManager: KeyManager
+) : SafStoragePlugin(context) {
+    override val root: DocumentFile
+        get() = storage.rootBackupDir ?: error("No storage set")
+
+    override fun getMasterKey(): SecretKey = keyManager.getMainKey()
+    override fun hasMasterKey(): Boolean = keyManager.hasMainKey()
+}

app/src/main/java/com/stevesoltys/seedvault/storage/Services.kt

@@ -0,0 +1,30 @@
+package com.stevesoltys.seedvault.storage
+
+import org.calyxos.backup.storage.api.BackupObserver
+import org.calyxos.backup.storage.api.StorageBackup
+import org.calyxos.backup.storage.backup.BackupJobService
+import org.calyxos.backup.storage.backup.BackupService
+import org.calyxos.backup.storage.backup.NotificationBackupObserver
+import org.koin.android.ext.android.inject
+
+/*
+test and debug with
+
+  adb shell dumpsys jobscheduler |
+  grep -A 23 -B 4 "Service: com.stevesoltys.seedvault/.storage.StorageBackupJobService"
+
+force running with:
+
+  adb shell cmd jobscheduler run -f com.stevesoltys.seedvault 0
+
+ */
+internal class StorageBackupJobService : BackupJobService(StorageBackupService::class.java)
+
+internal class StorageBackupService : BackupService() {
+    override val storageBackup: StorageBackup by inject()
+
+    // use lazy delegate because context isn't available during construction time
+    override val backupObserver: BackupObserver by lazy {
+        NotificationBackupObserver(applicationContext)
+    }
+}

app/src/main/java/com/stevesoltys/seedvault/storage/StorageModule.kt

@@ -0,0 +1,10 @@
+package com.stevesoltys.seedvault.storage
+
+import org.calyxos.backup.storage.api.StorageBackup
+import org.calyxos.backup.storage.api.StoragePlugin
+import org.koin.dsl.module
+
+val storageModule = module {
+    single<StoragePlugin> { SeedvaultStoragePlugin(get(), get(), get()) }
+    single { StorageBackup(get(), get()) }
+}

app/src/main/java/com/stevesoltys/seedvault/ui/RequireProvisioningViewModel.kt

@@ -9,7 +9,7 @@ import com.stevesoltys.seedvault.ui.storage.StorageViewModel
 abstract class RequireProvisioningViewModel(
     protected val app: Application,
     protected val settingsManager: SettingsManager,
-    private val keyManager: KeyManager
+    protected val keyManager: KeyManager
 ) : AndroidViewModel(app) {
 
     abstract val isRestoreOperation: Boolean

app/src/main/java/com/stevesoltys/seedvault/ui/files/FileSelectionFragment.kt

@@ -0,0 +1,32 @@
+package com.stevesoltys.seedvault.ui.files
+
+import android.os.Bundle
+import android.view.LayoutInflater
+import android.view.View
+import android.view.ViewGroup
+import com.stevesoltys.seedvault.R
+import com.stevesoltys.seedvault.settings.SettingsViewModel
+import org.calyxos.backup.storage.ui.backup.BackupContentFragment
+import org.koin.androidx.viewmodel.ext.android.sharedViewModel
+import org.koin.androidx.viewmodel.ext.android.viewModel
+
+class FileSelectionFragment() : BackupContentFragment() {
+
+    override val viewModel by viewModel<FileSelectionViewModel>()
+    private val settingsViewModel by sharedViewModel<SettingsViewModel>()
+
+    override fun onCreateView(
+        inflater: LayoutInflater,
+        container: ViewGroup?,
+        savedInstanceState: Bundle?
+    ): View {
+        requireActivity().setTitle(R.string.settings_backup_files_title)
+        return super.onCreateView(inflater, container, savedInstanceState)
+    }
+
+    override fun onDestroy() {
+        super.onDestroy()
+        // reload files summary when we navigate away (it might have changed)
+        settingsViewModel.loadFilesSummary()
+    }
+}

app/src/main/java/com/stevesoltys/seedvault/ui/files/FileSelectionViewModel.kt

@@ -0,0 +1,18 @@
+package com.stevesoltys.seedvault.ui.files
+
+import android.app.Application
+import androidx.lifecycle.viewModelScope
+import kotlinx.coroutines.launch
+import org.calyxos.backup.storage.api.StorageBackup
+import org.calyxos.backup.storage.ui.backup.BackupContentViewModel
+
+class FileSelectionViewModel(
+    app: Application,
+    override val storageBackup: StorageBackup
+) : BackupContentViewModel(app) {
+
+    init {
+        viewModelScope.launch { loadContent() }
+    }
+
+}

app/src/main/java/com/stevesoltys/seedvault/ui/recoverycode/RecoveryCodeInputFragment.kt

@@ -62,7 +62,7 @@ class RecoveryCodeInputFragment : Fragment() {
         inflater: LayoutInflater,
         container: ViewGroup?,
         savedInstanceState: Bundle?
-    ): View? {
+    ): View {
         val v: View = inflater.inflate(R.layout.fragment_recovery_code_input, container, false)
 
         introText = v.findViewById(R.id.introText)
@@ -93,6 +93,8 @@ class RecoveryCodeInputFragment : Fragment() {
     override fun onViewCreated(view: View, savedInstanceState: Bundle?) {
         super.onViewCreated(view, savedInstanceState)
 
+        activity?.setTitle(R.string.recovery_code_title)
+
         if (viewModel.isRestore) {
             introText.setText(R.string.recovery_code_input_intro)
             backView.visibility = VISIBLE

app/src/main/res/drawable/ic_library_add.xml

@@ -0,0 +1,10 @@
+<vector xmlns:android="http://schemas.android.com/apk/res/android"
+    android:width="24dp"
+    android:height="24dp"
+    android:tint="?android:attr/colorControlNormal"
+    android:viewportWidth="24"
+    android:viewportHeight="24">
+    <path
+        android:fillColor="@android:color/white"
+        android:pathData="M4,6L2,6v14c0,1.1 0.9,2 2,2h14v-2L4,20L4,6zM20,2L8,2c-1.1,0 -2,0.9 -2,2v12c0,1.1 0.9,2 2,2h12c1.1,0 2,-0.9 2,-2L22,4c0,-1.1 -0.9,-2 -2,-2zM19,11h-4v4h-2v-4L9,11L9,9h4L13,5h2v4h4v2z" />
+</vector>

app/src/main/res/drawable/ic_save_alt.xml

@@ -0,0 +1,10 @@
+<vector xmlns:android="http://schemas.android.com/apk/res/android"
+    android:width="24dp"
+    android:height="24dp"
+    android:tint="?android:attr/colorControlNormal"
+    android:viewportWidth="24"
+    android:viewportHeight="24">
+    <path
+        android:fillColor="@android:color/white"
+        android:pathData="M19,12v7L5,19v-7L3,12v7c0,1.1 0.9,2 2,2h14c1.1,0 2,-0.9 2,-2v-7h-2zM13,12.67l2.59,-2.58L17,11.5l-5,5 -5,-5 1.41,-1.41L11,12.67L11,3h2z" />
+</vector>

app/src/main/res/drawable/ic_vpn_key.xml

@@ -1,7 +1,7 @@
 <vector xmlns:android="http://schemas.android.com/apk/res/android"
     android:width="24dp"
     android:height="24dp"
-    android:tint="?attr/colorControlNormal"
+    android:tint="?android:attr/colorControlNormal"
     android:viewportWidth="24"
     android:viewportHeight="24">
     <path

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

@@ -8,7 +8,8 @@
     <string name="restore_backup_button">Restore backup</string>
 
     <!-- Settings -->
-    <string name="settings_backup">Backup my data</string>
+    <string name="settings_category_apps">App backup</string>
+    <string name="settings_backup">Backup my apps</string>
     <string name="settings_backup_location">Backup location</string>
     <string name="settings_backup_location_none">None</string>
     <string name="settings_backup_location_internal">Internal storage</string>
@@ -28,10 +29,20 @@
     <string name="settings_backup_status_summary">Last backup: %1$s</string>
     <string name="settings_backup_exclude_apps">Exclude apps</string>
     <string name="settings_backup_now">Backup now</string>
+    <string name="settings_category_storage">Storage backup (experimental)</string>
+    <string name="settings_backup_storage_title">Backup my files</string>
+    <string name="settings_backup_files_title">Included files and folders</string>
+    <string name="settings_backup_files_summary">None</string>
     <string name="settings_backup_recovery_code">Recovery code</string>
     <string name="settings_backup_recovery_code_summary">Verify existing code or generate a new one</string>
+    <string name="settings_backup_storage_dialog_title">Experimental feature</string>
+    <string name="settings_backup_storage_dialog_message">Backing up files is still experimental and might not work. Do not rely on it for important data.</string>
+    <string name="settings_backup_storage_dialog_ok">Enable anyway</string>
+    <string name="settings_backup_storage_code_dialog_title">Recovery code verification required</string>
+    <string name="settings_backup_storage_code_dialog_message">To enable storage backup, you need to first verify your recovery code or generate a new one.</string>
+    <string name="settings_backup_storage_code_dialog_ok">Verify code</string>
 
-    <!-- Storage -->
+    <!-- Storage Location -->
     <string name="storage_fragment_backup_title">Choose where to store backups</string>
     <string name="storage_fragment_restore_title">Where to find your backups?</string>
     <string name="storage_fragment_warning">People with access to your storage location can learn which apps you use, but do not get access to the apps\' data.</string>

app/src/main/res/xml/settings.xml

@@ -1,33 +1,43 @@
-<androidx.preference.PreferenceScreen xmlns:app="http://schemas.android.com/apk/res-auto"
+<androidx.preference.PreferenceScreen xmlns:android="http://schemas.android.com/apk/res/android"
+    xmlns:app="http://schemas.android.com/apk/res-auto"
     xmlns:tools="http://schemas.android.com/tools">
 
+    <androidx.preference.Preference
+        app:icon="@drawable/ic_save_alt"
+        app:key="backup_location"
+        app:summary="@string/settings_backup_location_none"
+        app:title="@string/settings_backup_location" />
+
+    <androidx.preference.Preference
+        app:fragment="com.stevesoltys.seedvault.ui.recoverycode.RecoveryCodeInputFragment"
+        app:icon="@drawable/ic_vpn_key"
+        app:key="backup_recovery_code"
+        app:summary="@string/settings_backup_recovery_code_summary"
+        app:title="@string/settings_backup_recovery_code" />
+
+    <PreferenceCategory android:title="@string/settings_category_apps">
+
         <androidx.preference.SwitchPreferenceCompat
+            app:allowDividerBelow="true"
             app:icon="@drawable/ic_cloud_upload"
             app:key="backup"
             app:persistent="false"
             app:title="@string/settings_backup" />
 
         <androidx.preference.Preference
-        app:allowDividerAbove="true"
             app:fragment="com.stevesoltys.seedvault.settings.AppStatusFragment"
             app:icon="@drawable/ic_apps"
             app:key="backup_status"
             app:title="@string/settings_backup_status_title"
             tools:summary="Last backup: Never" />
 
-    <androidx.preference.Preference
-        app:dependency="backup"
-        app:icon="@drawable/ic_storage"
-        app:key="backup_location"
-        app:summary="@string/settings_backup_location_none"
-        app:title="@string/settings_backup_location" />
-
         <androidx.preference.SwitchPreferenceCompat
             app:dependency="backup"
             app:key="auto_restore"
             app:persistent="false"
             app:summary="@string/settings_auto_restore_summary"
-        app:title="@string/settings_auto_restore_title" />
+            app:title="@string/settings_auto_restore_title"
+            tools:defaultValue="true" />
 
         <androidx.preference.SwitchPreferenceCompat
             app:defaultValue="true"
@@ -36,18 +46,30 @@
             app:summary="@string/settings_backup_apk_summary"
             app:title="@string/settings_backup_apk_title" />
 
+    </PreferenceCategory>
+
+    <PreferenceCategory android:title="@string/settings_category_storage">
+
+        <androidx.preference.SwitchPreferenceCompat
+            app:defaultValue="false"
+            app:icon="@drawable/ic_storage"
+            app:key="backup_storage"
+            app:title="@string/settings_backup_storage_title" />
+
         <androidx.preference.Preference
-        app:dependency="backup"
+            android:dependency="backup_storage"
-        app:fragment="com.stevesoltys.seedvault.ui.recoverycode.RecoveryCodeInputFragment"
+            app:dependency="backup_storage"
-        app:icon="@drawable/ic_vpn_key"
+            app:fragment="com.stevesoltys.seedvault.ui.files.FileSelectionFragment"
-        app:key="backup_recovery_code"
+            app:icon="@drawable/ic_library_add"
-        app:summary="@string/settings_backup_recovery_code_summary"
+            app:key="backup_files"
-        app:title="@string/settings_backup_recovery_code" />
+            app:summary="@string/settings_backup_files_summary"
+            app:title="@string/settings_backup_files_title" />
+
+    </PreferenceCategory>
 
     <androidx.preference.Preference
         app:allowDividerAbove="true"
         app:allowDividerBelow="false"
-        app:dependency="backup"
         app:icon="@drawable/ic_info_outline"
         app:selectable="false"
         app:summary="@string/settings_info" />

app/src/test/java/com/stevesoltys/seedvault/plugins/saf/DocumentFileTest.kt

@@ -1,11 +1,13 @@
 package com.stevesoltys.seedvault.plugins.saf
 
 import android.content.Context
+import android.content.pm.PackageManager
 import android.net.Uri
 import android.provider.DocumentsContract
 import androidx.documentfile.provider.DocumentFile
 import androidx.test.ext.junit.runners.AndroidJUnit4
 import com.stevesoltys.seedvault.TestApp
+import io.mockk.every
 import io.mockk.mockk
 import org.junit.After
 import org.junit.Assert.assertEquals
@@ -27,6 +29,14 @@ internal class DocumentFileTest {
         "content://com.android.externalstorage.documents/tree/" +
             "primary%3A/document/primary%3A.SeedVaultAndroidBackup"
     )
+
+    init {
+        // needed since 'androidx.documentfile:documentfile:1.0.1'
+        val pm: PackageManager = mockk()
+        every { context.packageManager } returns pm
+        every { pm.queryIntentContentProviders(any(), 0) } returns emptyList()
+    }
+
     private val parentFile: DocumentFile = DocumentFile.fromTreeUri(context, parentUri)!!
     private val uri: Uri = Uri.parse(
         "content://com.android.externalstorage.documents/tree/" +

build.gradle

@@ -1,10 +1,10 @@
 buildscript {
-
     // 1.3.21 Android 10
     // 1.3.61 Android 11
     // Check:
     // https://android.googlesource.com/platform/external/kotlinc/+/refs/tags/android-11.0.0_r3/build.txt
-    ext.kotlin_version = '1.3.61'
+    ext.aosp_kotlin_version = '1.3.61'
+    ext.kotlin_version = '1.4.31'
 
     repositories {
         jcenter()
@@ -13,10 +13,20 @@ buildscript {
     dependencies {
         //noinspection DifferentKotlinGradleVersion
         classpath "org.jetbrains.kotlin:kotlin-gradle-plugin:$kotlin_version"
-        classpath 'com.android.tools.build:gradle:4.1.0'
+        classpath "com.google.protobuf:protobuf-gradle-plugin:0.8.14"
+        classpath 'com.android.tools.build:gradle:4.1.2'
     }
 }
 
+ext {
+    buildToolsVersion = '30.0.2'
+    compileSdkVersion = 30
+    minSdkVersion = 29
+    targetSdkVersion = 30
+}
+
+apply from: 'gradle/dependencies.gradle'
+
 allprojects {
     repositories {
         mavenCentral()

contactsbackup/build.gradle

@@ -50,16 +50,12 @@ def aospDeps = fileTree(include: [
 dependencies {
     implementation aospDeps
 
-    //noinspection GradleDependency
     testImplementation "org.jetbrains.kotlin:kotlin-stdlib-jdk8:$kotlin_version"
-    testImplementation 'junit:junit:4.13.1'
+    testImplementation "junit:junit:$junit4_version"
-    def mockk_version = "1.10.2"
     testImplementation "io.mockk:mockk:$mockk_version"
 
-    //noinspection GradleDependency
     androidTestImplementation "org.jetbrains.kotlin:kotlin-stdlib-jdk8:$kotlin_version"
     androidTestImplementation 'androidx.test.ext:junit:1.1.2'
-    def espresso_version = "3.3.0"
     androidTestImplementation "androidx.test.espresso:espresso-core:$espresso_version"
     androidTestImplementation "io.mockk:mockk-android:$mockk_version"
 }

gradle.properties

@@ -1,3 +1,5 @@
 org.gradle.jvmargs=-Xmx1g
+org.gradle.configureondemand=true
 android.useAndroidX=true
 android.enableJetifier=false
+kotlin.code.style=official

gradle/dependencies.gradle

@@ -1,6 +1,17 @@
+ext {
+    // https://android.googlesource.com/platform/prebuilts/sdk/+/refs/tags/android-11.0.0_r3/current/androidx/Android.bp#2713
+    ext.room_version = "2.3.0-alpha02"
+    // http://aosp.opersys.com/xref/android-11.0.0_r27/xref/external/protobuf/java/pom.xml#7
+    ext.protobuf_version = "3.9.1"
+    junit4_version = "4.13.1"
+    junit5_version = "5.5.2" // careful, upgrading this can change a Cipher's IV size in tests!?
+    mockk_version = "1.10.2"
+    espresso_version = "3.3.0"
+}
+
 // To produce these binaries, in latest AOSP source tree, run
 // $ m
-def aospDeps = fileTree(include: [
+ext.aosp_libs = fileTree(include: [
     // For more information about this module:
     // https://android.googlesource.com/platform/frameworks/base/+/refs/tags/android-11.0.0_r3/Android.bp#507
     // framework_intermediates/classes-header.jar works for gradle build as well,
@@ -9,122 +20,82 @@ def aospDeps = fileTree(include: [
     // out/target/common/obj/JAVA_LIBRARIES/framework-minus-apex_intermediates/classes.jar
     'android.jar',
     // out/target/common/obj/JAVA_LIBRARIES/core-libart.com.android.art.release_intermediates/classes.jar
-        'libcore.jar'
+    'libcore.jar',
-], dir: 'libs')
+], dir: "$projectDir/app/libs")
 
-dependencies {
+ext.kotlin_libs = [
-    compileOnly aospDeps
+    std: [
-
+        dependencies.create('org.jetbrains.kotlin:kotlin-stdlib') {
-    /**
+            version { strictly "$aosp_kotlin_version" }
-     * Dependencies in AOSP
+        },
-     *
+        dependencies.create('org.jetbrains.kotlin:kotlin-stdlib-jdk8') {
-     * We try to keep the dependencies in sync with what AOSP ships as Seedvault is meant to be built
+            version { strictly "$aosp_kotlin_version" }
-     * with the AOSP build system and gradle builds are just for more pleasant development.
+        },
-     * Using the AOSP versions in gradle builds allows us to spot issues early on.
+        dependencies.create('org.jetbrains.kotlin:kotlin-stdlib-common') {
-     */
+            version { strictly "$aosp_kotlin_version" }
-
+        },
-    implementation('org.jetbrains.kotlin:kotlin-stdlib-jdk8') {
+    ],
-        version { strictly "$kotlin_version" }
+    coroutines: [
-    }
+        dependencies.create('org.jetbrains.kotlinx:kotlinx-coroutines-core') {
-    implementation('org.jetbrains.kotlin:kotlin-stdlib-common') {
-        version { strictly "$kotlin_version" }
-    }
-    implementation('org.jetbrains.kotlin:kotlin-stdlib') {
-        version { strictly "$kotlin_version" }
-    }
-
-    // These coroutine libraries get upgraded otherwise to versions incompatible with kotlin version
-    implementation('org.jetbrains.kotlinx:kotlinx-coroutines-core') {
             // https://android.googlesource.com/platform/prebuilts/tools/+/refs/tags/android-11.0.0_r3/common/m2/Android.bp#326
             version { strictly '1.3.0' }
-    }
+        },
-    implementation('org.jetbrains.kotlinx:kotlinx-coroutines-android') {
+        dependencies.create('org.jetbrains.kotlinx:kotlinx-coroutines-android') {
             // https://android.googlesource.com/platform/prebuilts/tools/+/refs/tags/android-11.0.0_r3/common/m2/Android.bp#340
             version { strictly '1.3.0' }
-    }
+        },
+    ],
+]
 
-    implementation('androidx.core:core-ktx') {
+ext.std_libs = [
     // https://android.googlesource.com/platform/prebuilts/sdk/+/refs/tags/android-11.0.0_r3/current/androidx/Android.bp#610
+    androidx_core: dependencies.create('androidx.core:core-ktx') {
         version { strictly '1.5.0-alpha01' }
-    }
+    },
-
-    // A newer version gets pulled in with AOSP via core, so we include this here explicitly
-    implementation('androidx.fragment:fragment-ktx') {
     // https://android.googlesource.com/platform/prebuilts/sdk/+/refs/tags/android-11.0.0_r3/current/androidx/Android.bp#930
+    androidx_fragment: dependencies.create('androidx.fragment:fragment-ktx') {
         version { strictly '1.3.0-alpha07' }
-    }
+    },
-
-    implementation('androidx.preference:preference') {
     // https://android.googlesource.com/platform/prebuilts/sdk/+/refs/tags/android-11.0.0_r3/current/androidx/Android.bp#2412
+    androidx_preference: dependencies.create('androidx.preference:preference') {
         version { strictly '1.1.1' } // should be 1.2.0-alpha01, but that is not even released, yet
-    }
+    },
-
-    implementation('androidx.lifecycle:lifecycle-viewmodel-ktx') {
     // https://android.googlesource.com/platform/prebuilts/sdk/+/refs/tags/android-11.0.0_r3/current/androidx/Android.bp#1553
+    androidx_lifecycle_viewmodel_ktx: dependencies.create('androidx.lifecycle:lifecycle-viewmodel-ktx') {
         version { strictly '2.3.0-alpha05' }
-    }
+    },
-
-    implementation('androidx.lifecycle:lifecycle-livedata-ktx') {
     // https://android.googlesource.com/platform/prebuilts/sdk/+/refs/tags/android-11.0.0_r3/current/androidx/Android.bp#1353
+    androidx_lifecycle_livedata_ktx: dependencies.create('androidx.lifecycle:lifecycle-livedata-ktx') {
         version { strictly '2.3.0-alpha05' }
-    }
+    },
-
-    implementation('androidx.constraintlayout:constraintlayout') {
     // https://android.googlesource.com/platform/prebuilts/sdk/+/refs/tags/android-11.0.0_r3/current/extras/constraint-layout-x/Android.bp#30
+    androidx_constraintlayout: dependencies.create('androidx.constraintlayout:constraintlayout') {
         version { strictly '2.0.0-beta7' }
-    }
+    },
-
+    // https://android.googlesource.com/platform/prebuilts/sdk/+/refs/tags/android-11.0.0_r3/current/androidx/Android.bp#708
-    implementation('com.google.android.material:material') {
+    androidx_documentfile: dependencies.create('androidx.documentfile:documentfile') {
+        version { strictly '1.0.1' } // should be 1.1.0-alpha01, but that is not even released, yet
+    },
     // https://android.googlesource.com/platform/prebuilts/sdk/+/refs/tags/android-11.0.0_r3/current/extras/material-design-x/Android.bp#6
+    com_google_android_material: dependencies.create('com.google.android.material:material') {
         version { strictly '1.1.0-alpha05' }
-    }
+    },
+]
 
+ext.lint_libs = [
+    exceptions: 'com.github.thirdegg:lint-rules:0.0.6-beta'
+]
 
-    /**
+ext.storage_libs = [
-     * External Dependencies
+    // https://android.googlesource.com/platform/prebuilts/sdk/+/refs/tags/android-11.0.0_r3/current/androidx/Android.bp#2711
-     *
+    androidx_room_runtime: dependencies.create('androidx.room:room-runtime') {
-     * If the dependencies below are updated,
+        version { strictly "$room_version" }
-     * please make sure to update the prebuilt libraries and the Android.bp files
+    },
-     * in the top-level `libs` folder to reflect that.
+    // http://aosp.opersys.com/xref/android-11.0.0_r27/xref/external/protobuf/java/pom.xml#7
-     * You can copy these libraries from ~/.gradle/caches/modules-2
+    com_google_protobuf_javalite: dependencies.create('com.google.protobuf:protobuf-javalite') {
-     */
+        version { strictly "$protobuf_version" }
-
+    },
-    def koin_version = '2.1.1' // later versions require newer kotlin version
+    com_google_crypto_tink_android: dependencies.create('com.google.crypto.tink:tink-android') {
-    //noinspection GradleDependency
+        version { strictly '1.5.0' }
-    implementation("org.koin:koin-android:$koin_version") {
+    },
-        exclude group: 'org.jetbrains.kotlin', module: 'kotlin-stdlib'
+]
-    }
-    //noinspection GradleDependency
-    implementation("org.koin:koin-androidx-viewmodel:$koin_version") {
-        exclude group: 'org.koin', module: 'koin-androidx-scope'
-        exclude group: 'androidx.lifecycle'
-    }
-
-    implementation('io.github.novacrypto:BIP39:2019.01.27') {
-        exclude group: 'com.madgag.spongycastle'
-    }
-
-    /**
-     * Test Dependencies (do not concern the AOSP build)
-     */
-
-    lintChecks 'com.github.thirdegg:lint-rules:0.0.5-alpha'
-
-    def junit_version = "5.5.2"  // careful, upgrading this can change a Cipher's IV size in tests!?
-    def mockk_version = "1.10.0"
-    testImplementation aospDeps  // anything less than 'implementation' fails tests run with gradlew
-    testImplementation 'androidx.test.ext:junit:1.1.2'
-    testImplementation('org.robolectric:robolectric:4.3.1') { // 4.4 has issue with non-idle Looper
-        // https://github.com/robolectric/robolectric/issues/5245
-        exclude group: "com.google.auto.service", module: "auto-service"
-    }
-    testImplementation "org.junit.jupiter:junit-jupiter-api:$junit_version"
-    testImplementation "io.mockk:mockk:$mockk_version"
-    testRuntimeOnly "org.junit.jupiter:junit-jupiter-engine:$junit_version"
-    testRuntimeOnly "org.junit.vintage:junit-vintage-engine:$junit_version"
-
-    androidTestImplementation 'androidx.test:runner:1.3.0'
-    androidTestImplementation 'androidx.test:rules:1.3.0'
-    androidTestImplementation 'androidx.test.ext:junit:1.1.2'
-    androidTestImplementation "io.mockk:mockk-android:$mockk_version"
-}

permissions_com.stevesoltys.seedvault.xml

@@ -5,5 +5,6 @@
         <permission name="android.permission.MANAGE_USB"/>
         <permission name="android.permission.INSTALL_PACKAGES"/>
         <permission name="android.permission.WRITE_SECURE_SETTINGS"/>
+        <permission name="android.permission.MANAGE_EXTERNAL_STORAGE"/>
     </privapp-permissions>
 </permissions>

settings.gradle

@@ -1,2 +1,4 @@
 include ':app'
 include ':contactsbackup'
+include ':storage:lib'
+include ':storage:demo'

storage/.gitignore

@@ -0,0 +1 @@
+release.sh

storage/demo/.gitignore

@@ -0,0 +1,2 @@
+/build
+/debug

storage/demo/build.gradle

@@ -0,0 +1,57 @@
+plugins {
+    id 'com.android.application'
+    id 'com.google.protobuf'
+    id 'kotlin-android'
+    id 'kotlin-kapt'
+}
+
+android {
+    compileSdkVersion rootProject.ext.compileSdkVersion
+    buildToolsVersion rootProject.ext.buildToolsVersion
+
+    defaultConfig {
+        applicationId "de.grobox.storagebackuptester"
+        minSdkVersion rootProject.ext.minSdkVersion
+        targetSdkVersion rootProject.ext.targetSdkVersion
+        versionCode 18
+        versionName "0.9.5"
+
+        testInstrumentationRunner "androidx.test.runner.AndroidJUnitRunner"
+        testInstrumentationRunnerArguments disableAnalytics: 'true'
+    }
+
+    buildTypes {
+        release {
+            minifyEnabled true
+            proguardFiles getDefaultProguardFile('proguard-android-optimize.txt'), 'proguard-rules.pro'
+        }
+    }
+    compileOptions {
+        sourceCompatibility JavaVersion.VERSION_1_8
+        targetCompatibility JavaVersion.VERSION_1_8
+    }
+    kotlinOptions {
+        jvmTarget = '1.8'
+        freeCompilerArgs += "-Xopt-in=kotlin.RequiresOptIn"
+    }
+    packagingOptions {
+        exclude 'META-INF/*.kotlin_module'
+        exclude 'META-INF/androidx.*.version'
+        exclude 'META-INF/services/kotlin*'
+        exclude 'kotlin/internal/internal.kotlin_builtins'
+    }
+}
+
+dependencies {
+    implementation project(':storage:lib')
+
+    implementation rootProject.ext.std_libs.androidx_core
+    // A newer version gets pulled in with AOSP via core, so we include fragment here explicitly
+    implementation rootProject.ext.std_libs.androidx_fragment
+    implementation rootProject.ext.std_libs.androidx_lifecycle_viewmodel_ktx
+    implementation rootProject.ext.std_libs.androidx_lifecycle_livedata_ktx
+    implementation rootProject.ext.std_libs.androidx_constraintlayout
+    implementation rootProject.ext.std_libs.com_google_android_material
+
+    implementation rootProject.ext.storage_libs.com_google_protobuf_javalite
+}

storage/demo/proguard-rules.pro

@@ -0,0 +1,23 @@
+# Add project specific ProGuard rules here.
+# You can control the set of applied configuration files using the
+# proguardFiles setting in build.gradle.
+#
+# For more details, see
+#   http://developer.android.com/guide/developing/tools/proguard.html
+
+# If your project uses WebView with JS, uncomment the following
+# and specify the fully qualified class name to the JavaScript interface
+# class:
+#-keepclassmembers class fqcn.of.javascript.interface.for.webview {
+#   public *;
+#}
+
+# Uncomment this to preserve the line number information for
+# debugging stack traces.
+#-keepattributes SourceFile,LineNumberTable
+
+# If you keep the line number information, uncomment this to
+# hide the original source file name.
+#-renamesourcefileattribute SourceFile
+
+-dontobfuscate

storage/demo/src/main/AndroidManifest.xml

@@ -0,0 +1,43 @@
+<?xml version="1.0" encoding="utf-8"?>
+<manifest xmlns:android="http://schemas.android.com/apk/res/android"
+    package="de.grobox.storagebackuptester">
+
+    <application
+        android:name=".App"
+        android:allowBackup="false"
+        android:icon="@mipmap/ic_launcher"
+        android:label="@string/app_name"
+        android:roundIcon="@mipmap/ic_launcher_round"
+        android:supportsRtl="true"
+        android:theme="@style/Theme.StorageBackupTester">
+
+        <activity android:name=".MainActivity">
+            <intent-filter>
+                <action android:name="android.intent.action.MAIN" />
+
+                <category android:name="android.intent.category.LAUNCHER" />
+            </intent-filter>
+        </activity>
+
+        <!-- Used to start actual BackupService depending on scheduling criteria -->
+        <service
+            android:name=".DemoBackupJobService"
+            android:exported="false"
+            android:label="BackupJobService"
+            android:permission="android.permission.BIND_JOB_SERVICE" />
+        <!-- Does the actual backup work as a foreground service -->
+        <service
+            android:name=".DemoBackupService"
+            android:exported="false"
+            android:foregroundServiceType="dataSync"
+            android:label="BackupService" />
+        <!-- Does restore as a foreground service -->
+        <service
+            android:name=".DemoRestoreService"
+            android:exported="false"
+            android:foregroundServiceType="dataSync"
+            android:label="RestoreService" />
+
+    </application>
+
+</manifest>

storage/demo/src/main/java/de/grobox/storagebackuptester/App.kt

@@ -0,0 +1,40 @@
+package de.grobox.storagebackuptester
+
+import android.app.Application
+import android.os.StrictMode
+import android.os.StrictMode.VmPolicy
+import android.util.Log
+import de.grobox.storagebackuptester.plugin.TestSafStoragePlugin
+import de.grobox.storagebackuptester.settings.SettingsManager
+import org.calyxos.backup.storage.api.StorageBackup
+
+class App : Application() {
+
+    val settingsManager: SettingsManager by lazy { SettingsManager(applicationContext) }
+    val storageBackup: StorageBackup by lazy {
+        val plugin = TestSafStoragePlugin(this) { settingsManager.getBackupLocation() }
+        StorageBackup(this, plugin)
+    }
+
+    override fun onCreate() {
+        super.onCreate()
+        StrictMode.setThreadPolicy(
+            StrictMode.ThreadPolicy.Builder()
+                .detectAll()
+                .penaltyLog()
+                .build()
+        )
+        StrictMode.setVmPolicy(
+            VmPolicy.Builder()
+                .detectAll()
+                .penaltyLog()
+                .build()
+        )
+    }
+
+    override fun onLowMemory() {
+        super.onLowMemory()
+        Log.e("TEST", "ON LOW MEMORY!!!")
+    }
+
+}

storage/demo/src/main/java/de/grobox/storagebackuptester/Job.kt

@@ -0,0 +1,46 @@
+package de.grobox.storagebackuptester
+
+import android.content.Context
+import org.calyxos.backup.storage.api.BackupObserver
+import org.calyxos.backup.storage.api.RestoreObserver
+import org.calyxos.backup.storage.api.StorageBackup
+import org.calyxos.backup.storage.backup.BackupJobService
+import org.calyxos.backup.storage.backup.BackupService
+import org.calyxos.backup.storage.backup.NotificationBackupObserver
+import org.calyxos.backup.storage.restore.NotificationRestoreObserver
+import org.calyxos.backup.storage.restore.RestoreService
+import java.util.concurrent.TimeUnit.HOURS
+
+// debug with:
+// adb shell dumpsys jobscheduler | grep -B 4 -A 24 "Service: de.grobox.storagebackuptester/.DemoBackupJobService"
+
+class DemoBackupJobService : BackupJobService(DemoBackupService::class.java) {
+    companion object {
+        fun scheduleJob(context: Context) {
+            scheduleJob(
+                context = context,
+                jobServiceClass = DemoBackupJobService::class.java,
+//                periodMillis = JobInfo.getMinPeriodMillis(), // for testing
+                periodMillis = HOURS.toMillis(12), // less than 15min won't work
+                deviceIdle = false,
+                charging = false,
+            )
+        }
+    }
+}
+
+class DemoBackupService : BackupService() {
+    // use lazy delegate because context isn't available during construction time
+    override val storageBackup: StorageBackup by lazy { (application as App).storageBackup }
+    override val backupObserver: BackupObserver by lazy {
+        NotificationBackupObserver(applicationContext)
+    }
+}
+
+class DemoRestoreService : RestoreService() {
+    // use lazy delegate because context isn't available during construction time
+    override val storageBackup: StorageBackup by lazy { (application as App).storageBackup }
+    override val restoreObserver: RestoreObserver by lazy {
+        NotificationRestoreObserver(applicationContext)
+    }
+}

storage/demo/src/main/java/de/grobox/storagebackuptester/LogAdapter.kt

@@ -0,0 +1,43 @@
+package de.grobox.storagebackuptester
+
+import android.view.LayoutInflater
+import android.view.View
+import android.view.ViewGroup
+import android.widget.TextView
+import androidx.recyclerview.widget.RecyclerView
+
+class LogAdapter : RecyclerView.Adapter<LogAdapter.ViewHolder>() {
+
+    val items: ArrayList<String> = ArrayList()
+
+    override fun onCreateViewHolder(parent: ViewGroup, viewType: Int): ViewHolder {
+        val v = LayoutInflater.from(parent.context).inflate(R.layout.item_log, parent, false)
+        return ViewHolder(v)
+    }
+
+    override fun onBindViewHolder(holder: ViewHolder, position: Int) {
+        val item = items[position]
+        holder.bind(item)
+    }
+
+    override fun getItemCount(): Int = items.size
+
+    fun addItem(item: String) {
+        items.add(item)
+        notifyItemInserted(items.size - 1)
+    }
+
+    fun clear() {
+        items.clear()
+        notifyDataSetChanged()
+    }
+
+    class ViewHolder(view: View) : RecyclerView.ViewHolder(view) {
+        private val logView: TextView = view.findViewById(R.id.logView)
+
+        fun bind(item: String) {
+            logView.text = item
+        }
+    }
+
+}

storage/demo/src/main/java/de/grobox/storagebackuptester/LogFragment.kt

@@ -0,0 +1,142 @@
+package de.grobox.storagebackuptester
+
+import android.Manifest.permission.ACCESS_MEDIA_LOCATION
+import android.Manifest.permission.WRITE_EXTERNAL_STORAGE
+import android.content.Intent
+import android.content.pm.PackageManager.PERMISSION_GRANTED
+import android.net.Uri
+import android.os.Build
+import android.os.Bundle
+import android.os.Environment
+import android.provider.Settings.ACTION_MANAGE_APP_ALL_FILES_ACCESS_PERMISSION
+import android.view.LayoutInflater
+import android.view.Menu
+import android.view.MenuInflater
+import android.view.MenuItem
+import android.view.View
+import android.view.View.INVISIBLE
+import android.view.View.VISIBLE
+import android.view.ViewGroup
+import android.widget.Button
+import android.widget.ProgressBar
+import android.widget.Toast
+import android.widget.Toast.LENGTH_SHORT
+import androidx.activity.result.contract.ActivityResultContracts.RequestMultiplePermissions
+import androidx.fragment.app.Fragment
+import androidx.fragment.app.activityViewModels
+import androidx.recyclerview.widget.RecyclerView
+import de.grobox.storagebackuptester.settings.SettingsFragment
+
+private const val EMAIL = "incoming+grote-storage-backup-tester-22079635-issue-@incoming.gitlab.com"
+
+open class LogFragment : Fragment() {
+
+    companion object {
+        fun newInstance(): LogFragment = LogFragment()
+    }
+
+    private val viewModel: MainViewModel by activityViewModels()
+
+    private lateinit var list: RecyclerView
+    private lateinit var progressBar: ProgressBar
+    private lateinit var horizontalProgressBar: ProgressBar
+    private lateinit var button: Button
+    private val adapter = LogAdapter()
+
+    private val permissionRequest =
+        registerForActivityResult(RequestMultiplePermissions()) { grantedMap ->
+            if (grantedMap[WRITE_EXTERNAL_STORAGE] == true) {
+                Toast.makeText(requireContext(), "Please try again now!", LENGTH_SHORT).show()
+            }
+        }
+
+    override fun onCreateView(
+        inflater: LayoutInflater,
+        container: ViewGroup?,
+        savedInstanceState: Bundle?
+    ): View {
+        setHasOptionsMenu(true)
+        val v = inflater.inflate(R.layout.fragment_log, container, false)
+        list = v.findViewById(R.id.listView)
+        list.adapter = adapter
+        progressBar = v.findViewById(R.id.progressBar)
+        horizontalProgressBar = v.findViewById(R.id.horizontalProgressBar)
+        button = v.findViewById(R.id.button)
+        viewModel.backupLog.observe(viewLifecycleOwner, { progress ->
+            progress.text?.let { adapter.addItem(it) }
+            horizontalProgressBar.max = progress.total
+            horizontalProgressBar.setProgress(progress.current, true)
+            list.postDelayed({
+                list.scrollToPosition(adapter.itemCount - 1)
+            }, 50)
+        })
+        viewModel.backupButtonEnabled.observe(viewLifecycleOwner, { enabled ->
+            button.isEnabled = enabled
+            progressBar.visibility = if (enabled) INVISIBLE else VISIBLE
+            if (!enabled) adapter.clear()
+        })
+        button.setOnClickListener {
+            if (!checkPermission()) return@setOnClickListener
+            viewModel.simulateBackup()
+        }
+        return v
+    }
+
+    override fun onStart() {
+        super.onStart()
+        requireActivity().setTitle(R.string.app_name)
+    }
+
+    override fun onCreateOptionsMenu(menu: Menu, inflater: MenuInflater) {
+        inflater.inflate(R.menu.fragment_main, menu)
+    }
+
+    override fun onOptionsItemSelected(item: MenuItem): Boolean {
+        return when (item.itemId) {
+            R.id.settings -> {
+                if (!checkPermission()) return false
+                parentFragmentManager.beginTransaction()
+                    .replace(R.id.container, SettingsFragment.newInstance())
+                    .addToBackStack("SETTINGS")
+                    .commit()
+                true
+            }
+            R.id.share -> {
+                val subject = adapter.items.takeLast(2).joinToString(" - ").replace("\n", "")
+                val text = adapter.items.takeLast(333).joinToString("\n")
+                val sendIntent: Intent = Intent().apply {
+                    action = Intent.ACTION_SEND
+                    putExtra(Intent.EXTRA_EMAIL, arrayOf(EMAIL))
+                    putExtra(Intent.EXTRA_SUBJECT, subject)
+                    putExtra(Intent.EXTRA_TEXT, text)
+                    type = "text/plain"
+                }
+                val shareIntent = Intent.createChooser(sendIntent, null)
+                startActivity(shareIntent)
+                true
+            }
+            else -> super.onOptionsItemSelected(item)
+        }
+    }
+
+    private fun checkPermission(): Boolean {
+        return if (Build.VERSION.SDK_INT >= 30) {
+            if (Environment.isExternalStorageManager()) return true
+            Toast.makeText(requireContext(), "Permission needed", LENGTH_SHORT).show()
+            val i = Intent(ACTION_MANAGE_APP_ALL_FILES_ACCESS_PERMISSION).apply {
+                data = Uri.parse("package:${requireContext().packageName}")
+            }
+            startActivity(i)
+            false
+        } else {
+            if (requireContext().checkSelfPermission(WRITE_EXTERNAL_STORAGE) == PERMISSION_GRANTED) {
+                true
+            } else {
+                Toast.makeText(requireContext(), "No storage permission", LENGTH_SHORT).show()
+                permissionRequest.launch(arrayOf(WRITE_EXTERNAL_STORAGE, ACCESS_MEDIA_LOCATION))
+                false
+            }
+        }
+    }
+
+}

storage/demo/src/main/java/de/grobox/storagebackuptester/MainActivity.kt

@@ -0,0 +1,31 @@
+package de.grobox.storagebackuptester
+
+import android.os.Bundle
+import android.util.Log
+import androidx.appcompat.app.AppCompatActivity
+import de.grobox.storagebackuptester.crypto.KeyManager
+
+class MainActivity : AppCompatActivity() {
+
+    override fun onCreate(savedInstanceState: Bundle?) {
+        super.onCreate(savedInstanceState)
+        setContentView(R.layout.activity_main)
+
+        if (savedInstanceState == null) {
+            supportFragmentManager.beginTransaction()
+                .replace(R.id.container, LogFragment.newInstance())
+                .commitNow()
+        }
+
+        KeyManager.storeMasterKey()
+
+        if (!KeyManager.hasMasterKey()) {
+            Log.e("TEST", "storing new key")
+            KeyManager.storeMasterKey()
+        } else {
+            Log.e("TEST", "already have key")
+        }
+
+    }
+
+}

storage/demo/src/main/java/de/grobox/storagebackuptester/MainViewModel.kt

@@ -0,0 +1,133 @@
+package de.grobox.storagebackuptester
+
+import android.app.Application
+import android.net.Uri
+import android.util.Log
+import androidx.lifecycle.LiveData
+import androidx.lifecycle.MutableLiveData
+import androidx.lifecycle.asLiveData
+import androidx.lifecycle.viewModelScope
+import de.grobox.storagebackuptester.backup.BackupProgress
+import de.grobox.storagebackuptester.backup.BackupStats
+import de.grobox.storagebackuptester.restore.RestoreProgress
+import de.grobox.storagebackuptester.restore.RestoreStats
+import de.grobox.storagebackuptester.scanner.scanTree
+import de.grobox.storagebackuptester.scanner.scanUri
+import kotlinx.coroutines.Dispatchers
+import kotlinx.coroutines.launch
+import kotlinx.coroutines.withContext
+import org.calyxos.backup.storage.api.SnapshotItem
+import org.calyxos.backup.storage.api.SnapshotResult
+import org.calyxos.backup.storage.api.StorageBackup
+import org.calyxos.backup.storage.backup.BackupJobService
+import org.calyxos.backup.storage.scanner.DocumentScanner
+import org.calyxos.backup.storage.scanner.MediaScanner
+import org.calyxos.backup.storage.ui.backup.BackupContentViewModel
+import org.calyxos.backup.storage.ui.restore.SnapshotViewModel
+
+private val logEmptyState = """
+    Press the button below to simulate a backup. Your files won't be changed and not uploaded anywhere. This is just to test code for a future real backup.
+    
+    Please come back to this app from time to time and run a backup again to see if it correctly identifies files that were added/changed.
+    
+    Note that after updating this app, it might need to re-backup all files again.
+    
+    Thanks for testing!
+""".trimIndent()
+private const val TAG = "MainViewModel"
+
+class MainViewModel(application: Application) : BackupContentViewModel(application),
+    SnapshotViewModel {
+
+    private val app: App = application as App
+    private val settingsManager = app.settingsManager
+    override val storageBackup: StorageBackup = app.storageBackup
+
+    private val _backupLog = MutableLiveData(BackupProgress(0, 0, logEmptyState))
+    val backupLog: LiveData<BackupProgress> = _backupLog
+
+    private val _buttonEnabled = MutableLiveData<Boolean>()
+    val backupButtonEnabled: LiveData<Boolean> = _buttonEnabled
+
+    private val _restoreLog = MutableLiveData<RestoreProgress>()
+    val restoreLog: LiveData<RestoreProgress> = _restoreLog
+
+    private val _restoreProgressVisible = MutableLiveData<Boolean>()
+    val restoreProgressVisible: LiveData<Boolean> = _restoreProgressVisible
+
+    override val snapshots: LiveData<SnapshotResult>
+        get() = storageBackup.getBackupSnapshots().asLiveData(Dispatchers.IO)
+
+    init {
+        viewModelScope.launch { loadContent() }
+    }
+
+    fun simulateBackup() {
+        _buttonEnabled.value = false
+        val backupObserver = BackupStats(app, storageBackup, _backupLog)
+        viewModelScope.launch(Dispatchers.IO) {
+            val text = storageBackup.getUriSummaryString()
+            _backupLog.postValue(BackupProgress(0, 0, "Scanning: $text\n"))
+            if (storageBackup.runBackup(backupObserver)) {
+                // only prune old backups when backup run was successful
+                storageBackup.pruneOldBackups(backupObserver)
+            }
+            _buttonEnabled.postValue(true)
+        }
+    }
+
+    suspend fun scanMediaUri(uri: Uri): String = withContext(Dispatchers.Default) {
+        scanUri(app, MediaScanner(app), uri)
+    }
+
+    suspend fun scanDocumentUri(uri: Uri): String = withContext(Dispatchers.Default) {
+        scanTree(app, DocumentScanner(app), uri)
+    }
+
+    fun clearDb() {
+        viewModelScope.launch(Dispatchers.IO) { storageBackup.clearCache() }
+    }
+
+    fun setBackupLocation(uri: Uri?) {
+        if (uri != null) clearDb()
+        settingsManager.setBackupLocation(uri)
+    }
+
+    fun hasBackupLocation(): Boolean {
+        return settingsManager.getBackupLocation() != null
+    }
+
+    fun setAutomaticBackupsEnabled(enabled: Boolean) {
+        if (enabled) DemoBackupJobService.scheduleJob(app)
+        else BackupJobService.cancelJob(app)
+        settingsManager.setAutomaticBackupsEnabled(enabled)
+    }
+
+    fun areAutomaticBackupsEnabled(): Boolean {
+        val enabled = settingsManager.areAutomaticBackupsEnabled()
+        if (enabled && !BackupJobService.isScheduled(app)) {
+            Log.w(TAG, "Automatic backups enabled, but job not scheduled. Scheduling...")
+            DemoBackupJobService.scheduleJob(app)
+        }
+        return enabled
+    }
+
+    fun onSnapshotClicked(item: SnapshotItem) {
+        val snapshot = item.snapshot
+        check(snapshot != null)
+
+        // example for how to do restore via foreground service
+//        app.startForegroundService(Intent(app, DemoRestoreService::class.java).apply {
+//            putExtra(EXTRA_TIMESTAMP_START, snapshot.timeStart)
+//        })
+
+        // example for how to do restore via fragment
+        _restoreProgressVisible.value = true
+        val restoreObserver = RestoreStats(app, _restoreLog)
+        viewModelScope.launch {
+            storageBackup.restoreBackupSnapshot(snapshot, restoreObserver)
+            _restoreProgressVisible.value = false
+        }
+    }
+
+}

storage/demo/src/main/java/de/grobox/storagebackuptester/backup/BackupStats.kt

@@ -0,0 +1,182 @@
+package de.grobox.storagebackuptester.backup
+
+import android.content.Context
+import android.provider.MediaStore
+import android.text.format.DateUtils.FORMAT_ABBREV_ALL
+import android.text.format.DateUtils.getRelativeTimeSpanString
+import android.text.format.Formatter
+import android.util.Log
+import androidx.lifecycle.MutableLiveData
+import org.calyxos.backup.storage.api.BackupFile
+import org.calyxos.backup.storage.api.StorageBackup
+import org.calyxos.backup.storage.backup.NotificationBackupObserver
+import kotlin.time.DurationUnit
+import kotlin.time.ExperimentalTime
+import kotlin.time.toDuration
+
+data class BackupProgress(
+    val current: Int,
+    val total: Int,
+    val text: String?,
+)
+
+internal class BackupStats(
+    private val context: Context,
+    private val storageBackup: StorageBackup,
+    private val liveData: MutableLiveData<BackupProgress>,
+) : NotificationBackupObserver(context) {
+    private var filesProcessed: Int = 0
+    private var totalFiles: Int = 0
+    private var filesUploaded: Int = 0
+    private var expectedSize: Long = 0L
+    private var size: Long = 0L
+    private var savedChunks: Int = 0
+    private val errorStrings = ArrayList<String>()
+
+    override suspend fun onBackupStart(
+        totalSize: Long,
+        numFiles: Int,
+        numSmallFiles: Int,
+        numLargeFiles: Int
+    ) {
+        super.onBackupStart(totalSize, numFiles, numSmallFiles, numLargeFiles)
+
+        totalFiles = numFiles
+        expectedSize = totalSize
+
+        val totalSizeStr = Formatter.formatShortFileSize(context, totalSize)
+        val text = "Backing up $totalFiles file(s) $totalSizeStr...\n" +
+                "  ($numSmallFiles small, $numLargeFiles large)\n"
+        liveData.postValue(BackupProgress(filesProcessed, totalFiles, text))
+    }
+
+    override suspend fun onFileBackedUp(
+        file: BackupFile,
+        wasUploaded: Boolean,
+        reusedChunks: Int,
+        bytesWritten: Long,
+        tag: String,
+    ) {
+        super.onFileBackedUp(file, wasUploaded, reusedChunks, bytesWritten, tag)
+
+        filesProcessed++
+        if (!wasUploaded) return
+
+        savedChunks += reusedChunks
+        filesUploaded++
+        size += bytesWritten
+
+        val sizeStr = Formatter.formatShortFileSize(context, file.size)
+        val now = System.currentTimeMillis()
+        val modStr = file.lastModified?.let {
+            getRelativeTimeSpanString(it, now, 0L, FORMAT_ABBREV_ALL)
+        } ?: "NULL"
+
+        val volume =
+            if (file.volume == MediaStore.VOLUME_EXTERNAL_PRIMARY) "" else "v: ${file.volume}"
+        val text = "${file.path}\n   s: $sizeStr m: $modStr $volume"
+        liveData.postValue(BackupProgress(filesProcessed, totalFiles, text))
+    }
+
+    override suspend fun onFileBackupError(file: BackupFile, tag: String) {
+        super.onFileBackupError(file, tag)
+
+        filesProcessed++
+        errorStrings.add("ERROR $tag: ${file.path}")
+        liveData.postValue(BackupProgress(filesProcessed, totalFiles, null))
+    }
+
+    @OptIn(ExperimentalTime::class)
+    override suspend fun onBackupComplete(backupDuration: Long?) {
+        super.onBackupComplete(backupDuration)
+
+        val sb = StringBuilder("\n")
+        errorStrings.forEach { sb.appendLine(it) }
+        sb.appendLine()
+
+        if (savedChunks > 0) sb.appendLine("Chunks re-used: $savedChunks")
+
+        Log.e("TEST", "Total file size: $expectedSize")
+        Log.e("TEST", "Actual size processed: $size")
+
+        val sizeStr = Formatter.formatShortFileSize(context, size)
+        if (backupDuration != null) {
+            val speed = getSpeed(size, backupDuration / 1000)
+
+            val duration = backupDuration.toDuration(DurationUnit.MILLISECONDS)
+            val perFile = if (filesUploaded > 0) duration.div(filesUploaded) else duration
+
+            sb.appendLine("New/changed files backed up: $filesUploaded ($sizeStr)")
+            if (filesUploaded > 0) sb.append("  ($perFile per file - ${speed}MB/sec)")
+        }
+        liveData.postValue(BackupProgress(filesProcessed, totalFiles, sb.toString()))
+    }
+
+    override suspend fun onPruneStart(snapshotsToDelete: List<Long>) {
+        super.onPruneStart(snapshotsToDelete)
+
+        filesProcessed = 0
+        totalFiles = snapshotsToDelete.size
+        size = 0L
+        val r = storageBackup.getSnapshotRetention()
+
+        if (totalFiles > 0) {
+            val text = """
+                Pruning $totalFiles old backup(s) from storage...
+                Retaining snapshots:
+                  - ${r.daily} daily
+                  - ${r.weekly} weekly
+                  - ${r.monthly} monthly
+                  - ${r.yearly} yearly
+                """.trimIndent()
+            liveData.postValue(BackupProgress(filesProcessed, totalFiles, text))
+        }
+    }
+
+    override suspend fun onPruneSnapshot(snapshot: Long, numChunksToDelete: Int, size: Long) {
+        super.onPruneSnapshot(snapshot, numChunksToDelete, size)
+
+        filesProcessed++
+        this.size += size
+        val now = System.currentTimeMillis()
+        val time = getRelativeTimeSpanString(snapshot, now, 0L, FORMAT_ABBREV_ALL)
+        val sizeStr = Formatter.formatShortFileSize(context, size)
+        val text = "Pruning snapshot from $time\n  deleting $numChunksToDelete chunks ($sizeStr)..."
+        liveData.postValue(BackupProgress(filesProcessed, totalFiles, text))
+    }
+
+    override suspend fun onPruneError(snapshot: Long?, e: Exception) {
+        super.onPruneError(snapshot, e)
+
+        val time = if (snapshot != null) {
+            filesProcessed++
+            val now = System.currentTimeMillis()
+            getRelativeTimeSpanString(snapshot, now, 0L, FORMAT_ABBREV_ALL)
+        } else "null"
+        val text = "ERROR $snapshot $time\n   e: ${e.message}"
+        liveData.postValue(BackupProgress(filesProcessed, totalFiles, text))
+    }
+
+    @OptIn(ExperimentalTime::class)
+    override suspend fun onPruneComplete(pruneDuration: Long) {
+        super.onPruneComplete(pruneDuration)
+
+        val sb = StringBuilder("\n")
+
+        val sizeStr = Formatter.formatShortFileSize(context, size)
+
+        val duration = pruneDuration.toDuration(DurationUnit.MILLISECONDS)
+        val perSnapshot = if (filesProcessed > 0) duration.div(filesProcessed) else duration
+
+        sb.appendLine("Deleting $filesProcessed old backup snapshot(s) took $duration.")
+        if (filesProcessed > 0) sb.append("  (freed $sizeStr - took $perSnapshot per snapshot)")
+        liveData.postValue(BackupProgress(filesProcessed, totalFiles, sb.toString()))
+    }
+
+}
+
+fun getSpeed(size: Long, duration: Long): Long {
+    val mb = size / 1024 / 1024
+    return if (duration == 0L) (mb.toDouble() / 0.01).toLong()
+    else mb / duration
+}

storage/demo/src/main/java/de/grobox/storagebackuptester/crypto/KeyManager.kt

@@ -0,0 +1,53 @@
+package de.grobox.storagebackuptester.crypto
+
+import android.security.keystore.KeyProperties.PURPOSE_DECRYPT
+import android.security.keystore.KeyProperties.PURPOSE_ENCRYPT
+import android.security.keystore.KeyProperties.PURPOSE_SIGN
+import android.security.keystore.KeyProperties.PURPOSE_VERIFY
+import android.security.keystore.KeyProtection
+import java.security.KeyStore
+import javax.crypto.SecretKey
+import javax.crypto.spec.SecretKeySpec
+
+object KeyManager {
+
+    private const val KEY_SIZE = 256
+    internal const val KEY_SIZE_BYTES = KEY_SIZE / 8
+    private const val KEY_ALIAS_MASTER = "com.stevesoltys.seedvault.master"
+    private const val ANDROID_KEY_STORE = "AndroidKeyStore"
+    private const val ALGORITHM_HMAC = "HmacSHA256"
+
+    private const val FAKE_SEED = "This is a legacy backup key 1234"
+
+    private val keyStore by lazy {
+        KeyStore.getInstance(ANDROID_KEY_STORE).apply {
+            load(null)
+        }
+    }
+
+    fun storeMasterKey() {
+        val seed = FAKE_SEED.toByteArray()
+        storeMasterKey(seed)
+    }
+
+    private fun storeMasterKey(seed: ByteArray) {
+        if (seed.size < KEY_SIZE_BYTES) throw IllegalArgumentException()
+        val secretKeySpec = SecretKeySpec(seed, 0, KEY_SIZE_BYTES, ALGORITHM_HMAC)
+        val ksEntry = KeyStore.SecretKeyEntry(secretKeySpec)
+        keyStore.setEntry(KEY_ALIAS_MASTER, ksEntry, getKeyProtection())
+    }
+
+    fun hasMasterKey(): Boolean = keyStore.containsAlias(KEY_ALIAS_MASTER)
+
+    fun getMasterKey(): SecretKey {
+        val ksEntry = keyStore.getEntry(KEY_ALIAS_MASTER, null) as KeyStore.SecretKeyEntry
+        return ksEntry.secretKey
+    }
+
+    private fun getKeyProtection(): KeyProtection {
+        val builder =
+            KeyProtection.Builder(PURPOSE_ENCRYPT or PURPOSE_DECRYPT or PURPOSE_SIGN or PURPOSE_VERIFY)
+        return builder.build()
+    }
+
+}

storage/demo/src/main/java/de/grobox/storagebackuptester/plugin/TestSafStoragePlugin.kt

@@ -0,0 +1,49 @@
+package de.grobox.storagebackuptester.plugin
+
+import android.content.Context
+import android.net.Uri
+import androidx.documentfile.provider.DocumentFile
+import de.grobox.storagebackuptester.crypto.KeyManager
+import org.calyxos.backup.storage.plugin.saf.SafStoragePlugin
+import java.io.IOException
+import java.io.OutputStream
+import javax.crypto.SecretKey
+
+@Suppress("BlockingMethodInNonBlockingContext")
+class TestSafStoragePlugin(
+    private val context: Context,
+    private val getLocationUri: () -> Uri?,
+) : SafStoragePlugin(context) {
+
+    override val root: DocumentFile?
+        get() {
+            val uri = getLocationUri() ?: return null
+            return DocumentFile.fromTreeUri(context, uri) ?: error("No doc file from tree Uri")
+        }
+
+    private val nullStream = object : OutputStream() {
+        override fun write(b: Int) {
+            // oops
+        }
+    }
+
+    override fun getMasterKey(): SecretKey {
+        return KeyManager.getMasterKey()
+    }
+
+    override fun hasMasterKey(): Boolean {
+        return KeyManager.hasMasterKey()
+    }
+
+    @Throws(IOException::class)
+    override fun getChunkOutputStream(chunkId: String): OutputStream {
+        if (getLocationUri() == null) return nullStream
+        return super.getChunkOutputStream(chunkId)
+    }
+
+    override fun getBackupSnapshotOutputStream(timestamp: Long): OutputStream {
+        if (root == null) return nullStream
+        return super.getBackupSnapshotOutputStream(timestamp)
+    }
+
+}

storage/demo/src/main/java/de/grobox/storagebackuptester/restore/DemoSnapshotFragment.kt

@@ -0,0 +1,42 @@
+package de.grobox.storagebackuptester.restore
+
+import android.os.Bundle
+import android.view.LayoutInflater
+import android.view.View
+import android.view.ViewGroup
+import android.view.ViewStub
+import android.widget.Button
+import androidx.fragment.app.activityViewModels
+import de.grobox.storagebackuptester.MainViewModel
+import de.grobox.storagebackuptester.R
+import org.calyxos.backup.storage.api.SnapshotItem
+import org.calyxos.backup.storage.ui.restore.SnapshotFragment
+
+class DemoSnapshotFragment : SnapshotFragment() {
+
+    override val viewModel: MainViewModel by activityViewModels()
+
+    override fun onCreateView(
+        inflater: LayoutInflater,
+        container: ViewGroup?,
+        savedInstanceState: Bundle?
+    ): View {
+        val v = super.onCreateView(inflater, container, savedInstanceState)
+        val bottomStub: ViewStub = v.findViewById(R.id.bottomStub)
+        bottomStub.layoutResource = R.layout.footer_snapshot
+        val footer = bottomStub.inflate()
+        footer.findViewById<Button>(R.id.button).setOnClickListener {
+            requireActivity().onBackPressed()
+        }
+        return v
+    }
+
+    override fun onSnapshotClicked(item: SnapshotItem) {
+        viewModel.onSnapshotClicked(item)
+        parentFragmentManager.beginTransaction()
+            .replace(R.id.container, RestoreFragment.newInstance())
+            .addToBackStack("RESTORE")
+            .commit()
+    }
+
+}

storage/demo/src/main/java/de/grobox/storagebackuptester/restore/RestoreFragment.kt

@@ -0,0 +1,68 @@
+package de.grobox.storagebackuptester.restore
+
+import android.os.Bundle
+import android.view.LayoutInflater
+import android.view.View
+import android.view.View.GONE
+import android.view.View.INVISIBLE
+import android.view.View.VISIBLE
+import android.view.ViewGroup
+import android.widget.Button
+import android.widget.ProgressBar
+import androidx.fragment.app.Fragment
+import androidx.fragment.app.activityViewModels
+import androidx.recyclerview.widget.RecyclerView
+import de.grobox.storagebackuptester.LogAdapter
+import de.grobox.storagebackuptester.MainViewModel
+import de.grobox.storagebackuptester.R
+
+class RestoreFragment : Fragment() {
+
+    companion object {
+        fun newInstance() = RestoreFragment()
+    }
+
+    private val viewModel: MainViewModel by activityViewModels()
+
+    private lateinit var list: RecyclerView
+    private lateinit var progressBar: ProgressBar
+    private lateinit var horizontalProgressBar: ProgressBar
+    private lateinit var button: Button
+    private val adapter = LogAdapter()
+
+    override fun onCreateView(
+        inflater: LayoutInflater,
+        container: ViewGroup?,
+        savedInstanceState: Bundle?
+    ): View {
+        setHasOptionsMenu(true)
+        val v = inflater.inflate(R.layout.fragment_log, container, false)
+        list = v.findViewById(R.id.listView)
+        list.adapter = adapter
+        progressBar = v.findViewById(R.id.progressBar)
+        horizontalProgressBar = v.findViewById(R.id.horizontalProgressBar)
+        button = v.findViewById(R.id.button)
+        button.visibility = GONE
+        return v
+    }
+
+    override fun onViewCreated(view: View, savedInstanceState: Bundle?) {
+        viewModel.restoreLog.observe(viewLifecycleOwner, { progress ->
+            progress.text?.let { adapter.addItem(it) }
+            horizontalProgressBar.max = progress.total
+            horizontalProgressBar.setProgress(progress.current, true)
+            list.postDelayed({
+                list.scrollToPosition(adapter.itemCount - 1)
+            }, 50)
+        })
+        viewModel.restoreProgressVisible.observe(viewLifecycleOwner, { visible ->
+            progressBar.visibility = if (visible) VISIBLE else INVISIBLE
+        })
+    }
+
+    override fun onStart() {
+        super.onStart()
+        requireActivity().title = "Restore"
+    }
+
+}

storage/demo/src/main/java/de/grobox/storagebackuptester/restore/RestoreStats.kt

@@ -0,0 +1,84 @@
+package de.grobox.storagebackuptester.restore
+
+import android.content.Context
+import android.text.format.DateUtils
+import android.text.format.Formatter
+import androidx.lifecycle.MutableLiveData
+import de.grobox.storagebackuptester.backup.getSpeed
+import org.calyxos.backup.storage.api.BackupFile
+import org.calyxos.backup.storage.restore.NotificationRestoreObserver
+import kotlin.time.DurationUnit
+import kotlin.time.ExperimentalTime
+import kotlin.time.toDuration
+
+data class RestoreProgress(
+    val current: Int,
+    val total: Int,
+    val text: String? = null,
+)
+
+class RestoreStats(
+    private val context: Context,
+    private val liveData: MutableLiveData<RestoreProgress>,
+) : NotificationRestoreObserver(context) {
+
+    private var filesProcessed: Int = 0
+    private var totalFiles: Int = 0
+    private var size: Long = 0L
+    private val errorStrings = ArrayList<String>()
+
+    override fun onRestoreStart(numFiles: Int, totalSize: Long) {
+        super.onRestoreStart(numFiles, totalSize)
+        totalFiles = numFiles
+
+        val totalSizeStr = Formatter.formatShortFileSize(context, totalSize)
+        val text = "Restoring $totalFiles file(s) $totalSizeStr...\n"
+        liveData.postValue(RestoreProgress(filesProcessed, totalFiles, text))
+    }
+
+    override fun onFileRestored(
+        file: BackupFile,
+        bytesWritten: Long,
+        tag: String,
+    ) {
+        super.onFileRestored(file, bytesWritten, tag)
+        filesProcessed++
+        size += bytesWritten
+
+        val sizeStr = Formatter.formatShortFileSize(context, file.size)
+        val now = System.currentTimeMillis()
+        val modStr = file.lastModified?.let {
+            DateUtils.getRelativeTimeSpanString(it, now, 0L, DateUtils.FORMAT_ABBREV_ALL)
+        } ?: "NULL"
+
+        val volume = if (file.volume == "") "" else "v: ${file.volume}"
+        val text = "${file.path}\n   s: $sizeStr m: $modStr $tag $volume"
+        liveData.postValue(RestoreProgress(filesProcessed, totalFiles, text))
+    }
+
+    override fun onFileRestoreError(file: BackupFile, e: Exception) {
+        super.onFileRestoreError(file, e)
+        filesProcessed++
+        errorStrings.add("E ${file.path}\n   e: ${e.message}")
+        liveData.postValue(RestoreProgress(filesProcessed, totalFiles))
+    }
+
+    @OptIn(ExperimentalTime::class)
+    override fun onRestoreComplete(restoreDuration: Long) {
+        super.onRestoreComplete(restoreDuration)
+        val sb = StringBuilder("\n")
+        errorStrings.forEach { sb.appendLine(it) }
+        sb.appendLine()
+
+        val sizeStr = Formatter.formatShortFileSize(context, size)
+        val speed = getSpeed(size, restoreDuration / 1000)
+
+        val duration = restoreDuration.toDuration(DurationUnit.MILLISECONDS)
+        val perFile = if (filesProcessed > 0) duration.div(filesProcessed) else duration
+
+        sb.appendLine("Files restored: $filesProcessed ($sizeStr)")
+        if (filesProcessed > 0) sb.append("  ($perFile per file - ${speed}MB/sec)")
+        liveData.postValue(RestoreProgress(filesProcessed, totalFiles, sb.toString()))
+    }
+
+}

storage/demo/src/main/java/de/grobox/storagebackuptester/scanner/DocumentScanFragment.kt

@@ -0,0 +1,21 @@
+package de.grobox.storagebackuptester.scanner
+
+import android.net.Uri
+import android.os.Bundle
+
+class DocumentScanFragment : MediaScanFragment() {
+
+    companion object {
+        fun newInstance(name: String, uri: Uri) = DocumentScanFragment().apply {
+            arguments = Bundle().apply {
+                putString("name", name)
+                putString("uri", uri.toString())
+            }
+        }
+    }
+
+    override suspend fun getText(): String {
+        return viewModel.scanDocumentUri(getUri())
+    }
+
+}

storage/demo/src/main/java/de/grobox/storagebackuptester/scanner/DocumentScanner.kt

@@ -0,0 +1,56 @@
+package de.grobox.storagebackuptester.scanner
+
+import android.annotation.SuppressLint
+import android.content.Context
+import android.net.Uri
+import android.provider.DocumentsContract
+import android.text.format.Formatter
+import org.calyxos.backup.storage.api.BackupFile
+import org.calyxos.backup.storage.scanner.DocumentScanner
+import java.text.SimpleDateFormat
+import java.util.Date
+import kotlin.time.ExperimentalTime
+import kotlin.time.measureTimedValue
+
+@OptIn(ExperimentalTime::class)
+fun scanTree(context: Context, documentScanner: DocumentScanner, treeUri: Uri): String {
+    val sb = StringBuilder()
+    val timedResult = measureTimedValue {
+        val documentId = DocumentsContract.getTreeDocumentId(treeUri)
+        val documentUri = DocumentsContract.buildDocumentUriUsingTree(treeUri, documentId)
+        scanDocument(context, documentScanner.scanUri(documentUri), sb)
+    }
+    return appendStats(context, sb, timedResult)
+}
+
+@SuppressLint("SimpleDateFormat")
+private val dateFormat = SimpleDateFormat("yyyy-MM-dd HH:mm:ss")
+
+fun scanDocument(
+    context: Context,
+    documentFiles: List<BackupFile>,
+    sb: StringBuilder? = null
+): ScanResult {
+    var totalSize = 0L
+    val warnings = StringBuilder()
+    for (documentFile in documentFiles) {
+        totalSize += documentFile.size
+        val lastModified = documentFile.lastModified?.let {
+            dateFormat.format(Date(it))
+        }
+        sb?.appendLine("┣ ${documentFile.path}")
+        sb?.appendLine("┃   lastModified: $lastModified")
+        sb?.appendLine("┃   size: ${Formatter.formatShortFileSize(context, documentFile.size)}")
+
+        if (lastModified == null) {
+            warnings.appendLine("WARNING: ${documentFile.path} has no lastModified timestamp.")
+        }
+        if (documentFile.size == 0L && !documentFile.path.endsWith(".nomedia")) {
+            warnings.appendLine("WARNING: ${documentFile.path} has no 0 size. Please check if real.")
+        }
+    }
+
+    if (sb?.isEmpty() == true) sb.appendLine("Empty folder")
+    else if (warnings.isNotEmpty()) sb?.appendLine()?.appendLine(warnings)
+    return ScanResult(documentFiles.size.toLong(), totalSize)
+}

storage/demo/src/main/java/de/grobox/storagebackuptester/scanner/MediaScanFragment.kt

@@ -0,0 +1,108 @@
+package de.grobox.storagebackuptester.scanner
+
+import android.content.Intent
+import android.net.Uri
+import android.os.Bundle
+import android.util.Log
+import android.view.LayoutInflater
+import android.view.Menu
+import android.view.MenuInflater
+import android.view.MenuItem
+import android.view.View
+import android.view.View.FOCUS_DOWN
+import android.view.View.INVISIBLE
+import android.view.View.VISIBLE
+import android.view.ViewGroup
+import android.widget.ProgressBar
+import android.widget.TextView
+import androidx.annotation.UiThread
+import androidx.core.widget.NestedScrollView
+import androidx.fragment.app.Fragment
+import androidx.fragment.app.activityViewModels
+import androidx.lifecycle.lifecycleScope
+import de.grobox.storagebackuptester.MainViewModel
+import de.grobox.storagebackuptester.R
+import kotlinx.coroutines.launch
+
+private const val EMAIL = "incoming+grote-storage-backup-tester-22079635-issue-@incoming.gitlab.com"
+
+open class MediaScanFragment : Fragment() {
+
+    companion object {
+        fun newInstance(name: String, uri: Uri) = MediaScanFragment().apply {
+            arguments = Bundle().apply {
+                putString("name", name)
+                putString("uri", uri.toString())
+            }
+        }
+    }
+
+    protected val viewModel: MainViewModel by activityViewModels()
+
+    private lateinit var scrollView: NestedScrollView
+    protected lateinit var logView: TextView
+    protected lateinit var progressBar: ProgressBar
+
+    override fun onCreateView(
+        inflater: LayoutInflater,
+        container: ViewGroup?,
+        savedInstanceState: Bundle?
+    ): View {
+        setHasOptionsMenu(true)
+        requireActivity().title = arguments?.getString("name")
+        val v = inflater.inflate(R.layout.fragment_scan, container, false)
+        scrollView = v.findViewById(R.id.scrollView)
+        logView = v.findViewById(R.id.logView)
+        progressBar = v.findViewById(R.id.progressBar)
+        loadText()
+        return v
+    }
+
+    override fun onCreateOptionsMenu(menu: Menu, inflater: MenuInflater) {
+        inflater.inflate(R.menu.fragment_scan, menu)
+    }
+
+    override fun onOptionsItemSelected(item: MenuItem): Boolean {
+        return when (item.itemId) {
+            R.id.refresh -> {
+                loadText()
+                true
+            }
+            R.id.share -> {
+                val sendIntent: Intent = Intent().apply {
+                    action = Intent.ACTION_SEND
+                    putExtra(Intent.EXTRA_EMAIL, arrayOf(EMAIL))
+                    putExtra(Intent.EXTRA_SUBJECT, arguments?.getString("name"))
+                    putExtra(Intent.EXTRA_TEXT, logView.text)
+                    type = "text/plain"
+                }
+                val shareIntent = Intent.createChooser(sendIntent, null)
+                startActivity(shareIntent)
+                true
+            }
+            else -> super.onOptionsItemSelected(item)
+        }
+    }
+
+    private fun loadText() {
+        progressBar.visibility = VISIBLE
+        lifecycleScope.launch {
+            logView.text = getText()
+            logView.postDelayed({
+                scrollView.fullScroll(FOCUS_DOWN)
+            }, 50)
+            progressBar.visibility = INVISIBLE
+        }
+    }
+
+    @UiThread
+    protected open suspend fun getText(): String {
+        Log.e("TEST", "loading text")
+        return viewModel.scanMediaUri(getUri())
+    }
+
+    protected fun getUri(): Uri {
+        return Uri.parse(arguments?.getString("uri"))
+    }
+
+}

storage/demo/src/main/java/de/grobox/storagebackuptester/scanner/MediaScanner.kt

@@ -0,0 +1,74 @@
+package de.grobox.storagebackuptester.scanner
+
+import android.annotation.SuppressLint
+import android.content.Context
+import android.net.Uri
+import android.text.format.Formatter
+import org.calyxos.backup.storage.api.BackupFile
+import org.calyxos.backup.storage.scanner.MediaScanner
+import java.text.SimpleDateFormat
+import java.util.Date
+import kotlin.time.ExperimentalTime
+import kotlin.time.TimedValue
+import kotlin.time.measureTimedValue
+
+data class ScanResult(
+    var itemsFound: Long,
+    var totalSize: Long
+) {
+    operator fun plusAssign(other: ScanResult) {
+        itemsFound += other.itemsFound
+        totalSize += other.totalSize
+    }
+}
+
+@OptIn(ExperimentalTime::class)
+fun scanUri(context: Context, mediaScanner: MediaScanner, uri: Uri): String {
+    val sb = StringBuilder()
+    val timedResult = measureTimedValue {
+        dump(context, mediaScanner.scanUri(uri), sb)
+    }
+    return appendStats(context, sb, timedResult)
+}
+
+@SuppressLint("SimpleDateFormat")
+private val dateFormat = SimpleDateFormat("yyyy-MM-dd HH:mm:ss")
+
+fun dump(context: Context, mediaFiles: List<BackupFile>, sb: StringBuilder? = null): ScanResult {
+    var itemsFound = 0L
+    var totalSize = 0L
+    for (mediaFile in mediaFiles) {
+        itemsFound++
+        totalSize += mediaFile.size
+        val dateModified = mediaFile.lastModified?.let {
+            dateFormat.format(Date(it))
+        }
+        sb?.appendLine(mediaFile.path)
+        sb?.appendLine("  modified: $dateModified")
+        sb?.appendLine("  size: ${Formatter.formatShortFileSize(context, mediaFile.size)}")
+    }
+
+    if (sb?.isEmpty() == true) sb.appendLine("No files found")
+    return ScanResult(itemsFound, totalSize)
+}
+
+@OptIn(ExperimentalTime::class)
+fun appendStats(
+    context: Context,
+    sb: StringBuilder,
+    timedResult: TimedValue<ScanResult>,
+    title: String? = null
+): String {
+    val result = timedResult.value
+    if (title != null || sb.isNotEmpty()) {
+        sb.appendLine(title ?: "")
+        sb.appendLine("━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━")
+        sb.appendLine()
+    }
+    sb.appendLine("Scanning took ${timedResult.duration}")
+    sb.appendLine("Files found: ${result.itemsFound}")
+    sb.appendLine("Total size: ${Formatter.formatShortFileSize(context, result.totalSize)}")
+    val avgSize = if (result.itemsFound > 0) result.totalSize / result.itemsFound else 0
+    sb.appendLine("Average size: ${Formatter.formatShortFileSize(context, avgSize)}")
+    return sb.toString()
+}

storage/demo/src/main/java/de/grobox/storagebackuptester/settings/InfoFragment.kt

@@ -0,0 +1,84 @@
+package de.grobox.storagebackuptester.settings
+
+import android.os.Build.VERSION.SDK_INT
+import android.os.Bundle
+import android.provider.DocumentsContract
+import android.provider.MediaStore
+import de.grobox.storagebackuptester.App
+import de.grobox.storagebackuptester.scanner.MediaScanFragment
+import kotlinx.coroutines.Dispatchers
+import kotlinx.coroutines.withContext
+import org.calyxos.backup.storage.api.EXTERNAL_STORAGE_PROVIDER_AUTHORITY
+import org.calyxos.backup.storage.api.mediaUris
+import org.calyxos.backup.storage.scanner.DocumentScanner
+import org.calyxos.backup.storage.scanner.MediaScanner
+
+class InfoFragment : MediaScanFragment() {
+
+    companion object {
+        fun newInstance(name: String) = InfoFragment().apply {
+            arguments = Bundle().apply {
+                putString("name", name)
+            }
+        }
+    }
+
+    private val storageBackup by lazy { (requireActivity().application as App).storageBackup }
+    private val mediaScanner by lazy { MediaScanner(requireContext()) }
+    private val documentScanner by lazy { DocumentScanner(requireContext()) }
+
+    override suspend fun getText(): String {
+        val sb = StringBuilder()
+        val context = requireContext()
+
+        val volumeNames = MediaStore.getExternalVolumeNames(context)
+        sb.appendLine("Storage Volumes:")
+        for (volumeName in volumeNames) {
+            val version = try {
+                MediaStore.getVersion(context, volumeName)
+            } catch (e: IllegalArgumentException) {
+                e.toString()
+            }
+            val gen = if (SDK_INT >= 30) try {
+                MediaStore.getGeneration(context, volumeName)
+            } catch (e: IllegalArgumentException) {
+                e.toString()
+            } else null
+            sb.appendLine("  $volumeName")
+            sb.appendLine("    version: $version")
+            if (gen != null) {
+                sb.appendLine("    generation:  $gen")
+            }
+        }
+        sb.appendLine()
+        sb.appendLine("Media files smaller than 100 KB: ${mediaFilesSmallerThan(100 * 1024)}")
+        sb.appendLine("Media files smaller than 500 KB: ${mediaFilesSmallerThan(500 * 1024)}")
+        sb.appendLine("Media files smaller than 1 MB: ${mediaFilesSmallerThan(1024 * 1024)}")
+        sb.appendLine()
+        sb.appendLine("Storage files smaller than 100 KB: ${docFilesSmallerThan(100 * 1024)}")
+        sb.appendLine("Storage files smaller than 500 KB: ${docFilesSmallerThan(500 * 1024)}")
+        sb.appendLine("Storage files smaller than 1 MB: ${docFilesSmallerThan(1024 * 1024)}")
+        return sb.toString()
+    }
+
+    private suspend fun mediaFilesSmallerThan(size: Long): Int = withContext(Dispatchers.IO) {
+        var count = 0
+        mediaUris.forEach {
+            count += mediaScanner.scanUri(it, size).size
+        }
+        count
+    }
+
+    private suspend fun docFilesSmallerThan(size: Long): Int = withContext(Dispatchers.IO) {
+        var count = 0
+        storageBackup.uris.forEach { uri ->
+            if (uri.authority == EXTERNAL_STORAGE_PROVIDER_AUTHORITY) {
+                val documentId = DocumentsContract.getTreeDocumentId(uri)
+                val documentUri = DocumentsContract.buildDocumentUriUsingTree(uri, documentId)
+                count += documentScanner.scanUri(documentUri, size).size
+            }
+        }
+        count
+    }
+
+}

storage/demo/src/main/java/de/grobox/storagebackuptester/settings/SettingsFragment.kt

@@ -0,0 +1,152 @@
+package de.grobox.storagebackuptester.settings
+
+import android.content.Intent.FLAG_GRANT_READ_URI_PERMISSION
+import android.content.Intent.FLAG_GRANT_WRITE_URI_PERMISSION
+import android.net.Uri
+import android.os.Bundle
+import android.view.LayoutInflater
+import android.view.Menu
+import android.view.MenuInflater
+import android.view.MenuItem
+import android.view.View
+import android.view.ViewGroup
+import android.widget.Toast
+import android.widget.Toast.LENGTH_SHORT
+import androidx.appcompat.app.AlertDialog
+import androidx.fragment.app.activityViewModels
+import de.grobox.storagebackuptester.MainViewModel
+import de.grobox.storagebackuptester.R
+import de.grobox.storagebackuptester.restore.DemoSnapshotFragment
+import de.grobox.storagebackuptester.scanner.DocumentScanFragment
+import de.grobox.storagebackuptester.scanner.MediaScanFragment
+import org.calyxos.backup.storage.api.MediaType
+import org.calyxos.backup.storage.ui.backup.BackupContentFragment
+import org.calyxos.backup.storage.ui.backup.BackupContentItem
+import org.calyxos.backup.storage.ui.backup.OpenTree
+
+class SettingsFragment : BackupContentFragment() {
+
+    companion object {
+        fun newInstance(): SettingsFragment = SettingsFragment()
+    }
+
+    override val viewModel: MainViewModel by activityViewModels()
+    private lateinit var backupLocationItem: MenuItem
+    private lateinit var jobItem: MenuItem
+    private lateinit var restoreItem: MenuItem
+
+    private val backupLocationRequest = registerForActivityResult(OpenTree()) { uri ->
+        onBackupUriReceived(uri)
+    }
+
+    override fun onCreateView(
+        inflater: LayoutInflater,
+        container: ViewGroup?,
+        savedInstanceState: Bundle?
+    ): View {
+        setHasOptionsMenu(true)
+        requireActivity().title = "Settings"
+        return super.onCreateView(inflater, container, savedInstanceState)
+    }
+
+    override fun onCreateOptionsMenu(menu: Menu, inflater: MenuInflater) {
+        inflater.inflate(R.menu.fragment_settings, menu)
+        backupLocationItem = menu.findItem(R.id.backup_location)
+        backupLocationItem.isChecked = viewModel.hasBackupLocation()
+        jobItem = menu.findItem(R.id.backup_job)
+        jobItem.isEnabled = backupLocationItem.isChecked
+        jobItem.isChecked = viewModel.areAutomaticBackupsEnabled()
+        restoreItem = menu.findItem(R.id.restore_backup)
+        restoreItem.isEnabled = backupLocationItem.isChecked
+    }
+
+    override fun onOptionsItemSelected(item: MenuItem): Boolean {
+        return when (item.itemId) {
+            R.id.info -> {
+                parentFragmentManager.beginTransaction()
+                    .replace(R.id.container, InfoFragment.newInstance("Media Info"))
+                    .addToBackStack("INFO")
+                    .commit()
+                true
+            }
+            R.id.backup_location -> {
+                if (item.isChecked) {
+                    viewModel.setBackupLocation(null)
+                    item.isChecked = false
+                    jobItem.isEnabled = false
+                    restoreItem.isEnabled = false
+                } else backupLocationRequest.launch(null)
+                true
+            }
+            R.id.backup_job -> {
+                if (item.isChecked) {
+                    viewModel.setAutomaticBackupsEnabled(false)
+                    item.isChecked = false
+                } else {
+                    viewModel.setAutomaticBackupsEnabled(true)
+                    item.isChecked = true
+                }
+                true
+            }
+            R.id.restore_backup -> {
+                onRestoreClicked()
+                true
+            }
+            R.id.clear_db -> {
+                viewModel.clearDb()
+                Toast.makeText(requireContext(), "Cache cleared", LENGTH_SHORT).show()
+                true
+            }
+            else -> super.onOptionsItemSelected(item)
+        }
+    }
+
+    override fun onContentClicked(view: View, item: BackupContentItem) {
+        val f = if (item.contentType is MediaType) {
+            MediaScanFragment.newInstance(item.getName(requireContext()), item.uri)
+        } else {
+            DocumentScanFragment.newInstance(item.getName(requireContext()), item.uri)
+        }
+        parentFragmentManager.beginTransaction()
+            .replace(R.id.container, f)
+            .addToBackStack("LOG")
+            .commit()
+    }
+
+    private fun onBackupUriReceived(uri: Uri?) {
+        if (uri == null) {
+            Toast.makeText(requireContext(), "No location set", LENGTH_SHORT).show()
+        } else {
+            requireContext().contentResolver.takePersistableUriPermission(
+                uri, FLAG_GRANT_READ_URI_PERMISSION or FLAG_GRANT_WRITE_URI_PERMISSION
+            )
+            viewModel.setBackupLocation(uri)
+            backupLocationItem.isChecked = true
+            jobItem.isEnabled = true
+            restoreItem.isEnabled = true
+        }
+    }
+
+    private fun onRestoreClicked() {
+        AlertDialog.Builder(requireContext())
+            .setIcon(android.R.drawable.stat_sys_warning)
+            .setTitle("Warning")
+            .setMessage("This will override data and should only be used on a clean phone. Not the one you just made the backup on.")
+            .setPositiveButton("I have been warned") { dialog, _ ->
+                onStartRestore()
+                dialog.dismiss()
+            }
+            .setNegativeButton(android.R.string.cancel) { dialog, _ ->
+                dialog.dismiss()
+            }
+            .show()
+    }
+
+    private fun onStartRestore() {
+        parentFragmentManager.beginTransaction()
+            .replace(R.id.container, DemoSnapshotFragment())
+            .addToBackStack("SNAPSHOTS")
+            .commit()
+    }
+
+}

storage/demo/src/main/java/de/grobox/storagebackuptester/settings/SettingsManager.kt

@@ -0,0 +1,37 @@
+package de.grobox.storagebackuptester.settings
+
+import android.content.Context
+import android.net.Uri
+
+private const val PREFS = "prefs"
+private const val PREF_BACKUP_LOCATION = "backupLocationUri"
+private const val PREF_AUTOMATIC_BACKUP = "automaticBackups"
+
+class SettingsManager(private val context: Context) {
+
+    fun setBackupLocation(uri: Uri?) {
+        context.getSharedPreferences(PREFS, 0)
+            .edit()
+            .putString(PREF_BACKUP_LOCATION, uri?.toString())
+            .apply()
+    }
+
+    fun getBackupLocation(): Uri? {
+        val uriStr = context.getSharedPreferences(PREFS, 0)
+            .getString(PREF_BACKUP_LOCATION, null)
+        return uriStr?.let { Uri.parse(it) }
+    }
+
+    fun setAutomaticBackupsEnabled(enabled: Boolean) {
+        context.getSharedPreferences(PREFS, 0)
+            .edit()
+            .putBoolean(PREF_AUTOMATIC_BACKUP, enabled)
+            .apply()
+    }
+
+    fun areAutomaticBackupsEnabled(): Boolean {
+        return context.getSharedPreferences(PREFS, 0)
+            .getBoolean(PREF_AUTOMATIC_BACKUP, false)
+    }
+
+}

storage/demo/src/main/res/drawable/ic_info.xml

@@ -0,0 +1,10 @@
+<vector xmlns:android="http://schemas.android.com/apk/res/android"
+    android:width="24dp"
+    android:height="24dp"
+    android:viewportWidth="24"
+    android:viewportHeight="24"
+    android:tint="?attr/colorControlNormal">
+  <path
+      android:fillColor="@android:color/white"
+      android:pathData="M12,2C6.48,2 2,6.48 2,12s4.48,10 10,10 10,-4.48 10,-10S17.52,2 12,2zM13,17h-2v-6h2v6zM13,9h-2L11,7h2v2z"/>
+</vector>

storage/demo/src/main/res/drawable/ic_launcher_background.xml

@@ -0,0 +1,170 @@
+<?xml version="1.0" encoding="utf-8"?>
+<vector xmlns:android="http://schemas.android.com/apk/res/android"
+    android:width="108dp"
+    android:height="108dp"
+    android:viewportWidth="108"
+    android:viewportHeight="108">
+    <path
+        android:fillColor="#303F9F"
+        android:pathData="M0,0h108v108h-108z" />
+    <path
+        android:fillColor="#00000000"
+        android:pathData="M9,0L9,108"
+        android:strokeWidth="0.8"
+        android:strokeColor="#33FFFFFF" />
+    <path
+        android:fillColor="#00000000"
+        android:pathData="M19,0L19,108"
+        android:strokeWidth="0.8"
+        android:strokeColor="#33FFFFFF" />
+    <path
+        android:fillColor="#00000000"
+        android:pathData="M29,0L29,108"
+        android:strokeWidth="0.8"
+        android:strokeColor="#33FFFFFF" />
+    <path
+        android:fillColor="#00000000"
+        android:pathData="M39,0L39,108"
+        android:strokeWidth="0.8"
+        android:strokeColor="#33FFFFFF" />
+    <path
+        android:fillColor="#00000000"
+        android:pathData="M49,0L49,108"
+        android:strokeWidth="0.8"
+        android:strokeColor="#33FFFFFF" />
+    <path
+        android:fillColor="#00000000"
+        android:pathData="M59,0L59,108"
+        android:strokeWidth="0.8"
+        android:strokeColor="#33FFFFFF" />
+    <path
+        android:fillColor="#00000000"
+        android:pathData="M69,0L69,108"
+        android:strokeWidth="0.8"
+        android:strokeColor="#33FFFFFF" />
+    <path
+        android:fillColor="#00000000"
+        android:pathData="M79,0L79,108"
+        android:strokeWidth="0.8"
+        android:strokeColor="#33FFFFFF" />
+    <path
+        android:fillColor="#00000000"
+        android:pathData="M89,0L89,108"
+        android:strokeWidth="0.8"
+        android:strokeColor="#33FFFFFF" />
+    <path
+        android:fillColor="#00000000"
+        android:pathData="M99,0L99,108"
+        android:strokeWidth="0.8"
+        android:strokeColor="#33FFFFFF" />
+    <path
+        android:fillColor="#00000000"
+        android:pathData="M0,9L108,9"
+        android:strokeWidth="0.8"
+        android:strokeColor="#33FFFFFF" />
+    <path
+        android:fillColor="#00000000"
+        android:pathData="M0,19L108,19"
+        android:strokeWidth="0.8"
+        android:strokeColor="#33FFFFFF" />
+    <path
+        android:fillColor="#00000000"
+        android:pathData="M0,29L108,29"
+        android:strokeWidth="0.8"
+        android:strokeColor="#33FFFFFF" />
+    <path
+        android:fillColor="#00000000"
+        android:pathData="M0,39L108,39"
+        android:strokeWidth="0.8"
+        android:strokeColor="#33FFFFFF" />
+    <path
+        android:fillColor="#00000000"
+        android:pathData="M0,49L108,49"
+        android:strokeWidth="0.8"
+        android:strokeColor="#33FFFFFF" />
+    <path
+        android:fillColor="#00000000"
+        android:pathData="M0,59L108,59"
+        android:strokeWidth="0.8"
+        android:strokeColor="#33FFFFFF" />
+    <path
+        android:fillColor="#00000000"
+        android:pathData="M0,69L108,69"
+        android:strokeWidth="0.8"
+        android:strokeColor="#33FFFFFF" />
+    <path
+        android:fillColor="#00000000"
+        android:pathData="M0,79L108,79"
+        android:strokeWidth="0.8"
+        android:strokeColor="#33FFFFFF" />
+    <path
+        android:fillColor="#00000000"
+        android:pathData="M0,89L108,89"
+        android:strokeWidth="0.8"
+        android:strokeColor="#33FFFFFF" />
+    <path
+        android:fillColor="#00000000"
+        android:pathData="M0,99L108,99"
+        android:strokeWidth="0.8"
+        android:strokeColor="#33FFFFFF" />
+    <path
+        android:fillColor="#00000000"
+        android:pathData="M19,29L89,29"
+        android:strokeWidth="0.8"
+        android:strokeColor="#33FFFFFF" />
+    <path
+        android:fillColor="#00000000"
+        android:pathData="M19,39L89,39"
+        android:strokeWidth="0.8"
+        android:strokeColor="#33FFFFFF" />
+    <path
+        android:fillColor="#00000000"
+        android:pathData="M19,49L89,49"
+        android:strokeWidth="0.8"
+        android:strokeColor="#33FFFFFF" />
+    <path
+        android:fillColor="#00000000"
+        android:pathData="M19,59L89,59"
+        android:strokeWidth="0.8"
+        android:strokeColor="#33FFFFFF" />
+    <path
+        android:fillColor="#00000000"
+        android:pathData="M19,69L89,69"
+        android:strokeWidth="0.8"
+        android:strokeColor="#33FFFFFF" />
+    <path
+        android:fillColor="#00000000"
+        android:pathData="M19,79L89,79"
+        android:strokeWidth="0.8"
+        android:strokeColor="#33FFFFFF" />
+    <path
+        android:fillColor="#00000000"
+        android:pathData="M29,19L29,89"
+        android:strokeWidth="0.8"
+        android:strokeColor="#33FFFFFF" />
+    <path
+        android:fillColor="#00000000"
+        android:pathData="M39,19L39,89"
+        android:strokeWidth="0.8"
+        android:strokeColor="#33FFFFFF" />
+    <path
+        android:fillColor="#00000000"
+        android:pathData="M49,19L49,89"
+        android:strokeWidth="0.8"
+        android:strokeColor="#33FFFFFF" />
+    <path
+        android:fillColor="#00000000"
+        android:pathData="M59,19L59,89"
+        android:strokeWidth="0.8"
+        android:strokeColor="#33FFFFFF" />
+    <path
+        android:fillColor="#00000000"
+        android:pathData="M69,19L69,89"
+        android:strokeWidth="0.8"
+        android:strokeColor="#33FFFFFF" />
+    <path
+        android:fillColor="#00000000"
+        android:pathData="M79,19L79,89"
+        android:strokeWidth="0.8"
+        android:strokeColor="#33FFFFFF" />
+</vector>

storage/demo/src/main/res/drawable/ic_launcher_foreground.xml

@@ -0,0 +1,16 @@
+<vector xmlns:android="http://schemas.android.com/apk/res/android"
+    android:width="108dp"
+    android:height="108dp"
+    android:tint="#FFFFFF"
+    android:viewportWidth="108"
+    android:viewportHeight="108">
+    <group
+        android:scaleX="2.349"
+        android:scaleY="2.349"
+        android:translateX="25.812"
+        android:translateY="25.812">
+        <path
+            android:fillColor="@android:color/white"
+            android:pathData="M2,20h20v-4L2,16v4zM4,17h2v2L4,19v-2zM2,4v4h20L22,4L2,4zM6,7L4,7L4,5h2v2zM2,14h20v-4L2,10v4zM4,11h2v2L4,13v-2z" />
+    </group>
+</vector>

storage/demo/src/main/res/drawable/ic_refresh.xml

@@ -0,0 +1,10 @@
+<vector xmlns:android="http://schemas.android.com/apk/res/android"
+    android:width="24dp"
+    android:height="24dp"
+    android:tint="?attr/colorControlNormal"
+    android:viewportWidth="24"
+    android:viewportHeight="24">
+    <path
+        android:fillColor="@android:color/white"
+        android:pathData="M17.65,6.35C16.2,4.9 14.21,4 12,4c-4.42,0 -7.99,3.58 -7.99,8s3.57,8 7.99,8c3.73,0 6.84,-2.55 7.73,-6h-2.08c-0.82,2.33 -3.04,4 -5.65,4 -3.31,0 -6,-2.69 -6,-6s2.69,-6 6,-6c1.66,0 3.14,0.69 4.22,1.78L13,11h7V4l-2.35,2.35z" />
+</vector>

storage/demo/src/main/res/drawable/ic_settings.xml

@@ -0,0 +1,10 @@
+<vector xmlns:android="http://schemas.android.com/apk/res/android"
+    android:width="24dp"
+    android:height="24dp"
+    android:viewportWidth="24"
+    android:viewportHeight="24"
+    android:tint="?attr/colorControlNormal">
+  <path
+      android:fillColor="@android:color/white"
+      android:pathData="M19.14,12.94c0.04,-0.3 0.06,-0.61 0.06,-0.94c0,-0.32 -0.02,-0.64 -0.07,-0.94l2.03,-1.58c0.18,-0.14 0.23,-0.41 0.12,-0.61l-1.92,-3.32c-0.12,-0.22 -0.37,-0.29 -0.59,-0.22l-2.39,0.96c-0.5,-0.38 -1.03,-0.7 -1.62,-0.94L14.4,2.81c-0.04,-0.24 -0.24,-0.41 -0.48,-0.41h-3.84c-0.24,0 -0.43,0.17 -0.47,0.41L9.25,5.35C8.66,5.59 8.12,5.92 7.63,6.29L5.24,5.33c-0.22,-0.08 -0.47,0 -0.59,0.22L2.74,8.87C2.62,9.08 2.66,9.34 2.86,9.48l2.03,1.58C4.84,11.36 4.8,11.69 4.8,12s0.02,0.64 0.07,0.94l-2.03,1.58c-0.18,0.14 -0.23,0.41 -0.12,0.61l1.92,3.32c0.12,0.22 0.37,0.29 0.59,0.22l2.39,-0.96c0.5,0.38 1.03,0.7 1.62,0.94l0.36,2.54c0.05,0.24 0.24,0.41 0.48,0.41h3.84c0.24,0 0.44,-0.17 0.47,-0.41l0.36,-2.54c0.59,-0.24 1.13,-0.56 1.62,-0.94l2.39,0.96c0.22,0.08 0.47,0 0.59,-0.22l1.92,-3.32c0.12,-0.22 0.07,-0.47 -0.12,-0.61L19.14,12.94zM12,15.6c-1.98,0 -3.6,-1.62 -3.6,-3.6s1.62,-3.6 3.6,-3.6s3.6,1.62 3.6,3.6S13.98,15.6 12,15.6z"/>
+</vector>

storage/demo/src/main/res/drawable/ic_share.xml

@@ -0,0 +1,10 @@
+<vector xmlns:android="http://schemas.android.com/apk/res/android"
+    android:width="24dp"
+    android:height="24dp"
+    android:tint="?attr/colorControlNormal"
+    android:viewportWidth="24"
+    android:viewportHeight="24">
+    <path
+        android:fillColor="@android:color/white"
+        android:pathData="M18,16.08c-0.76,0 -1.44,0.3 -1.96,0.77L8.91,12.7c0.05,-0.23 0.09,-0.46 0.09,-0.7s-0.04,-0.47 -0.09,-0.7l7.05,-4.11c0.54,0.5 1.25,0.81 2.04,0.81 1.66,0 3,-1.34 3,-3s-1.34,-3 -3,-3 -3,1.34 -3,3c0,0.24 0.04,0.47 0.09,0.7L8.04,9.81C7.5,9.31 6.79,9 6,9c-1.66,0 -3,1.34 -3,3s1.34,3 3,3c0.79,0 1.5,-0.31 2.04,-0.81l7.12,4.16c-0.05,0.21 -0.08,0.43 -0.08,0.65 0,1.61 1.31,2.92 2.92,2.92 1.61,0 2.92,-1.31 2.92,-2.92s-1.31,-2.92 -2.92,-2.92z" />
+</vector>

storage/demo/src/main/res/layout/activity_main.xml

@@ -0,0 +1,7 @@
+<?xml version="1.0" encoding="utf-8"?>
+<FrameLayout xmlns:android="http://schemas.android.com/apk/res/android"
+    xmlns:tools="http://schemas.android.com/tools"
+    android:id="@+id/container"
+    android:layout_width="match_parent"
+    android:layout_height="match_parent"
+    tools:context=".MainActivity" />

storage/demo/src/main/res/layout/footer_snapshot.xml

@@ -0,0 +1,16 @@
+<?xml version="1.0" encoding="utf-8"?>
+<androidx.constraintlayout.widget.ConstraintLayout xmlns:android="http://schemas.android.com/apk/res/android"
+    xmlns:app="http://schemas.android.com/apk/res-auto"
+    android:layout_width="match_parent"
+    android:layout_height="match_parent"
+    android:padding="16dp">
+
+    <Button
+        android:id="@+id/button"
+        android:layout_width="wrap_content"
+        android:layout_height="wrap_content"
+        android:text="Don't restore"
+        app:layout_constraintStart_toStartOf="parent"
+        app:layout_constraintTop_toTopOf="parent" />
+
+</androidx.constraintlayout.widget.ConstraintLayout>

storage/demo/src/main/res/layout/fragment_content.xml

@@ -0,0 +1,29 @@
+<?xml version="1.0" encoding="utf-8"?>
+<androidx.coordinatorlayout.widget.CoordinatorLayout xmlns:android="http://schemas.android.com/apk/res/android"
+    xmlns:app="http://schemas.android.com/apk/res-auto"
+    xmlns:tools="http://schemas.android.com/tools"
+    android:layout_width="match_parent"
+    android:layout_height="match_parent">
+
+    <androidx.recyclerview.widget.RecyclerView
+        android:id="@+id/list"
+        android:name="de.grobox.storagebackuptester.MainFragment"
+        android:layout_width="match_parent"
+        android:layout_height="match_parent"
+        android:layout_marginLeft="16dp"
+        android:layout_marginRight="16dp"
+        app:layoutManager="LinearLayoutManager"
+        tools:context=".settings.SettingsFragment"
+        tools:listitem="@layout/item_media" />
+
+    <com.google.android.material.floatingactionbutton.FloatingActionButton
+        android:id="@+id/fab"
+        android:layout_width="wrap_content"
+        android:layout_height="wrap_content"
+        android:layout_gravity="bottom|end"
+        android:layout_margin="16dp"
+        app:layout_behavior="com.google.android.material.behavior.HideBottomViewOnScrollBehavior"
+        android:contentDescription="Add"
+        android:src="@drawable/ic_add" />
+
+</androidx.coordinatorlayout.widget.CoordinatorLayout>

storage/demo/src/main/res/layout/fragment_log.xml

@@ -0,0 +1,53 @@
+<?xml version="1.0" encoding="utf-8"?>
+<androidx.constraintlayout.widget.ConstraintLayout xmlns:android="http://schemas.android.com/apk/res/android"
+    xmlns:app="http://schemas.android.com/apk/res-auto"
+    xmlns:tools="http://schemas.android.com/tools"
+    android:layout_width="match_parent"
+    android:layout_height="match_parent">
+
+    <ProgressBar
+        android:id="@+id/horizontalProgressBar"
+        style="?android:attr/progressBarStyleHorizontal"
+        android:layout_width="0dp"
+        android:layout_height="5dp"
+        app:layout_constraintEnd_toEndOf="parent"
+        app:layout_constraintStart_toStartOf="parent"
+        app:layout_constraintTop_toTopOf="parent"
+        tools:max="10"
+        tools:progress="7" />
+
+    <androidx.recyclerview.widget.RecyclerView
+        android:id="@+id/listView"
+        android:layout_width="match_parent"
+        android:layout_height="0dp"
+        android:layout_margin="8dp"
+        android:focusable="true"
+        app:layoutManager="androidx.recyclerview.widget.LinearLayoutManager"
+        app:layout_constraintBottom_toTopOf="@+id/button"
+        app:layout_constraintEnd_toEndOf="parent"
+        app:layout_constraintStart_toStartOf="parent"
+        app:layout_constraintTop_toBottomOf="@+id/horizontalProgressBar"
+        tools:listitem="@layout/item_log" />
+
+    <ProgressBar
+        android:id="@+id/progressBar"
+        android:layout_width="wrap_content"
+        android:layout_height="wrap_content"
+        android:layout_gravity="center"
+        android:visibility="invisible"
+        app:layout_constraintBottom_toTopOf="@+id/button"
+        app:layout_constraintEnd_toEndOf="parent"
+        app:layout_constraintStart_toStartOf="parent"
+        app:layout_constraintTop_toTopOf="parent"
+        tools:visibility="visible" />
+
+    <Button
+        android:id="@+id/button"
+        android:layout_width="wrap_content"
+        android:layout_height="wrap_content"
+        android:text="Run (Test) Backup Now"
+        app:layout_constraintBottom_toBottomOf="parent"
+        app:layout_constraintEnd_toEndOf="parent"
+        app:layout_constraintStart_toStartOf="parent" />
+
+</androidx.constraintlayout.widget.ConstraintLayout>

storage/demo/src/main/res/layout/fragment_scan.xml

@@ -0,0 +1,40 @@
+<?xml version="1.0" encoding="utf-8"?>
+<androidx.constraintlayout.widget.ConstraintLayout xmlns:android="http://schemas.android.com/apk/res/android"
+    xmlns:app="http://schemas.android.com/apk/res-auto"
+    xmlns:tools="http://schemas.android.com/tools"
+    android:layout_width="match_parent"
+    android:layout_height="match_parent">
+
+    <androidx.core.widget.NestedScrollView
+        android:id="@+id/scrollView"
+        android:layout_width="match_parent"
+        android:layout_height="match_parent"
+        android:fadeScrollbars="false"
+        android:scrollbars="vertical"
+        app:layout_constraintTop_toTopOf="parent">
+
+        <TextView
+            android:id="@+id/logView"
+            android:layout_width="match_parent"
+            android:layout_height="wrap_content"
+            android:layout_margin="8dp"
+            android:fontFamily="monospace"
+            android:lineSpacingExtra="8sp"
+            android:textIsSelectable="true"
+            android:textSize="12sp"
+            tools:text="@tools:sample/lorem/random" />
+
+    </androidx.core.widget.NestedScrollView>
+
+    <ProgressBar
+        android:id="@+id/progressBar"
+        android:layout_width="wrap_content"
+        android:layout_height="wrap_content"
+        android:layout_gravity="center"
+        app:layout_constraintBottom_toBottomOf="parent"
+        app:layout_constraintEnd_toEndOf="parent"
+        app:layout_constraintStart_toStartOf="parent"
+        app:layout_constraintTop_toTopOf="parent"
+        tools:visibility="visible" />
+
+</androidx.constraintlayout.widget.ConstraintLayout>

storage/demo/src/main/res/layout/item_log.xml

@@ -0,0 +1,13 @@
+<?xml version="1.0" encoding="utf-8"?>
+<TextView xmlns:android="http://schemas.android.com/apk/res/android"
+    xmlns:tools="http://schemas.android.com/tools"
+    android:id="@+id/logView"
+    android:layout_width="match_parent"
+    android:layout_height="wrap_content"
+    android:focusable="true"
+    android:fontFamily="monospace"
+    android:lineSpacingExtra="8sp"
+    android:textColor="@color/matrix"
+    android:textIsSelectable="true"
+    android:textSize="12sp"
+    tools:text="@tools:sample/lorem/random" />

storage/demo/src/main/res/menu/fragment_main.xml

@@ -0,0 +1,17 @@
+<?xml version="1.0" encoding="utf-8"?>
+<menu xmlns:android="http://schemas.android.com/apk/res/android"
+    xmlns:app="http://schemas.android.com/apk/res-auto">
+
+    <item
+        android:id="@+id/settings"
+        android:icon="@drawable/ic_settings"
+        android:title="Settings"
+        app:showAsAction="ifRoom" />
+
+    <item
+        android:id="@+id/share"
+        android:icon="@drawable/ic_share"
+        android:title="Share"
+        app:showAsAction="ifRoom" />
+
+</menu>

storage/demo/src/main/res/menu/fragment_scan.xml

@@ -0,0 +1,17 @@
+<?xml version="1.0" encoding="utf-8"?>
+<menu xmlns:android="http://schemas.android.com/apk/res/android"
+    xmlns:app="http://schemas.android.com/apk/res-auto">
+
+    <item
+        android:id="@+id/refresh"
+        android:icon="@drawable/ic_refresh"
+        android:title="Refresh"
+        app:showAsAction="always"/>
+
+    <item
+        android:id="@+id/share"
+        android:icon="@drawable/ic_share"
+        android:title="Share"
+        app:showAsAction="always"/>
+
+</menu>

storage/demo/src/main/res/menu/fragment_settings.xml

@@ -0,0 +1,31 @@
+<?xml version="1.0" encoding="utf-8"?>
+<menu xmlns:android="http://schemas.android.com/apk/res/android"
+    xmlns:app="http://schemas.android.com/apk/res-auto">
+
+    <item
+        android:id="@+id/info"
+        android:icon="@drawable/ic_info"
+        android:title="Info"
+        app:showAsAction="ifRoom" />
+    <item
+        android:id="@+id/backup_location"
+        android:checkable="true"
+        android:title="Store backups"
+        app:showAsAction="never" />
+    <item
+        android:id="@+id/backup_job"
+        android:checkable="true"
+        android:enabled="false"
+        android:title="Automatic backups"
+        app:showAsAction="never" />
+    <item
+        android:id="@+id/restore_backup"
+        android:enabled="false"
+        android:title="Restore backup"
+        app:showAsAction="never" />
+    <item
+        android:id="@+id/clear_db"
+        android:title="Clear cache"
+        app:showAsAction="never" />
+
+</menu>

storage/demo/src/main/res/mipmap-anydpi-v26/ic_launcher.xml

@@ -0,0 +1,5 @@
+<?xml version="1.0" encoding="utf-8"?>
+<adaptive-icon xmlns:android="http://schemas.android.com/apk/res/android">
+    <background android:drawable="@drawable/ic_launcher_background" />
+    <foreground android:drawable="@drawable/ic_launcher_foreground" />
+</adaptive-icon>

storage/demo/src/main/res/mipmap-anydpi-v26/ic_launcher_round.xml

@@ -0,0 +1,5 @@
+<?xml version="1.0" encoding="utf-8"?>
+<adaptive-icon xmlns:android="http://schemas.android.com/apk/res/android">
+    <background android:drawable="@drawable/ic_launcher_background" />
+    <foreground android:drawable="@drawable/ic_launcher_foreground" />
+</adaptive-icon>

storage/demo/src/main/res/values-night/themes.xml

@@ -0,0 +1,17 @@
+<resources xmlns:tools="http://schemas.android.com/tools">
+    <!-- Base application theme. -->
+    <style name="Theme.StorageBackupTester" parent="Theme.MaterialComponents.DayNight.DarkActionBar">
+        <!-- Primary brand color. -->
+        <item name="colorPrimary">@color/matrix</item>
+        <item name="colorPrimaryVariant">@color/purple_700</item>
+        <item name="colorOnPrimary">@color/white</item>
+        <!-- Secondary brand color. -->
+        <item name="colorSecondary">@color/teal_200</item>
+        <item name="colorSecondaryVariant">@color/teal_200</item>
+        <item name="colorOnSecondary">@color/black</item>
+        <!-- Status bar color. -->
+        <item name="android:statusBarColor" tools:targetApi="l">?attr/colorPrimaryVariant</item>
+        <!-- Customize your theme here. -->
+        <item name="colorAccent">@color/matrix</item>
+    </style>
+</resources>

storage/demo/src/main/res/values/colors.xml

@@ -0,0 +1,11 @@
+<?xml version="1.0" encoding="utf-8"?>
+<resources>
+    <color name="purple_200">#FFBB86FC</color>
+    <color name="purple_500">#FF6200EE</color>
+    <color name="purple_700">#FF3700B3</color>
+    <color name="teal_200">#FF03DAC5</color>
+    <color name="teal_700">#FF018786</color>
+    <color name="black">#151515</color>
+    <color name="white">#FAFAFA</color>
+    <color name="matrix">#689F38</color>
+</resources>

storage/demo/src/main/res/values/strings.xml

@@ -0,0 +1,3 @@
+<resources>
+    <string name="app_name">Storage Backup Tester</string>
+</resources>

storage/demo/src/main/res/values/themes.xml

@@ -0,0 +1,13 @@
+<resources>
+    <style name="Theme.StorageBackupTester" parent="Theme.MaterialComponents.DayNight.DarkActionBar">
+        <item name="colorPrimary">@color/matrix</item>
+        <item name="colorPrimaryVariant">@color/purple_700</item>
+        <item name="colorOnPrimary">@color/white</item>
+
+        <item name="colorSecondary">@color/teal_200</item>
+        <item name="colorSecondaryVariant">@color/teal_700</item>
+        <item name="colorOnSecondary">@color/black</item>
+
+        <item name="colorAccent">@color/matrix</item>
+    </style>
+</resources>

storage/lib/.gitignore

@@ -0,0 +1,2 @@
+build/*
+!build/outputs/aar/lib-release.aar

storage/lib/Android.bp

@@ -0,0 +1,15 @@
+android_library_import {
+    name: "seedvault-lib-storage",
+    aars: ["libs/storage.aar"],
+    sdk_version: "current",
+    static_libs: [
+        "androidx-constraintlayout_constraintlayout",
+        "com.google.android.material_material",
+    ]
+}
+
+java_import {
+    name: "seedvault-lib-tink-android",
+    jars: ["libs/tink-android-1.5.0.jar"],
+    sdk_version: "current",
+}

storage/lib/build.gradle

@@ -0,0 +1,92 @@
+plugins {
+    id 'com.android.library'
+    id 'com.google.protobuf'
+    id 'kotlin-android'
+    id 'kotlin-kapt'
+    id 'org.jetbrains.dokka' version '1.4.20'
+}
+
+android {
+    compileSdkVersion rootProject.ext.compileSdkVersion
+    buildToolsVersion rootProject.ext.buildToolsVersion
+
+    defaultConfig {
+        minSdkVersion rootProject.ext.minSdkVersion
+        targetSdkVersion rootProject.ext.targetSdkVersion
+        versionCode 1
+        versionName "0.1"
+
+        testInstrumentationRunner "androidx.test.runner.AndroidJUnitRunner"
+        testInstrumentationRunnerArguments disableAnalytics: 'true'
+
+        consumerProguardFiles "consumer-rules.pro"
+        javaCompileOptions {
+            annotationProcessorOptions {
+                arguments += ["room.schemaLocation": "$projectDir/schemas".toString()]
+            }
+        }
+    }
+
+    buildTypes {
+        all {
+            minifyEnabled true
+            proguardFiles getDefaultProguardFile('proguard-android-optimize.txt'), 'proguard-rules.pro'
+        }
+    }
+    compileOptions {
+        sourceCompatibility JavaVersion.VERSION_1_8
+        targetCompatibility JavaVersion.VERSION_1_8
+    }
+    kotlinOptions {
+        jvmTarget = '1.8'
+        freeCompilerArgs += '-Xopt-in=kotlin.RequiresOptIn'
+        freeCompilerArgs += '-Xexplicit-api=strict'
+    }
+    protobuf {
+        protoc {
+            artifact = "com.google.protobuf:protoc:$protobuf_version"
+        }
+        generateProtoTasks {
+            all().each { task ->
+                task.builtins {
+                    java {
+                        option "lite"
+                    }
+                }
+            }
+        }
+    }
+}
+
+kotlin {
+    explicitApi = 'strict'
+}
+
+dependencies {
+    implementation "org.jetbrains.kotlin:kotlin-stdlib:$kotlin_version"
+
+    implementation rootProject.ext.std_libs.androidx_core
+    // A newer version gets pulled in with AOSP via core, so we include fragment here explicitly
+    implementation rootProject.ext.std_libs.androidx_fragment
+    implementation rootProject.ext.std_libs.androidx_lifecycle_viewmodel_ktx
+    implementation rootProject.ext.std_libs.androidx_lifecycle_livedata_ktx
+    implementation rootProject.ext.std_libs.androidx_constraintlayout
+    implementation rootProject.ext.std_libs.androidx_documentfile
+    implementation rootProject.ext.std_libs.com_google_android_material
+
+    implementation rootProject.ext.storage_libs.androidx_room_runtime
+    implementation rootProject.ext.storage_libs.com_google_protobuf_javalite
+    implementation rootProject.ext.storage_libs.com_google_crypto_tink_android
+    kapt('androidx.room:room-compiler') {
+        version { strictly "$room_version" }
+    }
+
+    lintChecks rootProject.ext.lint_libs.exceptions
+
+    testImplementation "junit:junit:$junit4_version"
+    testImplementation "io.mockk:mockk:$mockk_version"
+    testImplementation "org.jetbrains.kotlin:kotlin-test-junit:$kotlin_version"
+
+    androidTestImplementation 'androidx.test.ext:junit:1.1.2'
+    androidTestImplementation "androidx.test.espresso:espresso-core:$espresso_version"
+}

storage/lib/libs/storage.aar

@@ -0,0 +1 @@
+../build/outputs/aar/lib-release.aar

storage/lib/proguard-rules.pro

@@ -0,0 +1,23 @@
+# Add project specific ProGuard rules here.
+# You can control the set of applied configuration files using the
+# proguardFiles setting in build.gradle.
+#
+# For more details, see
+#   http://developer.android.com/guide/developing/tools/proguard.html
+
+# If your project uses WebView with JS, uncomment the following
+# and specify the fully qualified class name to the JavaScript interface
+# class:
+#-keepclassmembers class fqcn.of.javascript.interface.for.webview {
+#   public *;
+#}
+
+# Uncomment this to preserve the line number information for
+# debugging stack traces.
+#-keepattributes SourceFile,LineNumberTable
+
+# If you keep the line number information, uncomment this to
+# hide the original source file name.
+#-renamesourcefileattribute SourceFile
+
+-keep class org.calyxos.backup.storage.** {*;}

storage/lib/schemas/org.calyxos.backup.storage.db.Db/1.json

@@ -0,0 +1,128 @@
+{
+  "formatVersion": 1,
+  "database": {
+    "version": 1,
+    "identityHash": "6286a22113131a780d1a28ba059d5a6d",
+    "entities": [
+      {
+        "tableName": "StoredUri",
+        "createSql": "CREATE TABLE IF NOT EXISTS `${TABLE_NAME}` (`uri` TEXT NOT NULL, PRIMARY KEY(`uri`))",
+        "fields": [
+          {
+            "fieldPath": "uri",
+            "columnName": "uri",
+            "affinity": "TEXT",
+            "notNull": true
+          }
+        ],
+        "primaryKey": {
+          "columnNames": [
+            "uri"
+          ],
+          "autoGenerate": false
+        },
+        "indices": [],
+        "foreignKeys": []
+      },
+      {
+        "tableName": "CachedFile",
+        "createSql": "CREATE TABLE IF NOT EXISTS `${TABLE_NAME}` (`uri` TEXT NOT NULL, `size` INTEGER NOT NULL, `last_modified` INTEGER, `generation_modified` INTEGER, `chunks` TEXT NOT NULL, `zip_index` INTEGER, `last_seen` INTEGER NOT NULL, PRIMARY KEY(`uri`))",
+        "fields": [
+          {
+            "fieldPath": "uri",
+            "columnName": "uri",
+            "affinity": "TEXT",
+            "notNull": true
+          },
+          {
+            "fieldPath": "size",
+            "columnName": "size",
+            "affinity": "INTEGER",
+            "notNull": true
+          },
+          {
+            "fieldPath": "lastModified",
+            "columnName": "last_modified",
+            "affinity": "INTEGER",
+            "notNull": false
+          },
+          {
+            "fieldPath": "generationModified",
+            "columnName": "generation_modified",
+            "affinity": "INTEGER",
+            "notNull": false
+          },
+          {
+            "fieldPath": "chunks",
+            "columnName": "chunks",
+            "affinity": "TEXT",
+            "notNull": true
+          },
+          {
+            "fieldPath": "zipIndex",
+            "columnName": "zip_index",
+            "affinity": "INTEGER",
+            "notNull": false
+          },
+          {
+            "fieldPath": "lastSeen",
+            "columnName": "last_seen",
+            "affinity": "INTEGER",
+            "notNull": true
+          }
+        ],
+        "primaryKey": {
+          "columnNames": [
+            "uri"
+          ],
+          "autoGenerate": false
+        },
+        "indices": [],
+        "foreignKeys": []
+      },
+      {
+        "tableName": "CachedChunk",
+        "createSql": "CREATE TABLE IF NOT EXISTS `${TABLE_NAME}` (`id` TEXT NOT NULL, `ref_count` INTEGER NOT NULL, `size` INTEGER NOT NULL, `version` INTEGER NOT NULL, PRIMARY KEY(`id`))",
+        "fields": [
+          {
+            "fieldPath": "id",
+            "columnName": "id",
+            "affinity": "TEXT",
+            "notNull": true
+          },
+          {
+            "fieldPath": "refCount",
+            "columnName": "ref_count",
+            "affinity": "INTEGER",
+            "notNull": true
+          },
+          {
+            "fieldPath": "size",
+            "columnName": "size",
+            "affinity": "INTEGER",
+            "notNull": true
+          },
+          {
+            "fieldPath": "version",
+            "columnName": "version",
+            "affinity": "INTEGER",
+            "notNull": true
+          }
+        ],
+        "primaryKey": {
+          "columnNames": [
+            "id"
+          ],
+          "autoGenerate": false
+        },
+        "indices": [],
+        "foreignKeys": []
+      }
+    ],
+    "views": [],
+    "setupQueries": [
+      "CREATE TABLE IF NOT EXISTS room_master_table (id INTEGER PRIMARY KEY,identity_hash TEXT)",
+      "INSERT OR REPLACE INTO room_master_table (id,identity_hash) VALUES(42, '6286a22113131a780d1a28ba059d5a6d')"
+    ]
+  }
+}

storage/lib/src/androidTest/java/org/calyxos/backup/storage/db/ChunksCacheTest.kt

@@ -0,0 +1,125 @@
+package org.calyxos.backup.storage.db
+
+import android.content.Context
+import androidx.room.Room
+import androidx.test.core.app.ApplicationProvider
+import androidx.test.ext.junit.runners.AndroidJUnit4
+import org.hamcrest.CoreMatchers.equalTo
+import org.hamcrest.MatcherAssert.assertThat
+import org.junit.After
+import org.junit.Assert.assertFalse
+import org.junit.Assert.assertNull
+import org.junit.Assert.assertTrue
+import org.junit.Before
+import org.junit.Test
+import org.junit.runner.RunWith
+import kotlin.random.Random
+
+@RunWith(AndroidJUnit4::class)
+internal class ChunksCacheTest {
+
+    private lateinit var chunksCache: ChunksCache
+    private lateinit var db: Db
+
+    private val chunk1 = CachedChunk("id1", 1, Random.nextLong())
+    private val chunk2 = CachedChunk("id2", 2, Random.nextLong())
+    private val chunk3 = CachedChunk("id3", 3, Random.nextLong())
+
+    @Before
+    fun createDb() {
+        val context = ApplicationProvider.getApplicationContext<Context>()
+        db = Room.inMemoryDatabaseBuilder(context, Db::class.java).build()
+        chunksCache = db.getChunksCache()
+        chunksCache.insert(chunk1)
+        chunksCache.insert(chunk2)
+        chunksCache.insert(chunk3)
+    }
+
+    @After
+    fun closeDb() {
+        db.close()
+    }
+
+    @Test
+    fun testInsertAndGet() {
+        assertThat(chunksCache.get(chunk1.id), equalTo(chunk1))
+        assertThat(chunksCache.get(chunk2.id), equalTo(chunk2))
+        assertThat(chunksCache.get(chunk3.id), equalTo(chunk3))
+    }
+
+    @Test
+    fun testInsertAndDelete() {
+        chunksCache.deleteChunks(listOf(chunk1))
+        assertThat(chunksCache.get(chunk1.id), equalTo(null))
+        assertThat(chunksCache.get(chunk2.id), equalTo(chunk2))
+        assertThat(chunksCache.get(chunk3.id), equalTo(chunk3))
+
+        chunksCache.deleteChunks(listOf(chunk2, chunk3))
+        assertThat(chunksCache.get(chunk1.id), equalTo(null))
+        assertThat(chunksCache.get(chunk2.id), equalTo(null))
+        assertThat(chunksCache.get(chunk3.id), equalTo(null))
+
+        chunksCache.insert(chunk1)
+        chunksCache.deleteChunks(listOf(chunk1.copy(refCount = 1337)))
+        assertThat(chunksCache.get(chunk1.id), equalTo(null))
+    }
+
+    @Test
+    fun testRefCounts() {
+        assertThat(chunksCache.getUnreferencedChunks(), equalTo(emptyList()))
+
+        chunksCache.decrementRefCount(listOf(chunk1.id, chunk2.id))
+        chunksCache.decrementRefCount(listOf(chunk2.id))
+        assertThat(
+            chunksCache.getUnreferencedChunks(),
+            equalTo(listOf(chunk1.copy(refCount = 0), chunk2.copy(refCount = 0)))
+        )
+
+        chunksCache.decrementRefCount(listOf(chunk3.id))
+        chunksCache.decrementRefCount(listOf(chunk3.id))
+        chunksCache.decrementRefCount(listOf(chunk3.id))
+        assertThat(
+            chunksCache.getUnreferencedChunks(),
+            equalTo(
+                listOf(
+                    chunk1.copy(refCount = 0),
+                    chunk2.copy(refCount = 0),
+                    chunk3.copy(refCount = 0)
+                )
+            )
+        )
+
+        chunksCache.incrementRefCount(listOf(chunk1.id, chunk2.id))
+        assertThat(chunksCache.getUnreferencedChunks(), equalTo(listOf(chunk3.copy(refCount = 0))))
+    }
+
+    @Test
+    fun testAreAllAvailableChunksCached() {
+        assertTrue(chunksCache.areAllAvailableChunksCached(db, listOf()))
+        assertTrue(chunksCache.areAllAvailableChunksCached(db, listOf("id1")))
+        assertTrue(chunksCache.areAllAvailableChunksCached(db, listOf("id1", "id2")))
+        assertTrue(chunksCache.areAllAvailableChunksCached(db, listOf("id1", "id2", "id3")))
+        assertTrue(chunksCache.areAllAvailableChunksCached(db, listOf("id1", "id2", "id3")))
+        assertFalse(chunksCache.areAllAvailableChunksCached(db, listOf("id1", "id2", "id3", "id4")))
+        assertFalse(chunksCache.areAllAvailableChunksCached(db, listOf("foo", "bar")))
+    }
+
+    @Test
+    fun testClearAndRepopulate() {
+        val newChunks = listOf(
+            chunk1.copy(id = "newId1", refCount = 4),
+            chunk2.copy(id = "newId2", refCount = 6),
+            chunk3.copy(id = "newId3", refCount = 8)
+        )
+        chunksCache.clearAndRepopulate(db, newChunks)
+
+        assertNull(chunksCache.get("id1"))
+        assertNull(chunksCache.get("id2"))
+        assertNull(chunksCache.get("id3"))
+
+        assertThat(chunksCache.get("newId1"), equalTo(newChunks[0]))
+        assertThat(chunksCache.get("newId2"), equalTo(newChunks[1]))
+        assertThat(chunksCache.get("newId3"), equalTo(newChunks[2]))
+    }
+
+}

storage/lib/src/androidTest/java/org/calyxos/backup/storage/db/FilesCacheTest.kt

@@ -0,0 +1,60 @@
+package org.calyxos.backup.storage.db
+
+import android.content.Context
+import android.net.Uri
+import androidx.room.Room
+import androidx.test.core.app.ApplicationProvider
+import androidx.test.ext.junit.runners.AndroidJUnit4
+import org.hamcrest.CoreMatchers.equalTo
+import org.hamcrest.MatcherAssert.assertThat
+import org.junit.After
+import org.junit.Before
+import org.junit.Test
+import org.junit.runner.RunWith
+import kotlin.random.Random
+
+@RunWith(AndroidJUnit4::class)
+internal class FilesCacheTest {
+
+    private lateinit var filesCache: FilesCache
+    private lateinit var db: Db
+
+    @Before
+    fun createDb() {
+        val context = ApplicationProvider.getApplicationContext<Context>()
+        db = Room.inMemoryDatabaseBuilder(context, Db::class.java).build()
+        filesCache = db.getFilesCache()
+    }
+
+    @After
+    fun closeDb() {
+        db.close()
+    }
+
+    @Test
+    fun testWriteAndRead() {
+        val uri1 = Uri.parse("content://foo/bar")
+        val file1 = CachedFile(
+            uri = uri1,
+            size = Random.nextLong(),
+            lastModified = Random.nextLong(),
+            chunks = listOf("foo", "bar"),
+            lastSeen = Random.nextLong()
+        )
+        val uri2 = Uri.parse("content://media/external")
+        val file2 = CachedFile(
+            uri = uri2,
+            size = Random.nextLong(),
+            lastModified = Random.nextLong(),
+            chunks = listOf("23", "42"),
+            lastSeen = Random.nextLong()
+        )
+        filesCache.insert(file1)
+        filesCache.insert(file2)
+        assertThat(filesCache.getByUri(uri1), equalTo(file1))
+        assertThat(filesCache.getByUri(uri2), equalTo(file2))
+
+        assertThat(filesCache.getByUri(Uri.parse("doesntExist")), equalTo(null))
+    }
+
+}

storage/lib/src/androidTest/java/org/calyxos/backup/storage/db/UriStoreTest.kt

@@ -0,0 +1,60 @@
+package org.calyxos.backup.storage.db
+
+import android.content.Context
+import android.net.Uri
+import androidx.room.Room
+import androidx.test.core.app.ApplicationProvider
+import androidx.test.ext.junit.runners.AndroidJUnit4
+import org.calyxos.backup.storage.toStoredUri
+import org.hamcrest.CoreMatchers.equalTo
+import org.hamcrest.MatcherAssert.assertThat
+import org.junit.After
+import org.junit.Before
+import org.junit.Test
+import org.junit.runner.RunWith
+
+@RunWith(AndroidJUnit4::class)
+internal class UriStoreTest {
+
+    private lateinit var uriStore: UriStore
+    private lateinit var db: Db
+
+    private val uri1 = Uri.parse("content://foo/bar/1").toStoredUri()
+    private val uri2 = Uri.parse("content://foo/bar/2").toStoredUri()
+    private val uri3 = Uri.parse("content://foo/bar/3").toStoredUri()
+
+    @Before
+    fun createDb() {
+        val context = ApplicationProvider.getApplicationContext<Context>()
+        db = Room.inMemoryDatabaseBuilder(context, Db::class.java).build()
+        uriStore = db.getUriStore()
+    }
+
+    @After
+    fun closeDb() {
+        db.close()
+    }
+
+    @Test
+    fun testInsertAndGet() {
+        uriStore.addStoredUri(uri1)
+        assertThat(uriStore.getStoredUris(), equalTo(listOf(uri1)))
+        uriStore.addStoredUri(uri2)
+        uriStore.addStoredUri(uri3)
+        assertThat(uriStore.getStoredUris(), equalTo(listOf(uri1, uri2, uri3)))
+    }
+
+    @Test
+    fun testInsertAndRemove() {
+        uriStore.addStoredUri(uri1)
+        assertThat(uriStore.getStoredUris(), equalTo(listOf(uri1)))
+        uriStore.removeStoredUri(uri1)
+        assertThat(uriStore.getStoredUris(), equalTo(emptyList()))
+        uriStore.addStoredUri(uri2)
+        uriStore.addStoredUri(uri3)
+        assertThat(uriStore.getStoredUris(), equalTo(listOf(uri2, uri3)))
+        uriStore.removeStoredUri(uri3)
+        assertThat(uriStore.getStoredUris(), equalTo(listOf(uri2)))
+    }
+
+}

storage/lib/src/main/AndroidManifest.xml

@@ -0,0 +1,34 @@
+<?xml version="1.0" encoding="utf-8"?>
+<manifest xmlns:android="http://schemas.android.com/apk/res/android"
+    xmlns:tools="http://schemas.android.com/tools"
+    package="org.calyxos.backup.storage">
+
+    <uses-permission
+        android:name="android.permission.READ_EXTERNAL_STORAGE"
+        android:maxSdkVersion="29" />
+    <uses-permission
+        android:name="android.permission.WRITE_EXTERNAL_STORAGE"
+        android:maxSdkVersion="29" />
+
+    <uses-permission
+        android:name="android.permission.MANAGE_EXTERNAL_STORAGE"
+        tools:ignore="ScopedStorage" />
+
+    <!-- Needed to backup original media files e.g. without stripped EXIF metadata -->
+    <uses-permission android:name="android.permission.ACCESS_MEDIA_LOCATION" />
+
+    <!--
+    Needed to restore owning app of media files
+    http://aosp.opersys.com/xref/android-11.0.0_r17/xref/packages/providers/MediaProvider/src/com/android/providers/media/util/PermissionUtils.java#88
+    -->
+    <uses-permission
+        android:name="android.permission.BACKUP"
+        tools:ignore="ProtectedPermissions" />
+
+    <!-- Needed to schedule the periodic backup job -->
+    <uses-permission android:name="android.permission.RECEIVE_BOOT_COMPLETED" />
+
+    <!-- Needed to run a periodic backup service that doesn't get killed -->
+    <uses-permission android:name="android.permission.FOREGROUND_SERVICE" />
+
+</manifest>

storage/lib/src/main/java/org/calyxos/backup/storage/ByteArrayUtils.kt

@@ -0,0 +1,5 @@
+package org.calyxos.backup.storage
+
+internal fun ByteArray.toHexString() = joinToString("") { "%02x".format(it) }
+
+internal fun String.toByteArrayFromHex() = chunked(2).map { it.toInt(16).toByte() }.toByteArray()

storage/lib/src/main/java/org/calyxos/backup/storage/TimeUtils.kt

@@ -0,0 +1,38 @@
+package org.calyxos.backup.storage
+
+import android.util.Log
+import kotlin.contracts.ExperimentalContracts
+import kotlin.contracts.InvocationKind
+import kotlin.contracts.contract
+import kotlin.time.Duration
+import kotlin.time.DurationUnit
+import kotlin.time.ExperimentalTime
+import kotlin.time.toDuration
+
+/**
+ * We don't use [kotlin.time.measureTime] or [kotlin.time.measureTimedValue],
+ * because those are not available in the Kotlin version shipped with Android 11.
+ * So when building with AOSP 11, things will blow up.
+ */
+
+@OptIn(ExperimentalContracts::class, ExperimentalTime::class)
+internal inline fun measure(block: () -> Unit): Duration {
+    contract {
+        callsInPlace(block, InvocationKind.EXACTLY_ONCE)
+    }
+    val start = System.currentTimeMillis()
+    block()
+    return (System.currentTimeMillis() - start).toDuration(DurationUnit.MILLISECONDS)
+}
+
+@OptIn(ExperimentalContracts::class, ExperimentalTime::class)
+internal inline fun <T> measure(text: String, block: () -> T): T {
+    contract {
+        callsInPlace(block, InvocationKind.EXACTLY_ONCE)
+    }
+    val start = System.currentTimeMillis()
+    val result = block()
+    val duration = (System.currentTimeMillis() - start).toDuration(DurationUnit.MILLISECONDS)
+    Log.e("Time", "$text took $duration")
+    return result
+}

storage/lib/src/main/java/org/calyxos/backup/storage/UriUtils.kt

@@ -0,0 +1,57 @@
+package org.calyxos.backup.storage
+
+import android.content.ContentResolver
+import android.net.Uri
+import android.provider.MediaStore
+import org.calyxos.backup.storage.api.MediaType
+import org.calyxos.backup.storage.api.mediaItems
+import org.calyxos.backup.storage.backup.BackupMediaFile
+import org.calyxos.backup.storage.db.StoredUri
+import java.io.IOException
+import java.io.InputStream
+import java.io.OutputStream
+
+internal fun Uri.toStoredUri(): StoredUri = StoredUri(this)
+
+internal fun Uri.getDocumentPath(): String? {
+    return lastPathSegment?.split(':')?.getOrNull(1)
+}
+
+internal fun Uri.getVolume(): String? {
+    val volume = lastPathSegment?.split(':')?.getOrNull(0)
+    return if (volume == "primary") MediaStore.VOLUME_EXTERNAL_PRIMARY else volume
+}
+
+@Throws(IOException::class)
+public fun Uri.openInputStream(contentResolver: ContentResolver): InputStream {
+    return try {
+        contentResolver.openInputStream(this)
+    } catch (e: IllegalArgumentException) {
+        // This is necessary, because contrary to the documentation, files that have been deleted
+        // after we retrieved their Uri, will throw an IllegalArgumentException
+        throw IOException(e)
+    } ?: throw IOException("Stream for $this returned null")
+}
+
+@Throws(IOException::class)
+public fun Uri.openOutputStream(contentResolver: ContentResolver): OutputStream {
+    return try {
+        contentResolver.openOutputStream(this, "wt")
+    } catch (e: IllegalArgumentException) {
+        // This is necessary, because contrary to the documentation, files that have been deleted
+        // after we retrieved their Uri, will throw an IllegalArgumentException
+        throw IOException(e)
+    } ?: throw IOException("Stream for $this returned null")
+}
+
+internal fun Uri.getMediaType(): MediaType? {
+    val str = toString()
+    for (item in mediaItems) {
+        if (str.startsWith(item.contentUri.toString())) return item
+    }
+    return null
+}
+
+internal fun Uri.getBackupMediaType(): BackupMediaFile.MediaType? {
+    return getMediaType()?.backupType
+}

storage/lib/src/main/java/org/calyxos/backup/storage/api/BackupContentType.kt

@@ -0,0 +1,86 @@
+package org.calyxos.backup.storage.api
+
+import android.net.Uri
+import android.provider.MediaStore
+import androidx.annotation.DrawableRes
+import androidx.annotation.StringRes
+import org.calyxos.backup.storage.R
+import org.calyxos.backup.storage.backup.BackupMediaFile
+import org.calyxos.backup.storage.getDocumentPath
+
+// hidden in DocumentsContract
+public const val EXTERNAL_STORAGE_PROVIDER_AUTHORITY: String =
+    "com.android.externalstorage.documents"
+
+public val mediaItems: List<MediaType> = listOf(
+    MediaType.Images,
+    MediaType.Video,
+    MediaType.Audio,
+    MediaType.Downloads
+)
+
+public val mediaUris: List<Uri> = listOf(
+    MediaType.Images.contentUri,
+    MediaType.Video.contentUri,
+    MediaType.Audio.contentUri,
+    MediaType.Downloads.contentUri
+)
+
+public sealed class BackupContentType(
+    @DrawableRes
+    public val drawableRes: Int
+) {
+    public object Custom : BackupContentType(R.drawable.ic_folder) {
+        public fun getName(uri: Uri): String {
+            val path = uri.getDocumentPath()!!
+            return if (path.isBlank()) "/" else path
+        }
+    }
+}
+
+public sealed class MediaType(
+    public val contentUri: Uri,
+    @StringRes
+    public val nameRes: Int,
+    @DrawableRes
+    drawableRes: Int,
+    public val backupType: BackupMediaFile.MediaType,
+) : BackupContentType(drawableRes) {
+    public object Images : MediaType(
+        contentUri = MediaStore.Images.Media.EXTERNAL_CONTENT_URI,
+        nameRes = R.string.content_images,
+        drawableRes = R.drawable.ic_photo_library,
+        backupType = BackupMediaFile.MediaType.IMAGES,
+    )
+
+    public object Video : MediaType(
+        contentUri = MediaStore.Video.Media.EXTERNAL_CONTENT_URI,
+        nameRes = R.string.content_videos,
+        drawableRes = R.drawable.ic_video_library,
+        backupType = BackupMediaFile.MediaType.VIDEO,
+    )
+
+    public object Audio : MediaType(
+        contentUri = MediaStore.Audio.Media.EXTERNAL_CONTENT_URI,
+        nameRes = R.string.content_audio,
+        drawableRes = R.drawable.ic_music_library,
+        backupType = BackupMediaFile.MediaType.AUDIO,
+    )
+
+    public object Downloads : MediaType(
+        contentUri = MediaStore.Downloads.EXTERNAL_CONTENT_URI,
+        nameRes = R.string.content_downloads,
+        drawableRes = R.drawable.ic_download_library,
+        backupType = BackupMediaFile.MediaType.DOWNLOADS,
+    )
+
+    internal companion object {
+        fun fromBackupMediaType(type: BackupMediaFile.MediaType): MediaType = when (type) {
+            BackupMediaFile.MediaType.IMAGES -> Images
+            BackupMediaFile.MediaType.VIDEO -> Video
+            BackupMediaFile.MediaType.AUDIO -> Audio
+            BackupMediaFile.MediaType.DOWNLOADS -> Downloads
+            else -> throw AssertionError("Unrecognized media type: $type")
+        }
+    }
+}

storage/lib/src/main/java/org/calyxos/backup/storage/api/BackupFile.kt

@@ -0,0 +1,14 @@
+package org.calyxos.backup.storage.api
+
+import android.provider.MediaStore
+
+public interface BackupFile {
+    public val path: String
+
+    /**
+     * empty string for [MediaStore.VOLUME_EXTERNAL_PRIMARY]
+     */
+    public val volume: String
+    public val size: Long
+    public val lastModified: Long?
+}

storage/lib/src/main/java/org/calyxos/backup/storage/api/BackupObserver.kt

@@ -0,0 +1,54 @@
+package org.calyxos.backup.storage.api
+
+public interface BackupObserver {
+
+    public suspend fun onStartScanning()
+
+    /**
+     * Called after scanning files when starting the backup.
+     *
+     * @param totalSize the total size of all files to be backed up.
+     * @param numFiles the number of all files to be backed up.
+     * The sum of [numSmallFiles] and [numLargeFiles].
+     * @param numSmallFiles the number of small files to be backed up.
+     * @param numLargeFiles the number of large files to be backed up.
+     */
+    public suspend fun onBackupStart(
+        totalSize: Long,
+        numFiles: Int,
+        numSmallFiles: Int,
+        numLargeFiles: Int,
+    )
+
+    public suspend fun onFileBackedUp(
+        file: BackupFile,
+        wasUploaded: Boolean,
+        reusedChunks: Int,
+        bytesWritten: Long,
+        tag: String,
+    )
+
+    public suspend fun onFileBackupError(
+        file: BackupFile,
+        tag: String,
+    )
+
+    /**
+     * If backupDuration is null, the overall backup failed.
+     */
+    public suspend fun onBackupComplete(backupDuration: Long?)
+
+    public suspend fun onPruneStartScanning()
+
+    public suspend fun onPruneStart(snapshotsToDelete: List<Long>)
+
+    public suspend fun onPruneSnapshot(snapshot: Long, numChunksToDelete: Int, size: Long)
+
+    /**
+     * If snapshot is null, the overall operation failed.
+     */
+    public suspend fun onPruneError(snapshot: Long?, e: Exception)
+
+    public suspend fun onPruneComplete(pruneDuration: Long)
+
+}