Merge pull request #47 from stevesoltys/develop

Merge develop into master

.gitignore

@@ -46,4 +46,7 @@ gradle-app.setting
 .DS_Store
 
 ## Android
-gen/
+gen/
+
+## Prebuilt
+Backup.apk

.travis.yml

@@ -1,17 +1,42 @@
+dist: trusty
+
+jdk:
+  - openjdk11
+
 language: android
 android:
   components:
-  - build-tools-28.0.3
+    - build-tools-29.0.2
-  - android-28
+    - android-29
+
+licenses:
+  - android-sdk-license-.+
+  - '.+'
+
+before_install:
+  - mkdir "$ANDROID_HOME/licenses" || true
+  - echo -e "\n8933bad161af4178b1185d1a37fbf41ea5269c55" >> "$ANDROID_HOME/licenses/android-sdk-license"
+  - echo -e "\nd56f5187479451eabf01fb78af6dfcb131a6481e" >> "$ANDROID_HOME/licenses/android-sdk-license"
+  - echo -e "\n24333f8a63b6825ea9c5514f83c2829b004d1fee" >> "$ANDROID_HOME/licenses/android-sdk-license"
+  - echo -e "\n84831b9409646a918e30573bab4c9c91346d8abd" >> "$ANDROID_HOME/licenses/android-sdk-preview-license"
+
+before_cache:
+  - rm -f  $HOME/.gradle/caches/modules-2/modules-2.lock
+  - rm -fr $HOME/.gradle/caches/*/plugin-resolution/
+
+script: ./gradlew check assemble
+
+cache:
+  directories:
+    - $HOME/.gradle/caches/
+    - $HOME/.gradle/wrapper/
+    - $HOME/.android/build-cache
+
 deploy:
-  provider: releases
+  provider: script
-  api_key:
+  script: ./deploy-prebuilt.sh
-    secure: 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
+  skip_cleanup: true
-  file:
-    - app/build/outputs/apk/release/app-release-unsigned.apk
-    - app/src/main/permissions_com.stevesoltys.backup.xml
-    - app/src/main/whitelist_com.stevesoltys.backup.xml
   on:
-    repo: stevesoltys/backup
+    repo: stevesoltys/seedvault
-    tags: true
+    all_branches: true
-  skip_cleanup: true
+    condition: $TRAVIS_BRANCH =~ ^(master|develop)$

Android.mk

@@ -0,0 +1,27 @@
+LOCAL_PATH := $(call my-dir)
+
+include $(CLEAR_VARS)
+LOCAL_MODULE := permissions_com.stevesoltys.seedvault.xml
+LOCAL_MODULE_CLASS := ETC
+LOCAL_MODULE_TAGS := optional
+LOCAL_MODULE_PATH := $(TARGET_OUT_ETC)/permissions
+LOCAL_SRC_FILES := $(LOCAL_MODULE)
+include $(BUILD_PREBUILT)
+
+include $(CLEAR_VARS)
+LOCAL_MODULE := whitelist_com.stevesoltys.seedvault.xml
+LOCAL_MODULE_CLASS := ETC
+LOCAL_MODULE_TAGS := optional
+LOCAL_MODULE_PATH := $(TARGET_OUT_ETC)/sysconfig
+LOCAL_SRC_FILES := $(LOCAL_MODULE)
+include $(BUILD_PREBUILT)
+
+include $(CLEAR_VARS)
+LOCAL_MODULE := Seedvault
+LOCAL_SRC_FILES := Seedvault.apk
+LOCAL_CERTIFICATE := platform
+LOCAL_MODULE_CLASS := APPS
+LOCAL_PRIVILEGED_MODULE := true
+LOCAL_DEX_PREOPT := false
+LOCAL_REQUIRED_MODULES := permissions_com.stevesoltys.seedvault.xml whitelist_com.stevesoltys.seedvault.xml
+include $(BUILD_PREBUILT)

CHANGELOG.md

@@ -1,3 +1,17 @@
+## [1.0.0-alpha1] - 2019-12-14
+### Added
+- Automatic daily backups that run in the background.
+- User friendly UI for creating and restoring backups.
+- Support to backing up to and restoring from removable storage.
+
+### Updated
+- Application can now be configured in the settings app.
+- BIP39 is now used for key generation.
+
+### Notes
+- This contains breaking changes, any backups made prior to this release can no longer be restored.
+- Application can no longer be built in the Android source tree. It must be built using Gradle and binaries can now be found here: https://github.com/stevesoltys/seedvault-prebuilt
+
 ## [0.3.0] - 2019-03-14
 ### Fixed
 - Transport encryption. Some of the application data was not included during encryption.
@@ -11,7 +25,7 @@
 
 ## [0.1.2] - 2019-02-11
 ### Fixed
-- Downgrade SDK target version to 26 due to [#15](https://github.com/stevesoltys/backup/issues/15).
+- Downgrade SDK target version to 26 due to [#15](https://github.com/stevesoltys/seedvault/issues/15).
 
 ## [0.1.1] - 2019-02-11
 ### Added
@@ -20,4 +34,4 @@
 - Upgrade target SDK version to 28.
 
 ### Fixed
-- Ignore `com.android.providers.downloads.ui` to resolve [#14](https://github.com/stevesoltys/backup/issues/14).
+- Ignore `com.android.providers.downloads.ui` to resolve [#14](https://github.com/stevesoltys/seedvault/issues/14).

LICENSE

@@ -1,21 +1,202 @@
-The MIT License (MIT)
 
-Copyright (c) 2017 Steve Soltys
+                                 Apache License
+                           Version 2.0, January 2004
+                        http://www.apache.org/licenses/
 
-Permission is hereby granted, free of charge, to any person obtaining a copy
+   TERMS AND CONDITIONS FOR USE, REPRODUCTION, AND DISTRIBUTION
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-to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
-copies of the Software, and to permit persons to whom the Software is
-furnished to do so, subject to the following conditions:
 
-The above copyright notice and this permission notice shall be included in
+   1. Definitions.
-all copies or substantial portions of the Software.
 
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+      and distribution as defined by Sections 1 through 9 of this document.
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+   5. Submission of Contributions. Unless You explicitly state otherwise,
+      any Contribution intentionally submitted for inclusion in the Work
+      by You to the Licensor shall be under the terms and conditions of
+      this License, without any additional terms or conditions.
+      Notwithstanding the above, nothing herein shall supersede or modify
+      the terms of any separate license agreement you may have executed
+      with Licensor regarding such Contributions.
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+   6. Trademarks. This License does not grant permission to use the trade
+      names, trademarks, service marks, or product names of the Licensor,
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+      agreed to in writing, Licensor provides the Work (and each
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+
+   END OF TERMS AND CONDITIONS
+
+   APPENDIX: How to apply the Apache License to your work.
+
+      To apply the Apache License to your work, attach the following
+      boilerplate notice, with the fields enclosed by brackets "[]"
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+   Copyright [2019] [Steve Soltys]
+
+   Licensed under the Apache License, Version 2.0 (the "License");
+   you may not use this file except in compliance with the License.
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+
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+
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+   limitations under the License.

README.md

@@ -1,28 +1,30 @@
-# Backup
+# Seedvault
-[![Build Status](https://travis-ci.com/stevesoltys/backup.svg?branch=master)](https://travis-ci.com/stevesoltys/backup)
+[![Build Status](https://travis-ci.com/stevesoltys/seedvault.svg?branch=master)](https://travis-ci.com/stevesoltys/seedvault)
 
 A backup application for the [Android Open Source Project](https://source.android.com/).
 
 ## Features
-- Backup application data to a zip file.
+- Backup application data to a flash drive.
-- Restore application data from a zip file.
+- Restore application data from a flash drive.
-- Password-based encryption.
+- User-friendly encryption using a mnemonic phrase (BIP39).
+- Automatic daily backups that run in the background.
 
 ## Getting Started
-- Check out [the wiki](https://github.com/stevesoltys/backup/wiki) for information on building the application with 
+- Check out [the wiki](https://github.com/stevesoltys/seedvault/wiki) for information on building the application with 
 AOSP.
 
 ## What makes this different?
 This application is compiled with the operating system and does not require a rooted device for use. It uses the same 
-internal APIs as `adb backup` and only requires the permission `android.permission.BACKUP` for this.
+internal APIs as `adb backup` and requires a minimal number of permissions to achieve this.
-
-## Contributing
-Bug reports and pull requests are welcome on GitHub at https://github.com/stevesoltys/backup. 
 
 ## Permissions
+* `android.permission.BACKUP` to back up application data.
+* `android.permission.MANAGE_DOCUMENTS` to retrieve the available storage roots. 
+* `android.permission.MANAGE_USB` to access the serial number of USB mass storage devices.
+* `android.permission.WRITE_SECURE_SETTINGS` to change system backup settings.
 
-* `android.permission.BACKUP` to be allowed to back up apps
+## Contributing
-* `android.permission.RECEIVE_BOOT_COMPLETED` to schedule automatic backups after boot
+Bug reports and pull requests are welcome on GitHub at https://github.com/stevesoltys/seedvault. 
 
 ## License
-This application is available as open source under the terms of the [MIT License](http://opensource.org/licenses/MIT).
+This application is available as open source under the terms of the [Apache-2.0 License](https://opensource.org/licenses/Apache-2.0).

app/build.gradle

@@ -1,15 +1,18 @@
 import groovy.xml.XmlUtil
 
 apply plugin: 'com.android.application'
+apply plugin: 'kotlin-android'
+apply plugin: 'kotlin-android-extensions'
 
 android {
 
-    compileSdkVersion 28
+    compileSdkVersion 29
-    buildToolsVersion '28.0.3'
+    buildToolsVersion '29.0.2'
 
     defaultConfig {
-        minSdkVersion 26
+        minSdkVersion 29
-        targetSdkVersion 28
+        targetSdkVersion 29
+        testInstrumentationRunner "androidx.test.runner.AndroidJUnitRunner"
     }
 
     buildTypes {
@@ -25,6 +28,23 @@ android {
         targetCompatibility 1.8
         sourceCompatibility 1.8
     }
+    testOptions {
+        unitTests.all {
+            useJUnitPlatform()
+            testLogging {
+                events "passed", "skipped", "failed"
+            }
+        }
+    }
+
+    sourceSets {
+        test {
+            java.srcDirs += "$projectDir/src/sharedTest/java"
+        }
+        androidTest {
+            java.srcDirs += "$projectDir/src/sharedTest/java"
+        }
+    }
 
     // optional signingConfigs
     def keystorePropertiesFile = rootProject.file("keystore.properties")
@@ -41,11 +61,15 @@ android {
             }
         }
         buildTypes.release.signingConfig = signingConfigs.release
+        buildTypes.debug.signingConfig = signingConfigs.release
     }
 }
 
 gradle.projectsEvaluated {
     tasks.withType(JavaCompile) {
+        if (JavaVersion.current() >= JavaVersion.VERSION_1_9) {
+            options.compilerArgs.addAll(['--release', '8'])
+        }
         options.compilerArgs.add('-Xbootclasspath/p:app/libs/android.jar:app/libs/libcore.jar')
     }
 }
@@ -60,6 +84,7 @@ preBuild.doLast {
         parsedXml.component[1].remove(jdkNode)
 
         def sdkString = "Android API " + android.compileSdkVersion.substring("android-".length()) + " Platform"
+        //noinspection GroovyResultOfObjectAllocationIgnored // the note gets inserted
         new Node(parsedXml.component[1], 'orderEntry', ['type': 'jdk', 'jdkName': sdkString, 'jdkType': 'Android SDK'])
         XmlUtil.serialize(parsedXml, new FileOutputStream(imlFile))
 
@@ -68,15 +93,37 @@ preBuild.doLast {
     }
 }
 
-dependencies {
+// To produce these binaries, in latest AOSP source tree, run
-    // To produce these binaries, in latest AOSP source tree, run
+// $ make
-    // $ make
+def aospDeps = fileTree(include: [
-    compileOnly fileTree(include: [
+        // out/target/common/obj/JAVA_LIBRARIES/framework_intermediates/classes.jar
-            // out/target/common/obj/JAVA_LIBRARIES/framework_intermediates/classes.jar
+        'android.jar',
-            'android.jar',
+        // out/target/common/obj/JAVA_LIBRARIES/core-libart_intermediates/classes.jar
-            // out/target/common/obj/JAVA_LIBRARIES/core-libart_intermediates/classes.jar
+        'libcore.jar'
-            'libcore.jar'
+], dir: 'libs')
-    ], dir: 'libs')
 
-    implementation group: 'commons-io', name: 'commons-io', version: '2.6'
+dependencies {
+    compileOnly aospDeps
+
+    implementation "org.jetbrains.kotlin:kotlin-stdlib-jdk8:$kotlin_version"
+
+    implementation 'commons-io:commons-io:2.6'
+    implementation 'io.github.novacrypto:BIP39:2019.01.27'
+    implementation 'org.koin:koin-androidx-viewmodel:2.0.1'
+
+    implementation 'androidx.core:core-ktx:1.1.0'
+    implementation 'androidx.preference:preference-ktx:1.1.0'
+    implementation 'com.google.android.material:material:1.0.0'
+    implementation 'androidx.lifecycle:lifecycle-extensions:2.1.0'
+    implementation 'androidx.constraintlayout:constraintlayout:1.1.3'
+
+    lintChecks 'com.github.thirdegg:lint-rules:0.0.4-alpha'
+
+    testImplementation aospDeps
+    testImplementation 'org.junit.jupiter:junit-jupiter-api:5.5.2'
+    testImplementation 'io.mockk:mockk:1.9.3'
+    testRuntimeOnly 'org.junit.jupiter:junit-jupiter-engine:5.5.2'
+
+    androidTestImplementation 'androidx.test:runner:1.2.0'
+    androidTestImplementation 'androidx.test:rules:1.2.0'
 }

app/src/androidTest/java/com/stevesoltys/seedvault/CipherUniqueNonceTest.kt

@@ -0,0 +1,33 @@
+package com.stevesoltys.seedvault
+
+import android.util.Log
+import androidx.test.filters.LargeTest
+import androidx.test.runner.AndroidJUnit4
+import com.stevesoltys.seedvault.crypto.CipherFactoryImpl
+import com.stevesoltys.seedvault.crypto.KeyManagerTestImpl
+import org.junit.Assert.assertTrue
+import org.junit.Test
+import org.junit.runner.RunWith
+
+private val TAG = CipherUniqueNonceTest::class.java.simpleName
+private const val ITERATIONS = 1_000_000
+
+@LargeTest
+@RunWith(AndroidJUnit4::class)
+class CipherUniqueNonceTest {
+
+    private val keyManager = KeyManagerTestImpl()
+    private val cipherFactory = CipherFactoryImpl(keyManager)
+
+    private val nonceSet = HashSet<ByteArray>()
+
+    @Test
+    fun testUniqueNonce() {
+        for (i in 1..ITERATIONS) {
+            val iv = cipherFactory.createEncryptionCipher().iv
+            Log.w(TAG, "$i: ${iv.toHexString()}")
+            assertTrue(nonceSet.add(iv))
+        }
+    }
+
+}

app/src/androidTest/java/com/stevesoltys/seedvault/DocumentsStorageTest.kt

@@ -0,0 +1,71 @@
+package com.stevesoltys.seedvault
+
+import androidx.documentfile.provider.DocumentFile
+import androidx.test.platform.app.InstrumentationRegistry
+import androidx.test.runner.AndroidJUnit4
+import com.stevesoltys.seedvault.settings.SettingsManager
+import com.stevesoltys.seedvault.plugins.saf.DocumentsStorage
+import com.stevesoltys.seedvault.plugins.saf.createOrGetFile
+import org.junit.After
+import org.junit.Assert.assertArrayEquals
+import org.junit.Assert.assertNotNull
+import org.junit.Before
+import org.junit.Test
+import org.junit.runner.RunWith
+import org.koin.core.KoinComponent
+import org.koin.core.inject
+import kotlin.random.Random
+
+private const val filename = "test-file"
+
+@RunWith(AndroidJUnit4::class)
+class DocumentsStorageTest : KoinComponent {
+
+    private val context = InstrumentationRegistry.getInstrumentation().targetContext
+    private val settingsManager by inject<SettingsManager>()
+    private val storage = DocumentsStorage(context, settingsManager)
+
+    private lateinit var file: DocumentFile
+
+    @Before
+    fun setup() {
+        assertNotNull("Select a storage location in the app first!", storage.rootBackupDir)
+        file = storage.rootBackupDir?.createOrGetFile(filename)
+                ?: throw RuntimeException("Could not create test file")
+    }
+
+    @After
+    fun tearDown() {
+        file.delete()
+    }
+
+    @Test
+    fun testWritingAndReadingFile() {
+        // write to output stream
+        val outputStream = storage.getOutputStream(file)
+        val content = ByteArray(1337).apply { Random.nextBytes(this) }
+        outputStream.write(content)
+        outputStream.flush()
+        outputStream.close()
+
+        // read written data from input stream
+        val inputStream = storage.getInputStream(file)
+        val readContent = inputStream.readBytes()
+        inputStream.close()
+        assertArrayEquals(content, readContent)
+
+        // write smaller content to same file
+        val outputStream2 = storage.getOutputStream(file)
+        val content2 = ByteArray(42).apply { Random.nextBytes(this) }
+        outputStream2.write(content2)
+        outputStream2.flush()
+        outputStream2.close()
+
+        // read written data from input stream
+        val inputStream2 = storage.getInputStream(file)
+        val readContent2 = inputStream2.readBytes()
+        inputStream2.close()
+        assertArrayEquals(content2, readContent2)
+    }
+
+}

app/src/debug/res/values/config.xml

@@ -0,0 +1,10 @@
+<?xml version="1.0" encoding="utf-8"?>
+<resources>
+    <bool name="show_restore_in_settings">true</bool>
+
+    <string-array name="storage_authority_whitelist">
+        <item>com.android.externalstorage.documents</item>
+        <item>org.nextcloud.documents</item>
+        <item>org.nextcloud.beta.documents</item>
+    </string-array>
+</resources>

app/src/main/Android.mk

@@ -1,35 +0,0 @@
-LOCAL_PATH := $(call my-dir)
-
-include $(CLEAR_VARS)
-LOCAL_MODULE := permissions_com.stevesoltys.backup.xml
-LOCAL_MODULE_CLASS := ETC
-LOCAL_MODULE_TAGS := optional
-LOCAL_MODULE_PATH := $(TARGET_OUT_ETC)/permissions
-LOCAL_SRC_FILES := $(LOCAL_MODULE)
-include $(BUILD_PREBUILT)
-
-include $(CLEAR_VARS)
-LOCAL_MODULE := whitelist_com.stevesoltys.backup.xml
-LOCAL_MODULE_CLASS := ETC
-LOCAL_MODULE_TAGS := optional
-LOCAL_MODULE_PATH := $(TARGET_OUT_ETC)/sysconfig
-LOCAL_SRC_FILES := $(LOCAL_MODULE)
-include $(BUILD_PREBUILT)
-
-include $(CLEAR_VARS)
-LOCAL_MODULE_TAGS := optional
-LOCAL_PREBUILT_STATIC_JAVA_LIBRARIES := \
-    commons-io:../../libs/commons-io-2.6.jar
-include $(BUILD_MULTI_PREBUILT)
-
-include $(CLEAR_VARS)
-LOCAL_PACKAGE_NAME := Backup
-LOCAL_MODULE_TAGS := optional
-LOCAL_REQUIRED_MODULES := permissions_com.stevesoltys.backup.xml whitelist_com.stevesoltys.backup.xml
-LOCAL_PRIVILEGED_MODULE := true
-LOCAL_PRIVATE_PLATFORM_APIS := true
-LOCAL_CERTIFICATE := platform
-LOCAL_STATIC_JAVA_LIBRARIES := commons-io
-LOCAL_SRC_FILES := $(call all-java-files-under, java)
-LOCAL_RESOURCE_DIR := $(LOCAL_PATH)/res
-include $(BUILD_PACKAGE)

app/src/main/AndroidManifest.xml

@@ -1,59 +1,86 @@
 <?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="com.stevesoltys.backup"
+    package="com.stevesoltys.seedvault"
-    android:versionCode="5"
+    android:versionCode="6"
-    android:versionName="0.3.0">
+    android:versionName="1.0.0-alpha1">
-
-    <uses-sdk
-        android:minSdkVersion="26"
-        android:targetSdkVersion="28"
-        tools:ignore="GradleOverrides,OldTargetApi" />
 
     <uses-permission
         android:name="android.permission.BACKUP"
         tools:ignore="ProtectedPermissions" />
 
-    <uses-permission android:name="android.permission.RECEIVE_BOOT_COMPLETED" />
+    <!-- This is needed to retrieve the available storage roots -->
+    <uses-permission
+        android:name="android.permission.MANAGE_DOCUMENTS"
+        tools:ignore="ProtectedPermissions" />
+
+    <!-- This is needed to access the serial number of USB mass storage devices -->
+    <uses-permission
+        android:name="android.permission.MANAGE_USB"
+        tools:ignore="ProtectedPermissions" />
+
+    <!-- This is needed to change system backup settings -->
+    <uses-permission
+        android:name="android.permission.WRITE_SECURE_SETTINGS"
+        tools:ignore="ProtectedPermissions" />
 
     <application
-        android:name=".Backup"
+        android:name=".App"
-        android:supportsRtl="true"
+        android:allowBackup="false"
-        android:theme="@style/AppTheme"
         android:icon="@mipmap/ic_launcher"
         android:label="@string/app_name"
-        android:allowBackup="false"
+        android:roundIcon="@mipmap/ic_launcher_round"
+        android:supportsRtl="true"
+        android:theme="@style/AppTheme"
         tools:ignore="GoogleAppIndexingWarning">
 
         <activity
-            android:name="com.stevesoltys.backup.activity.MainActivity"
+            android:name=".settings.SettingsActivity"
-            android:label="@string/app_name">
+            android:exported="true" />
+
+        <activity
+            android:name=".ui.storage.StorageActivity"
+            android:theme="@style/AppTheme.NoActionBar" />
+
+        <activity
+            android:name=".ui.storage.PermissionGrantActivity"
+            android:exported="false"
+            android:permission="android.permission.MANAGE_DOCUMENTS" />
+
+        <activity
+            android:name=".ui.recoverycode.RecoveryCodeActivity"
+            android:label="@string/recovery_code_title"
+            android:theme="@style/AppTheme.NoActionBar" />
+
+        <activity
+            android:name=".restore.RestoreActivity"
+            android:exported="true"
+            android:label="@string/restore_title"
+            android:theme="@style/AppTheme.NoActionBar">
             <intent-filter>
-                <action android:name="android.intent.action.MAIN" />
+                <action android:name="com.stevesoltys.seedvault.RESTORE_BACKUP" />
-                <category android:name="android.intent.category.LAUNCHER" />
+                <category android:name="android.intent.category.DEFAULT" />
             </intent-filter>
         </activity>
 
-        <activity
-            android:name="com.stevesoltys.backup.activity.backup.CreateBackupActivity"
-            android:parentActivityName="com.stevesoltys.backup.activity.MainActivity" />
-
-        <activity
-            android:name="com.stevesoltys.backup.activity.restore.RestoreBackupActivity"
-            android:parentActivityName="com.stevesoltys.backup.activity.MainActivity" />
-
         <service
-            android:name="com.stevesoltys.backup.transport.ConfigurableBackupTransportService"
+            android:name=".transport.ConfigurableBackupTransportService"
             android:exported="false">
             <intent-filter>
                 <action android:name="android.backup.TRANSPORT_HOST" />
             </intent-filter>
         </service>
 
-        <service
+        <receiver
-            android:name=".service.backup.BackupJobService"
+            android:name=".UsbIntentReceiver"
-            android:exported="false"
+            android:exported="true">
-            android:permission="android.permission.BIND_JOB_SERVICE" />
+            <intent-filter>
+                <action android:name="android.hardware.usb.action.USB_DEVICE_ATTACHED" />
+            </intent-filter>
+            <meta-data
+                android:name="android.hardware.usb.action.USB_DEVICE_ATTACHED"
+                android:resource="@xml/device_filter" />
+        </receiver>
 
     </application>
 </manifest>

app/src/main/java/com/stevesoltys/backup/Backup.java

@@ -1,12 +0,0 @@
-package com.stevesoltys.backup;
-
-import android.app.Application;
-
-/**
- * @author Steve Soltys
- */
-public class Backup extends Application {
-
-    public static final int JOB_ID_BACKGROUND_BACKUP = 1;
-
-}

app/src/main/java/com/stevesoltys/backup/activity/MainActivity.java

@@ -1,105 +0,0 @@
-package com.stevesoltys.backup.activity;
-
-import android.app.Activity;
-import android.content.Intent;
-import android.os.Bundle;
-import android.util.Log;
-import android.view.View;
-import android.widget.Button;
-
-import com.stevesoltys.backup.R;
-
-import static android.view.View.GONE;
-import static android.view.View.VISIBLE;
-import static com.stevesoltys.backup.settings.SettingsManager.areBackupsScheduled;
-
-public class MainActivity extends Activity implements View.OnClickListener {
-
-    public static final int OPEN_DOCUMENT_TREE_REQUEST_CODE = 1;
-
-    public static final int OPEN_DOCUMENT_TREE_BACKUP_REQUEST_CODE = 2;
-
-    public static final int LOAD_DOCUMENT_REQUEST_CODE = 3;
-
-    private MainActivityController controller;
-    private Button automaticBackupsButton;
-    private Button changeLocationButton;
-
-    @Override
-    protected void onCreate(Bundle savedInstanceState) {
-        super.onCreate(savedInstanceState);
-        setContentView(R.layout.activity_main);
-
-        controller = new MainActivityController();
-
-        findViewById(R.id.create_backup_button).setOnClickListener(this);
-        findViewById(R.id.restore_backup_button).setOnClickListener(this);
-
-        automaticBackupsButton = findViewById(R.id.automatic_backups_button);
-        automaticBackupsButton.setOnClickListener(this);
-        if (areBackupsScheduled(this)) automaticBackupsButton.setVisibility(GONE);
-
-        changeLocationButton = findViewById(R.id.change_backup_location_button);
-        changeLocationButton.setOnClickListener(this);
-    }
-
-    @Override
-    protected void onStart() {
-        super.onStart();
-        if (controller.isChangeBackupLocationButtonVisible(this)) {
-            changeLocationButton.setVisibility(VISIBLE);
-        } else {
-            changeLocationButton.setVisibility(GONE);
-        }
-    }
-
-    @Override
-    public void onClick(View view) {
-        int viewId = view.getId();
-
-        switch (viewId) {
-
-            case R.id.create_backup_button:
-                controller.onBackupButtonClicked(this);
-                break;
-
-            case R.id.restore_backup_button:
-                controller.showLoadDocumentActivity(this);
-                break;
-
-            case R.id.automatic_backups_button:
-                if (controller.onAutomaticBackupsButtonClicked(this)) {
-                    automaticBackupsButton.setVisibility(GONE);
-                }
-                break;
-
-            case R.id.change_backup_location_button:
-                controller.onChangeBackupLocationButtonClicked(this);
-                break;
-        }
-    }
-
-    @Override
-    public void onActivityResult(int requestCode, int resultCode, Intent result) {
-
-        if (resultCode != Activity.RESULT_OK) {
-            Log.e(MainActivity.class.getName(), "Error in activity result: " + requestCode);
-            return;
-        }
-
-        switch (requestCode) {
-
-            case OPEN_DOCUMENT_TREE_REQUEST_CODE:
-                controller.handleChooseFolderResult(result, this, false);
-                break;
-
-            case OPEN_DOCUMENT_TREE_BACKUP_REQUEST_CODE:
-                controller.handleChooseFolderResult(result, this, true);
-                break;
-
-            case LOAD_DOCUMENT_REQUEST_CODE:
-                controller.handleLoadDocumentResult(result, this);
-                break;
-        }
-    }
-}

app/src/main/java/com/stevesoltys/backup/activity/MainActivityController.java

@@ -1,155 +0,0 @@
-package com.stevesoltys.backup.activity;
-
-import android.app.Activity;
-import android.app.job.JobInfo;
-import android.app.job.JobScheduler;
-import android.content.ActivityNotFoundException;
-import android.content.ComponentName;
-import android.content.Intent;
-import android.net.Uri;
-import android.widget.Toast;
-
-import com.stevesoltys.backup.activity.backup.CreateBackupActivity;
-import com.stevesoltys.backup.activity.restore.RestoreBackupActivity;
-import com.stevesoltys.backup.service.backup.BackupJobService;
-import com.stevesoltys.backup.transport.ConfigurableBackupTransportService;
-
-import static android.app.job.JobInfo.NETWORK_TYPE_UNMETERED;
-import static android.content.Intent.ACTION_OPEN_DOCUMENT;
-import static android.content.Intent.ACTION_OPEN_DOCUMENT_TREE;
-import static android.content.Intent.CATEGORY_OPENABLE;
-import static android.content.Intent.FLAG_GRANT_PERSISTABLE_URI_PERMISSION;
-import static android.content.Intent.FLAG_GRANT_READ_URI_PERMISSION;
-import static android.content.Intent.FLAG_GRANT_WRITE_URI_PERMISSION;
-import static com.stevesoltys.backup.Backup.JOB_ID_BACKGROUND_BACKUP;
-import static com.stevesoltys.backup.activity.MainActivity.OPEN_DOCUMENT_TREE_BACKUP_REQUEST_CODE;
-import static com.stevesoltys.backup.activity.MainActivity.OPEN_DOCUMENT_TREE_REQUEST_CODE;
-import static com.stevesoltys.backup.settings.SettingsManager.getBackupFolderUri;
-import static com.stevesoltys.backup.settings.SettingsManager.getBackupPassword;
-import static com.stevesoltys.backup.settings.SettingsManager.setBackupFolderUri;
-import static com.stevesoltys.backup.settings.SettingsManager.setBackupsScheduled;
-import static java.util.Objects.requireNonNull;
-import static java.util.concurrent.TimeUnit.DAYS;
-
-/**
- * @author Steve Soltys
- * @author Torsten Grote
- */
-public class MainActivityController {
-
-    public static final String DOCUMENT_MIME_TYPE = "application/octet-stream";
-
-    void onBackupButtonClicked(Activity parent) {
-        Uri folderUri = getBackupFolderUri(parent);
-        if (folderUri == null) {
-            showChooseFolderActivity(parent, true);
-        } else {
-            // ensure that backup service is started
-            parent.startService(new Intent(parent, ConfigurableBackupTransportService.class));
-            showCreateBackupActivity(parent);
-        }
-    }
-
-    boolean isChangeBackupLocationButtonVisible(Activity parent) {
-        return getBackupFolderUri(parent) != null;
-    }
-
-    private void showChooseFolderActivity(Activity parent, boolean continueToBackup) {
-        Intent openTreeIntent = new Intent(ACTION_OPEN_DOCUMENT_TREE);
-        openTreeIntent.addFlags(FLAG_GRANT_PERSISTABLE_URI_PERMISSION |
-                FLAG_GRANT_READ_URI_PERMISSION | FLAG_GRANT_WRITE_URI_PERMISSION);
-
-        try {
-            Intent documentChooser = Intent.createChooser(openTreeIntent, "Select the backup location");
-            int requestCode = continueToBackup ? OPEN_DOCUMENT_TREE_BACKUP_REQUEST_CODE : OPEN_DOCUMENT_TREE_REQUEST_CODE;
-            parent.startActivityForResult(documentChooser, requestCode);
-
-        } catch (ActivityNotFoundException ex) {
-            Toast.makeText(parent, "Please install a file manager.", Toast.LENGTH_SHORT).show();
-        }
-    }
-
-    void showLoadDocumentActivity(Activity parent) {
-        Intent loadDocumentIntent = new Intent(ACTION_OPEN_DOCUMENT);
-        loadDocumentIntent.addCategory(CATEGORY_OPENABLE);
-        loadDocumentIntent.setType(DOCUMENT_MIME_TYPE);
-
-        try {
-            Intent documentChooser = Intent.createChooser(loadDocumentIntent, "Select the backup location");
-            parent.startActivityForResult(documentChooser, MainActivity.LOAD_DOCUMENT_REQUEST_CODE);
-
-        } catch (ActivityNotFoundException ex) {
-            Toast.makeText(parent, "Please install a file manager.", Toast.LENGTH_SHORT).show();
-        }
-    }
-
-    boolean onAutomaticBackupsButtonClicked(Activity parent) {
-        if (getBackupFolderUri(parent) == null || getBackupPassword(parent) == null) {
-            Toast.makeText(parent, "Please make at least one manual backup first.", Toast.LENGTH_SHORT).show();
-            return false;
-        }
-
-        // schedule backups
-        final ComponentName serviceName = new ComponentName(parent, BackupJobService.class);
-        JobInfo job = new JobInfo.Builder(JOB_ID_BACKGROUND_BACKUP, serviceName)
-                .setRequiredNetworkType(NETWORK_TYPE_UNMETERED)
-                .setRequiresBatteryNotLow(true)
-                .setRequiresStorageNotLow(true)  // TODO warn the user instead
-                .setPeriodic(DAYS.toMillis(1))
-                .setRequiresCharging(true)
-                .setPersisted(true)
-                .build();
-        JobScheduler scheduler = requireNonNull(parent.getSystemService(JobScheduler.class));
-        scheduler.schedule(job);
-
-        // remember that backups were scheduled
-        setBackupsScheduled(parent);
-
-        // show Toast informing the user
-        Toast.makeText(parent, "Backups will run automatically now", Toast.LENGTH_SHORT).show();
-
-        return true;
-    }
-
-    void onChangeBackupLocationButtonClicked(Activity parent) {
-        showChooseFolderActivity(parent, false);
-    }
-
-    void handleChooseFolderResult(Intent result, Activity parent, boolean continueToBackup) {
-
-        if (result == null || result.getData() == null) {
-            return;
-        }
-
-        Uri folderUri = result.getData();
-
-        // persist permission to access backup folder across reboots
-        int takeFlags = result.getFlags() &
-                (FLAG_GRANT_READ_URI_PERMISSION | FLAG_GRANT_WRITE_URI_PERMISSION);
-        parent.getContentResolver().takePersistableUriPermission(folderUri, takeFlags);
-
-        // store backup folder location in settings
-        setBackupFolderUri(parent, folderUri);
-
-        if (!continueToBackup) return;
-
-        showCreateBackupActivity(parent);
-    }
-
-    private void showCreateBackupActivity(Activity parent) {
-        Intent intent = new Intent(parent, CreateBackupActivity.class);
-        parent.startActivity(intent);
-    }
-
-    void handleLoadDocumentResult(Intent result, Activity parent) {
-
-        if (result == null) {
-            return;
-        }
-
-        Intent intent = new Intent(parent, RestoreBackupActivity.class);
-        intent.setData(result.getData());
-        parent.startActivity(intent);
-    }
-
-}

app/src/main/java/com/stevesoltys/backup/activity/PackageListActivity.java

@@ -1,60 +0,0 @@
-package com.stevesoltys.backup.activity;
-
-import android.app.Activity;
-import android.view.MenuItem;
-import android.view.View;
-import android.widget.AdapterView;
-import android.widget.ListView;
-
-import com.stevesoltys.backup.R;
-
-import java.util.HashSet;
-import java.util.Set;
-import java.util.stream.IntStream;
-
-/**
- * @author Steve Soltys
- */
-public abstract class PackageListActivity extends Activity implements AdapterView.OnItemClickListener {
-
-    protected ListView packageListView;
-
-    protected final Set<String> selectedPackageList = new HashSet<>();
-
-    public void onItemClick(AdapterView<?> parent, View view, int position, long id) {
-        String clickedPackage = (String) packageListView.getItemAtPosition(position);
-
-        if (!selectedPackageList.remove(clickedPackage)) {
-            selectedPackageList.add(clickedPackage);
-            packageListView.setItemChecked(position, true);
-
-        } else {
-            packageListView.setItemChecked(position, false);
-        }
-    }
-
-    @Override
-    public boolean onOptionsItemSelected(MenuItem item) {
-
-        if (item.getItemId() == R.id.action_unselect_all) {
-
-            IntStream.range(0, packageListView.getCount())
-                    .forEach(position -> {
-                        selectedPackageList.remove((String) packageListView.getItemAtPosition(position));
-                        packageListView.setItemChecked(position, false);
-                    });
-
-            return true;
-        }
-
-        return super.onOptionsItemSelected(item);
-    }
-
-    public void preSelectAllPackages() {
-        IntStream.range(0, packageListView.getCount())
-                .forEach(position -> {
-                    selectedPackageList.add((String) packageListView.getItemAtPosition(position));
-                    packageListView.setItemChecked(position, true);
-                });
-    }
-}

app/src/main/java/com/stevesoltys/backup/activity/PopupWindowUtil.java

@@ -1,32 +0,0 @@
-package com.stevesoltys.backup.activity;
-
-import android.app.Activity;
-import android.content.Context;
-import android.graphics.Color;
-import android.graphics.drawable.ColorDrawable;
-import android.view.Gravity;
-import android.view.LayoutInflater;
-import android.view.View;
-import android.view.ViewGroup;
-import android.widget.PopupWindow;
-import com.stevesoltys.backup.R;
-
-/**
- * @author Steve Soltys
- */
-public class PopupWindowUtil {
-
-    public static PopupWindow showLoadingPopupWindow(Activity parent) {
-        LayoutInflater inflater = (LayoutInflater) parent.getSystemService(Context.LAYOUT_INFLATER_SERVICE);
-        ViewGroup popupViewGroup = parent.findViewById(R.id.popup_layout);
-        View popupView = inflater.inflate(R.layout.progress_popup_window, popupViewGroup);
-
-        PopupWindow popupWindow = new PopupWindow(popupView, 750, 350, true);
-        popupWindow.setBackgroundDrawable(new ColorDrawable(Color.WHITE));
-        popupWindow.setElevation(10);
-        popupWindow.setFocusable(false);
-        popupWindow.showAtLocation(popupView, Gravity.CENTER, 0, 0);
-        popupWindow.setOutsideTouchable(false);
-        return popupWindow;
-    }
-}

app/src/main/java/com/stevesoltys/backup/activity/backup/BackupPopupWindowListener.java

@@ -1,37 +0,0 @@
-package com.stevesoltys.backup.activity.backup;
-
-import android.os.RemoteException;
-import android.util.Log;
-import android.view.View;
-import android.widget.Button;
-import com.stevesoltys.backup.R;
-import com.stevesoltys.backup.session.backup.BackupResult;
-import com.stevesoltys.backup.session.backup.BackupSession;
-
-/**
- * @author Steve Soltys
- */
-public class BackupPopupWindowListener implements Button.OnClickListener {
-
-    private static final String TAG = BackupPopupWindowListener.class.getName();
-
-    private final BackupSession backupSession;
-
-    public BackupPopupWindowListener(BackupSession backupSession) {
-        this.backupSession = backupSession;
-    }
-
-    @Override
-    public void onClick(View view) {
-        int viewId = view.getId();
-
-        if (viewId == R.id.popup_cancel_button) {
-            try {
-                backupSession.stop(BackupResult.CANCELLED);
-
-            } catch (RemoteException e) {
-                Log.e(TAG, "Error cancelling backup session: ", e);
-            }
-        }
-    }
-}

app/src/main/java/com/stevesoltys/backup/activity/backup/CreateBackupActivity.java

@@ -1,45 +0,0 @@
-package com.stevesoltys.backup.activity.backup;
-
-import android.os.AsyncTask;
-import android.os.Bundle;
-import android.view.Menu;
-import android.view.MenuInflater;
-import android.view.View;
-
-import com.stevesoltys.backup.R;
-import com.stevesoltys.backup.activity.PackageListActivity;
-
-public class CreateBackupActivity extends PackageListActivity implements View.OnClickListener {
-
-    private CreateBackupActivityController controller;
-
-    @Override
-    public void onClick(View view) {
-        int viewId = view.getId();
-
-        if (viewId == R.id.create_confirm_button) {
-            controller.onCreateBackupButtonClicked(selectedPackageList, this);
-        }
-    }
-
-    @Override
-    protected void onCreate(Bundle savedInstanceState) {
-        super.onCreate(savedInstanceState);
-
-        setContentView(R.layout.activity_create_backup);
-        findViewById(R.id.create_confirm_button).setOnClickListener(this);
-
-        packageListView = findViewById(R.id.create_package_list);
-        selectedPackageList.clear();
-
-        controller = new CreateBackupActivityController();
-        AsyncTask.execute(() -> controller.populatePackageList(packageListView, CreateBackupActivity.this));
-    }
-
-    @Override
-    public boolean onCreateOptionsMenu(Menu menu) {
-        MenuInflater inflater = getMenuInflater();
-        inflater.inflate(R.menu.backup_menu, menu);
-        return true;
-    }
-}

app/src/main/java/com/stevesoltys/backup/activity/backup/CreateBackupActivityController.java

@@ -1,133 +0,0 @@
-package com.stevesoltys.backup.activity.backup;
-
-import android.app.Activity;
-import android.app.AlertDialog;
-import android.os.RemoteException;
-import android.text.InputType;
-import android.util.Log;
-import android.view.View;
-import android.widget.ArrayAdapter;
-import android.widget.EditText;
-import android.widget.ListView;
-import android.widget.PopupWindow;
-import android.widget.TextView;
-import android.widget.Toast;
-
-import com.stevesoltys.backup.R;
-import com.stevesoltys.backup.activity.PopupWindowUtil;
-import com.stevesoltys.backup.service.PackageService;
-import com.stevesoltys.backup.service.backup.BackupService;
-import com.stevesoltys.backup.settings.SettingsManager;
-
-import java.util.Set;
-import java.util.concurrent.atomic.AtomicReference;
-
-/**
- * @author Steve Soltys
- */
-class CreateBackupActivityController {
-
-    private static final String TAG = CreateBackupActivityController.class.getName();
-
-    private final BackupService backupService = new BackupService();
-
-    private final PackageService packageService = new PackageService();
-
-    void populatePackageList(ListView packageListView, CreateBackupActivity parent) {
-        AtomicReference<PopupWindow> popupWindow = new AtomicReference<>();
-
-        parent.runOnUiThread(() -> {
-            popupWindow.set(PopupWindowUtil.showLoadingPopupWindow(parent));
-            TextView textView = popupWindow.get().getContentView().findViewById(R.id.popup_text_view);
-            textView.setText(R.string.loading_packages);
-
-            View popupWindowButton = popupWindow.get().getContentView().findViewById(R.id.popup_cancel_button);
-            popupWindowButton.setOnClickListener(view -> parent.finish());
-        });
-
-        String[] eligiblePackageList;
-
-        try {
-            eligiblePackageList = packageService.getEligiblePackages();
-        } catch (RemoteException e) {
-            Log.e(TAG, "Error while obtaining package list: ", e);
-            Toast.makeText(parent, "Error obtaining package list", Toast.LENGTH_SHORT).show();
-            parent.finish();
-            return;
-        }
-
-        parent.runOnUiThread(() -> {
-            if (popupWindow.get() != null) {
-                popupWindow.get().dismiss();
-            }
-
-            packageListView.setOnItemClickListener(parent);
-            packageListView.setAdapter(new ArrayAdapter<>(parent, R.layout.checked_list_item, eligiblePackageList));
-            packageListView.setChoiceMode(ListView.CHOICE_MODE_MULTIPLE);
-            parent.preSelectAllPackages();
-        });
-    }
-
-    void onCreateBackupButtonClicked(Set<String> selectedPackages, Activity parent) {
-        String password = SettingsManager.getBackupPassword(parent);
-        if (password == null) {
-            showEnterPasswordAlert(selectedPackages, parent);
-        } else {
-            backupService.backupPackageData(selectedPackages, parent);
-        }
-    }
-
-    private void showEnterPasswordAlert(Set<String> selectedPackages, Activity parent) {
-        final EditText passwordTextView = new EditText(parent);
-        passwordTextView.setInputType(InputType.TYPE_CLASS_TEXT | InputType.TYPE_TEXT_VARIATION_PASSWORD);
-
-        new AlertDialog.Builder(parent)
-                .setTitle("Enter a password")
-                .setMessage("You'll need this to restore your backup, so write it down!")
-                .setView(passwordTextView)
-
-                .setPositiveButton("Set password", (dialog, button) -> {
-                    if (passwordTextView.getText().length() == 0) {
-                        Toast.makeText(parent, "Please enter a password", Toast.LENGTH_SHORT).show();
-                        dialog.cancel();
-                        showEnterPasswordAlert(selectedPackages, parent);
-                    } else {
-                        showConfirmPasswordAlert(selectedPackages, parent,
-                                passwordTextView.getText().toString());
-                    }
-                })
-
-                .setNegativeButton("Cancel", (dialog, button) -> dialog.cancel())
-                .show();
-    }
-
-    private void showConfirmPasswordAlert(Set<String> selectedPackages, Activity parent,
-                                          String originalPassword) {
-        final EditText passwordTextView = new EditText(parent);
-        passwordTextView.setInputType(InputType.TYPE_CLASS_TEXT | InputType.TYPE_TEXT_VARIATION_PASSWORD);
-
-        new AlertDialog.Builder(parent)
-                .setTitle("Confirm password")
-                .setView(passwordTextView)
-
-                .setPositiveButton("Confirm", (dialog, button) -> {
-                    String password = passwordTextView.getText().toString();
-
-                    if (originalPassword.equals(password)) {
-                        SettingsManager.setBackupPassword(parent, password);
-                        backupService.backupPackageData(selectedPackages, parent);
-
-                    } else {
-                        new AlertDialog.Builder(parent)
-                                .setMessage("Passwords do not match, please try again.")
-                                .setPositiveButton("Ok", (dialog2, button2) -> dialog2.dismiss())
-                                .show();
-
-                        dialog.cancel();
-                    }
-                })
-
-                .setNegativeButton("Cancel", (dialog, button) -> dialog.cancel())
-                .show();
-    }
-}

app/src/main/java/com/stevesoltys/backup/activity/restore/RestoreBackupActivity.java

@@ -1,50 +0,0 @@
-package com.stevesoltys.backup.activity.restore;
-
-import android.net.Uri;
-import android.os.AsyncTask;
-import android.os.Bundle;
-import android.view.Menu;
-import android.view.MenuInflater;
-import android.view.View;
-
-import com.stevesoltys.backup.R;
-import com.stevesoltys.backup.activity.PackageListActivity;
-
-public class RestoreBackupActivity extends PackageListActivity implements View.OnClickListener {
-
-    private RestoreBackupActivityController controller;
-
-    private Uri contentUri;
-
-    @Override
-    public void onClick(View view) {
-        int viewId = view.getId();
-
-        if (viewId == R.id.restore_confirm_button) {
-            controller.showEnterPasswordAlert(selectedPackageList, contentUri, this);
-        }
-    }
-
-    @Override
-    protected void onCreate(Bundle savedInstanceState) {
-        super.onCreate(savedInstanceState);
-
-        setContentView(R.layout.activity_restore_backup);
-        findViewById(R.id.restore_confirm_button).setOnClickListener(this);
-
-        packageListView = findViewById(R.id.restore_package_list);
-        selectedPackageList.clear();
-
-        contentUri = getIntent().getData();
-
-        controller = new RestoreBackupActivityController();
-        AsyncTask.execute(() -> controller.populatePackageList(packageListView, contentUri, this));
-    }
-
-    @Override
-    public boolean onCreateOptionsMenu(Menu menu) {
-        MenuInflater inflater = getMenuInflater();
-        inflater.inflate(R.menu.backup_menu, menu);
-        return true;
-    }
-}

app/src/main/java/com/stevesoltys/backup/activity/restore/RestoreBackupActivityController.java

@@ -1,116 +0,0 @@
-package com.stevesoltys.backup.activity.restore;
-
-import android.app.Activity;
-import android.app.AlertDialog;
-import android.net.Uri;
-import android.os.ParcelFileDescriptor;
-import android.text.InputType;
-import android.util.Log;
-import android.view.View;
-import android.widget.ArrayAdapter;
-import android.widget.EditText;
-import android.widget.ListView;
-import android.widget.PopupWindow;
-import android.widget.TextView;
-
-import com.stevesoltys.backup.R;
-import com.stevesoltys.backup.activity.PopupWindowUtil;
-import com.stevesoltys.backup.service.restore.RestoreService;
-
-import java.io.File;
-import java.io.FileInputStream;
-import java.io.IOException;
-import java.util.LinkedList;
-import java.util.List;
-import java.util.Set;
-import java.util.concurrent.atomic.AtomicReference;
-import java.util.zip.ZipEntry;
-import java.util.zip.ZipInputStream;
-
-import libcore.io.IoUtils;
-
-import static com.stevesoltys.backup.transport.component.provider.ContentProviderBackupConstants.DEFAULT_FULL_BACKUP_DIRECTORY;
-
-/**
- * @author Steve Soltys
- */
-class RestoreBackupActivityController {
-
-    private static final String TAG = RestoreBackupActivityController.class.getName();
-
-    private final RestoreService restoreService = new RestoreService();
-
-    void populatePackageList(ListView packageListView, Uri contentUri, RestoreBackupActivity parent) {
-        AtomicReference<PopupWindow> popupWindow = new AtomicReference<>();
-
-        parent.runOnUiThread(() -> {
-            popupWindow.set(PopupWindowUtil.showLoadingPopupWindow(parent));
-            TextView textView = popupWindow.get().getContentView().findViewById(R.id.popup_text_view);
-            textView.setText(R.string.loading_backup);
-
-            View popupWindowButton = popupWindow.get().getContentView().findViewById(R.id.popup_cancel_button);
-            popupWindowButton.setOnClickListener(view -> parent.finish());
-        });
-
-        List<String> eligiblePackageList = new LinkedList<>();
-
-        try {
-            eligiblePackageList.addAll(getEligiblePackages(contentUri, parent));
-
-        } catch (IOException e) {
-            Log.e(TAG, "Error while obtaining package list: ", e);
-        }
-
-        parent.runOnUiThread(() -> {
-            if (popupWindow.get() != null) {
-                popupWindow.get().dismiss();
-            }
-
-            packageListView.setOnItemClickListener(parent);
-            packageListView.setAdapter(new ArrayAdapter<>(parent, R.layout.checked_list_item, eligiblePackageList));
-            packageListView.setChoiceMode(ListView.CHOICE_MODE_MULTIPLE);
-            parent.preSelectAllPackages();
-        });
-    }
-
-    private List<String> getEligiblePackages(Uri contentUri, Activity context) throws IOException {
-        List<String> results = new LinkedList<>();
-
-        ParcelFileDescriptor fileDescriptor = context.getContentResolver().openFileDescriptor(contentUri, "r");
-        FileInputStream fileInputStream = new FileInputStream(fileDescriptor.getFileDescriptor());
-        ZipInputStream inputStream = new ZipInputStream(fileInputStream);
-
-        ZipEntry zipEntry;
-        while ((zipEntry = inputStream.getNextEntry()) != null) {
-            String zipEntryPath = zipEntry.getName();
-
-            if (zipEntryPath.startsWith(DEFAULT_FULL_BACKUP_DIRECTORY)) {
-                String fileName = new File(zipEntryPath).getName();
-                results.add(fileName);
-            }
-
-            inputStream.closeEntry();
-        }
-
-        IoUtils.closeQuietly(inputStream);
-        IoUtils.closeQuietly(fileDescriptor.getFileDescriptor());
-        return results;
-    }
-
-    void showEnterPasswordAlert(Set<String> selectedPackages, Uri contentUri, Activity parent) {
-        final EditText passwordTextView = new EditText(parent);
-        passwordTextView.setInputType(InputType.TYPE_CLASS_TEXT | InputType.TYPE_TEXT_VARIATION_PASSWORD);
-
-        new AlertDialog.Builder(parent)
-                .setTitle("Enter a password")
-                .setMessage("If you didn't enter one while creating the backup, you can leave this blank.")
-                .setView(passwordTextView)
-
-                .setPositiveButton("Confirm", (dialog, button) ->
-                        restoreService.restorePackages(selectedPackages, contentUri, parent,
-                                passwordTextView.getText().toString()))
-
-                .setNegativeButton("Cancel", (dialog, button) -> dialog.cancel())
-                .show();
-    }
-}

app/src/main/java/com/stevesoltys/backup/activity/restore/RestorePopupWindowListener.java

@@ -1,41 +0,0 @@
-package com.stevesoltys.backup.activity.restore;
-
-import android.os.RemoteException;
-import android.util.Log;
-import android.view.View;
-import android.widget.Button;
-
-import com.stevesoltys.backup.R;
-import com.stevesoltys.backup.session.restore.RestoreResult;
-import com.stevesoltys.backup.session.restore.RestoreSession;
-
-/**
- * @author Steve Soltys
- */
-public class RestorePopupWindowListener implements Button.OnClickListener {
-
-    private static final String TAG = RestorePopupWindowListener.class.getName();
-
-    private final RestoreSession restoreSession;
-
-    public RestorePopupWindowListener(RestoreSession restoreSession) {
-        this.restoreSession = restoreSession;
-    }
-
-    @Override
-    public void onClick(View view) {
-        int viewId = view.getId();
-
-        switch (viewId) {
-
-            case R.id.popup_cancel_button:
-                try {
-                    restoreSession.stop(RestoreResult.CANCELLED);
-
-                } catch (RemoteException e) {
-                    Log.e(TAG, "Error cancelling restore session: ", e);
-                }
-                break;
-        }
-    }
-}

app/src/main/java/com/stevesoltys/backup/security/CipherUtil.java

@@ -1,79 +0,0 @@
-package com.stevesoltys.backup.security;
-
-import javax.crypto.*;
-import javax.crypto.spec.IvParameterSpec;
-import java.security.InvalidAlgorithmParameterException;
-import java.security.InvalidKeyException;
-import java.security.NoSuchAlgorithmException;
-
-/**
- * A utility class for encrypting and decrypting data using a {@link Cipher}.
- *
- * @author Steve Soltys
- */
-public class CipherUtil {
-
-    /**
-     * The cipher algorithm.
-     */
-    public static final String CIPHER_ALGORITHM = "AES/CBC/PKCS5Padding";
-
-    /**
-     * .
-     * Encrypts the given payload using the provided secret key.
-     *
-     * @param payload   The payload.
-     * @param secretKey The secret key.
-     * @param iv        The initialization vector.
-     */
-    public static byte[] encrypt(byte[] payload, SecretKey secretKey, byte[] iv) throws NoSuchPaddingException,
-            NoSuchAlgorithmException, BadPaddingException, IllegalBlockSizeException,
-            InvalidAlgorithmParameterException, InvalidKeyException {
-
-        return startEncrypt(secretKey, iv).doFinal(payload);
-    }
-
-    /**
-     * Initializes a cipher in {@link Cipher#ENCRYPT_MODE}.
-     *
-     * @param secretKey The secret key.
-     * @param iv        The initialization vector.
-     * @return The initialized cipher.
-     */
-    public static Cipher startEncrypt(SecretKey secretKey, byte[] iv) throws NoSuchPaddingException,
-            NoSuchAlgorithmException, InvalidAlgorithmParameterException, InvalidKeyException {
-
-        Cipher cipher = Cipher.getInstance(CIPHER_ALGORITHM);
-        cipher.init(Cipher.ENCRYPT_MODE, secretKey, new IvParameterSpec(iv));
-        return cipher;
-    }
-
-    /**
-     * Decrypts the given payload using the provided secret key.
-     *
-     * @param payload   The payload.
-     * @param secretKey The secret key.
-     * @param iv        The initialization vector.
-     */
-    public static byte[] decrypt(byte[] payload, SecretKey secretKey, byte[] iv) throws NoSuchPaddingException,
-            NoSuchAlgorithmException, BadPaddingException, IllegalBlockSizeException,
-            InvalidAlgorithmParameterException, InvalidKeyException {
-
-        return startDecrypt(secretKey, iv).doFinal(payload);
-    }
-
-    /**
-     * Initializes a cipher in {@link Cipher#DECRYPT_MODE}.
-     *
-     * @param secretKey The secret key.
-     * @param iv        The initialization vector.
-     * @return The initialized cipher.
-     */
-    public static Cipher startDecrypt(SecretKey secretKey, byte[] iv) throws NoSuchPaddingException,
-            NoSuchAlgorithmException, InvalidAlgorithmParameterException, InvalidKeyException {
-
-        Cipher cipher = Cipher.getInstance(CIPHER_ALGORITHM);
-        cipher.init(Cipher.DECRYPT_MODE, secretKey, new IvParameterSpec(iv));
-        return cipher;
-    }
-}

app/src/main/java/com/stevesoltys/backup/security/KeyGenerator.java

@@ -1,44 +0,0 @@
-package com.stevesoltys.backup.security;
-
-import javax.crypto.SecretKey;
-import javax.crypto.SecretKeyFactory;
-import javax.crypto.spec.PBEKeySpec;
-import javax.crypto.spec.SecretKeySpec;
-import java.security.NoSuchAlgorithmException;
-import java.security.spec.InvalidKeySpecException;
-import java.security.spec.KeySpec;
-
-/**
- * A utility class which can be used for generating an AES secret key using PBKDF2.
- *
- * @author Steve Soltys
- */
-public class KeyGenerator {
-
-    /**
-     * The number of iterations for key generation.
-     */
-    private static final int ITERATIONS = 32767;
-
-    /**
-     * The generated key length.
-     */
-    private static final int KEY_LENGTH = 256;
-
-    /**
-     * Generates an AES secret key using PBKDF2.
-     *
-     * @param password The password.
-     * @param salt     The salt.
-     * @return The generated key.
-     */
-    public static SecretKey generate(String password, byte[] salt)
-            throws NoSuchAlgorithmException, InvalidKeySpecException {
-
-        SecretKeyFactory secretKeyFactory = SecretKeyFactory.getInstance("PBKDF2WithHmacSHA1");
-        KeySpec keySpec = new PBEKeySpec(password.toCharArray(), salt, ITERATIONS, KEY_LENGTH);
-
-        SecretKey secretKey = secretKeyFactory.generateSecret(keySpec);
-        return new SecretKeySpec(secretKey.getEncoded(), "AES");
-    }
-}

app/src/main/java/com/stevesoltys/backup/service/PackageService.java

@@ -1,48 +0,0 @@
-package com.stevesoltys.backup.service;
-
-import android.app.backup.IBackupManager;
-import android.content.pm.IPackageManager;
-import android.content.pm.PackageInfo;
-import android.os.RemoteException;
-import android.os.ServiceManager;
-import android.os.UserHandle;
-
-import java.util.List;
-import java.util.Set;
-
-import static com.google.android.collect.Sets.newArraySet;
-
-/**
- * @author Steve Soltys
- */
-public class PackageService {
-
-    private final IBackupManager backupManager;
-
-    private final IPackageManager packageManager;
-
-    private static final Set<String> IGNORED_PACKAGES = newArraySet(
-            "com.android.externalstorage",
-            "com.android.providers.downloads.ui",
-            "com.android.providers.downloads",
-            "com.android.providers.media",
-            "com.android.providers.calendar",
-            "com.android.providers.contacts",
-            "com.stevesoltys.backup"
-    );
-
-    public PackageService() {
-        backupManager = IBackupManager.Stub.asInterface(ServiceManager.getService("backup"));
-        packageManager = IPackageManager.Stub.asInterface(ServiceManager.getService("package"));
-    }
-
-    public String[] getEligiblePackages() throws RemoteException {
-        List<PackageInfo> packages = packageManager.getInstalledPackages(0, UserHandle.USER_SYSTEM).getList();
-        String[] packageArray = packages.stream()
-                .map(packageInfo -> packageInfo.packageName)
-                .filter(packageName -> !IGNORED_PACKAGES.contains(packageName))
-                .toArray(String[]::new);
-
-        return backupManager.filterAppsEligibleForBackup(packageArray);
-    }
-}

app/src/main/java/com/stevesoltys/backup/service/TransportService.java

@@ -1,56 +0,0 @@
-package com.stevesoltys.backup.service;
-
-import android.app.backup.IBackupManager;
-import android.os.RemoteException;
-import android.os.ServiceManager;
-
-import com.stevesoltys.backup.session.backup.BackupSession;
-import com.stevesoltys.backup.session.backup.BackupSessionObserver;
-import com.stevesoltys.backup.session.restore.RestoreSession;
-import com.stevesoltys.backup.session.restore.RestoreSessionObserver;
-
-import java.util.Set;
-
-/**
- * @author Steve Soltys
- */
-public class TransportService {
-
-    private static final String BACKUP_TRANSPORT = "com.stevesoltys.backup.transport.ConfigurableBackupTransport";
-
-    private final IBackupManager backupManager;
-
-    public TransportService() {
-        backupManager = IBackupManager.Stub.asInterface(ServiceManager.getService("backup"));
-    }
-
-    public BackupSession backup(BackupSessionObserver observer, Set<String> packages) throws RemoteException {
-
-        if (!BACKUP_TRANSPORT.equals(backupManager.getCurrentTransport())) {
-            backupManager.selectBackupTransport(BACKUP_TRANSPORT);
-        }
-
-        if (!backupManager.isBackupEnabled()) {
-            backupManager.setBackupEnabled(true);
-        }
-
-        BackupSession backupSession = new BackupSession(backupManager, observer, packages);
-        backupSession.start();
-        return backupSession;
-    }
-
-    public RestoreSession restore(RestoreSessionObserver observer, Set<String> packages) throws RemoteException {
-
-        if (!BACKUP_TRANSPORT.equals(backupManager.getCurrentTransport())) {
-            backupManager.selectBackupTransport(BACKUP_TRANSPORT);
-        }
-
-        if (!backupManager.isBackupEnabled()) {
-            backupManager.setBackupEnabled(true);
-        }
-
-        RestoreSession restoreSession = new RestoreSession(backupManager, observer, packages);
-        restoreSession.start();
-        return restoreSession;
-    }
-}

app/src/main/java/com/stevesoltys/backup/service/backup/BackupJobService.java

@@ -1,61 +0,0 @@
-package com.stevesoltys.backup.service.backup;
-
-import android.app.backup.BackupManager;
-import android.app.backup.IBackupManager;
-import android.app.job.JobParameters;
-import android.app.job.JobService;
-import android.content.Intent;
-import android.os.RemoteException;
-import android.util.Log;
-
-import com.stevesoltys.backup.service.PackageService;
-import com.stevesoltys.backup.transport.ConfigurableBackupTransportService;
-
-import static android.app.backup.BackupManager.FLAG_NON_INCREMENTAL_BACKUP;
-import static android.os.ServiceManager.getService;
-
-public class BackupJobService extends JobService {
-
-    private final static String TAG = BackupJobService.class.getName();
-
-    private final IBackupManager backupManager;
-    private final PackageService packageService = new PackageService();
-
-    public BackupJobService() {
-        backupManager = IBackupManager.Stub.asInterface(getService("backup"));
-    }
-
-    @Override
-    public boolean onStartJob(JobParameters params) {
-        Log.i(TAG, "Triggering full backup");
-        startService(new Intent(this, ConfigurableBackupTransportService.class));
-        try {
-            String[] packages = packageService.getEligiblePackages();
-            // TODO use an observer to know when backups fail
-            int result = backupManager.requestBackup(packages, null, null, FLAG_NON_INCREMENTAL_BACKUP);
-            if (result == BackupManager.SUCCESS) {
-                Log.i(TAG, "Backup succeeded ");
-            } else {
-                Log.e(TAG, "Backup failed: " + result);
-            }
-
-        // TODO show notification on backup error
-        } catch (RemoteException e) {
-            Log.e(TAG, "Error during backup: ", e);
-        } finally {
-            jobFinished(params, false);
-        }
-        return true;
-    }
-
-    @Override
-    public boolean onStopJob(JobParameters params) {
-        try {
-            backupManager.cancelBackups();
-        } catch (RemoteException e) {
-            Log.e(TAG, "Error cancelling backup: ", e);
-        }
-        return true;
-    }
-
-}

app/src/main/java/com/stevesoltys/backup/service/backup/BackupObserver.java

@@ -1,82 +0,0 @@
-package com.stevesoltys.backup.service.backup;
-
-import android.app.Activity;
-import android.app.backup.BackupProgress;
-import android.widget.PopupWindow;
-import android.widget.ProgressBar;
-import android.widget.TextView;
-import android.widget.Toast;
-
-import com.stevesoltys.backup.R;
-import com.stevesoltys.backup.session.backup.BackupResult;
-import com.stevesoltys.backup.session.backup.BackupSession;
-import com.stevesoltys.backup.session.backup.BackupSessionObserver;
-
-import static com.stevesoltys.backup.transport.ConfigurableBackupTransportService.getBackupTransport;
-
-/**
- * @author Steve Soltys
- */
-class BackupObserver implements BackupSessionObserver {
-
-    private final Activity context;
-
-    private final PopupWindow popupWindow;
-
-    BackupObserver(Activity context, PopupWindow popupWindow) {
-        this.context = context;
-        this.popupWindow = popupWindow;
-    }
-
-    @Override
-    public void backupPackageStarted(BackupSession backupSession, String packageName, BackupProgress backupProgress) {
-        context.runOnUiThread(() -> {
-
-            TextView textView = popupWindow.getContentView().findViewById(R.id.popup_text_view);
-
-            if (textView != null) {
-                textView.setText(packageName);
-            }
-
-            ProgressBar progressBar = popupWindow.getContentView().findViewById(R.id.popup_progress_bar);
-
-            if (progressBar != null) {
-                progressBar.setMax((int) backupProgress.bytesExpected);
-                progressBar.setProgress((int) backupProgress.bytesTransferred);
-            }
-        });
-    }
-
-    @Override
-    public void backupPackageCompleted(BackupSession backupSession, String packageName, BackupResult result) {
-        context.runOnUiThread(() -> {
-
-            TextView textView = popupWindow.getContentView().findViewById(R.id.popup_text_view);
-
-            if (textView != null) {
-                textView.setText(packageName);
-            }
-        });
-    }
-
-    @Override
-    public void backupSessionCompleted(BackupSession backupSession, BackupResult backupResult) {
-
-        if (backupResult == BackupResult.SUCCESS) getBackupTransport(context).backupFinished();
-
-        context.runOnUiThread(() -> {
-            if (backupResult == BackupResult.SUCCESS) {
-                Toast.makeText(context, R.string.backup_success, Toast.LENGTH_LONG).show();
-
-            } else if (backupResult == BackupResult.CANCELLED) {
-                Toast.makeText(context, R.string.backup_cancelled, Toast.LENGTH_LONG).show();
-
-            } else {
-                Toast.makeText(context, R.string.backup_failure, Toast.LENGTH_LONG).show();
-            }
-
-            popupWindow.dismiss();
-            context.finish();
-        });
-    }
-}

app/src/main/java/com/stevesoltys/backup/service/backup/BackupService.java

@@ -1,46 +0,0 @@
-package com.stevesoltys.backup.service.backup;
-
-import android.app.Activity;
-import android.util.Log;
-import android.view.View;
-import android.widget.PopupWindow;
-import android.widget.TextView;
-
-import com.stevesoltys.backup.R;
-import com.stevesoltys.backup.activity.PopupWindowUtil;
-import com.stevesoltys.backup.activity.backup.BackupPopupWindowListener;
-import com.stevesoltys.backup.service.TransportService;
-import com.stevesoltys.backup.session.backup.BackupSession;
-
-import java.util.Set;
-
-/**
- * @author Steve Soltys
- */
-public class BackupService {
-
-    private static final String TAG = BackupService.class.getName();
-
-    private final TransportService transportService = new TransportService();
-
-    public void backupPackageData(Set<String> selectedPackages, Activity parent) {
-        try {
-            selectedPackages.add("@pm@");
-
-            Log.i(TAG, "Backing up " + selectedPackages.size() + " packages...");
-
-            PopupWindow popupWindow = PopupWindowUtil.showLoadingPopupWindow(parent);
-            BackupObserver backupObserver = new BackupObserver(parent, popupWindow);
-            BackupSession backupSession = transportService.backup(backupObserver, selectedPackages);
-
-            View popupWindowButton = popupWindow.getContentView().findViewById(R.id.popup_cancel_button);
-            popupWindowButton.setOnClickListener(new BackupPopupWindowListener(backupSession));
-
-            TextView textView = popupWindow.getContentView().findViewById(R.id.popup_text_view);
-            textView.setText(R.string.initializing);
-
-        } catch (Exception e) {
-            Log.e(TAG, "Error while running backup: ", e);
-        }
-    }
-}

app/src/main/java/com/stevesoltys/backup/service/restore/RestoreObserver.java

@@ -1,73 +0,0 @@
-package com.stevesoltys.backup.service.restore;
-
-import android.app.Activity;
-import android.widget.PopupWindow;
-import android.widget.ProgressBar;
-import android.widget.TextView;
-import android.widget.Toast;
-
-import com.stevesoltys.backup.R;
-import com.stevesoltys.backup.session.restore.RestoreResult;
-import com.stevesoltys.backup.session.restore.RestoreSessionObserver;
-
-/**
- * @author Steve Soltys
- */
-class RestoreObserver implements RestoreSessionObserver {
-
-    private final Activity context;
-
-    private final PopupWindow popupWindow;
-
-    private final int packageCount;
-
-    RestoreObserver(Activity context, PopupWindow popupWindow, int packageCount) {
-        this.context = context;
-        this.popupWindow = popupWindow;
-        this.packageCount = packageCount;
-    }
-
-    @Override
-    public void restoreSessionStarted(int packageCount) {
-        context.runOnUiThread(() -> {
-            TextView textView = popupWindow.getContentView().findViewById(R.id.popup_text_view);
-            textView.setText(R.string.initializing);
-        });
-    }
-
-    @Override
-    public void restorePackageStarted(int packageIndex, String packageName) {
-        context.runOnUiThread(() -> {
-            ProgressBar progressBar = popupWindow.getContentView().findViewById(R.id.popup_progress_bar);
-
-            if (progressBar != null) {
-                progressBar.setMax(packageCount);
-                progressBar.setProgress(packageIndex);
-            }
-
-            TextView textView = popupWindow.getContentView().findViewById(R.id.popup_text_view);
-
-            if (textView != null) {
-                textView.setText(packageName);
-            }
-        });
-    }
-
-    @Override
-    public void restoreSessionCompleted(RestoreResult restoreResult) {
-        context.runOnUiThread(() -> {
-            if (restoreResult == RestoreResult.SUCCESS) {
-                Toast.makeText(context, R.string.restore_success, Toast.LENGTH_LONG).show();
-
-            } else if (restoreResult == RestoreResult.CANCELLED) {
-                Toast.makeText(context, R.string.restore_cancelled, Toast.LENGTH_LONG).show();
-
-            } else {
-                Toast.makeText(context, R.string.restore_failure, Toast.LENGTH_LONG).show();
-            }
-
-            popupWindow.dismiss();
-            context.finish();
-        });
-    }
-}

app/src/main/java/com/stevesoltys/backup/service/restore/RestoreService.java

@@ -1,48 +0,0 @@
-package com.stevesoltys.backup.service.restore;
-
-import android.app.Activity;
-import android.net.Uri;
-import android.os.RemoteException;
-import android.util.Log;
-import android.view.View;
-import android.widget.PopupWindow;
-
-import com.stevesoltys.backup.R;
-import com.stevesoltys.backup.activity.PopupWindowUtil;
-import com.stevesoltys.backup.activity.restore.RestorePopupWindowListener;
-import com.stevesoltys.backup.service.TransportService;
-import com.stevesoltys.backup.session.restore.RestoreSession;
-import com.stevesoltys.backup.transport.ConfigurableBackupTransport;
-
-import java.util.Set;
-
-import static com.stevesoltys.backup.transport.ConfigurableBackupTransportService.getBackupTransport;
-
-/**
- * @author Steve Soltys
- */
-public class RestoreService {
-
-    private static final String TAG = RestoreService.class.getName();
-
-    private final TransportService transportService = new TransportService();
-
-    public void restorePackages(Set<String> selectedPackages, Uri contentUri, Activity parent, String password) {
-        ConfigurableBackupTransport backupTransport = getBackupTransport(parent.getApplication());
-        backupTransport.prepareRestore(password, contentUri);
-        try {
-            PopupWindow popupWindow = PopupWindowUtil.showLoadingPopupWindow(parent);
-            RestoreObserver restoreObserver = new RestoreObserver(parent, popupWindow, selectedPackages.size());
-            RestoreSession restoreSession = transportService.restore(restoreObserver, selectedPackages);
-
-            View popupWindowButton = popupWindow.getContentView().findViewById(R.id.popup_cancel_button);
-
-            if (popupWindowButton != null) {
-                popupWindowButton.setOnClickListener(new RestorePopupWindowListener(restoreSession));
-            }
-
-        } catch (RemoteException e) {
-            Log.e(TAG, "Error while running restore: ", e);
-        }
-    }
-}

app/src/main/java/com/stevesoltys/backup/session/backup/BackupMonitor.java

@@ -1,20 +0,0 @@
-package com.stevesoltys.backup.session.backup;
-
-import android.app.backup.IBackupManagerMonitor;
-import android.os.Bundle;
-import android.util.Log;
-
-import static android.app.backup.BackupManagerMonitor.EXTRA_LOG_EVENT_CATEGORY;
-import static android.app.backup.BackupManagerMonitor.EXTRA_LOG_EVENT_ID;
-import static android.app.backup.BackupManagerMonitor.EXTRA_LOG_EVENT_PACKAGE_NAME;
-
-class BackupMonitor extends IBackupManagerMonitor.Stub {
-
-    @Override
-    public void onEvent(Bundle bundle) {
-        Log.d("BackupMonitor", "ID: " + bundle.getInt(EXTRA_LOG_EVENT_ID));
-        Log.d("BackupMonitor", "CATEGORY: " + bundle.getInt(EXTRA_LOG_EVENT_CATEGORY, -1));
-        Log.d("BackupMonitor", "PACKAGE: " + bundle.getString(EXTRA_LOG_EVENT_PACKAGE_NAME, "?"));
-    }
-
-}

app/src/main/java/com/stevesoltys/backup/session/backup/BackupResult.java

@@ -1,8 +0,0 @@
-package com.stevesoltys.backup.session.backup;
-
-/**
- * @author Steve Soltys
- */
-public enum BackupResult {
-    SUCCESS, FAILURE, CANCELLED
-}

app/src/main/java/com/stevesoltys/backup/session/backup/BackupSession.java

@@ -1,67 +0,0 @@
-package com.stevesoltys.backup.session.backup;
-
-import android.app.backup.BackupManager;
-import android.app.backup.BackupProgress;
-import android.app.backup.IBackupManager;
-import android.app.backup.IBackupObserver;
-import android.os.RemoteException;
-
-import java.util.Set;
-
-import static android.app.backup.BackupManager.FLAG_NON_INCREMENTAL_BACKUP;
-
-/**
- * @author Steve Soltys
- */
-public class BackupSession extends IBackupObserver.Stub {
-
-    private final IBackupManager backupManager;
-
-    private final BackupSessionObserver backupSessionObserver;
-
-    private final Set<String> packages;
-
-    public BackupSession(IBackupManager backupManager, BackupSessionObserver backupSessionObserver,
-                         Set<String> packages) {
-        this.backupManager = backupManager;
-        this.backupSessionObserver = backupSessionObserver;
-        this.packages = packages;
-    }
-
-    public void start() throws RemoteException {
-        String [] selectedPackageArray = packages.toArray(new String[0]);
-        backupManager.requestBackup(selectedPackageArray, this, new BackupMonitor(), FLAG_NON_INCREMENTAL_BACKUP);
-    }
-
-    public void stop(BackupResult result) throws RemoteException {
-        backupManager.cancelBackups();
-        backupSessionObserver.backupSessionCompleted(this, result);
-    }
-
-    @Override
-    public void onUpdate(String currentPackage, BackupProgress backupProgress) {
-        backupSessionObserver.backupPackageStarted(this, currentPackage, backupProgress);
-    }
-
-    @Override
-    public void onResult(String currentPackage, int status) {
-        backupSessionObserver.backupPackageCompleted(this, currentPackage, getBackupResult(status));
-    }
-
-    @Override
-    public void backupFinished(int status) {
-        backupSessionObserver.backupSessionCompleted(this, getBackupResult(status));
-    }
-
-    private BackupResult getBackupResult(int status) {
-        if (status == BackupManager.SUCCESS) {
-            return BackupResult.SUCCESS;
-
-        } else if (status == BackupManager.ERROR_BACKUP_CANCELLED) {
-            return BackupResult.CANCELLED;
-
-        } else {
-            return BackupResult.FAILURE;
-        }
-    }
-}

app/src/main/java/com/stevesoltys/backup/session/backup/BackupSessionObserver.java

@@ -1,15 +0,0 @@
-package com.stevesoltys.backup.session.backup;
-
-import android.app.backup.BackupProgress;
-
-/**
- * @author Steve Soltys
- */
-public interface BackupSessionObserver {
-
-    void backupPackageStarted(BackupSession backupSession, String packageName, BackupProgress backupProgress);
-
-    void backupPackageCompleted(BackupSession backupSession, String packageName, BackupResult result);
-
-    void backupSessionCompleted(BackupSession backupSession, BackupResult result);
-}

app/src/main/java/com/stevesoltys/backup/session/restore/RestoreResult.java

@@ -1,8 +0,0 @@
-package com.stevesoltys.backup.session.restore;
-
-/**
- * @author Steve Soltys
- */
-public enum RestoreResult {
-    SUCCESS, CANCELLED, FAILURE
-}

app/src/main/java/com/stevesoltys/backup/session/restore/RestoreSession.java

@@ -1,95 +0,0 @@
-package com.stevesoltys.backup.session.restore;
-
-import android.app.backup.*;
-import android.os.RemoteException;
-
-import java.util.Set;
-
-/**
- * @author Steve Soltys
- */
-public class RestoreSession extends IRestoreObserver.Stub {
-
-    private final IBackupManager backupManager;
-
-    private final RestoreSessionObserver observer;
-
-    private final Set<String> packages;
-
-    private IRestoreSession restoreSession;
-
-    public RestoreSession(IBackupManager backupManager, RestoreSessionObserver observer, Set<String> packages) {
-        this.backupManager = backupManager;
-        this.observer = observer;
-        this.packages = packages;
-    }
-
-    public void start() throws RemoteException {
-
-        if (restoreSession != null || packages.isEmpty()) {
-            observer.restoreSessionCompleted(RestoreResult.FAILURE);
-            return;
-        }
-
-        restoreSession = backupManager.beginRestoreSession(null, null);
-
-        if (restoreSession == null) {
-            stop(RestoreResult.FAILURE);
-            return;
-        }
-
-        int result = restoreSession.getAvailableRestoreSets(this, null);
-
-        if (result != BackupManager.SUCCESS) {
-            stop(RestoreResult.FAILURE);
-        }
-    }
-
-    public void stop(RestoreResult restoreResult) throws RemoteException {
-        clearSession();
-        observer.restoreSessionCompleted(restoreResult);
-    }
-
-    private void clearSession() throws RemoteException {
-        if (restoreSession != null) {
-            restoreSession.endRestoreSession();
-            restoreSession = null;
-        }
-    }
-
-    @Override
-    public void restoreSetsAvailable(RestoreSet[] restoreSets) throws RemoteException {
-        if (restoreSets.length > 0) {
-            RestoreSet restoreSet = restoreSets[0];
-            String[] packageArray = packages.toArray(new String[0]);
-            int result = restoreSession.restoreSome(restoreSet.token, this, null, packageArray);
-
-            if (result != BackupManager.SUCCESS) {
-                stop(RestoreResult.FAILURE);
-            }
-        }
-    }
-
-    @Override
-    public void restoreStarting(int numPackages) {
-        observer.restoreSessionStarted(numPackages);
-    }
-
-    @Override
-    public void onUpdate(int nowBeingRestored, String currentPackage) {
-        observer.restorePackageStarted(nowBeingRestored, currentPackage);
-    }
-
-    @Override
-    public void restoreFinished(int result) throws RemoteException {
-        if (result == BackupManager.SUCCESS) {
-            stop(RestoreResult.SUCCESS);
-
-        } else if (result == BackupManager.ERROR_BACKUP_CANCELLED) {
-            stop(RestoreResult.CANCELLED);
-
-        } else  {
-            stop(RestoreResult.FAILURE);
-        }
-    }
-}

app/src/main/java/com/stevesoltys/backup/session/restore/RestoreSessionObserver.java

@@ -1,13 +0,0 @@
-package com.stevesoltys.backup.session.restore;
-
-/**
- * @author Steve Soltys
- */
-public interface RestoreSessionObserver {
-
-    void restoreSessionStarted(int packageCount);
-
-    void restorePackageStarted(int packageIndex, String packageName);
-
-    void restoreSessionCompleted(RestoreResult restoreResult);
-}

app/src/main/java/com/stevesoltys/backup/settings/SettingsManager.java

@@ -1,57 +0,0 @@
-package com.stevesoltys.backup.settings;
-
-import android.annotation.Nullable;
-import android.content.Context;
-import android.net.Uri;
-
-import static android.preference.PreferenceManager.getDefaultSharedPreferences;
-
-public class SettingsManager {
-
-    private static final String PREF_KEY_BACKUP_URI = "backupUri";
-    private static final String PREF_KEY_BACKUP_PASSWORD = "backupLegacyPassword";
-    private static final String PREF_KEY_BACKUPS_SCHEDULED = "backupsScheduled";
-
-    public static void setBackupFolderUri(Context context, Uri uri) {
-        getDefaultSharedPreferences(context)
-                .edit()
-                .putString(PREF_KEY_BACKUP_URI, uri.toString())
-                .apply();
-    }
-
-    @Nullable
-    public static Uri getBackupFolderUri(Context context) {
-        String uriStr = getDefaultSharedPreferences(context).getString(PREF_KEY_BACKUP_URI, null);
-        if (uriStr == null) return null;
-        return Uri.parse(uriStr);
-    }
-
-    /**
-     * This is insecure and not supposed to be part of a release,
-     * but rather an intermediate step towards a generated passphrase.
-     */
-    public static void setBackupPassword(Context context, String password) {
-        getDefaultSharedPreferences(context)
-                .edit()
-                .putString(PREF_KEY_BACKUP_PASSWORD, password)
-                .apply();
-    }
-
-    @Nullable
-    public static String getBackupPassword(Context context) {
-        return getDefaultSharedPreferences(context).getString(PREF_KEY_BACKUP_PASSWORD, null);
-    }
-
-    public static void setBackupsScheduled(Context context) {
-        getDefaultSharedPreferences(context)
-                .edit()
-                .putBoolean(PREF_KEY_BACKUPS_SCHEDULED, true)
-                .apply();
-    }
-
-    @Nullable
-    public static Boolean areBackupsScheduled(Context context) {
-        return getDefaultSharedPreferences(context).getBoolean(PREF_KEY_BACKUPS_SCHEDULED, false);
-    }
-
-}

app/src/main/java/com/stevesoltys/backup/transport/ConfigurableBackupTransport.java

@@ -1,189 +0,0 @@
-package com.stevesoltys.backup.transport;
-
-import android.app.backup.BackupTransport;
-import android.app.backup.RestoreDescription;
-import android.app.backup.RestoreSet;
-import android.content.Context;
-import android.content.pm.PackageInfo;
-import android.net.Uri;
-import android.os.ParcelFileDescriptor;
-import android.util.Log;
-
-import com.stevesoltys.backup.transport.component.BackupComponent;
-import com.stevesoltys.backup.transport.component.RestoreComponent;
-import com.stevesoltys.backup.transport.component.provider.ContentProviderBackupComponent;
-import com.stevesoltys.backup.transport.component.provider.ContentProviderRestoreComponent;
-
-import static android.app.backup.BackupAgent.FLAG_CLIENT_SIDE_ENCRYPTION_ENABLED;
-import static android.os.Build.VERSION.SDK_INT;
-
-/**
- * @author Steve Soltys
- */
-public class ConfigurableBackupTransport extends BackupTransport {
-
-    private static final String TRANSPORT_DIRECTORY_NAME =
-            "com.stevesoltys.backup.transport.ConfigurableBackupTransport";
-
-    private static final String TAG = TRANSPORT_DIRECTORY_NAME;
-
-    private final BackupComponent backupComponent;
-
-    private final RestoreComponent restoreComponent;
-
-    ConfigurableBackupTransport(Context context) {
-        backupComponent = new ContentProviderBackupComponent(context);
-        restoreComponent = new ContentProviderRestoreComponent(context);
-    }
-
-    public void prepareRestore(String password, Uri fileUri) {
-        restoreComponent.prepareRestore(password, fileUri);
-    }
-
-    @Override
-    public String transportDirName() {
-        return TRANSPORT_DIRECTORY_NAME;
-    }
-
-    @Override
-    public String name() {
-        // TODO: Make this class non-static in ConfigurableBackupTransportService and use Context and a ComponentName.
-        return this.getClass().getName();
-    }
-
-    @Override
-    public int getTransportFlags() {
-        if (SDK_INT >= 28) return FLAG_CLIENT_SIDE_ENCRYPTION_ENABLED;
-        return 0;
-    }
-
-    @Override
-    public boolean isAppEligibleForBackup(PackageInfo targetPackage, boolean isFullBackup) {
-        return true;
-    }
-
-    @Override
-    public long requestBackupTime() {
-        return backupComponent.requestBackupTime();
-    }
-
-    @Override
-    public String dataManagementLabel() {
-        return backupComponent.dataManagementLabel();
-    }
-
-    @Override
-    public int initializeDevice() {
-        return backupComponent.initializeDevice();
-    }
-
-    @Override
-    public String currentDestinationString() {
-        return backupComponent.currentDestinationString();
-    }
-
-    /* Methods related to Backup */
-
-    @Override
-    public int performBackup(PackageInfo packageInfo, ParcelFileDescriptor inFd, int flags) {
-        return backupComponent.performIncrementalBackup(packageInfo, inFd, flags);
-    }
-
-    @Override
-    public int performBackup(PackageInfo targetPackage, ParcelFileDescriptor fileDescriptor) {
-        Log.w(TAG, "Warning: Legacy performBackup() method called.");
-        return performBackup(targetPackage, fileDescriptor, 0);
-    }
-
-    @Override
-    public int checkFullBackupSize(long size) {
-        return backupComponent.checkFullBackupSize(size);
-    }
-
-    @Override
-    public int performFullBackup(PackageInfo targetPackage, ParcelFileDescriptor socket, int flags) {
-        // TODO handle flags
-        return performFullBackup(targetPackage, socket);
-    }
-
-    @Override
-    public int performFullBackup(PackageInfo targetPackage, ParcelFileDescriptor fileDescriptor) {
-        return backupComponent.performFullBackup(targetPackage, fileDescriptor);
-    }
-
-    @Override
-    public int sendBackupData(int numBytes) {
-        return backupComponent.sendBackupData(numBytes);
-    }
-
-    @Override
-    public void cancelFullBackup() {
-        backupComponent.cancelFullBackup();
-    }
-
-    @Override
-    public int finishBackup() {
-        return backupComponent.finishBackup();
-    }
-
-    @Override
-    public long requestFullBackupTime() {
-        return backupComponent.requestFullBackupTime();
-    }
-
-    @Override
-    public long getBackupQuota(String packageName, boolean isFullBackup) {
-        return backupComponent.getBackupQuota(packageName, isFullBackup);
-    }
-
-    @Override
-    public int clearBackupData(PackageInfo packageInfo) {
-        return backupComponent.clearBackupData(packageInfo);
-    }
-
-    public void backupFinished() {
-        backupComponent.backupFinished();
-    }
-
-    /* Methods related to Restore */
-
-    @Override
-    public long getCurrentRestoreSet() {
-        return restoreComponent.getCurrentRestoreSet();
-    }
-
-    @Override
-    public int startRestore(long token, PackageInfo[] packages) {
-        return restoreComponent.startRestore(token, packages);
-    }
-
-    @Override
-    public int getNextFullRestoreDataChunk(ParcelFileDescriptor socket) {
-        return restoreComponent.getNextFullRestoreDataChunk(socket);
-    }
-
-    @Override
-    public RestoreSet[] getAvailableRestoreSets() {
-        return restoreComponent.getAvailableRestoreSets();
-    }
-
-    @Override
-    public RestoreDescription nextRestorePackage() {
-        return restoreComponent.nextRestorePackage();
-    }
-
-    @Override
-    public int getRestoreData(ParcelFileDescriptor outputFileDescriptor) {
-        return restoreComponent.getRestoreData(outputFileDescriptor);
-    }
-
-    @Override
-    public int abortFullRestore() {
-        return restoreComponent.abortFullRestore();
-    }
-
-    @Override
-    public void finishRestore() {
-        restoreComponent.finishRestore();
-    }
-}

app/src/main/java/com/stevesoltys/backup/transport/ConfigurableBackupTransportService.java

@@ -1,43 +0,0 @@
-package com.stevesoltys.backup.transport;
-
-import android.app.Service;
-import android.content.Context;
-import android.content.Intent;
-import android.os.IBinder;
-import android.util.Log;
-
-/**
- * @author Steve Soltys
- */
-public class ConfigurableBackupTransportService extends Service {
-
-    private static final String TAG = ConfigurableBackupTransportService.class.getName();
-
-    private static ConfigurableBackupTransport backupTransport = null;
-
-    public static ConfigurableBackupTransport getBackupTransport(Context context) {
-
-        if (backupTransport == null) {
-            backupTransport = new ConfigurableBackupTransport(context);
-        }
-
-        return backupTransport;
-    }
-
-    @Override
-    public void onCreate() {
-        super.onCreate();
-        Log.d(TAG, "Service created.");
-    }
-
-    @Override
-    public IBinder onBind(Intent intent) {
-        return getBackupTransport(getApplicationContext()).getBinder();
-    }
-
-    @Override
-    public void onDestroy() {
-        super.onDestroy();
-        Log.d(TAG, "Service destroyed.");
-    }
-}

app/src/main/java/com/stevesoltys/backup/transport/component/BackupComponent.java

@@ -1,38 +0,0 @@
-package com.stevesoltys.backup.transport.component;
-
-import android.content.pm.PackageInfo;
-import android.os.ParcelFileDescriptor;
-
-/**
- * @author Steve Soltys
- */
-public interface BackupComponent {
-
-    String currentDestinationString();
-
-    String dataManagementLabel();
-
-    int initializeDevice();
-
-    int clearBackupData(PackageInfo packageInfo);
-
-    int finishBackup();
-
-    int performIncrementalBackup(PackageInfo targetPackage, ParcelFileDescriptor data, int flags);
-
-    int performFullBackup(PackageInfo targetPackage, ParcelFileDescriptor fileDescriptor);
-
-    int checkFullBackupSize(long size);
-
-    int sendBackupData(int numBytes);
-
-    void cancelFullBackup();
-
-    long getBackupQuota(String packageName, boolean fullBackup);
-
-    long requestBackupTime();
-
-    long requestFullBackupTime();
-
-    void backupFinished();
-}

app/src/main/java/com/stevesoltys/backup/transport/component/RestoreComponent.java

@@ -1,31 +0,0 @@
-package com.stevesoltys.backup.transport.component;
-
-import android.app.backup.RestoreDescription;
-import android.app.backup.RestoreSet;
-import android.content.pm.PackageInfo;
-import android.net.Uri;
-import android.os.ParcelFileDescriptor;
-
-/**
- * @author Steve Soltys
- */
-public interface RestoreComponent {
-
-    void prepareRestore(String password, Uri fileUri);
-
-    int startRestore(long token, PackageInfo[] packages);
-
-    RestoreDescription nextRestorePackage();
-
-    int getRestoreData(ParcelFileDescriptor outputFileDescriptor);
-
-    int getNextFullRestoreDataChunk(ParcelFileDescriptor socket);
-
-    int abortFullRestore();
-
-    long getCurrentRestoreSet();
-
-    void finishRestore();
-
-    RestoreSet[] getAvailableRestoreSets();
-}

app/src/main/java/com/stevesoltys/backup/transport/component/provider/ContentProviderBackupComponent.java

@@ -1,366 +0,0 @@
-package com.stevesoltys.backup.transport.component.provider;
-
-import android.app.backup.BackupDataInput;
-import android.content.Context;
-import android.content.pm.PackageInfo;
-import android.net.Uri;
-import android.os.ParcelFileDescriptor;
-import android.util.Base64;
-import android.util.Log;
-
-import com.stevesoltys.backup.security.CipherUtil;
-import com.stevesoltys.backup.security.KeyGenerator;
-import com.stevesoltys.backup.settings.SettingsManager;
-import com.stevesoltys.backup.transport.component.BackupComponent;
-
-import org.apache.commons.io.IOUtils;
-
-import java.io.FileInputStream;
-import java.io.FileOutputStream;
-import java.io.IOException;
-import java.io.InputStream;
-import java.text.SimpleDateFormat;
-import java.util.Arrays;
-import java.util.Date;
-import java.util.Locale;
-import java.util.zip.ZipEntry;
-import java.util.zip.ZipOutputStream;
-
-import javax.crypto.Cipher;
-import javax.crypto.SecretKey;
-
-import libcore.io.IoUtils;
-
-import static android.app.backup.BackupTransport.FLAG_INCREMENTAL;
-import static android.app.backup.BackupTransport.FLAG_NON_INCREMENTAL;
-import static android.app.backup.BackupTransport.TRANSPORT_ERROR;
-import static android.app.backup.BackupTransport.TRANSPORT_NON_INCREMENTAL_BACKUP_REQUIRED;
-import static android.app.backup.BackupTransport.TRANSPORT_OK;
-import static android.app.backup.BackupTransport.TRANSPORT_PACKAGE_REJECTED;
-import static android.app.backup.BackupTransport.TRANSPORT_QUOTA_EXCEEDED;
-import static android.provider.DocumentsContract.buildDocumentUriUsingTree;
-import static android.provider.DocumentsContract.createDocument;
-import static android.provider.DocumentsContract.getTreeDocumentId;
-import static com.stevesoltys.backup.activity.MainActivityController.DOCUMENT_MIME_TYPE;
-import static com.stevesoltys.backup.transport.component.provider.ContentProviderBackupConstants.DEFAULT_BACKUP_QUOTA;
-import static com.stevesoltys.backup.transport.component.provider.ContentProviderBackupConstants.DEFAULT_FULL_BACKUP_DIRECTORY;
-import static com.stevesoltys.backup.transport.component.provider.ContentProviderBackupConstants.DEFAULT_INCREMENTAL_BACKUP_DIRECTORY;
-import static java.util.Objects.requireNonNull;
-
-/**
- * @author Steve Soltys
- */
-public class ContentProviderBackupComponent implements BackupComponent {
-
-    private static final String TAG = ContentProviderBackupComponent.class.getSimpleName();
-
-    private static final String DOCUMENT_SUFFIX = "yyyy-MM-dd_HH_mm_ss";
-
-    private static final String DESTINATION_DESCRIPTION = "Backing up to zip file";
-
-    private static final String TRANSPORT_DATA_MANAGEMENT_LABEL = "";
-
-    private static final int INITIAL_BUFFER_SIZE = 512;
-
-    private final Context context;
-
-    private ContentProviderBackupState backupState;
-
-    public ContentProviderBackupComponent(Context context) {
-        this.context = context;
-    }
-
-    @Override
-    public void cancelFullBackup() {
-        clearBackupState(false);
-    }
-
-    @Override
-    public int checkFullBackupSize(long size) {
-        int result = TRANSPORT_OK;
-
-        if (size <= 0) {
-            result = TRANSPORT_PACKAGE_REJECTED;
-
-        } else if (size > DEFAULT_BACKUP_QUOTA) {
-            result = TRANSPORT_QUOTA_EXCEEDED;
-        }
-
-        return result;
-    }
-
-    @Override
-    public int clearBackupData(PackageInfo packageInfo) {
-        return TRANSPORT_OK;
-    }
-
-    @Override
-    public String currentDestinationString() {
-        return DESTINATION_DESCRIPTION;
-    }
-
-    @Override
-    public String dataManagementLabel() {
-        return TRANSPORT_DATA_MANAGEMENT_LABEL;
-    }
-
-    @Override
-    public int finishBackup() {
-        return clearBackupState(false);
-    }
-
-    @Override
-    public long getBackupQuota(String packageName, boolean fullBackup) {
-        return DEFAULT_BACKUP_QUOTA;
-    }
-
-    @Override
-    public int initializeDevice() {
-        return TRANSPORT_OK;
-    }
-
-    @Override
-    public int performFullBackup(PackageInfo targetPackage, ParcelFileDescriptor fileDescriptor) {
-
-        if (backupState != null && backupState.getInputFileDescriptor() != null) {
-            Log.e(TAG, "Attempt to initiate full backup while one is in progress");
-            return TRANSPORT_ERROR;
-        }
-
-        try {
-            initializeBackupState();
-            backupState.setPackageName(targetPackage.packageName);
-
-            backupState.setInputFileDescriptor(fileDescriptor);
-            backupState.setInputStream(new FileInputStream(fileDescriptor.getFileDescriptor()));
-            backupState.setBytesTransferred(0);
-
-            Cipher cipher = CipherUtil.startEncrypt(backupState.getSecretKey(), backupState.getSalt());
-            backupState.setCipher(cipher);
-
-            ZipEntry zipEntry = new ZipEntry(DEFAULT_FULL_BACKUP_DIRECTORY + backupState.getPackageName());
-            backupState.getOutputStream().putNextEntry(zipEntry);
-
-        } catch (Exception ex) {
-            Log.e(TAG, "Error creating backup file for " + targetPackage.packageName + ": ", ex);
-            clearBackupState(true);
-            return TRANSPORT_ERROR;
-        }
-
-        return TRANSPORT_OK;
-    }
-
-    @Override
-    public int performIncrementalBackup(PackageInfo packageInfo, ParcelFileDescriptor data, int flags) {
-        boolean isIncremental = (flags & FLAG_INCREMENTAL) != 0;
-        if (isIncremental) {
-            Log.w(TAG, "Can not handle incremental backup. Requesting non-incremental for " + packageInfo.packageName);
-            return TRANSPORT_NON_INCREMENTAL_BACKUP_REQUIRED;
-        }
-
-        boolean isNonIncremental = (flags & FLAG_NON_INCREMENTAL) != 0;
-        if (isNonIncremental) {
-            Log.i(TAG, "Performing non-incremental backup for " + packageInfo.packageName);
-        } else {
-            Log.i(TAG, "Performing backup for " + packageInfo.packageName);
-        }
-
-        BackupDataInput backupDataInput = new BackupDataInput(data.getFileDescriptor());
-
-        try {
-            initializeBackupState();
-            backupState.setPackageName(packageInfo.packageName);
-
-            return transferIncrementalBackupData(backupDataInput);
-
-        } catch (Exception ex) {
-            Log.e(TAG, "Error reading backup input: ", ex);
-            return TRANSPORT_ERROR;
-        }
-    }
-
-    @Override
-    public long requestBackupTime() {
-        return 0;
-    }
-
-    @Override
-    public long requestFullBackupTime() {
-        return 0;
-    }
-
-    @Override
-    public int sendBackupData(int numBytes) {
-
-        if (backupState == null) {
-            Log.e(TAG, "Attempted sendBackupData() before performFullBackup()");
-            return TRANSPORT_ERROR;
-        }
-
-        long bytesTransferred = backupState.getBytesTransferred() + numBytes;
-
-        if (bytesTransferred > DEFAULT_BACKUP_QUOTA) {
-            return TRANSPORT_QUOTA_EXCEEDED;
-        }
-
-        InputStream inputStream = backupState.getInputStream();
-        ZipOutputStream outputStream = backupState.getOutputStream();
-
-        try {
-            byte[] payload = IOUtils.readFully(inputStream, numBytes);
-
-            if (backupState.getCipher() != null) {
-                payload = backupState.getCipher().update(payload);
-            }
-
-            outputStream.write(payload, 0, numBytes);
-            backupState.setBytesTransferred(bytesTransferred);
-
-        } catch (Exception ex) {
-            Log.e(TAG, "Error handling backup data for " + backupState.getPackageName() + ": ", ex);
-            return TRANSPORT_ERROR;
-        }
-        return TRANSPORT_OK;
-    }
-
-    private int transferIncrementalBackupData(BackupDataInput backupDataInput) throws IOException {
-        ZipOutputStream outputStream = backupState.getOutputStream();
-
-        int bufferSize = INITIAL_BUFFER_SIZE;
-        byte[] buffer = new byte[bufferSize];
-
-        while (backupDataInput.readNextHeader()) {
-            String chunkFileName = Base64.encodeToString(backupDataInput.getKey().getBytes(), Base64.DEFAULT);
-            int dataSize = backupDataInput.getDataSize();
-
-            if (dataSize >= 0) {
-                ZipEntry zipEntry = new ZipEntry(DEFAULT_INCREMENTAL_BACKUP_DIRECTORY +
-                        backupState.getPackageName() + "/" + chunkFileName);
-                outputStream.putNextEntry(zipEntry);
-
-                if (dataSize > bufferSize) {
-                    bufferSize = dataSize;
-                    buffer = new byte[bufferSize];
-                }
-
-                backupDataInput.readEntityData(buffer, 0, dataSize);
-
-                try {
-                    if (backupState.getSecretKey() != null) {
-                        byte[] payload = Arrays.copyOfRange(buffer, 0, dataSize);
-                        SecretKey secretKey = backupState.getSecretKey();
-                        byte[] salt = backupState.getSalt();
-
-                        outputStream.write(CipherUtil.encrypt(payload, secretKey, salt));
-
-                    } else {
-                        outputStream.write(buffer, 0, dataSize);
-                    }
-
-                } catch (Exception ex) {
-                    Log.e(TAG, "Error performing incremental backup for " + backupState.getPackageName() + ": ", ex);
-                    clearBackupState(true);
-                    return TRANSPORT_ERROR;
-                }
-            }
-        }
-
-        return TRANSPORT_OK;
-    }
-
-    @Override
-    public void backupFinished() {
-        clearBackupState(true);
-    }
-
-    private void initializeBackupState() throws Exception {
-        if (backupState == null) {
-            backupState = new ContentProviderBackupState();
-        }
-
-        if (backupState.getOutputStream() == null) {
-            initializeOutputStream();
-
-            ZipEntry saltZipEntry = new ZipEntry(ContentProviderBackupConstants.SALT_FILE_PATH);
-            backupState.getOutputStream().putNextEntry(saltZipEntry);
-            backupState.getOutputStream().write(backupState.getSalt());
-            backupState.getOutputStream().closeEntry();
-
-            String password = requireNonNull(SettingsManager.getBackupPassword(context));
-            backupState.setSecretKey(KeyGenerator.generate(password, backupState.getSalt()));
-        }
-    }
-
-    private void initializeOutputStream() throws IOException {
-        Uri folderUri = SettingsManager.getBackupFolderUri(context);
-        // TODO notify about failure with notification
-        Uri fileUri = createBackupFile(folderUri);
-
-        ParcelFileDescriptor outputFileDescriptor = context.getContentResolver().openFileDescriptor(fileUri, "w");
-        if (outputFileDescriptor == null) throw new IOException();
-        backupState.setOutputFileDescriptor(outputFileDescriptor);
-
-        FileOutputStream fileOutputStream = new FileOutputStream(outputFileDescriptor.getFileDescriptor());
-        ZipOutputStream zipOutputStream = new ZipOutputStream(fileOutputStream);
-        backupState.setOutputStream(zipOutputStream);
-    }
-
-    private Uri createBackupFile(Uri folderUri) throws IOException {
-        Uri documentUri = buildDocumentUriUsingTree(folderUri, getTreeDocumentId(folderUri));
-        try {
-            Uri fileUri = createDocument(context.getContentResolver(), documentUri, DOCUMENT_MIME_TYPE, getBackupFileName());
-            if (fileUri == null) throw new IOException();
-            return fileUri;
-
-        } catch (SecurityException e) {
-            // happens when folder was deleted and thus Uri permission don't exist anymore
-            throw new IOException(e);
-        }
-    }
-
-    private String getBackupFileName() {
-        SimpleDateFormat dateFormat = new SimpleDateFormat(DOCUMENT_SUFFIX, Locale.US);
-        String date = dateFormat.format(new Date());
-        return "backup-" + date;
-    }
-
-    private int clearBackupState(boolean closeFile) {
-
-        if (backupState == null) {
-            return TRANSPORT_OK;
-        }
-
-        try {
-            IoUtils.closeQuietly(backupState.getInputFileDescriptor());
-            backupState.setInputFileDescriptor(null);
-
-            ZipOutputStream outputStream = backupState.getOutputStream();
-
-            if (outputStream != null) {
-
-                if (backupState.getCipher() != null) {
-                    outputStream.write(backupState.getCipher().doFinal());
-                    backupState.setCipher(null);
-                }
-
-                outputStream.closeEntry();
-            }
-            if (closeFile) {
-                Log.d(TAG, "Closing backup file...");
-                if (outputStream != null) {
-                    outputStream.finish();
-                    outputStream.close();
-                }
-
-                IoUtils.closeQuietly(backupState.getOutputFileDescriptor());
-                backupState = null;
-            }
-
-        } catch (Exception ex) {
-            Log.e(TAG, "Error cancelling full backup: ", ex);
-            return TRANSPORT_ERROR;
-        }
-
-        return TRANSPORT_OK;
-    }
-}

app/src/main/java/com/stevesoltys/backup/transport/component/provider/ContentProviderBackupConstants.java

@@ -1,16 +0,0 @@
-package com.stevesoltys.backup.transport.component.provider;
-
-/**
- * @author Steve Soltys
- */
-public interface ContentProviderBackupConstants {
-
-    String SALT_FILE_PATH = "salt";
-
-    String DEFAULT_FULL_BACKUP_DIRECTORY = "full/";
-
-    String DEFAULT_INCREMENTAL_BACKUP_DIRECTORY = "incr/";
-
-    long DEFAULT_BACKUP_QUOTA = Long.MAX_VALUE;
-
-}

app/src/main/java/com/stevesoltys/backup/transport/component/provider/ContentProviderBackupState.java

@@ -1,109 +0,0 @@
-package com.stevesoltys.backup.transport.component.provider;
-
-import android.os.ParcelFileDescriptor;
-
-import java.io.InputStream;
-import java.security.SecureRandom;
-import java.util.zip.ZipOutputStream;
-
-import javax.crypto.Cipher;
-import javax.crypto.SecretKey;
-
-/**
- * @author Steve Soltys
- */
-class ContentProviderBackupState {
-
-    private static final SecureRandom SECURE_RANDOM = new SecureRandom();
-
-    private ParcelFileDescriptor inputFileDescriptor;
-
-    private ParcelFileDescriptor outputFileDescriptor;
-
-    private InputStream inputStream;
-
-    private ZipOutputStream outputStream;
-
-    private Cipher cipher;
-
-    private long bytesTransferred;
-
-    private String packageName;
-
-    private byte[] salt;
-
-    private SecretKey secretKey;
-
-    ContentProviderBackupState() {
-        salt = new byte[16];
-        SECURE_RANDOM.nextBytes(salt);
-    }
-
-    long getBytesTransferred() {
-        return bytesTransferred;
-    }
-
-    void setBytesTransferred(long bytesTransferred) {
-        this.bytesTransferred = bytesTransferred;
-    }
-
-    Cipher getCipher() {
-        return cipher;
-    }
-
-    void setCipher(Cipher cipher) {
-        this.cipher = cipher;
-    }
-
-    ParcelFileDescriptor getInputFileDescriptor() {
-        return inputFileDescriptor;
-    }
-
-    void setInputFileDescriptor(ParcelFileDescriptor inputFileDescriptor) {
-        this.inputFileDescriptor = inputFileDescriptor;
-    }
-
-    InputStream getInputStream() {
-        return inputStream;
-    }
-
-    void setInputStream(InputStream inputStream) {
-        this.inputStream = inputStream;
-    }
-
-    ParcelFileDescriptor getOutputFileDescriptor() {
-        return outputFileDescriptor;
-    }
-
-    void setOutputFileDescriptor(ParcelFileDescriptor outputFileDescriptor) {
-        this.outputFileDescriptor = outputFileDescriptor;
-    }
-
-    ZipOutputStream getOutputStream() {
-        return outputStream;
-    }
-
-    void setOutputStream(ZipOutputStream outputStream) {
-        this.outputStream = outputStream;
-    }
-
-    String getPackageName() {
-        return packageName;
-    }
-
-    void setPackageName(String packageName) {
-        this.packageName = packageName;
-    }
-
-    byte[] getSalt() {
-        return salt;
-    }
-
-    SecretKey getSecretKey() {
-        return secretKey;
-    }
-
-    void setSecretKey(SecretKey secretKey) {
-        this.secretKey = secretKey;
-    }
-}

app/src/main/java/com/stevesoltys/backup/transport/component/provider/ContentProviderRestoreComponent.java

@@ -1,360 +0,0 @@
-package com.stevesoltys.backup.transport.component.provider;
-
-import android.annotation.Nullable;
-import android.app.backup.BackupDataOutput;
-import android.app.backup.RestoreDescription;
-import android.app.backup.RestoreSet;
-import android.content.ContentResolver;
-import android.content.Context;
-import android.content.pm.PackageInfo;
-import android.net.Uri;
-import android.os.ParcelFileDescriptor;
-import android.util.Base64;
-import android.util.Log;
-
-import com.android.internal.util.Preconditions;
-import com.stevesoltys.backup.security.CipherUtil;
-import com.stevesoltys.backup.security.KeyGenerator;
-import com.stevesoltys.backup.transport.component.RestoreComponent;
-
-import java.io.File;
-import java.io.FileInputStream;
-import java.io.FileNotFoundException;
-import java.io.FileOutputStream;
-import java.io.IOException;
-import java.io.OutputStream;
-import java.util.Arrays;
-import java.util.LinkedList;
-import java.util.List;
-import java.util.Optional;
-import java.util.zip.ZipEntry;
-import java.util.zip.ZipInputStream;
-
-import javax.crypto.SecretKey;
-
-import libcore.io.IoUtils;
-import libcore.io.Streams;
-
-import static android.app.backup.BackupTransport.NO_MORE_DATA;
-import static android.app.backup.BackupTransport.TRANSPORT_ERROR;
-import static android.app.backup.BackupTransport.TRANSPORT_OK;
-import static android.app.backup.BackupTransport.TRANSPORT_PACKAGE_REJECTED;
-import static android.app.backup.RestoreDescription.TYPE_FULL_STREAM;
-import static android.app.backup.RestoreDescription.TYPE_KEY_VALUE;
-import static com.stevesoltys.backup.transport.component.provider.ContentProviderBackupConstants.DEFAULT_FULL_BACKUP_DIRECTORY;
-import static com.stevesoltys.backup.transport.component.provider.ContentProviderBackupConstants.DEFAULT_INCREMENTAL_BACKUP_DIRECTORY;
-import static java.util.Objects.requireNonNull;
-
-/**
- * @author Steve Soltys
- */
-public class ContentProviderRestoreComponent implements RestoreComponent {
-
-    private static final String TAG = ContentProviderRestoreComponent.class.getName();
-
-    private static final int DEFAULT_RESTORE_SET = 1;
-
-    private static final int DEFAULT_BUFFER_SIZE = 2048;
-
-    @Nullable
-    private String password;
-    @Nullable
-    private Uri fileUri;
-
-    private ContentProviderRestoreState restoreState;
-
-    private final Context context;
-
-    public ContentProviderRestoreComponent(Context context) {
-        this.context = context;
-    }
-
-    @Override
-    public void prepareRestore(String password, Uri fileUri) {
-        this.password = password;
-        this.fileUri = fileUri;
-    }
-
-    @Override
-    public int startRestore(long token, PackageInfo[] packages) {
-        restoreState = new ContentProviderRestoreState();
-        restoreState.setPackages(packages);
-        restoreState.setPackageIndex(-1);
-
-        String password = requireNonNull(this.password);
-
-        if (!password.isEmpty()) {
-            try {
-                ParcelFileDescriptor inputFileDescriptor = buildInputFileDescriptor();
-                ZipInputStream inputStream = buildInputStream(inputFileDescriptor);
-                seekToEntry(inputStream, ContentProviderBackupConstants.SALT_FILE_PATH);
-
-                restoreState.setSalt(Streams.readFullyNoClose(inputStream));
-                restoreState.setSecretKey(KeyGenerator.generate(password, restoreState.getSalt()));
-
-                IoUtils.closeQuietly(inputFileDescriptor);
-                IoUtils.closeQuietly(inputStream);
-
-            } catch (Exception ex) {
-                Log.e(TAG, "Salt not found", ex);
-            }
-        }
-
-        try {
-            List<ZipEntry> zipEntries = new LinkedList<>();
-
-            ParcelFileDescriptor inputFileDescriptor = buildInputFileDescriptor();
-            ZipInputStream inputStream = buildInputStream(inputFileDescriptor);
-
-            ZipEntry zipEntry;
-            while ((zipEntry = inputStream.getNextEntry()) != null) {
-                zipEntries.add(zipEntry);
-                inputStream.closeEntry();
-            }
-
-            IoUtils.closeQuietly(inputFileDescriptor);
-            IoUtils.closeQuietly(inputStream);
-
-            restoreState.setZipEntries(zipEntries);
-
-        } catch (Exception ex) {
-            Log.e(TAG, "Error while caching zip entries", ex);
-        }
-
-        return TRANSPORT_OK;
-    }
-
-    @Override
-    public RestoreDescription nextRestorePackage() {
-        Preconditions.checkNotNull(restoreState, "startRestore() not called");
-
-        int packageIndex = restoreState.getPackageIndex();
-        PackageInfo[] packages = restoreState.getPackages();
-
-        while (++packageIndex < packages.length) {
-            restoreState.setPackageIndex(packageIndex);
-            String name = packages[packageIndex].packageName;
-
-            if (containsPackageFile(DEFAULT_INCREMENTAL_BACKUP_DIRECTORY + name)) {
-                restoreState.setRestoreType(TYPE_KEY_VALUE);
-                return new RestoreDescription(name, restoreState.getRestoreType());
-
-            } else if (containsPackageFile(DEFAULT_FULL_BACKUP_DIRECTORY + name)) {
-                restoreState.setRestoreType(TYPE_FULL_STREAM);
-                return new RestoreDescription(name, restoreState.getRestoreType());
-            }
-        }
-        return RestoreDescription.NO_MORE_PACKAGES;
-    }
-
-    private boolean containsPackageFile(String fileName) {
-        return restoreState.getZipEntries().stream()
-                .anyMatch(zipEntry -> zipEntry.getName().startsWith(fileName));
-    }
-
-    @Override
-    public int getRestoreData(ParcelFileDescriptor outputFileDescriptor) {
-        Preconditions.checkState(restoreState != null, "startRestore() not called");
-        Preconditions.checkState(restoreState.getPackageIndex() >= 0, "nextRestorePackage() not called");
-        Preconditions.checkState(restoreState.getRestoreType() == TYPE_KEY_VALUE,
-                "getRestoreData() for non-key/value dataset");
-
-        PackageInfo packageInfo = restoreState.getPackages()[restoreState.getPackageIndex()];
-
-        try {
-            return transferIncrementalRestoreData(packageInfo.packageName, outputFileDescriptor);
-
-        } catch (Exception ex) {
-            Log.e(TAG, "Unable to read backup records: ", ex);
-            return TRANSPORT_ERROR;
-        }
-    }
-
-    private int transferIncrementalRestoreData(String packageName, ParcelFileDescriptor outputFileDescriptor)
-            throws Exception {
-
-        ParcelFileDescriptor inputFileDescriptor = buildInputFileDescriptor();
-        ZipInputStream inputStream = buildInputStream(inputFileDescriptor);
-        BackupDataOutput backupDataOutput = new BackupDataOutput(outputFileDescriptor.getFileDescriptor());
-
-        Optional<ZipEntry> zipEntryOptional = seekToEntry(inputStream,
-                DEFAULT_INCREMENTAL_BACKUP_DIRECTORY + packageName);
-
-        while (zipEntryOptional.isPresent()) {
-            String fileName = new File(zipEntryOptional.get().getName()).getName();
-            String blobKey = new String(Base64.decode(fileName, Base64.DEFAULT));
-
-            byte[] backupData = readBackupData(inputStream);
-            backupDataOutput.writeEntityHeader(blobKey, backupData.length);
-            backupDataOutput.writeEntityData(backupData, backupData.length);
-            inputStream.closeEntry();
-
-            zipEntryOptional = seekToEntry(inputStream, DEFAULT_INCREMENTAL_BACKUP_DIRECTORY + packageName);
-        }
-
-        IoUtils.closeQuietly(inputFileDescriptor);
-        IoUtils.closeQuietly(outputFileDescriptor);
-        return TRANSPORT_OK;
-    }
-
-    private byte[] readBackupData(ZipInputStream inputStream) throws Exception {
-        byte[] backupData = Streams.readFullyNoClose(inputStream);
-        SecretKey secretKey = restoreState.getSecretKey();
-        byte[] initializationVector = restoreState.getSalt();
-
-        if (secretKey != null) {
-            backupData = CipherUtil.decrypt(backupData, secretKey, initializationVector);
-        }
-
-        return backupData;
-    }
-
-    @Override
-    public int getNextFullRestoreDataChunk(ParcelFileDescriptor outputFileDescriptor) {
-        Preconditions.checkState(restoreState.getRestoreType() == TYPE_FULL_STREAM,
-                "Asked for full restore data for non-stream package");
-
-        ParcelFileDescriptor inputFileDescriptor = restoreState.getInputFileDescriptor();
-
-        if (inputFileDescriptor == null) {
-            String name = restoreState.getPackages()[restoreState.getPackageIndex()].packageName;
-
-            try {
-                inputFileDescriptor = buildInputFileDescriptor();
-                restoreState.setInputFileDescriptor(inputFileDescriptor);
-
-                ZipInputStream inputStream = buildInputStream(inputFileDescriptor);
-                restoreState.setInputStream(inputStream);
-
-                if (!seekToEntry(inputStream, DEFAULT_FULL_BACKUP_DIRECTORY + name).isPresent()) {
-                    IoUtils.closeQuietly(inputFileDescriptor);
-                    IoUtils.closeQuietly(outputFileDescriptor);
-                    return TRANSPORT_PACKAGE_REJECTED;
-                }
-
-            } catch (IOException ex) {
-                Log.e(TAG, "Unable to read archive for " + name, ex);
-
-                IoUtils.closeQuietly(inputFileDescriptor);
-                IoUtils.closeQuietly(outputFileDescriptor);
-                return TRANSPORT_PACKAGE_REJECTED;
-            }
-        }
-
-        return transferFullRestoreData(outputFileDescriptor);
-    }
-
-    private int transferFullRestoreData(ParcelFileDescriptor outputFileDescriptor) {
-        ZipInputStream inputStream = restoreState.getInputStream();
-        OutputStream outputStream = new FileOutputStream(outputFileDescriptor.getFileDescriptor());
-
-        byte[] buffer = new byte[DEFAULT_BUFFER_SIZE];
-        int bytesRead = NO_MORE_DATA;
-
-        try {
-            bytesRead = inputStream.read(buffer);
-
-            if (bytesRead <= 0) {
-                bytesRead = NO_MORE_DATA;
-
-                if (restoreState.getCipher() != null) {
-                    buffer = restoreState.getCipher().doFinal();
-                    bytesRead = buffer.length;
-
-                    outputStream.write(buffer, 0, bytesRead);
-                    restoreState.setCipher(null);
-                }
-
-            } else {
-                if (restoreState.getSecretKey() != null) {
-                    SecretKey secretKey = restoreState.getSecretKey();
-                    byte[] salt = restoreState.getSalt();
-
-                    if (restoreState.getCipher() == null) {
-                        restoreState.setCipher(CipherUtil.startDecrypt(secretKey, salt));
-                    }
-
-                    buffer = restoreState.getCipher().update(Arrays.copyOfRange(buffer, 0, bytesRead));
-                    bytesRead = buffer.length;
-                }
-
-                outputStream.write(buffer, 0, bytesRead);
-            }
-
-        } catch (Exception e) {
-            Log.e(TAG, "Exception while streaming restore data: ", e);
-            return TRANSPORT_ERROR;
-
-        } finally {
-            if (bytesRead == NO_MORE_DATA) {
-
-                if (restoreState.getInputFileDescriptor() != null) {
-                    IoUtils.closeQuietly(restoreState.getInputFileDescriptor());
-                }
-
-                restoreState.setInputFileDescriptor(null);
-                restoreState.setInputStream(null);
-            }
-
-            IoUtils.closeQuietly(outputFileDescriptor);
-        }
-
-        return bytesRead;
-    }
-
-    @Override
-    public int abortFullRestore() {
-        resetFullRestoreState();
-        return TRANSPORT_OK;
-    }
-
-    @Override
-    public long getCurrentRestoreSet() {
-        return DEFAULT_RESTORE_SET;
-    }
-
-    @Override
-    public void finishRestore() {
-        if (restoreState.getRestoreType() == TYPE_FULL_STREAM) {
-            resetFullRestoreState();
-        }
-
-        restoreState = null;
-    }
-
-    @Override
-    public RestoreSet[] getAvailableRestoreSets() {
-        return new RestoreSet[]{new RestoreSet("Local disk image", "flash", DEFAULT_RESTORE_SET)};
-    }
-
-    private void resetFullRestoreState() {
-        Preconditions.checkNotNull(restoreState);
-        Preconditions.checkState(restoreState.getRestoreType() == TYPE_FULL_STREAM);
-
-        IoUtils.closeQuietly(restoreState.getInputFileDescriptor());
-        restoreState = null;
-    }
-
-    private ParcelFileDescriptor buildInputFileDescriptor() throws FileNotFoundException {
-        ContentResolver contentResolver = context.getContentResolver();
-        return contentResolver.openFileDescriptor(requireNonNull(fileUri), "r");
-    }
-
-    private ZipInputStream buildInputStream(ParcelFileDescriptor inputFileDescriptor) {
-        FileInputStream fileInputStream = new FileInputStream(inputFileDescriptor.getFileDescriptor());
-        return new ZipInputStream(fileInputStream);
-    }
-
-    private Optional<ZipEntry> seekToEntry(ZipInputStream inputStream, String entryPath) throws IOException {
-        ZipEntry zipEntry;
-        while ((zipEntry = inputStream.getNextEntry()) != null) {
-
-            if (zipEntry.getName().startsWith(entryPath)) {
-                return Optional.of(zipEntry);
-            }
-            inputStream.closeEntry();
-        }
-
-        return Optional.empty();
-    }
-}

app/src/main/java/com/stevesoltys/backup/transport/component/provider/ContentProviderRestoreState.java

@@ -1,106 +0,0 @@
-package com.stevesoltys.backup.transport.component.provider;
-
-import android.content.pm.PackageInfo;
-import android.os.ParcelFileDescriptor;
-
-import javax.crypto.Cipher;
-import javax.crypto.SecretKey;
-import java.util.List;
-import java.util.zip.ZipEntry;
-import java.util.zip.ZipInputStream;
-
-/**
- * @author Steve Soltys
- */
-class ContentProviderRestoreState {
-
-    private ParcelFileDescriptor inputFileDescriptor;
-
-    private PackageInfo[] packages;
-
-    private int packageIndex;
-
-    private int restoreType;
-
-    private ZipInputStream inputStream;
-
-    private Cipher cipher;
-
-    private byte[] salt;
-
-    private SecretKey secretKey;
-
-    private List<ZipEntry> zipEntries;
-
-    Cipher getCipher() {
-        return cipher;
-    }
-
-    ParcelFileDescriptor getInputFileDescriptor() {
-        return inputFileDescriptor;
-    }
-
-    void setCipher(Cipher cipher) {
-        this.cipher = cipher;
-    }
-
-    void setInputFileDescriptor(ParcelFileDescriptor inputFileDescriptor) {
-        this.inputFileDescriptor = inputFileDescriptor;
-    }
-
-    ZipInputStream getInputStream() {
-        return inputStream;
-    }
-
-    void setInputStream(ZipInputStream inputStream) {
-        this.inputStream = inputStream;
-    }
-
-    int getPackageIndex() {
-        return packageIndex;
-    }
-
-    void setPackageIndex(int packageIndex) {
-        this.packageIndex = packageIndex;
-    }
-
-    PackageInfo[] getPackages() {
-        return packages;
-    }
-
-    void setPackages(PackageInfo[] packages) {
-        this.packages = packages;
-    }
-
-    int getRestoreType() {
-        return restoreType;
-    }
-
-    void setRestoreType(int restoreType) {
-        this.restoreType = restoreType;
-    }
-
-    byte[] getSalt() {
-        return salt;
-    }
-
-    void setSalt(byte[] salt) {
-        this.salt = salt;
-    }
-
-    public SecretKey getSecretKey() {
-        return secretKey;
-    }
-
-    public void setSecretKey(SecretKey secretKey) {
-        this.secretKey = secretKey;
-    }
-
-    public List<ZipEntry> getZipEntries() {
-        return zipEntries;
-    }
-
-    public void setZipEntries(List<ZipEntry> zipEntries) {
-        this.zipEntries = zipEntries;
-    }
-}

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

@@ -0,0 +1,66 @@
+package com.stevesoltys.seedvault
+
+import android.app.Application
+import android.app.backup.BackupManager.PACKAGE_MANAGER_SENTINEL
+import android.app.backup.IBackupManager
+import android.content.Context.BACKUP_SERVICE
+import android.os.Build
+import android.os.ServiceManager.getService
+import com.stevesoltys.seedvault.crypto.cryptoModule
+import com.stevesoltys.seedvault.header.headerModule
+import com.stevesoltys.seedvault.metadata.metadataModule
+import com.stevesoltys.seedvault.restore.RestoreViewModel
+import com.stevesoltys.seedvault.settings.SettingsManager
+import com.stevesoltys.seedvault.settings.SettingsViewModel
+import com.stevesoltys.seedvault.transport.backup.backupModule
+import com.stevesoltys.seedvault.plugins.saf.documentsProviderModule
+import com.stevesoltys.seedvault.transport.restore.restoreModule
+import com.stevesoltys.seedvault.ui.recoverycode.RecoveryCodeViewModel
+import com.stevesoltys.seedvault.ui.storage.BackupStorageViewModel
+import com.stevesoltys.seedvault.ui.storage.RestoreStorageViewModel
+import org.koin.android.ext.koin.androidContext
+import org.koin.android.ext.koin.androidLogger
+import org.koin.androidx.viewmodel.dsl.viewModel
+import org.koin.core.context.startKoin
+import org.koin.dsl.module
+
+/**
+ * @author Steve Soltys
+ * @author Torsten Grote
+ */
+class App : Application() {
+
+    private val appModule = module {
+        single { SettingsManager(this@App) }
+        single { BackupNotificationManager(this@App) }
+        factory<IBackupManager> { IBackupManager.Stub.asInterface(getService(BACKUP_SERVICE)) }
+
+        viewModel { SettingsViewModel(this@App, get(), get()) }
+        viewModel { RecoveryCodeViewModel(this@App, get()) }
+        viewModel { BackupStorageViewModel(this@App, get(), get()) }
+        viewModel { RestoreStorageViewModel(this@App, get(), get()) }
+        viewModel { RestoreViewModel(this@App, get(), get(), get()) }
+    }
+
+    override fun onCreate() {
+        super.onCreate()
+        startKoin {
+            androidLogger()
+            androidContext(this@App)
+            modules(listOf(
+                    cryptoModule,
+                    headerModule,
+                    metadataModule,
+                    documentsProviderModule,  // storage plugin
+                    backupModule,
+                    restoreModule,
+                    appModule
+            ))
+        }
+    }
+
+}
+
+const val MAGIC_PACKAGE_MANAGER = PACKAGE_MANAGER_SENTINEL
+
+fun isDebugBuild() = Build.TYPE == "userdebug"

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

@@ -0,0 +1,20 @@
+package com.stevesoltys.seedvault
+
+import android.app.backup.BackupManagerMonitor.*
+import android.app.backup.IBackupManagerMonitor
+import android.os.Bundle
+import android.util.Log
+import android.util.Log.DEBUG
+
+private val TAG = BackupMonitor::class.java.name
+
+class BackupMonitor : IBackupManagerMonitor.Stub() {
+
+    override fun onEvent(bundle: Bundle) {
+        if (!Log.isLoggable(TAG, DEBUG)) return
+        Log.d(TAG, "ID: " + bundle.getInt(EXTRA_LOG_EVENT_ID))
+        Log.d(TAG, "CATEGORY: " + bundle.getInt(EXTRA_LOG_EVENT_CATEGORY, -1))
+        Log.d(TAG, "PACKAGE: " + bundle.getString(EXTRA_LOG_EVENT_PACKAGE_NAME, "?"))
+    }
+
+}

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

@@ -0,0 +1,97 @@
+package com.stevesoltys.seedvault
+
+import android.app.NotificationChannel
+import android.app.NotificationManager
+import android.app.NotificationManager.IMPORTANCE_DEFAULT
+import android.app.NotificationManager.IMPORTANCE_LOW
+import android.app.PendingIntent
+import android.app.backup.BackupTransport.TRANSPORT_PACKAGE_REJECTED
+import android.content.Context
+import android.content.Intent
+import androidx.core.app.NotificationCompat.*
+import com.stevesoltys.seedvault.settings.SettingsActivity
+import java.util.*
+
+private const val CHANNEL_ID_OBSERVER = "NotificationBackupObserver"
+private const val CHANNEL_ID_ERROR = "NotificationError"
+private const val NOTIFICATION_ID_OBSERVER = 1
+private const val NOTIFICATION_ID_ERROR = 2
+
+class BackupNotificationManager(private val context: Context) {
+
+    private val nm = context.getSystemService(NotificationManager::class.java)!!.apply {
+        createNotificationChannel(getObserverChannel())
+        createNotificationChannel(getErrorChannel())
+    }
+
+    private fun getObserverChannel(): NotificationChannel {
+        val title = context.getString(R.string.notification_channel_title)
+        return NotificationChannel(CHANNEL_ID_OBSERVER, title, IMPORTANCE_LOW).apply {
+            enableVibration(false)
+        }
+    }
+
+    private fun getErrorChannel(): NotificationChannel {
+        val title = context.getString(R.string.notification_error_channel_title)
+        return NotificationChannel(CHANNEL_ID_ERROR, title, IMPORTANCE_DEFAULT)
+    }
+
+    private val observerBuilder = Builder(context, CHANNEL_ID_OBSERVER).apply {
+        setSmallIcon(R.drawable.ic_cloud_upload)
+    }
+
+    private val errorBuilder = Builder(context, CHANNEL_ID_ERROR).apply {
+        setSmallIcon(R.drawable.ic_cloud_error)
+    }
+
+    fun onBackupUpdate(app: CharSequence, transferred: Int, expected: Int, userInitiated: Boolean) {
+        val notification = observerBuilder.apply {
+            setContentTitle(context.getString(R.string.notification_title))
+            setContentText(app)
+            setWhen(Date().time)
+            setProgress(expected, transferred, false)
+            priority = if (userInitiated) PRIORITY_DEFAULT else PRIORITY_LOW
+        }.build()
+        nm.notify(NOTIFICATION_ID_OBSERVER, notification)
+    }
+
+    fun onBackupResult(app: CharSequence, status: Int, userInitiated: Boolean) {
+        val title = context.getString(when (status) {
+            0 -> R.string.notification_backup_result_complete
+            TRANSPORT_PACKAGE_REJECTED -> R.string.notification_backup_result_rejected
+            else -> R.string.notification_backup_result_error
+        })
+        val notification = observerBuilder.apply {
+            setContentTitle(title)
+            setContentText(app)
+            setWhen(Date().time)
+            priority = if (userInitiated) PRIORITY_DEFAULT else PRIORITY_LOW
+        }.build()
+        nm.notify(NOTIFICATION_ID_OBSERVER, notification)
+    }
+
+    fun onBackupFinished() {
+        nm.cancel(NOTIFICATION_ID_OBSERVER)
+    }
+
+    fun onBackupError() {
+        val intent = Intent(context, SettingsActivity::class.java)
+        val pendingIntent = PendingIntent.getActivity(context, 0, intent, 0)
+        val actionText = context.getString(R.string.notification_error_action)
+        val action = Action(R.drawable.ic_storage, actionText, pendingIntent)
+        val notification = errorBuilder.apply {
+            setContentTitle(context.getString(R.string.notification_error_title))
+            setContentText(context.getString(R.string.notification_error_text))
+            setWhen(Date().time)
+            setOnlyAlertOnce(true)
+            setAutoCancel(true)
+            mActions = arrayListOf(action)
+        }.build()
+        nm.notify(NOTIFICATION_ID_ERROR, notification)
+    }
+
+    fun onBackupErrorSeen() {
+        nm.cancel(NOTIFICATION_ID_ERROR)
+    }
+
+}

app/src/main/java/com/stevesoltys/seedvault/Base64Utils.kt

@@ -0,0 +1,18 @@
+package com.stevesoltys.seedvault
+
+import java.nio.charset.Charset
+import java.util.*
+
+val Utf8: Charset = Charset.forName("UTF-8")
+
+fun ByteArray.encodeBase64(): String {
+    return Base64.getUrlEncoder().withoutPadding().encodeToString(this)
+}
+
+fun String.encodeBase64(): String {
+    return toByteArray(Utf8).encodeBase64()
+}
+
+fun String.decodeBase64(): String {
+    return String(Base64.getUrlDecoder().decode(this))
+}

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

@@ -0,0 +1,76 @@
+package com.stevesoltys.seedvault
+
+import android.app.backup.BackupProgress
+import android.app.backup.IBackupObserver
+import android.content.Context
+import android.content.pm.PackageManager
+import android.util.Log
+import android.util.Log.INFO
+import android.util.Log.isLoggable
+import org.koin.core.KoinComponent
+import org.koin.core.inject
+
+private val TAG = NotificationBackupObserver::class.java.simpleName
+
+class NotificationBackupObserver(context: Context, private val userInitiated: Boolean) : IBackupObserver.Stub(), KoinComponent {
+
+    private val pm = context.packageManager
+    private val nm: BackupNotificationManager by inject()
+
+    /**
+     * This method could be called several times for packages with full data backup.
+     * It will tell how much of backup data is already saved and how much is expected.
+     *
+     * @param currentBackupPackage The name of the package that now being backed up.
+     * @param backupProgress Current progress of backup for the package.
+     */
+    override fun onUpdate(currentBackupPackage: String, backupProgress: BackupProgress) {
+        val transferred = backupProgress.bytesTransferred.toInt()
+        val expected = backupProgress.bytesExpected.toInt()
+        if (isLoggable(TAG, INFO)) {
+            Log.i(TAG, "Update. Target: $currentBackupPackage, $transferred/$expected")
+        }
+        val app = getAppName(currentBackupPackage)
+        nm.onBackupUpdate(app, transferred, expected, userInitiated)
+    }
+
+    /**
+     * Backup of one package or initialization of one transport has completed.  This
+     * method will be called at most one time for each package or transport, and might not
+     * be not called if the operation fails before backupFinished(); for example, if the
+     * requested package/transport does not exist.
+     *
+     * @param target The name of the package that was backed up, or of the transport
+     *                  that was initialized
+     * @param status Zero on success; a nonzero error code if the backup operation failed.
+     */
+    override fun onResult(target: String, status: Int) {
+        if (isLoggable(TAG, INFO)) {
+            Log.i(TAG, "Completed. Target: $target, status: $status")
+        }
+        nm.onBackupResult(getAppName(target), status, userInitiated)
+    }
+
+    /**
+     * The backup process has completed.  This method will always be called,
+     * even if no individual package backup operations were attempted.
+     *
+     * @param status Zero on success; a nonzero error code if the backup operation
+     *   as a whole failed.
+     */
+    override fun backupFinished(status: Int) {
+        if (isLoggable(TAG, INFO)) {
+            Log.i(TAG, "Backup finished. Status: $status")
+        }
+        nm.onBackupFinished()
+    }
+
+    private fun getAppName(packageId: String): CharSequence = getAppName(pm, packageId)
+
+}
+
+fun getAppName(pm: PackageManager, packageId: String): CharSequence {
+    if (packageId == MAGIC_PACKAGE_MANAGER) return packageId
+    val appInfo = pm.getApplicationInfo(packageId, 0)
+    return pm.getApplicationLabel(appInfo)
+}

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

@@ -0,0 +1,108 @@
+package com.stevesoltys.seedvault
+
+import android.content.BroadcastReceiver
+import android.content.Context
+import android.content.Intent
+import android.database.ContentObserver
+import android.hardware.usb.UsbDevice
+import android.hardware.usb.UsbInterface
+import android.hardware.usb.UsbManager.*
+import android.net.Uri
+import android.os.Handler
+import android.provider.DocumentsContract
+import android.util.Log
+import com.stevesoltys.seedvault.settings.FlashDrive
+import com.stevesoltys.seedvault.settings.SettingsManager
+import com.stevesoltys.seedvault.transport.requestBackup
+import com.stevesoltys.seedvault.ui.storage.AUTHORITY_STORAGE
+import org.koin.core.KoinComponent
+import org.koin.core.inject
+import java.util.*
+import java.util.concurrent.TimeUnit.HOURS
+
+private val TAG = UsbIntentReceiver::class.java.simpleName
+
+class UsbIntentReceiver : UsbMonitor(), KoinComponent {
+
+    private val settingsManager by inject<SettingsManager>()
+
+    override fun shouldMonitorStatus(context: Context, action: String, device: UsbDevice): Boolean {
+        if (action != ACTION_USB_DEVICE_ATTACHED) return false
+        Log.d(TAG, "Checking if this is the current backup drive.")
+        val savedFlashDrive = settingsManager.getFlashDrive() ?: return false
+        val attachedFlashDrive = FlashDrive.from(device)
+        return if (savedFlashDrive == attachedFlashDrive) {
+            Log.d(TAG, "Matches stored device, checking backup time...")
+            if (Date().time - settingsManager.getBackupTime() >= HOURS.toMillis(24)) {
+                Log.d(TAG, "Last backup older than 24 hours, requesting a backup...")
+                true
+            } else {
+                Log.d(TAG, "We have a recent backup, not requesting a new one.")
+                false
+            }
+        } else {
+            Log.d(TAG, "Different device attached, ignoring...")
+            false
+        }
+    }
+
+    override fun onStatusChanged(context: Context, action: String, device: UsbDevice) {
+        Thread {
+            requestBackup(context)
+        }.start()
+    }
+
+}
+
+/**
+ * When we get the [ACTION_USB_DEVICE_ATTACHED] broadcast, the storage is not yet available.
+ * So we need to use a ContentObserver to request a backup only once available.
+ */
+abstract class UsbMonitor : BroadcastReceiver() {
+
+    override fun onReceive(context: Context, intent: Intent) {
+        val action = intent.action ?: return
+        if (intent.action == ACTION_USB_DEVICE_ATTACHED || intent.action == ACTION_USB_DEVICE_DETACHED) {
+            val device = intent.extras?.getParcelable<UsbDevice>(EXTRA_DEVICE) ?: return
+            Log.d(TAG, "New USB mass-storage device attached.")
+            device.log()
+
+            if (!shouldMonitorStatus(context, action, device)) return
+
+            val rootsUri = DocumentsContract.buildRootsUri(AUTHORITY_STORAGE)
+            val contentResolver = context.contentResolver
+            val observer = object : ContentObserver(Handler()) {
+                override fun onChange(selfChange: Boolean, uri: Uri?) {
+                    super.onChange(selfChange, uri)
+                    onStatusChanged(context, action, device)
+                    contentResolver.unregisterContentObserver(this)
+                }
+            }
+            contentResolver.registerContentObserver(rootsUri, true, observer)
+        }
+    }
+
+    abstract fun shouldMonitorStatus(context: Context, action: String, device: UsbDevice): Boolean
+
+    abstract fun onStatusChanged(context: Context, action: String, device: UsbDevice)
+
+}
+
+internal fun UsbDevice.isMassStorage(): Boolean {
+    for (i in 0 until interfaceCount) {
+        if (getInterface(i).isMassStorage()) return true
+    }
+    return false
+}
+
+private fun UsbInterface.isMassStorage(): Boolean {
+    return interfaceClass == 8 && interfaceProtocol == 80 && interfaceSubclass == 6
+}
+
+private fun UsbDevice.log() {
+    Log.d(TAG, "  name: $manufacturerName $productName")
+    Log.d(TAG, "  serialNumber: $serialNumber")
+    Log.d(TAG, "  productId: $productId")
+    Log.d(TAG, "  vendorId: $vendorId")
+    Log.d(TAG, "  isMassStorage: ${isMassStorage()}")
+}

app/src/main/java/com/stevesoltys/seedvault/crypto/CipherFactory.kt

@@ -0,0 +1,31 @@
+package com.stevesoltys.seedvault.crypto
+
+import javax.crypto.Cipher
+import javax.crypto.Cipher.DECRYPT_MODE
+import javax.crypto.Cipher.ENCRYPT_MODE
+import javax.crypto.spec.GCMParameterSpec
+
+private const val CIPHER_TRANSFORMATION = "AES/GCM/NoPadding"
+internal const val GCM_AUTHENTICATION_TAG_LENGTH = 128
+
+interface CipherFactory {
+    fun createEncryptionCipher(): Cipher
+    fun createDecryptionCipher(iv: ByteArray): Cipher
+}
+
+internal class CipherFactoryImpl(private val keyManager: KeyManager) : CipherFactory {
+
+    override fun createEncryptionCipher(): Cipher {
+        return Cipher.getInstance(CIPHER_TRANSFORMATION).apply {
+            init(ENCRYPT_MODE, keyManager.getBackupKey())
+        }
+    }
+
+    override fun createDecryptionCipher(iv: ByteArray): Cipher {
+        return Cipher.getInstance(CIPHER_TRANSFORMATION).apply {
+            val spec = GCMParameterSpec(GCM_AUTHENTICATION_TAG_LENGTH, iv)
+            init(DECRYPT_MODE, keyManager.getBackupKey(), spec)
+        }
+    }
+
+}

app/src/main/java/com/stevesoltys/seedvault/crypto/Crypto.kt

@@ -0,0 +1,185 @@
+package com.stevesoltys.seedvault.crypto
+
+import com.stevesoltys.seedvault.header.*
+import java.io.EOFException
+import java.io.IOException
+import java.io.InputStream
+import java.io.OutputStream
+import javax.crypto.Cipher
+import kotlin.math.min
+
+/**
+ * A backup stream starts with a version byte followed by an encrypted [VersionHeader].
+ *
+ * The header will be encrypted with AES/GCM to provide authentication.
+ * It can be written using [encryptHeader] and read using [decryptHeader].
+ * The latter throws a [SecurityException],
+ * if the expected version and package name do not match the encrypted header.
+ *
+ * After the header, follows one or more data segments.
+ * Each segment begins with a clear-text [SegmentHeader]
+ * that contains the length of the segment
+ * and a nonce acting as the initialization vector for the encryption.
+ * The segment can be written using [encryptSegment] and read using [decryptSegment].
+ * The latter throws a [SecurityException],
+ * if the length of the segment is specified larger than allowed.
+ */
+interface Crypto {
+
+    /**
+     * Encrypts a backup stream header ([VersionHeader]) and writes it to the given [OutputStream].
+     *
+     * The header using a small segment containing only
+     * the version number, the package name and (optionally) the key of a key/value stream.
+     */
+    @Throws(IOException::class)
+    fun encryptHeader(outputStream: OutputStream, versionHeader: VersionHeader)
+
+    /**
+     * Encrypts a new backup segment from the given cleartext payload
+     * and writes it to the given [OutputStream].
+     *
+     * A segment starts with a [SegmentHeader] which includes the length of the segment
+     * and a nonce which is used as initialization vector for the encryption.
+     *
+     * After the header follows the encrypted payload.
+     * Larger backup streams such as from a full backup are encrypted in multiple segments
+     * to avoid having to load the entire stream into memory when doing authenticated encryption.
+     *
+     * The given cleartext can later be decrypted
+     * by calling [decryptSegment] on the same byte stream.
+     */
+    @Throws(IOException::class)
+    fun encryptSegment(outputStream: OutputStream, cleartext: ByteArray)
+
+    /**
+     * Like [encryptSegment],
+     * but if the given cleartext [ByteArray] is larger than [MAX_SEGMENT_CLEARTEXT_LENGTH],
+     * multiple segments will be written.
+     */
+    @Throws(IOException::class)
+    fun encryptMultipleSegments(outputStream: OutputStream, cleartext: ByteArray)
+
+    /**
+     * Reads and decrypts a [VersionHeader] from the given [InputStream]
+     * and ensures that the expected version, package name and key match
+     * what is found in the header.
+     * If a mismatch is found, a [SecurityException] is thrown.
+     *
+     * @return The read [VersionHeader] present in the beginning of the given [InputStream].
+     */
+    @Throws(IOException::class, SecurityException::class)
+    fun decryptHeader(inputStream: InputStream, expectedVersion: Byte, expectedPackageName: String,
+                      expectedKey: String? = null): VersionHeader
+
+    /**
+     * Reads and decrypts a segment from the given [InputStream].
+     *
+     * @return The decrypted segment payload as passed into [encryptSegment]
+     */
+    @Throws(EOFException::class, IOException::class, SecurityException::class)
+    fun decryptSegment(inputStream: InputStream): ByteArray
+
+    /**
+     * Like [decryptSegment], but decrypts multiple segments and does not throw [EOFException].
+     */
+    @Throws(IOException::class, SecurityException::class)
+    fun decryptMultipleSegments(inputStream: InputStream): ByteArray
+}
+
+internal class CryptoImpl(
+        private val cipherFactory: CipherFactory,
+        private val headerWriter: HeaderWriter,
+        private val headerReader: HeaderReader) : Crypto {
+
+    @Throws(IOException::class)
+    override fun encryptHeader(outputStream: OutputStream, versionHeader: VersionHeader) {
+        val bytes = headerWriter.getEncodedVersionHeader(versionHeader)
+
+        encryptSegment(outputStream, bytes)
+    }
+
+    @Throws(IOException::class)
+    override fun encryptSegment(outputStream: OutputStream, cleartext: ByteArray) {
+        val cipher = cipherFactory.createEncryptionCipher()
+
+        check(cipher.getOutputSize(cleartext.size) <= MAX_SEGMENT_LENGTH) {
+            "Cipher's output size ${cipher.getOutputSize(cleartext.size)} is larger than maximum segment length ($MAX_SEGMENT_LENGTH)"
+        }
+        encryptSegment(cipher, outputStream, cleartext)
+    }
+
+    @Throws(IOException::class)
+    override fun encryptMultipleSegments(outputStream: OutputStream, cleartext: ByteArray) {
+        var end = 0
+        while (end < cleartext.size) {
+            val start = end
+            end = min(cleartext.size, start + MAX_SEGMENT_CLEARTEXT_LENGTH)
+            val segment = cleartext.copyOfRange(start, end)
+            val cipher = cipherFactory.createEncryptionCipher()
+            encryptSegment(cipher, outputStream, segment)
+        }
+    }
+
+    @Throws(IOException::class)
+    private fun encryptSegment(cipher: Cipher, outputStream: OutputStream, segment: ByteArray) {
+        val encrypted = cipher.doFinal(segment)
+        val segmentHeader = SegmentHeader(encrypted.size.toShort(), cipher.iv)
+        headerWriter.writeSegmentHeader(outputStream, segmentHeader)
+        outputStream.write(encrypted)
+    }
+
+    @Throws(IOException::class, SecurityException::class)
+    override fun decryptHeader(inputStream: InputStream, expectedVersion: Byte,
+                               expectedPackageName: String, expectedKey: String?): VersionHeader {
+        val decrypted = decryptSegment(inputStream, MAX_VERSION_HEADER_SIZE)
+        val header = headerReader.getVersionHeader(decrypted)
+
+        if (header.version != expectedVersion) {
+            throw SecurityException("Invalid version '${header.version.toInt()}' in header, expected '${expectedVersion.toInt()}'.")
+        }
+        if (header.packageName != expectedPackageName) {
+            throw SecurityException("Invalid package name '${header.packageName}' in header, expected '$expectedPackageName'.")
+        }
+        if (header.key != expectedKey) {
+            throw SecurityException("Invalid key '${header.key}' in header, expected '$expectedKey'.")
+        }
+
+        return header
+    }
+
+    @Throws(EOFException::class, IOException::class, SecurityException::class)
+    override fun decryptSegment(inputStream: InputStream): ByteArray {
+        return decryptSegment(inputStream, MAX_SEGMENT_LENGTH)
+    }
+
+    @Throws(IOException::class, SecurityException::class)
+    override fun decryptMultipleSegments(inputStream: InputStream): ByteArray {
+        var result = ByteArray(0)
+        while (true) {
+            try {
+                result += decryptSegment(inputStream, MAX_SEGMENT_LENGTH)
+            } catch (e: EOFException) {
+                if (result.isEmpty()) throw IOException(e)
+                return result
+            }
+        }
+    }
+
+    @Throws(EOFException::class, IOException::class, SecurityException::class)
+    private fun decryptSegment(inputStream: InputStream, maxSegmentLength: Int): ByteArray {
+        val segmentHeader = headerReader.readSegmentHeader(inputStream)
+        if (segmentHeader.segmentLength > maxSegmentLength) {
+            throw SecurityException("Segment length too long: ${segmentHeader.segmentLength} > $maxSegmentLength")
+        }
+
+        val buffer = ByteArray(segmentHeader.segmentLength.toInt())
+        val bytesRead = inputStream.read(buffer)
+        if (bytesRead == -1) throw EOFException()
+        if (bytesRead != buffer.size) throw IOException()
+        val cipher = cipherFactory.createDecryptionCipher(segmentHeader.nonce)
+
+        return cipher.doFinal(buffer)
+    }
+
+}

app/src/main/java/com/stevesoltys/seedvault/crypto/CryptoModule.kt

@@ -0,0 +1,9 @@
+package com.stevesoltys.seedvault.crypto
+
+import org.koin.dsl.module
+
+val cryptoModule = module {
+    factory<CipherFactory> { CipherFactoryImpl(get()) }
+    single<KeyManager> { KeyManagerImpl() }
+    single<Crypto> { CryptoImpl(get(), get(), get()) }
+}

app/src/main/java/com/stevesoltys/seedvault/crypto/KeyManager.kt

@@ -0,0 +1,72 @@
+package com.stevesoltys.seedvault.crypto
+
+import android.os.Build.VERSION.SDK_INT
+import android.security.keystore.KeyProperties.*
+import android.security.keystore.KeyProtection
+import java.security.KeyStore
+import java.security.KeyStore.SecretKeyEntry
+import javax.crypto.SecretKey
+import javax.crypto.spec.SecretKeySpec
+
+internal const val KEY_SIZE = 256
+private const val KEY_SIZE_BYTES = KEY_SIZE / 8
+private const val KEY_ALIAS = "com.stevesoltys.seedvault"
+private const val ANDROID_KEY_STORE = "AndroidKeyStore"
+
+interface KeyManager {
+    /**
+     * Store a new backup key derived from the given [seed].
+     *
+     * The seed needs to be larger or equal to [KEY_SIZE_BYTES].
+     */
+    fun storeBackupKey(seed: ByteArray)
+
+    /**
+     * @return true if a backup key already exists in the [KeyStore].
+     */
+    fun hasBackupKey(): Boolean
+
+    /**
+     * Returns the backup key, so it can be used for encryption or decryption.
+     *
+     * Note that any attempt to export the key will return null or an empty [ByteArray],
+     * because the key can not leave the [KeyStore]'s hardware security module.
+     */
+    fun getBackupKey(): SecretKey
+}
+
+internal class KeyManagerImpl : KeyManager {
+
+    private val keyStore by lazy {
+        KeyStore.getInstance(ANDROID_KEY_STORE).apply {
+            load(null)
+        }
+    }
+
+    override fun storeBackupKey(seed: ByteArray) {
+        if (seed.size < KEY_SIZE_BYTES) throw IllegalArgumentException()
+        // TODO check if using first 256 of 512 bytes produced by PBKDF2WithHmacSHA512 is safe!
+        val secretKeySpec = SecretKeySpec(seed, 0, KEY_SIZE_BYTES, "AES")
+        val ksEntry = SecretKeyEntry(secretKeySpec)
+        keyStore.setEntry(KEY_ALIAS, ksEntry, getKeyProtection())
+    }
+
+    override fun hasBackupKey() = keyStore.containsAlias(KEY_ALIAS) &&
+            keyStore.entryInstanceOf(KEY_ALIAS, SecretKeyEntry::class.java)
+
+    override fun getBackupKey(): SecretKey {
+        val ksEntry = keyStore.getEntry(KEY_ALIAS, null) as SecretKeyEntry
+        return ksEntry.secretKey
+    }
+
+    private fun getKeyProtection(): KeyProtection {
+        val builder = KeyProtection.Builder(PURPOSE_ENCRYPT or PURPOSE_DECRYPT)
+                .setBlockModes(BLOCK_MODE_GCM)
+                .setEncryptionPaddings(ENCRYPTION_PADDING_NONE)
+                .setRandomizedEncryptionRequired(true)
+        // unlocking is required only for decryption, so when restoring from backup
+        if (SDK_INT >= 28) builder.setUnlockedDeviceRequired(true)
+        return builder.build()
+    }
+
+}

app/src/main/java/com/stevesoltys/seedvault/header/Header.kt

@@ -0,0 +1,48 @@
+package com.stevesoltys.seedvault.header
+
+import com.stevesoltys.seedvault.crypto.GCM_AUTHENTICATION_TAG_LENGTH
+
+internal const val VERSION: Byte = 0
+internal const val MAX_PACKAGE_LENGTH_SIZE = 255
+internal const val MAX_KEY_LENGTH_SIZE = MAX_PACKAGE_LENGTH_SIZE
+internal const val MAX_VERSION_HEADER_SIZE = 1 + Short.SIZE_BYTES * 2 + MAX_PACKAGE_LENGTH_SIZE + MAX_KEY_LENGTH_SIZE
+
+/**
+ * After the first version byte of each backup stream
+ * must follow followed this header encrypted with authentication.
+ */
+data class VersionHeader(
+        internal val version: Byte = VERSION, //  1 byte
+        internal val packageName: String,     // ?? bytes (max 255)
+        internal val key: String? = null      // ?? bytes
+) {
+    init {
+        check(packageName.length <= MAX_PACKAGE_LENGTH_SIZE) {
+            "Package $packageName has name longer than $MAX_PACKAGE_LENGTH_SIZE"
+        }
+        key?.let {
+            check(key.length <= MAX_KEY_LENGTH_SIZE) { "Key $key is longer than $MAX_KEY_LENGTH_SIZE" }
+        }
+    }
+}
+
+
+internal const val SEGMENT_LENGTH_SIZE: Int = Short.SIZE_BYTES
+internal const val MAX_SEGMENT_LENGTH: Int = Short.MAX_VALUE.toInt()
+internal const val MAX_SEGMENT_CLEARTEXT_LENGTH: Int = MAX_SEGMENT_LENGTH - GCM_AUTHENTICATION_TAG_LENGTH / 8
+internal const val IV_SIZE: Int = 12
+internal const val SEGMENT_HEADER_SIZE = SEGMENT_LENGTH_SIZE + IV_SIZE
+
+/**
+ * Each data segment must start with this header
+ */
+class SegmentHeader(
+        internal val segmentLength: Short,    //  2 bytes
+        internal val nonce: ByteArray         // 12 bytes
+) {
+    init {
+        check(nonce.size == IV_SIZE) {
+            "Nonce size of ${nonce.size} is not the expected IV size of $IV_SIZE"
+        }
+    }
+}

app/src/main/java/com/stevesoltys/seedvault/header/HeaderModule.kt

@@ -0,0 +1,8 @@
+package com.stevesoltys.seedvault.header
+
+import org.koin.dsl.module
+
+val headerModule = module {
+    single<HeaderWriter> { HeaderWriterImpl() }
+    single<HeaderReader> { HeaderReaderImpl() }
+}

app/src/main/java/com/stevesoltys/seedvault/header/HeaderReader.kt

@@ -0,0 +1,73 @@
+package com.stevesoltys.seedvault.header
+
+import com.stevesoltys.seedvault.Utf8
+import java.io.EOFException
+import java.io.IOException
+import java.io.InputStream
+import java.nio.ByteBuffer
+
+interface HeaderReader {
+    @Throws(IOException::class, UnsupportedVersionException::class)
+    fun readVersion(inputStream: InputStream): Byte
+
+    @Throws(SecurityException::class)
+    fun getVersionHeader(byteArray: ByteArray): VersionHeader
+
+    @Throws(EOFException::class, IOException::class)
+    fun readSegmentHeader(inputStream: InputStream): SegmentHeader
+}
+
+internal class HeaderReaderImpl : HeaderReader {
+
+    @Throws(IOException::class, UnsupportedVersionException::class)
+    override fun readVersion(inputStream: InputStream): Byte {
+        val version = inputStream.read().toByte()
+        if (version < 0) throw IOException()
+        if (version > VERSION) throw UnsupportedVersionException(version)
+        return version
+    }
+
+    override fun getVersionHeader(byteArray: ByteArray): VersionHeader {
+        val buffer = ByteBuffer.wrap(byteArray)
+        val version = buffer.get()
+
+        val packageLength = buffer.short.toInt()
+        if (packageLength <= 0) throw SecurityException("Invalid package length: $packageLength")
+        if (packageLength > MAX_PACKAGE_LENGTH_SIZE) throw SecurityException("Too large package length: $packageLength")
+        if (packageLength > buffer.remaining()) throw SecurityException("Not enough bytes for package name")
+        val packageName = ByteArray(packageLength)
+                .apply { buffer.get(this) }
+                .toString(Utf8)
+
+        val keyLength = buffer.short.toInt()
+        if (keyLength < 0) throw SecurityException("Invalid key length: $keyLength")
+        if (keyLength > MAX_KEY_LENGTH_SIZE) throw SecurityException("Too large key length: $keyLength")
+        if (keyLength > buffer.remaining()) throw SecurityException("Not enough bytes for key")
+        val key = if (keyLength == 0) null else ByteArray(keyLength)
+                .apply { buffer.get(this) }
+                .toString(Utf8)
+
+        if (buffer.remaining() != 0) throw SecurityException("Found extra bytes in header")
+
+        return VersionHeader(version, packageName, key)
+    }
+
+    @Throws(EOFException::class, IOException::class)
+    override fun readSegmentHeader(inputStream: InputStream): SegmentHeader {
+        val buffer = ByteArray(SEGMENT_HEADER_SIZE)
+        val bytesRead = inputStream.read(buffer)
+        if (bytesRead == -1) throw EOFException()
+        if (bytesRead != SEGMENT_HEADER_SIZE) {
+            throw IOException("Read $bytesRead bytes, but expected $SEGMENT_HEADER_SIZE")
+        }
+
+        val segmentLength = ByteBuffer.wrap(buffer, 0, SEGMENT_LENGTH_SIZE).short
+        if (segmentLength <= 0) throw IOException()
+        val nonce = buffer.copyOfRange(SEGMENT_LENGTH_SIZE, buffer.size)
+
+        return SegmentHeader(segmentLength, nonce)
+    }
+
+}
+
+class UnsupportedVersionException(val version: Byte) : IOException()

app/src/main/java/com/stevesoltys/seedvault/header/HeaderWriter.kt

@@ -0,0 +1,51 @@
+package com.stevesoltys.seedvault.header
+
+import com.stevesoltys.seedvault.Utf8
+import java.io.IOException
+import java.io.OutputStream
+import java.nio.ByteBuffer
+
+interface HeaderWriter {
+    @Throws(IOException::class)
+    fun writeVersion(outputStream: OutputStream, header: VersionHeader)
+
+    fun getEncodedVersionHeader(header: VersionHeader): ByteArray
+
+    @Throws(IOException::class)
+    fun writeSegmentHeader(outputStream: OutputStream, header: SegmentHeader)
+}
+
+internal class HeaderWriterImpl : HeaderWriter {
+
+    @Throws(IOException::class)
+    override fun writeVersion(outputStream: OutputStream, header: VersionHeader) {
+        val headerBytes = ByteArray(1)
+        headerBytes[0] = header.version
+        outputStream.write(headerBytes)
+    }
+
+    override fun getEncodedVersionHeader(header: VersionHeader): ByteArray {
+        val packageBytes = header.packageName.toByteArray(Utf8)
+        val keyBytes = header.key?.toByteArray(Utf8)
+        val size = 1 + 2 + packageBytes.size + 2 + (keyBytes?.size ?: 0)
+        return ByteBuffer.allocate(size).apply {
+            put(header.version)
+            putShort(packageBytes.size.toShort())
+            put(packageBytes)
+            if (keyBytes == null) {
+                putShort(0.toShort())
+            } else {
+                putShort(keyBytes.size.toShort())
+                put(keyBytes)
+            }
+        }.array()
+    }
+
+    override fun writeSegmentHeader(outputStream: OutputStream, header: SegmentHeader) {
+        val buffer = ByteBuffer.allocate(SEGMENT_HEADER_SIZE)
+                .putShort(header.segmentLength)
+                .put(header.nonce)
+        outputStream.write(buffer.array())
+    }
+
+}

app/src/main/java/com/stevesoltys/seedvault/metadata/Metadata.kt

@@ -0,0 +1,28 @@
+package com.stevesoltys.seedvault.metadata
+
+import android.os.Build
+import android.os.Build.VERSION.SDK_INT
+import com.stevesoltys.seedvault.header.VERSION
+import java.io.InputStream
+
+data class BackupMetadata(
+        internal val version: Byte = VERSION,
+        internal val token: Long,
+        internal val androidVersion: Int = SDK_INT,
+        internal val deviceName: String = "${Build.MANUFACTURER} ${Build.MODEL}"
+)
+
+internal const val JSON_VERSION = "version"
+internal const val JSON_TOKEN = "token"
+internal const val JSON_ANDROID_VERSION = "androidVersion"
+internal const val JSON_DEVICE_NAME = "deviceName"
+
+internal class DecryptionFailedException(cause: Throwable) : Exception(cause)
+
+class EncryptedBackupMetadata private constructor(val token: Long, val inputStream: InputStream?, val error: Boolean) {
+    constructor(token: Long, inputStream: InputStream) : this(token, inputStream, false)
+    /**
+     * Indicates that there was an error retrieving the encrypted backup metadata.
+     */
+    constructor(token: Long) : this(token, null, true)
+}

app/src/main/java/com/stevesoltys/seedvault/metadata/MetadataModule.kt

@@ -0,0 +1,8 @@
+package com.stevesoltys.seedvault.metadata
+
+import org.koin.dsl.module
+
+val metadataModule = module {
+    single<MetadataWriter> { MetadataWriterImpl(get()) }
+    single<MetadataReader> { MetadataReaderImpl(get()) }
+}

app/src/main/java/com/stevesoltys/seedvault/metadata/MetadataReader.kt

@@ -0,0 +1,65 @@
+package com.stevesoltys.seedvault.metadata
+
+import androidx.annotation.VisibleForTesting
+import com.stevesoltys.seedvault.Utf8
+import com.stevesoltys.seedvault.crypto.Crypto
+import com.stevesoltys.seedvault.header.UnsupportedVersionException
+import com.stevesoltys.seedvault.header.VERSION
+import org.json.JSONException
+import org.json.JSONObject
+import java.io.IOException
+import java.io.InputStream
+import javax.crypto.AEADBadTagException
+
+interface MetadataReader {
+
+    @Throws(SecurityException::class, DecryptionFailedException::class, UnsupportedVersionException::class, IOException::class)
+    fun readMetadata(inputStream: InputStream, expectedToken: Long): BackupMetadata
+
+}
+
+internal class MetadataReaderImpl(private val crypto: Crypto) : MetadataReader {
+
+    @Throws(SecurityException::class, DecryptionFailedException::class, UnsupportedVersionException::class, IOException::class)
+    override fun readMetadata(inputStream: InputStream, expectedToken: Long): BackupMetadata {
+        val version = inputStream.read().toByte()
+        if (version < 0) throw IOException()
+        if (version > VERSION) throw UnsupportedVersionException(version)
+        val metadataBytes = try {
+            crypto.decryptMultipleSegments(inputStream)
+        } catch (e: AEADBadTagException) {
+            throw DecryptionFailedException(e)
+        }
+        return decode(metadataBytes, version, expectedToken)
+    }
+
+    @VisibleForTesting
+    @Throws(SecurityException::class)
+    internal fun decode(bytes: ByteArray, expectedVersion: Byte, expectedToken: Long): BackupMetadata {
+        // NOTE: We don't do extensive validation of the parsed input here,
+        // because it was encrypted with authentication, so we should be able to trust it.
+        //
+        // However, it is important to ensure that the expected unauthenticated version and token
+        // matches the authenticated version and token in the JSON.
+        try {
+            val json = JSONObject(bytes.toString(Utf8))
+            val version = json.getInt(JSON_VERSION).toByte()
+            if (version != expectedVersion) {
+                throw SecurityException("Invalid version '${version.toInt()}' in metadata, expected '${expectedVersion.toInt()}'.")
+            }
+            val token = json.getLong(JSON_TOKEN)
+            if (token != expectedToken) {
+                throw SecurityException("Invalid token '$token' in metadata, expected '$expectedToken'.")
+            }
+            return BackupMetadata(
+                    version = version,
+                    token = token,
+                    androidVersion = json.getInt(JSON_ANDROID_VERSION),
+                    deviceName = json.getString(JSON_DEVICE_NAME)
+            )
+        } catch (e: JSONException) {
+            throw SecurityException(e)
+        }
+    }
+
+}

app/src/main/java/com/stevesoltys/seedvault/metadata/MetadataWriter.kt

@@ -0,0 +1,36 @@
+package com.stevesoltys.seedvault.metadata
+
+import androidx.annotation.VisibleForTesting
+import com.stevesoltys.seedvault.Utf8
+import com.stevesoltys.seedvault.crypto.Crypto
+import org.json.JSONObject
+import java.io.IOException
+import java.io.OutputStream
+
+interface MetadataWriter {
+
+    @Throws(IOException::class)
+    fun write(outputStream: OutputStream, token: Long)
+
+}
+
+internal class MetadataWriterImpl(private val crypto: Crypto): MetadataWriter {
+
+    @Throws(IOException::class)
+    override fun write(outputStream: OutputStream, token: Long) {
+        val metadata = BackupMetadata(token = token)
+        outputStream.write(ByteArray(1).apply { this[0] = metadata.version })
+        crypto.encryptMultipleSegments(outputStream, encode(metadata))
+    }
+
+    @VisibleForTesting
+    internal fun encode(metadata: BackupMetadata): ByteArray {
+        val json = JSONObject()
+        json.put(JSON_VERSION, metadata.version.toInt())
+        json.put(JSON_TOKEN, metadata.token)
+        json.put(JSON_ANDROID_VERSION, metadata.androidVersion)
+        json.put(JSON_DEVICE_NAME, metadata.deviceName)
+        return json.toString().toByteArray(Utf8)
+    }
+
+}

app/src/main/java/com/stevesoltys/seedvault/plugins/saf/DocumentsProviderBackupPlugin.kt

@@ -0,0 +1,50 @@
+package com.stevesoltys.seedvault.plugins.saf
+
+import android.content.pm.PackageManager
+import com.stevesoltys.seedvault.transport.backup.BackupPlugin
+import com.stevesoltys.seedvault.transport.backup.FullBackupPlugin
+import com.stevesoltys.seedvault.transport.backup.KVBackupPlugin
+import java.io.IOException
+import java.io.OutputStream
+
+internal class DocumentsProviderBackupPlugin(
+        private val storage: DocumentsStorage,
+        packageManager: PackageManager) : BackupPlugin {
+
+    override val kvBackupPlugin: KVBackupPlugin by lazy {
+        DocumentsProviderKVBackup(storage)
+    }
+
+    override val fullBackupPlugin: FullBackupPlugin by lazy {
+        DocumentsProviderFullBackup(storage)
+    }
+
+    @Throws(IOException::class)
+    override fun initializeDevice() {
+        // get or create root backup dir
+        storage.rootBackupDir ?: throw IOException()
+
+        // create backup folders
+        val kvDir = storage.currentKvBackupDir
+        val fullDir = storage.currentFullBackupDir
+
+        // wipe existing data
+        storage.getSetDir()?.findFile(FILE_BACKUP_METADATA)?.delete()
+        kvDir?.deleteContents()
+        fullDir?.deleteContents()
+    }
+
+    @Throws(IOException::class)
+    override fun getMetadataOutputStream(): OutputStream {
+        val setDir = storage.getSetDir() ?: throw IOException()
+        val metadataFile = setDir.createOrGetFile(FILE_BACKUP_METADATA)
+        return storage.getOutputStream(metadataFile)
+    }
+
+    override val providerPackageName: String? by lazy {
+        val authority = storage.getAuthority() ?: return@lazy null
+        val providerInfo = packageManager.resolveContentProvider(authority, 0) ?: return@lazy null
+        providerInfo.packageName
+    }
+
+}

app/src/main/java/com/stevesoltys/seedvault/plugins/saf/DocumentsProviderFullBackup.kt

@@ -0,0 +1,32 @@
+package com.stevesoltys.seedvault.plugins.saf
+
+import android.content.pm.PackageInfo
+import android.util.Log
+import com.stevesoltys.seedvault.transport.backup.DEFAULT_QUOTA_FULL_BACKUP
+import com.stevesoltys.seedvault.transport.backup.FullBackupPlugin
+import java.io.IOException
+import java.io.OutputStream
+
+private val TAG = DocumentsProviderFullBackup::class.java.simpleName
+
+internal class DocumentsProviderFullBackup(
+        private val storage: DocumentsStorage) : FullBackupPlugin {
+
+    override fun getQuota() = DEFAULT_QUOTA_FULL_BACKUP
+
+    @Throws(IOException::class)
+    override fun getOutputStream(targetPackage: PackageInfo): OutputStream {
+        val file = storage.currentFullBackupDir?.createOrGetFile(targetPackage.packageName)
+                ?: throw IOException()
+        return storage.getOutputStream(file)
+    }
+
+    @Throws(IOException::class)
+    override fun removeDataOfPackage(packageInfo: PackageInfo) {
+        val packageName = packageInfo.packageName
+        Log.i(TAG, "Deleting $packageName...")
+        val file = storage.currentFullBackupDir?.findFile(packageName) ?: return
+        if (!file.delete()) throw IOException("Failed to delete $packageName")
+    }
+
+}

app/src/main/java/com/stevesoltys/seedvault/plugins/saf/DocumentsProviderFullRestorePlugin.kt

@@ -0,0 +1,24 @@
+package com.stevesoltys.seedvault.plugins.saf
+
+import android.content.pm.PackageInfo
+import com.stevesoltys.seedvault.transport.restore.FullRestorePlugin
+import java.io.IOException
+import java.io.InputStream
+
+internal class DocumentsProviderFullRestorePlugin(
+        private val documentsStorage: DocumentsStorage) : FullRestorePlugin {
+
+    @Throws(IOException::class)
+    override fun hasDataForPackage(token: Long, packageInfo: PackageInfo): Boolean {
+        val backupDir = documentsStorage.getFullBackupDir(token) ?: throw IOException()
+        return backupDir.findFile(packageInfo.packageName) != null
+    }
+
+    @Throws(IOException::class)
+    override fun getInputStreamForPackage(token: Long, packageInfo: PackageInfo): InputStream {
+        val backupDir = documentsStorage.getFullBackupDir(token) ?: throw IOException()
+        val packageFile = backupDir.findFile(packageInfo.packageName) ?: throw IOException()
+        return documentsStorage.getInputStream(packageFile)
+    }
+
+}

app/src/main/java/com/stevesoltys/seedvault/plugins/saf/DocumentsProviderKVBackup.kt

@@ -0,0 +1,53 @@
+package com.stevesoltys.seedvault.plugins.saf
+
+import android.content.pm.PackageInfo
+import androidx.documentfile.provider.DocumentFile
+import com.stevesoltys.seedvault.transport.backup.DEFAULT_QUOTA_KEY_VALUE_BACKUP
+import com.stevesoltys.seedvault.transport.backup.KVBackupPlugin
+import java.io.IOException
+import java.io.OutputStream
+
+internal class DocumentsProviderKVBackup(private val storage: DocumentsStorage) : KVBackupPlugin {
+
+    private var packageFile: DocumentFile? = null
+
+    override fun getQuota(): Long = DEFAULT_QUOTA_KEY_VALUE_BACKUP
+
+    @Throws(IOException::class)
+    override fun hasDataForPackage(packageInfo: PackageInfo): Boolean {
+        val packageFile = storage.currentKvBackupDir?.findFile(packageInfo.packageName)
+                ?: return false
+        return packageFile.listFiles().isNotEmpty()
+    }
+
+    @Throws(IOException::class)
+    override fun ensureRecordStorageForPackage(packageInfo: PackageInfo) {
+        // remember package file for subsequent operations
+        packageFile = storage.getOrCreateKVBackupDir().createOrGetDirectory(packageInfo.packageName)
+    }
+
+    @Throws(IOException::class)
+    override fun removeDataOfPackage(packageInfo: PackageInfo) {
+        // we cannot use the cached this.packageFile here,
+        // because this can be called before [ensureRecordStorageForPackage]
+        val packageFile = storage.currentKvBackupDir?.findFile(packageInfo.packageName) ?: return
+        packageFile.delete()
+    }
+
+    @Throws(IOException::class)
+    override fun deleteRecord(packageInfo: PackageInfo, key: String) {
+        val packageFile = this.packageFile ?: throw AssertionError()
+        packageFile.assertRightFile(packageInfo)
+        val keyFile = packageFile.findFile(key) ?: return
+        keyFile.delete()
+    }
+
+    @Throws(IOException::class)
+    override fun getOutputStreamForRecord(packageInfo: PackageInfo, key: String): OutputStream {
+        val packageFile = this.packageFile ?: throw AssertionError()
+        packageFile.assertRightFile(packageInfo)
+        val keyFile = packageFile.createOrGetFile(key)
+        return storage.getOutputStream(keyFile)
+    }
+
+}

app/src/main/java/com/stevesoltys/seedvault/plugins/saf/DocumentsProviderKVRestorePlugin.kt

@@ -0,0 +1,40 @@
+package com.stevesoltys.seedvault.plugins.saf
+
+import android.content.pm.PackageInfo
+import androidx.documentfile.provider.DocumentFile
+import com.stevesoltys.seedvault.transport.restore.KVRestorePlugin
+import java.io.IOException
+import java.io.InputStream
+
+internal class DocumentsProviderKVRestorePlugin(private val storage: DocumentsStorage) : KVRestorePlugin {
+
+    private var packageDir: DocumentFile? = null
+
+    override fun hasDataForPackage(token: Long, packageInfo: PackageInfo): Boolean {
+        return try {
+            val backupDir = storage.getKVBackupDir(token) ?: return false
+            // remember package file for subsequent operations
+            packageDir = backupDir.findFile(packageInfo.packageName)
+            packageDir != null
+        } catch (e: IOException) {
+            false
+        }
+    }
+
+    override fun listRecords(token: Long, packageInfo: PackageInfo): List<String> {
+        val packageDir = this.packageDir ?: throw AssertionError()
+        packageDir.assertRightFile(packageInfo)
+        return packageDir.listFiles()
+                .filter { file -> file.name != null }
+                .map { file -> file.name!! }
+    }
+
+    @Throws(IOException::class)
+    override fun getInputStreamForRecord(token: Long, packageInfo: PackageInfo, key: String): InputStream {
+        val packageDir = this.packageDir ?: throw AssertionError()
+        packageDir.assertRightFile(packageInfo)
+        val keyFile = packageDir.findFile(key) ?: throw IOException()
+        return storage.getInputStream(keyFile)
+    }
+
+}

app/src/main/java/com/stevesoltys/seedvault/plugins/saf/DocumentsProviderModule.kt

@@ -0,0 +1,12 @@
+package com.stevesoltys.seedvault.plugins.saf
+
+import com.stevesoltys.seedvault.transport.backup.BackupPlugin
+import com.stevesoltys.seedvault.transport.restore.RestorePlugin
+import org.koin.android.ext.koin.androidContext
+import org.koin.dsl.module
+
+val documentsProviderModule = module {
+    single { DocumentsStorage(androidContext(), get()) }
+    single<BackupPlugin> { DocumentsProviderBackupPlugin(get(), androidContext().packageManager) }
+    single<RestorePlugin> { DocumentsProviderRestorePlugin(androidContext(), get()) }
+}

app/src/main/java/com/stevesoltys/seedvault/plugins/saf/DocumentsProviderRestorePlugin.kt

@@ -0,0 +1,89 @@
+package com.stevesoltys.seedvault.plugins.saf
+
+import android.content.Context
+import android.net.Uri
+import android.util.Log
+import androidx.annotation.WorkerThread
+import androidx.documentfile.provider.DocumentFile
+import com.stevesoltys.seedvault.metadata.EncryptedBackupMetadata
+import com.stevesoltys.seedvault.transport.restore.FullRestorePlugin
+import com.stevesoltys.seedvault.transport.restore.KVRestorePlugin
+import com.stevesoltys.seedvault.transport.restore.RestorePlugin
+import java.io.IOException
+
+private val TAG = DocumentsProviderRestorePlugin::class.java.simpleName
+
+internal class DocumentsProviderRestorePlugin(
+        private val context: Context,
+        private val storage: DocumentsStorage) : RestorePlugin {
+
+    override val kvRestorePlugin: KVRestorePlugin by lazy {
+        DocumentsProviderKVRestorePlugin(storage)
+    }
+
+    override val fullRestorePlugin: FullRestorePlugin by lazy {
+        DocumentsProviderFullRestorePlugin(storage)
+    }
+
+    @WorkerThread
+    override fun hasBackup(uri: Uri): Boolean {
+        val parent = DocumentFile.fromTreeUri(context, uri) ?: throw AssertionError()
+        val rootDir = parent.findFileBlocking(context, DIRECTORY_ROOT) ?: return false
+        val backupSets = getBackups(context, rootDir)
+        return backupSets.isNotEmpty()
+    }
+
+    override fun getAvailableBackups(): Sequence<EncryptedBackupMetadata>? {
+        val rootDir = storage.rootBackupDir ?: return null
+        val backupSets = getBackups(context, rootDir)
+        val iterator = backupSets.iterator()
+        return generateSequence {
+            if (!iterator.hasNext()) return@generateSequence null  // end sequence
+            val backupSet = iterator.next()
+            try {
+                val stream = storage.getInputStream(backupSet.metadataFile)
+                EncryptedBackupMetadata(backupSet.token, stream)
+            } catch (e: IOException) {
+                Log.e(TAG, "Error getting InputStream for backup metadata.", e)
+                EncryptedBackupMetadata(backupSet.token)
+            }
+        }
+    }
+
+    @WorkerThread
+    fun getBackups(context: Context, rootDir: DocumentFile): List<BackupSet> {
+        val backupSets = ArrayList<BackupSet>()
+        val files = try {
+            // block until the DocumentsProvider has results
+            rootDir.listFilesBlocking(context)
+        } catch (e: IOException) {
+            Log.e(TAG, "Error loading backups from storage", e)
+            return backupSets
+        }
+        for (set in files) {
+            if (!set.isDirectory || set.name == null) {
+                if (set.name != FILE_NO_MEDIA) {
+                    Log.w(TAG, "Found invalid backup set folder: ${set.name}")
+                }
+                continue
+            }
+            val token = try {
+                set.name!!.toLong()
+            } catch (e: NumberFormatException) {
+                Log.w(TAG, "Found invalid backup set folder: ${set.name}")
+                continue
+            }
+            // block until children of set are available
+            val metadata = set.findFileBlocking(context, FILE_BACKUP_METADATA)
+            if (metadata == null) {
+                Log.w(TAG, "Missing metadata file in backup set folder: ${set.name}")
+            } else {
+                backupSets.add(BackupSet(token, metadata))
+            }
+        }
+        return backupSets
+    }
+
+}
+
+class BackupSet(val token: Long, val metadataFile: DocumentFile)

app/src/main/java/com/stevesoltys/seedvault/plugins/saf/DocumentsStorage.kt

@@ -0,0 +1,204 @@
+package com.stevesoltys.seedvault.plugins.saf
+
+import android.annotation.SuppressLint
+import android.content.Context
+import android.content.pm.PackageInfo
+import android.database.ContentObserver
+import android.net.Uri
+import android.provider.DocumentsContract.*
+import android.provider.DocumentsContract.Document.*
+import android.util.Log
+import androidx.documentfile.provider.DocumentFile
+import com.stevesoltys.seedvault.settings.SettingsManager
+import com.stevesoltys.seedvault.settings.Storage
+import libcore.io.IoUtils.closeQuietly
+import java.io.IOException
+import java.io.InputStream
+import java.io.OutputStream
+import java.util.concurrent.TimeUnit.MINUTES
+
+const val DIRECTORY_ROOT = ".AndroidBackup"
+const val DIRECTORY_FULL_BACKUP = "full"
+const val DIRECTORY_KEY_VALUE_BACKUP = "kv"
+const val FILE_BACKUP_METADATA = ".backup.metadata"
+const val FILE_NO_MEDIA = ".nomedia"
+private const val MIME_TYPE = "application/octet-stream"
+
+private val TAG = DocumentsStorage::class.java.simpleName
+
+internal class DocumentsStorage(
+        private val context: Context,
+        private val settingsManager: SettingsManager) {
+
+    private val storage: Storage? = settingsManager.getStorage()
+    private val token: Long = settingsManager.getBackupToken()
+
+    internal val rootBackupDir: DocumentFile? by lazy {
+        val parent = storage?.getDocumentFile(context) ?: return@lazy null
+        try {
+            val rootDir = parent.createOrGetDirectory(DIRECTORY_ROOT)
+            // create .nomedia file to prevent Android's MediaScanner from trying to index the backup
+            rootDir.createOrGetFile(FILE_NO_MEDIA)
+            rootDir
+        } catch (e: IOException) {
+            Log.e(TAG, "Error creating root backup dir.", e)
+            null
+        }
+    }
+
+    private val currentToken: Long by lazy {
+        if (token != 0L) token
+        else settingsManager.getAndSaveNewBackupToken().apply {
+            Log.d(TAG, "Using a fresh backup token: $this")
+        }
+    }
+
+    private val currentSetDir: DocumentFile? by lazy {
+        val currentSetName = currentToken.toString()
+        try {
+            rootBackupDir?.createOrGetDirectory(currentSetName)
+        } catch (e: IOException) {
+            Log.e(TAG, "Error creating current restore set dir.", e)
+            null
+        }
+    }
+
+    val currentFullBackupDir: DocumentFile? by lazy {
+        try {
+            currentSetDir?.createOrGetDirectory(DIRECTORY_FULL_BACKUP)
+        } catch (e: IOException) {
+            Log.e(TAG, "Error creating full backup dir.", e)
+            null
+        }
+    }
+
+    val currentKvBackupDir: DocumentFile? by lazy {
+        try {
+            currentSetDir?.createOrGetDirectory(DIRECTORY_KEY_VALUE_BACKUP)
+        } catch (e: IOException) {
+            Log.e(TAG, "Error creating K/V backup dir.", e)
+            null
+        }
+    }
+
+    fun getAuthority(): String? = storage?.uri?.authority
+
+    fun getSetDir(token: Long = currentToken): DocumentFile? {
+        if (token == currentToken) return currentSetDir
+        return rootBackupDir?.findFile(token.toString())
+    }
+
+    fun getKVBackupDir(token: Long = currentToken): DocumentFile? {
+        if (token == currentToken) return currentKvBackupDir ?: throw IOException()
+        return getSetDir(token)?.findFile(DIRECTORY_KEY_VALUE_BACKUP)
+    }
+
+    @Throws(IOException::class)
+    fun getOrCreateKVBackupDir(token: Long = currentToken): DocumentFile {
+        if (token == currentToken) return currentKvBackupDir ?: throw IOException()
+        val setDir = getSetDir(token) ?: throw IOException()
+        return setDir.createOrGetDirectory(DIRECTORY_KEY_VALUE_BACKUP)
+    }
+
+    fun getFullBackupDir(token: Long = currentToken): DocumentFile? {
+        if (token == currentToken) return currentFullBackupDir ?: throw IOException()
+        return getSetDir(token)?.findFile(DIRECTORY_FULL_BACKUP)
+    }
+
+    @Throws(IOException::class)
+    fun getInputStream(file: DocumentFile): InputStream {
+        return context.contentResolver.openInputStream(file.uri) ?: throw IOException()
+    }
+
+    @Throws(IOException::class)
+    fun getOutputStream(file: DocumentFile): OutputStream {
+        return context.contentResolver.openOutputStream(file.uri, "wt") ?: throw IOException()
+    }
+
+}
+
+@Throws(IOException::class)
+fun DocumentFile.createOrGetFile(name: String, mimeType: String = MIME_TYPE): DocumentFile {
+    return findFile(name) ?: createFile(mimeType, name) ?: throw IOException()
+}
+
+@Throws(IOException::class)
+fun DocumentFile.createOrGetDirectory(name: String): DocumentFile {
+    return findFile(name) ?: createDirectory(name) ?: throw IOException()
+}
+
+@Throws(IOException::class)
+fun DocumentFile.deleteContents() {
+    for (file in listFiles()) file.delete()
+}
+
+fun DocumentFile.assertRightFile(packageInfo: PackageInfo) {
+    if (name != packageInfo.packageName) throw AssertionError()
+}
+
+/**
+ * Works like [DocumentFile.listFiles] except that it waits until the DocumentProvider has a result.
+ * This prevents getting an empty list even though there are children to be listed.
+ */
+@Throws(IOException::class)
+fun DocumentFile.listFilesBlocking(context: Context): ArrayList<DocumentFile> {
+    val resolver = context.contentResolver
+    val childrenUri = buildChildDocumentsUriUsingTree(uri, getDocumentId(uri))
+    val projection = arrayOf(COLUMN_DOCUMENT_ID, COLUMN_MIME_TYPE)
+    val result = ArrayList<DocumentFile>()
+
+    @SuppressLint("Recycle")  // gets closed in with(), only earlier exit when null
+    var cursor = resolver.query(childrenUri, projection, null, null, null)
+            ?: throw IOException()
+    val loading = cursor.extras.getBoolean(EXTRA_LOADING, false)
+    if (loading) {
+        Log.d(TAG, "Wait for children to get loaded...")
+        var loaded = false
+        cursor.registerContentObserver(object : ContentObserver(null) {
+            override fun onChange(selfChange: Boolean, uri: Uri?) {
+                Log.d(TAG, "Children loaded. Continue...")
+                loaded = true
+            }
+        })
+        val timeout = MINUTES.toMillis(2)
+        var time = 0
+        while (!loaded && time < timeout) {
+            Thread.sleep(50)
+            time += 50
+        }
+        if (time >= timeout) Log.w(TAG, "Timed out while waiting for children to load")
+        closeQuietly(cursor)
+        // do a new query after content was loaded
+        @SuppressLint("Recycle")  // gets closed after with block
+        cursor = resolver.query(childrenUri, projection, null, null, null)
+                ?: throw IOException()
+    }
+    with(cursor) {
+        while (moveToNext()) {
+            val documentId = getString(0)
+            val isDirectory = getString(1) == MIME_TYPE_DIR
+            val file = if (isDirectory) {
+                val treeUri = buildTreeDocumentUri(uri.authority, documentId)
+                DocumentFile.fromTreeUri(context, treeUri)!!
+            } else {
+                val documentUri = buildDocumentUriUsingTree(uri, documentId)
+                DocumentFile.fromSingleUri(context, documentUri)!!
+            }
+            result.add(file)
+        }
+    }
+    return result
+}
+
+fun DocumentFile.findFileBlocking(context: Context, displayName: String): DocumentFile? {
+    val files = try {
+        listFilesBlocking(context)
+    } catch (e: IOException) {
+        Log.e(TAG, "Error finding file blocking", e)
+        return null
+    }
+    for (doc in files) {
+        if (displayName == doc.name) return doc
+    }
+    return null
+}

app/src/main/java/com/stevesoltys/seedvault/restore/RestoreActivity.kt

@@ -0,0 +1,46 @@
+package com.stevesoltys.seedvault.restore
+
+import android.os.Bundle
+import androidx.annotation.CallSuper
+import androidx.lifecycle.Observer
+import com.stevesoltys.seedvault.R
+import com.stevesoltys.seedvault.ui.RequireProvisioningActivity
+import com.stevesoltys.seedvault.ui.RequireProvisioningViewModel
+import org.koin.androidx.viewmodel.ext.android.viewModel
+
+class RestoreActivity : RequireProvisioningActivity() {
+
+    private val viewModel: RestoreViewModel by viewModel()
+
+    override fun getViewModel(): RequireProvisioningViewModel = viewModel
+
+    override fun onCreate(savedInstanceState: Bundle?) {
+        super.onCreate(savedInstanceState)
+
+        if (isSetupWizard) hideSystemUI()
+
+        setContentView(R.layout.activity_fragment_container)
+
+        viewModel.chosenRestoreSet.observe(this, Observer { set ->
+            if (set != null) showFragment(RestoreProgressFragment())
+        })
+
+        if (savedInstanceState == null) {
+            showFragment(RestoreSetFragment())
+        }
+    }
+
+    @CallSuper
+    override fun onStart() {
+        super.onStart()
+        if (isFinishing) return
+
+        // check that backup is provisioned
+        if (!viewModel.validLocationIsSet()) {
+            showStorageActivity()
+        } else if (!viewModel.recoveryCodeIsSet()) {
+            showRecoveryCodeActivity()
+        }
+    }
+
+}

app/src/main/java/com/stevesoltys/seedvault/restore/RestoreProgressFragment.kt

@@ -0,0 +1,73 @@
+package com.stevesoltys.seedvault.restore
+
+import android.app.Activity.RESULT_OK
+import android.os.Bundle
+import android.view.LayoutInflater
+import android.view.View
+import android.view.View.INVISIBLE
+import android.view.View.VISIBLE
+import android.view.ViewGroup
+import android.view.WindowManager.LayoutParams.FLAG_KEEP_SCREEN_ON
+import androidx.fragment.app.Fragment
+import androidx.lifecycle.Observer
+import com.stevesoltys.seedvault.R
+import com.stevesoltys.seedvault.getAppName
+import com.stevesoltys.seedvault.isDebugBuild
+import com.stevesoltys.seedvault.settings.SettingsManager
+import kotlinx.android.synthetic.main.fragment_restore_progress.*
+import org.koin.android.ext.android.inject
+import org.koin.androidx.viewmodel.ext.android.sharedViewModel
+
+class RestoreProgressFragment : Fragment() {
+
+    private val viewModel: RestoreViewModel by sharedViewModel()
+    private val settingsManager: SettingsManager by inject()
+
+    override fun onCreateView(inflater: LayoutInflater, container: ViewGroup?,
+                              savedInstanceState: Bundle?): View? {
+        return inflater.inflate(R.layout.fragment_restore_progress, container, false)
+    }
+
+    override fun onActivityCreated(savedInstanceState: Bundle?) {
+        super.onActivityCreated(savedInstanceState)
+
+        // decryption will fail when the device is locked, so keep the screen on to prevent locking
+        requireActivity().window.addFlags(FLAG_KEEP_SCREEN_ON)
+
+        viewModel.chosenRestoreSet.observe(this, Observer { set ->
+            backupNameView.text = set.device
+        })
+
+        viewModel.restoreProgress.observe(this, Observer { currentPackage ->
+            val appName = getAppName(requireActivity().packageManager, currentPackage)
+            val displayName = if (isDebugBuild()) "$appName (${currentPackage})" else appName
+            currentPackageView.text = getString(R.string.restore_current_package, displayName)
+        })
+
+        viewModel.restoreFinished.observe(this, Observer { finished ->
+            progressBar.visibility = INVISIBLE
+            button.visibility = VISIBLE
+            if (finished == 0) {
+                // success
+                currentPackageView.text = getString(R.string.restore_finished_success)
+                warningView.text = if (settingsManager.getStorage()?.isUsb == true) {
+                    getString(R.string.restore_finished_warning_only_installed, getString(R.string.restore_finished_warning_ejectable))
+                } else {
+                    getString(R.string.restore_finished_warning_only_installed, null)
+                }
+                warningView.visibility = VISIBLE
+            } else {
+                // error
+                currentPackageView.text = getString(R.string.restore_finished_error)
+                currentPackageView.setTextColor(warningView.textColors)
+            }
+            activity?.window?.clearFlags(FLAG_KEEP_SCREEN_ON)
+        })
+
+        button.setOnClickListener {
+            requireActivity().setResult(RESULT_OK)
+            requireActivity().finishAfterTransition()
+        }
+    }
+
+}

app/src/main/java/com/stevesoltys/seedvault/restore/RestoreSetAdapter.kt

@@ -0,0 +1,42 @@
+package com.stevesoltys.seedvault.restore
+
+import android.app.backup.RestoreSet
+import android.view.LayoutInflater
+import android.view.View
+import android.view.ViewGroup
+import android.widget.TextView
+import androidx.recyclerview.widget.RecyclerView.Adapter
+import androidx.recyclerview.widget.RecyclerView.ViewHolder
+import com.stevesoltys.seedvault.R
+import com.stevesoltys.seedvault.restore.RestoreSetAdapter.RestoreSetViewHolder
+
+internal class RestoreSetAdapter(
+        private val listener: RestoreSetClickListener,
+        private val items: Array<out RestoreSet>) : Adapter<RestoreSetViewHolder>() {
+
+    override fun onCreateViewHolder(parent: ViewGroup, viewType: Int): RestoreSetViewHolder {
+        val v = LayoutInflater.from(parent.context)
+                .inflate(R.layout.list_item_restore_set, parent, false) as View
+        return RestoreSetViewHolder(v)
+    }
+
+    override fun getItemCount() = items.size
+
+    override fun onBindViewHolder(holder: RestoreSetViewHolder, position: Int) {
+        holder.bind(items[position])
+    }
+
+    inner class RestoreSetViewHolder(private val v: View) : ViewHolder(v) {
+
+        private val titleView = v.findViewById<TextView>(R.id.titleView)
+        private val subtitleView = v.findViewById<TextView>(R.id.subtitleView)
+
+        internal fun bind(item: RestoreSet) {
+            v.setOnClickListener { listener.onRestoreSetClicked(item) }
+            titleView.text = item.name
+            subtitleView.text = "Android Backup" // TODO change to backup date when available
+        }
+
+    }
+
+}

app/src/main/java/com/stevesoltys/seedvault/restore/RestoreSetFragment.kt

@@ -0,0 +1,60 @@
+package com.stevesoltys.seedvault.restore
+
+import android.app.backup.RestoreSet
+import android.os.Bundle
+import android.view.LayoutInflater
+import android.view.View
+import android.view.View.INVISIBLE
+import android.view.View.VISIBLE
+import android.view.ViewGroup
+import androidx.fragment.app.Fragment
+import androidx.lifecycle.Observer
+import com.stevesoltys.seedvault.R
+import kotlinx.android.synthetic.main.fragment_restore_set.*
+import org.koin.androidx.viewmodel.ext.android.sharedViewModel
+
+class RestoreSetFragment : Fragment() {
+
+    private val viewModel: RestoreViewModel by sharedViewModel()
+
+    override fun onCreateView(inflater: LayoutInflater, container: ViewGroup?,
+                              savedInstanceState: Bundle?): View? {
+        return inflater.inflate(R.layout.fragment_restore_set, container, false)
+    }
+
+    override fun onActivityCreated(savedInstanceState: Bundle?) {
+        super.onActivityCreated(savedInstanceState)
+
+        viewModel.restoreSets.observe(this, Observer { result -> onRestoreSetsLoaded(result) })
+
+        backView.setOnClickListener { requireActivity().finishAfterTransition() }
+    }
+
+    override fun onStart() {
+        super.onStart()
+        if (viewModel.recoveryCodeIsSet() && viewModel.validLocationIsSet()) {
+            viewModel.loadRestoreSets()
+        }
+    }
+
+    private fun onRestoreSetsLoaded(result: RestoreSetResult) {
+        if (result.hasError()) {
+            errorView.visibility = VISIBLE
+            listView.visibility = INVISIBLE
+            progressBar.visibility = INVISIBLE
+
+            errorView.text = result.errorMsg
+        } else {
+            errorView.visibility = INVISIBLE
+            listView.visibility = VISIBLE
+            progressBar.visibility = INVISIBLE
+
+            listView.adapter = RestoreSetAdapter(viewModel, result.sets)
+        }
+    }
+
+}
+
+internal interface RestoreSetClickListener {
+    fun onRestoreSetClicked(set: RestoreSet)
+}

app/src/main/java/com/stevesoltys/seedvault/restore/RestoreViewModel.kt

@@ -0,0 +1,155 @@
+package com.stevesoltys.seedvault.restore
+
+import android.app.Application
+import android.app.backup.IBackupManager
+import android.app.backup.IRestoreObserver
+import android.app.backup.IRestoreSession
+import android.app.backup.RestoreSet
+import android.os.UserHandle
+import android.util.Log
+import androidx.annotation.WorkerThread
+import androidx.lifecycle.LiveData
+import androidx.lifecycle.MutableLiveData
+import com.stevesoltys.seedvault.BackupMonitor
+import com.stevesoltys.seedvault.R
+import com.stevesoltys.seedvault.crypto.KeyManager
+import com.stevesoltys.seedvault.settings.SettingsManager
+import com.stevesoltys.seedvault.transport.TRANSPORT_ID
+import com.stevesoltys.seedvault.transport.restore.RestorePlugin
+import com.stevesoltys.seedvault.ui.RequireProvisioningViewModel
+
+private val TAG = RestoreViewModel::class.java.simpleName
+
+internal class RestoreViewModel(
+        app: Application,
+        settingsManager: SettingsManager,
+        keyManager: KeyManager,
+        private val backupManager: IBackupManager
+) : RequireProvisioningViewModel(app, settingsManager, keyManager), RestoreSetClickListener {
+
+    override val isRestoreOperation = true
+
+    private var session: IRestoreSession? = null
+    private var observer: RestoreObserver? = null
+    private val monitor = BackupMonitor()
+
+    private val mRestoreSets = MutableLiveData<RestoreSetResult>()
+    internal val restoreSets: LiveData<RestoreSetResult> get() = mRestoreSets
+
+    private val mChosenRestoreSet = MutableLiveData<RestoreSet>()
+    internal val chosenRestoreSet: LiveData<RestoreSet> get() = mChosenRestoreSet
+
+    private val mRestoreProgress = MutableLiveData<String>()
+    internal val restoreProgress: LiveData<String> get() = mRestoreProgress
+
+    private val mRestoreFinished = MutableLiveData<Int>()
+    // Zero on success; a nonzero error code if the restore operation as a whole failed.
+    internal val restoreFinished: LiveData<Int> get() = mRestoreFinished
+
+    internal fun loadRestoreSets() {
+        val session = this.session ?: backupManager.beginRestoreSessionForUser(UserHandle.myUserId(), null, TRANSPORT_ID)
+        this.session = session
+
+        if (session == null) {
+            Log.e(TAG, "beginRestoreSession() returned null session")
+            mRestoreSets.value = RestoreSetResult(app.getString(R.string.restore_set_error))
+            return
+        }
+        val observer = this.observer ?: RestoreObserver()
+        this.observer = observer
+
+        val setResult = session.getAvailableRestoreSets(observer, monitor)
+        if (setResult != 0) {
+            Log.e(TAG, "getAvailableRestoreSets() returned non-zero value")
+            mRestoreSets.value = RestoreSetResult(app.getString(R.string.restore_set_error))
+            return
+        }
+    }
+
+    override fun onRestoreSetClicked(set: RestoreSet) {
+        val session = this.session
+        check(session != null) { "Restore set clicked, but no session available" }
+        session.restoreAll(set.token, observer, monitor)
+
+        mChosenRestoreSet.value = set
+    }
+
+    override fun onCleared() {
+        super.onCleared()
+        endSession()
+    }
+
+    private fun endSession() {
+        session?.endRestoreSession()
+        session = null
+        observer = null
+    }
+
+    @WorkerThread
+    private inner class RestoreObserver : IRestoreObserver.Stub() {
+
+        /**
+         * Supply a list of the restore datasets available from the current transport.
+         * This method is invoked as a callback following the application's use of the
+         * [IRestoreSession.getAvailableRestoreSets] method.
+         *
+         * @param restoreSets An array of [RestoreSet] objects
+         *   describing all of the available datasets that are candidates for restoring to
+         *   the current device. If no applicable datasets exist, restoreSets will be null.
+         */
+        override fun restoreSetsAvailable(restoreSets: Array<out RestoreSet>?) {
+            if (restoreSets == null || restoreSets.isEmpty()) {
+                mRestoreSets.postValue(RestoreSetResult(app.getString(R.string.restore_set_empty_result)))
+            } else {
+                mRestoreSets.postValue(RestoreSetResult(restoreSets))
+            }
+        }
+
+        /**
+         * The restore operation has begun.
+         *
+         * @param numPackages The total number of packages being processed in this restore operation.
+         */
+        override fun restoreStarting(numPackages: Int) {
+            // noop
+        }
+
+        /**
+         * An indication of which package is being restored currently,
+         * out of the total number provided in the [restoreStarting] callback.
+         * This method is not guaranteed to be called.
+         *
+         * @param nowBeingRestored The index, between 1 and the numPackages parameter
+         *   to the [restoreStarting] callback, of the package now being restored.
+         * @param currentPackage The name of the package now being restored.
+         */
+        override fun onUpdate(nowBeingRestored: Int, currentPackage: String) {
+            // nowBeingRestored reporting is buggy, so don't use it
+            mRestoreProgress.postValue(currentPackage)
+        }
+
+        /**
+         * The restore operation has completed.
+         *
+         * @param result Zero on success; a nonzero error code if the restore operation
+         *   as a whole failed.
+         */
+        override fun restoreFinished(result: Int) {
+            mRestoreFinished.postValue(result)
+            endSession()
+        }
+
+    }
+
+}
+
+internal class RestoreSetResult(
+        internal val sets: Array<out RestoreSet>,
+        internal val errorMsg: String?) {
+
+    internal constructor(sets: Array<out RestoreSet>) : this(sets, null)
+
+    internal constructor(errorMsg: String) : this(emptyArray(), errorMsg)
+
+    internal fun hasError(): Boolean = errorMsg != null
+}

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

@@ -0,0 +1,29 @@
+package com.stevesoltys.seedvault.settings
+
+import android.os.Bundle
+import android.text.method.LinkMovementMethod
+import android.view.LayoutInflater
+import android.view.View
+import android.view.ViewGroup
+import androidx.fragment.app.DialogFragment
+import com.stevesoltys.seedvault.R
+import kotlinx.android.synthetic.main.fragment_about.*
+
+class AboutDialogFragment : DialogFragment() {
+
+    companion object {
+        internal val TAG = AboutDialogFragment::class.java.simpleName
+    }
+
+    override fun onCreateView(inflater: LayoutInflater, container: ViewGroup?, savedInstanceState: Bundle?): View? {
+        return inflater.inflate(R.layout.fragment_about, container, false)
+    }
+
+    override fun onViewCreated(view: View, savedInstanceState: Bundle?) {
+        val linkMovementMethod = LinkMovementMethod.getInstance()
+        licenseView.movementMethod = linkMovementMethod
+        authorView.movementMethod = linkMovementMethod
+        sponsorView.movementMethod = linkMovementMethod
+    }
+
+}

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

@@ -0,0 +1,37 @@
+package com.stevesoltys.seedvault.settings
+
+import android.content.ContentResolver
+import android.provider.Settings
+import java.util.concurrent.TimeUnit.DAYS
+
+private val SETTING = Settings.Secure.BACKUP_MANAGER_CONSTANTS
+private const val DELIMITER = ','
+
+private const val KEY_VALUE_BACKUP_INTERVAL_MILLISECONDS = "key_value_backup_interval_milliseconds"
+private const val FULL_BACKUP_INTERVAL_MILLISECONDS = "full_backup_interval_milliseconds"
+
+object BackupManagerSettings {
+
+    /**
+     * This clears the backup settings, so that default values will be used.
+     */
+    fun enableAutomaticBackups(resolver: ContentResolver) {
+        // setting this to null will cause the BackupManagerConstants to use default values
+        setSettingValue(resolver, null)
+    }
+
+    /**
+     * This sets the backup intervals to a longer than default value. Currently 30 days
+     */
+    fun disableAutomaticBackups(resolver: ContentResolver) {
+        val value = DAYS.toMillis(30)
+        val kv = "$KEY_VALUE_BACKUP_INTERVAL_MILLISECONDS=$value"
+        val full = "$FULL_BACKUP_INTERVAL_MILLISECONDS=$value"
+        setSettingValue(resolver, "$kv$DELIMITER$full")
+    }
+
+    private fun setSettingValue(resolver: ContentResolver, value: String?) {
+        Settings.Secure.putString(resolver, SETTING, value)
+    }
+
+}

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

@@ -0,0 +1,44 @@
+package com.stevesoltys.seedvault.settings
+
+import android.os.Bundle
+import androidx.annotation.CallSuper
+import com.stevesoltys.seedvault.BackupNotificationManager
+import com.stevesoltys.seedvault.R
+import com.stevesoltys.seedvault.ui.RequireProvisioningActivity
+import com.stevesoltys.seedvault.ui.RequireProvisioningViewModel
+import org.koin.android.ext.android.inject
+import org.koin.androidx.viewmodel.ext.android.viewModel
+
+class SettingsActivity : RequireProvisioningActivity() {
+
+    private val viewModel: SettingsViewModel by viewModel()
+    private val notificationManager: BackupNotificationManager by inject()
+
+    override fun getViewModel(): RequireProvisioningViewModel = viewModel
+
+    override fun onCreate(savedInstanceState: Bundle?) {
+        super.onCreate(savedInstanceState)
+
+        setContentView(R.layout.activity_fragment_container)
+
+        supportActionBar!!.setDisplayHomeAsUpEnabled(true)
+
+        if (savedInstanceState == null) showFragment(SettingsFragment())
+    }
+
+    @CallSuper
+    override fun onStart() {
+        super.onStart()
+        if (isFinishing) return
+
+        // check that backup is provisioned
+        if (!viewModel.recoveryCodeIsSet()) {
+            showRecoveryCodeActivity()
+        } else if (!viewModel.validLocationIsSet()) {
+            showStorageActivity()
+            // remove potential error notifications
+            notificationManager.onBackupErrorSeen()
+        }
+    }
+
+}

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

@@ -0,0 +1,187 @@
+package com.stevesoltys.seedvault.settings
+
+import android.app.backup.IBackupManager
+import android.content.Context
+import android.content.Context.BACKUP_SERVICE
+import android.content.Intent
+import android.content.IntentFilter
+import android.hardware.usb.UsbDevice
+import android.hardware.usb.UsbManager.ACTION_USB_DEVICE_ATTACHED
+import android.hardware.usb.UsbManager.ACTION_USB_DEVICE_DETACHED
+import android.os.Bundle
+import android.os.RemoteException
+import android.provider.Settings
+import android.provider.Settings.Secure.BACKUP_AUTO_RESTORE
+import android.text.format.DateUtils.MINUTE_IN_MILLIS
+import android.text.format.DateUtils.getRelativeTimeSpanString
+import android.util.Log
+import android.view.Menu
+import android.view.MenuInflater
+import android.view.MenuItem
+import androidx.preference.Preference
+import androidx.preference.Preference.OnPreferenceChangeListener
+import androidx.preference.PreferenceFragmentCompat
+import androidx.preference.TwoStatePreference
+import com.stevesoltys.seedvault.R
+import com.stevesoltys.seedvault.UsbMonitor
+import com.stevesoltys.seedvault.isMassStorage
+import com.stevesoltys.seedvault.restore.RestoreActivity
+import org.koin.android.ext.android.inject
+import org.koin.androidx.viewmodel.ext.android.sharedViewModel
+import java.util.*
+
+private val TAG = SettingsFragment::class.java.name
+
+class SettingsFragment : PreferenceFragmentCompat() {
+
+    private val viewModel: SettingsViewModel by sharedViewModel()
+    private val settingsManager: SettingsManager by inject()
+    private val backupManager: IBackupManager by inject()
+
+    private lateinit var backup: TwoStatePreference
+    private lateinit var autoRestore: TwoStatePreference
+    private lateinit var backupLocation: Preference
+
+    private var menuBackupNow: MenuItem? = null
+    private var menuRestore: MenuItem? = null
+
+    private var storage: Storage? = null
+    private val usbFilter = IntentFilter(ACTION_USB_DEVICE_ATTACHED).apply {
+        addAction(ACTION_USB_DEVICE_DETACHED)
+    }
+    private val usbReceiver = object : UsbMonitor() {
+        override fun shouldMonitorStatus(context: Context, action: String, device: UsbDevice): Boolean {
+            return device.isMassStorage()
+        }
+
+        override fun onStatusChanged(context: Context, action: String, device: UsbDevice) {
+            setMenuItemStates()
+        }
+    }
+
+    override fun onCreatePreferences(savedInstanceState: Bundle?, rootKey: String?) {
+        setPreferencesFromResource(R.xml.settings, rootKey)
+        setHasOptionsMenu(true)
+
+        backup = findPreference<TwoStatePreference>("backup")!!
+        backup.onPreferenceChangeListener = OnPreferenceChangeListener { _, newValue ->
+            val enabled = newValue as Boolean
+            try {
+                backupManager.isBackupEnabled = enabled
+                return@OnPreferenceChangeListener true
+            } catch (e: RemoteException) {
+                e.printStackTrace()
+                backup.isChecked = !enabled
+                return@OnPreferenceChangeListener false
+            }
+        }
+
+        backupLocation = findPreference<Preference>("backup_location")!!
+        backupLocation.setOnPreferenceClickListener {
+            viewModel.chooseBackupLocation()
+            true
+        }
+
+        autoRestore = findPreference<TwoStatePreference>("auto_restore")!!
+        autoRestore.onPreferenceChangeListener = OnPreferenceChangeListener { _, newValue ->
+            val enabled = newValue as Boolean
+            try {
+                backupManager.setAutoRestore(enabled)
+                return@OnPreferenceChangeListener true
+            } catch (e: RemoteException) {
+                Log.e(TAG, "Error communicating with BackupManager", e)
+                autoRestore.isChecked = !enabled
+                return@OnPreferenceChangeListener false
+            }
+        }
+    }
+
+    override fun onStart() {
+        super.onStart()
+
+        // we need to re-set the title when returning to this fragment
+        activity?.setTitle(R.string.backup)
+
+        storage = settingsManager.getStorage()
+        setBackupState()
+        setAutoRestoreState()
+        setBackupLocationSummary()
+        setMenuItemStates()
+
+        if (storage?.isUsb == true) context?.registerReceiver(usbReceiver, usbFilter)
+    }
+
+    override fun onStop() {
+        super.onStop()
+        if (storage?.isUsb == true) context?.unregisterReceiver(usbReceiver)
+    }
+
+    override fun onCreateOptionsMenu(menu: Menu, inflater: MenuInflater) {
+        super.onCreateOptionsMenu(menu, inflater)
+        inflater.inflate(R.menu.settings_menu, menu)
+        menuBackupNow = menu.findItem(R.id.action_backup)
+        menuRestore = menu.findItem(R.id.action_restore)
+        if (resources.getBoolean(R.bool.show_restore_in_settings)) {
+            menuRestore?.isVisible = true
+        }
+        setMenuItemStates()
+    }
+
+    override fun onOptionsItemSelected(item: MenuItem): Boolean = when {
+        item.itemId == R.id.action_backup -> {
+            viewModel.backupNow()
+            true
+        }
+        item.itemId == R.id.action_restore -> {
+            startActivity(Intent(requireContext(), RestoreActivity::class.java))
+            true
+        }
+        item.itemId == R.id.action_about -> {
+            AboutDialogFragment().show(fragmentManager!!, AboutDialogFragment.TAG)
+            true
+        }
+        else -> super.onOptionsItemSelected(item)
+    }
+
+    private fun setBackupState() {
+        try {
+            backup.isChecked = backupManager.isBackupEnabled
+            backup.isEnabled = true
+        } catch (e: RemoteException) {
+            Log.e(TAG, "Error communicating with BackupManager", e)
+            backup.isEnabled = false
+        }
+    }
+
+    private fun setAutoRestoreState() {
+        activity?.contentResolver?.let {
+            autoRestore.isChecked = Settings.Secure.getInt(it, BACKUP_AUTO_RESTORE, 1) == 1
+        }
+    }
+
+    private fun setBackupLocationSummary() {
+        // get name of storage location
+        val storageName = storage?.name ?: getString(R.string.settings_backup_location_none)
+
+        // get time of last backup
+        val lastBackupInMillis = settingsManager.getBackupTime()
+        val lastBackup = if (lastBackupInMillis == 0L) {
+            getString(R.string.settings_backup_last_backup_never)
+        } else {
+            getRelativeTimeSpanString(lastBackupInMillis, Date().time, MINUTE_IN_MILLIS, 0)
+        }
+        backupLocation.summary = getString(R.string.settings_backup_location_summary, storageName, lastBackup)
+    }
+
+    private fun setMenuItemStates() {
+        val context = context ?: return
+        if (menuBackupNow != null && menuRestore != null) {
+            val storage = this.storage
+            val enabled = storage != null &&
+                    (!storage.isUsb || storage.getDocumentFile(context).isDirectory)
+            menuBackupNow?.isEnabled = enabled
+            menuRestore?.isEnabled = enabled
+        }
+    }
+
+}

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

@@ -0,0 +1,134 @@
+package com.stevesoltys.seedvault.settings
+
+import android.content.Context
+import android.hardware.usb.UsbDevice
+import android.net.Uri
+import androidx.documentfile.provider.DocumentFile
+import androidx.preference.PreferenceManager
+import java.util.*
+
+private const val PREF_KEY_STORAGE_URI = "storageUri"
+private const val PREF_KEY_STORAGE_NAME = "storageName"
+private const val PREF_KEY_STORAGE_IS_USB = "storageIsUsb"
+
+private const val PREF_KEY_FLASH_DRIVE_NAME = "flashDriveName"
+private const val PREF_KEY_FLASH_DRIVE_SERIAL_NUMBER = "flashSerialNumber"
+private const val PREF_KEY_FLASH_DRIVE_VENDOR_ID = "flashDriveVendorId"
+private const val PREF_KEY_FLASH_DRIVE_PRODUCT_ID = "flashDriveProductId"
+
+private const val PREF_KEY_BACKUP_TOKEN = "backupToken"
+private const val PREF_KEY_BACKUP_TIME = "backupTime"
+
+class SettingsManager(context: Context) {
+
+    private val prefs = PreferenceManager.getDefaultSharedPreferences(context)
+
+    // FIXME Storage is currently plugin specific and not generic
+    fun setStorage(storage: Storage) {
+        prefs.edit()
+                .putString(PREF_KEY_STORAGE_URI, storage.uri.toString())
+                .putString(PREF_KEY_STORAGE_NAME, storage.name)
+                .putBoolean(PREF_KEY_STORAGE_IS_USB, storage.isUsb)
+                .apply()
+    }
+
+    fun getStorage(): Storage? {
+        val uriStr = prefs.getString(PREF_KEY_STORAGE_URI, null) ?: return null
+        val uri = Uri.parse(uriStr)
+        val name = prefs.getString(PREF_KEY_STORAGE_NAME, null) ?: throw IllegalStateException("no storage name")
+        val isUsb = prefs.getBoolean(PREF_KEY_STORAGE_IS_USB, false)
+        return Storage(uri, name, isUsb)
+    }
+
+    fun setFlashDrive(usb: FlashDrive?) {
+        if (usb == null) {
+            prefs.edit()
+                    .remove(PREF_KEY_FLASH_DRIVE_NAME)
+                    .remove(PREF_KEY_FLASH_DRIVE_SERIAL_NUMBER)
+                    .remove(PREF_KEY_FLASH_DRIVE_VENDOR_ID)
+                    .remove(PREF_KEY_FLASH_DRIVE_PRODUCT_ID)
+                    .apply()
+        } else {
+            prefs.edit()
+                    .putString(PREF_KEY_FLASH_DRIVE_NAME, usb.name)
+                    .putString(PREF_KEY_FLASH_DRIVE_SERIAL_NUMBER, usb.serialNumber)
+                    .putInt(PREF_KEY_FLASH_DRIVE_VENDOR_ID, usb.vendorId)
+                    .putInt(PREF_KEY_FLASH_DRIVE_PRODUCT_ID, usb.productId)
+                    .apply()
+        }
+    }
+
+    fun getFlashDrive(): FlashDrive? {
+        val name = prefs.getString(PREF_KEY_FLASH_DRIVE_NAME, null) ?: return null
+        val serialNumber = prefs.getString(PREF_KEY_FLASH_DRIVE_SERIAL_NUMBER, null)
+        val vendorId = prefs.getInt(PREF_KEY_FLASH_DRIVE_VENDOR_ID, -1)
+        val productId = prefs.getInt(PREF_KEY_FLASH_DRIVE_PRODUCT_ID, -1)
+        return FlashDrive(name, serialNumber, vendorId, productId)
+    }
+
+    /**
+     * Generates and returns a new backup token while saving it as well.
+     * Subsequent calls to [getBackupToken] will return this new token once saved.
+     */
+    fun getAndSaveNewBackupToken(): Long = Date().time.apply {
+        prefs.edit()
+                .putLong(PREF_KEY_BACKUP_TOKEN, this)
+                .apply()
+    }
+
+    /**
+     * Returns the current backup token or 0 if none exists.
+     */
+    fun getBackupToken(): Long {
+        return prefs.getLong(PREF_KEY_BACKUP_TOKEN, 0L)
+    }
+
+    /**
+     * Sets the last backup time to "now".
+     */
+    fun saveNewBackupTime() {
+        prefs.edit()
+                .putLong(PREF_KEY_BACKUP_TIME, Date().time)
+                .apply()
+    }
+
+    /**
+     * Sets the last backup time to "never".
+     */
+    fun resetBackupTime() {
+        prefs.edit()
+                .putLong(PREF_KEY_BACKUP_TIME, 0L)
+                .apply()
+    }
+
+    /**
+     * Returns the last backup time in unix epoch milli seconds.
+     */
+    fun getBackupTime(): Long {
+        return prefs.getLong(PREF_KEY_BACKUP_TIME, 0L)
+    }
+
+}
+
+data class Storage(
+        val uri: Uri,
+        val name: String,
+        val isUsb: Boolean) {
+    fun getDocumentFile(context: Context) = DocumentFile.fromTreeUri(context, uri)
+            ?: throw AssertionError("Should only happen on API < 21.")
+}
+
+data class FlashDrive(
+        val name: String,
+        val serialNumber: String?,
+        val vendorId: Int,
+        val productId: Int) {
+    companion object {
+        fun from(device: UsbDevice) = FlashDrive(
+                name = "${device.manufacturerName} ${device.productName}",
+                serialNumber = device.serialNumber,
+                vendorId = device.vendorId,
+                productId = device.productId
+        )
+    }
+}

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

@@ -0,0 +1,20 @@
+package com.stevesoltys.seedvault.settings
+
+import android.app.Application
+import com.stevesoltys.seedvault.crypto.KeyManager
+import com.stevesoltys.seedvault.transport.requestBackup
+import com.stevesoltys.seedvault.ui.RequireProvisioningViewModel
+
+class SettingsViewModel(
+        app: Application,
+        settingsManager: SettingsManager,
+        keyManager: KeyManager
+) : RequireProvisioningViewModel(app, settingsManager, keyManager) {
+
+    override val isRestoreOperation = false
+
+    fun backupNow() {
+        Thread { requestBackup(app) }.start()
+    }
+
+}

app/src/main/java/com/stevesoltys/seedvault/transport/ConfigurableBackupTransport.kt

@@ -0,0 +1,162 @@
+package com.stevesoltys.seedvault.transport
+
+import android.app.backup.BackupAgent.FLAG_CLIENT_SIDE_ENCRYPTION_ENABLED
+import android.app.backup.BackupTransport
+import android.app.backup.RestoreDescription
+import android.app.backup.RestoreSet
+import android.content.Context
+import android.content.Intent
+import android.content.pm.PackageInfo
+import android.os.ParcelFileDescriptor
+import android.util.Log
+import com.stevesoltys.seedvault.settings.SettingsActivity
+import com.stevesoltys.seedvault.transport.backup.BackupCoordinator
+import com.stevesoltys.seedvault.transport.restore.RestoreCoordinator
+import org.koin.core.KoinComponent
+import org.koin.core.inject
+
+val TRANSPORT_ID: String = ConfigurableBackupTransport::class.java.name
+
+private const val TRANSPORT_DIRECTORY_NAME = "com.stevesoltys.seedvault.transport.ConfigurableBackupTransport"
+private val TAG = ConfigurableBackupTransport::class.java.simpleName
+
+/**
+ * @author Steve Soltys
+ * @author Torsten Grote
+ */
+class ConfigurableBackupTransport internal constructor(private val context: Context) : BackupTransport(), KoinComponent {
+
+    private val backupCoordinator by inject<BackupCoordinator>()
+    private val restoreCoordinator by inject<RestoreCoordinator>()
+
+    override fun transportDirName(): String {
+        return TRANSPORT_DIRECTORY_NAME
+    }
+
+    override fun name(): String {
+        return TRANSPORT_ID
+    }
+
+    override fun getTransportFlags(): Int {
+        return FLAG_CLIENT_SIDE_ENCRYPTION_ENABLED
+    }
+
+    override fun dataManagementIntent(): Intent {
+        return Intent(context, SettingsActivity::class.java)
+    }
+
+    override fun dataManagementLabel(): String {
+        return "Please file a bug if you see this! 1"
+    }
+
+    override fun currentDestinationString(): String {
+        return "Please file a bug if you see this! 2"
+    }
+
+    // ------------------------------------------------------------------------------------
+    // General backup methods
+    //
+
+    override fun initializeDevice(): Int {
+        return backupCoordinator.initializeDevice()
+    }
+
+    override fun isAppEligibleForBackup(targetPackage: PackageInfo, isFullBackup: Boolean): Boolean {
+        return backupCoordinator.isAppEligibleForBackup(targetPackage, isFullBackup)
+    }
+
+    override fun getBackupQuota(packageName: String, isFullBackup: Boolean): Long {
+        return backupCoordinator.getBackupQuota(packageName, isFullBackup)
+    }
+
+    override fun clearBackupData(packageInfo: PackageInfo): Int {
+        return backupCoordinator.clearBackupData(packageInfo)
+    }
+
+    override fun finishBackup(): Int {
+        return backupCoordinator.finishBackup()
+    }
+
+    // ------------------------------------------------------------------------------------
+    // Key/value incremental backup support
+    //
+
+    override fun requestBackupTime(): Long {
+        return backupCoordinator.requestBackupTime()
+    }
+
+    override fun performBackup(packageInfo: PackageInfo, inFd: ParcelFileDescriptor, flags: Int): Int {
+        return backupCoordinator.performIncrementalBackup(packageInfo, inFd, flags)
+    }
+
+    override fun performBackup(targetPackage: PackageInfo, fileDescriptor: ParcelFileDescriptor): Int {
+        Log.w(TAG, "Warning: Legacy performBackup() method called.")
+        return performBackup(targetPackage, fileDescriptor, 0)
+    }
+
+    // ------------------------------------------------------------------------------------
+    // Full backup
+    //
+
+    override fun requestFullBackupTime(): Long {
+        return backupCoordinator.requestFullBackupTime()
+    }
+
+    override fun checkFullBackupSize(size: Long): Int {
+        return backupCoordinator.checkFullBackupSize(size)
+    }
+
+    override fun performFullBackup(targetPackage: PackageInfo, socket: ParcelFileDescriptor, flags: Int): Int {
+        return backupCoordinator.performFullBackup(targetPackage, socket, flags)
+    }
+
+    override fun performFullBackup(targetPackage: PackageInfo, fileDescriptor: ParcelFileDescriptor): Int {
+        Log.w(TAG, "Warning: Legacy performFullBackup() method called.")
+        return backupCoordinator.performFullBackup(targetPackage, fileDescriptor, 0)
+    }
+
+    override fun sendBackupData(numBytes: Int): Int {
+        return backupCoordinator.sendBackupData(numBytes)
+    }
+
+    override fun cancelFullBackup() {
+        backupCoordinator.cancelFullBackup()
+    }
+
+    // ------------------------------------------------------------------------------------
+    // Restore
+    //
+
+    override fun getAvailableRestoreSets(): Array<RestoreSet>? {
+        return restoreCoordinator.getAvailableRestoreSets()
+    }
+
+    override fun getCurrentRestoreSet(): Long {
+        return restoreCoordinator.getCurrentRestoreSet()
+    }
+
+    override fun startRestore(token: Long, packages: Array<PackageInfo>): Int {
+        return restoreCoordinator.startRestore(token, packages)
+    }
+
+    override fun getNextFullRestoreDataChunk(socket: ParcelFileDescriptor): Int {
+        return restoreCoordinator.getNextFullRestoreDataChunk(socket)
+    }
+
+    override fun nextRestorePackage(): RestoreDescription? {
+        return restoreCoordinator.nextRestorePackage()
+    }
+
+    override fun getRestoreData(outputFileDescriptor: ParcelFileDescriptor): Int {
+        return restoreCoordinator.getRestoreData(outputFileDescriptor)
+    }
+
+    override fun abortFullRestore(): Int {
+        return restoreCoordinator.abortFullRestore()
+    }
+
+    override fun finishRestore() {
+        restoreCoordinator.finishRestore()
+    }
+
+}

app/src/main/java/com/stevesoltys/seedvault/transport/ConfigurableBackupTransportService.kt

@@ -0,0 +1,73 @@
+package com.stevesoltys.seedvault.transport
+
+import android.app.Service
+import android.app.backup.BackupManager
+import android.app.backup.BackupManager.FLAG_NON_INCREMENTAL_BACKUP
+import android.app.backup.BackupTransport.FLAG_USER_INITIATED
+import android.app.backup.IBackupManager
+import android.content.Context
+import android.content.Context.BACKUP_SERVICE
+import android.content.Intent
+import android.os.IBinder
+import android.os.RemoteException
+import android.util.Log
+import androidx.annotation.WorkerThread
+import com.stevesoltys.seedvault.BackupMonitor
+import com.stevesoltys.seedvault.BackupNotificationManager
+import com.stevesoltys.seedvault.NotificationBackupObserver
+import com.stevesoltys.seedvault.R
+import org.koin.core.context.GlobalContext.get
+
+private val TAG = ConfigurableBackupTransportService::class.java.simpleName
+
+/**
+ * @author Steve Soltys
+ * @author Torsten Grote
+ */
+class ConfigurableBackupTransportService : Service() {
+
+    private var transport: ConfigurableBackupTransport? = null
+
+    override fun onCreate() {
+        super.onCreate()
+        transport = ConfigurableBackupTransport(applicationContext)
+        Log.d(TAG, "Service created.")
+    }
+
+    override fun onBind(intent: Intent): IBinder {
+        val transport = this.transport ?: throw IllegalStateException("no transport in onBind()")
+        return transport.binder.apply {
+            Log.d(TAG, "Transport bound.")
+        }
+    }
+
+    override fun onDestroy() {
+        super.onDestroy()
+        transport = null
+        Log.d(TAG, "Service destroyed.")
+    }
+
+}
+
+@WorkerThread
+fun requestBackup(context: Context) {
+    // show notification
+    val nm: BackupNotificationManager = get().koin.get()
+    nm.onBackupUpdate(context.getString(R.string.notification_backup_starting), 0, 1, true)
+
+    val observer = NotificationBackupObserver(context, true)
+    val flags = FLAG_NON_INCREMENTAL_BACKUP or FLAG_USER_INITIATED
+    val packages = PackageService.eligiblePackages
+    val result = try {
+        val backupManager: IBackupManager = get().koin.get()
+        backupManager.requestBackup(packages, observer, BackupMonitor(), flags)
+    } catch (e: RemoteException) {
+        Log.e(TAG, "Error during backup: ", e)
+        nm.onBackupError()
+    }
+    if (result == BackupManager.SUCCESS) {
+        Log.i(TAG, "Backup succeeded ")
+    } else {
+        Log.e(TAG, "Backup failed: $result")
+    }
+}

app/src/main/java/com/stevesoltys/seedvault/transport/PackageService.kt

@@ -0,0 +1,60 @@
+package com.stevesoltys.seedvault.transport
+
+import android.app.backup.IBackupManager
+import android.content.pm.IPackageManager
+import android.content.pm.PackageInfo
+import android.os.RemoteException
+import android.os.ServiceManager.getService
+import android.os.UserHandle
+import android.util.Log
+import com.google.android.collect.Sets.newArraySet
+import com.stevesoltys.seedvault.MAGIC_PACKAGE_MANAGER
+import org.koin.core.KoinComponent
+import org.koin.core.inject
+import java.util.*
+
+private val TAG = PackageService::class.java.simpleName
+
+private val IGNORED_PACKAGES = newArraySet(
+        "com.android.externalstorage",
+        "com.android.providers.downloads.ui",
+        "com.android.providers.downloads",
+        "com.android.providers.media",
+        "com.android.providers.calendar",
+        "com.android.providers.contacts",
+        "com.stevesoltys.seedvault"
+)
+
+/**
+ * @author Steve Soltys
+ * @author Torsten Grote
+ */
+internal object PackageService : KoinComponent {
+
+    private val backupManager: IBackupManager by inject()
+    private val packageManager: IPackageManager = IPackageManager.Stub.asInterface(getService("package"))
+
+    val eligiblePackages: Array<String>
+        @Throws(RemoteException::class)
+        get() {
+            val packages: List<PackageInfo> = packageManager.getInstalledPackages(0, UserHandle.USER_SYSTEM).list as List<PackageInfo>
+            val packageList = packages
+                    .map { packageInfo -> packageInfo.packageName }
+                    .filter { packageName -> !IGNORED_PACKAGES.contains(packageName) }
+                    .sorted()
+
+            Log.d(TAG, "Got ${packageList.size} packages: $packageList")
+
+            // TODO why is this filtering out so much?
+            val eligibleApps = backupManager.filterAppsEligibleForBackupForUser(UserHandle.myUserId(), packageList.toTypedArray())
+
+            Log.d(TAG, "Filtering left ${eligibleApps.size} eligible packages: ${Arrays.toString(eligibleApps)}")
+
+            // add magic @pm@ package (PACKAGE_MANAGER_SENTINEL) which holds package manager data
+            val packageArray = eligibleApps.toMutableList()
+            packageArray.add(MAGIC_PACKAGE_MANAGER)
+
+            return packageArray.toTypedArray()
+        }
+
+}

app/src/main/java/com/stevesoltys/seedvault/transport/backup/BackupCoordinator.kt

@@ -0,0 +1,214 @@
+package com.stevesoltys.seedvault.transport.backup
+
+import android.app.backup.BackupTransport.*
+import android.content.Context
+import android.content.pm.PackageInfo
+import android.os.ParcelFileDescriptor
+import android.util.Log
+import com.stevesoltys.seedvault.BackupNotificationManager
+import com.stevesoltys.seedvault.MAGIC_PACKAGE_MANAGER
+import com.stevesoltys.seedvault.metadata.MetadataWriter
+import com.stevesoltys.seedvault.settings.SettingsManager
+import java.io.IOException
+import java.util.concurrent.TimeUnit.DAYS
+
+private val TAG = BackupCoordinator::class.java.simpleName
+
+/**
+ * @author Steve Soltys
+ * @author Torsten Grote
+ */
+internal class BackupCoordinator(
+        private val context: Context,
+        private val plugin: BackupPlugin,
+        private val kv: KVBackup,
+        private val full: FullBackup,
+        private val metadataWriter: MetadataWriter,
+        private val settingsManager: SettingsManager,
+        private val nm: BackupNotificationManager) {
+
+    private var calledInitialize = false
+    private var calledClearBackupData = false
+
+    // ------------------------------------------------------------------------------------
+    // Transport initialization and quota
+    //
+
+    /**
+     * Initialize the storage for this device, erasing all stored data.
+     * The transport may send the request immediately, or may buffer it.
+     * After this is called,
+     * [finishBackup] will be called to ensure the request is sent and received successfully.
+     *
+     * If the transport returns anything other than [TRANSPORT_OK] from this method,
+     * the OS will halt the current initialize operation and schedule a retry in the near future.
+     * Even if the transport is in a state
+     * such that attempting to "initialize" the backend storage is meaningless -
+     * for example, if there is no current live data-set at all,
+     * or there is no authenticated account under which to store the data remotely -
+     * the transport should return [TRANSPORT_OK] here
+     * and treat the initializeDevice() / finishBackup() pair as a graceful no-op.
+     *
+     * @return One of [TRANSPORT_OK] (OK so far) or
+     * [TRANSPORT_ERROR] (to retry following network error or other failure).
+     */
+    fun initializeDevice(): Int {
+        Log.i(TAG, "Initialize Device!")
+        return try {
+            plugin.initializeDevice()
+            writeBackupMetadata(settingsManager.getBackupToken())
+            // [finishBackup] will only be called when we return [TRANSPORT_OK] here
+            // so we remember that we initialized successfully
+            calledInitialize = true
+            TRANSPORT_OK
+        } catch (e: IOException) {
+            Log.e(TAG, "Error initializing device", e)
+            // Show error notification if we were ready for backups
+            if (getBackupBackoff() == 0L) nm.onBackupError()
+            TRANSPORT_ERROR
+        }
+    }
+
+    fun isAppEligibleForBackup(targetPackage: PackageInfo, @Suppress("UNUSED_PARAMETER") isFullBackup: Boolean): Boolean {
+        // We need to exclude the DocumentsProvider used to store backup data.
+        // Otherwise, it gets killed when we back it up, terminating our backup.
+        return targetPackage.packageName != plugin.providerPackageName
+    }
+
+    fun getBackupQuota(packageName: String, isFullBackup: Boolean): Long {
+        Log.i(TAG, "Get backup quota for $packageName. Is full backup: $isFullBackup.")
+        val quota = if (isFullBackup) full.getQuota() else kv.getQuota()
+        Log.i(TAG, "Reported quota of $quota bytes.")
+        return quota
+    }
+
+    // ------------------------------------------------------------------------------------
+    // Key/value incremental backup support
+    //
+
+    /**
+     * Verify that this is a suitable time for a key/value backup pass.
+     * This should return zero if a backup is reasonable right now, some positive value otherwise.
+     * This method will be called outside of the [performIncrementalBackup]/[finishBackup] pair.
+     *
+     * If this is not a suitable time for a backup, the transport should return a backoff delay,
+     * in milliseconds, after which the Backup Manager should try again.
+     *
+     * @return Zero if this is a suitable time for a backup pass, or a positive time delay
+     *   in milliseconds to suggest deferring the backup pass for a while.
+     */
+    fun requestBackupTime(): Long = getBackupBackoff().apply {
+        Log.i(TAG, "Request incremental backup time. Returned $this")
+    }
+
+    fun performIncrementalBackup(packageInfo: PackageInfo, data: ParcelFileDescriptor, flags: Int): Int {
+        // backups of package manager metadata do not respect backoff
+        // we need to reject them manually when now is not a good time for a backup
+        if (packageInfo.packageName == MAGIC_PACKAGE_MANAGER && getBackupBackoff() != 0L) {
+            return TRANSPORT_PACKAGE_REJECTED
+        }
+
+        val result = kv.performBackup(packageInfo, data, flags)
+        if (result == TRANSPORT_OK) settingsManager.saveNewBackupTime()
+        return result
+    }
+
+    // ------------------------------------------------------------------------------------
+    // Full backup
+    //
+
+    /**
+     * Verify that this is a suitable time for a full-data backup pass.
+     * This should return zero if a backup is reasonable right now, some positive value otherwise.
+     * This method will be called outside of the [performFullBackup]/[finishBackup] pair.
+     *
+     * If this is not a suitable time for a backup, the transport should return a backoff delay,
+     * in milliseconds, after which the Backup Manager should try again.
+     *
+     * @return Zero if this is a suitable time for a backup pass, or a positive time delay
+     *   in milliseconds to suggest deferring the backup pass for a while.
+     *
+     * @see [requestBackupTime]
+     */
+    fun requestFullBackupTime(): Long = getBackupBackoff().apply {
+        Log.i(TAG, "Request full backup time. Returned $this")
+    }
+
+    fun checkFullBackupSize(size: Long) = full.checkFullBackupSize(size)
+
+    fun performFullBackup(targetPackage: PackageInfo, fileDescriptor: ParcelFileDescriptor, flags: Int): Int {
+        val result = full.performFullBackup(targetPackage, fileDescriptor, flags)
+        if (result == TRANSPORT_OK) settingsManager.saveNewBackupTime()
+        return result
+    }
+
+    fun sendBackupData(numBytes: Int) = full.sendBackupData(numBytes)
+
+    fun cancelFullBackup() = full.cancelFullBackup()
+
+    // Clear and Finish
+
+    /**
+     * Erase the given application's data from the backup destination.
+     * This clears out the given package's data from the current backup set,
+     * making it as though the app had never yet been backed up.
+     * After this is called, [finishBackup] must be called
+     * to ensure that the operation is recorded successfully.
+     *
+     * @return the same error codes as [performFullBackup].
+     */
+    fun clearBackupData(packageInfo: PackageInfo): Int {
+        val packageName = packageInfo.packageName
+        Log.i(TAG, "Clear Backup Data of $packageName.")
+        try {
+            kv.clearBackupData(packageInfo)
+        } catch (e: IOException) {
+            Log.w(TAG, "Error clearing K/V backup data for $packageName", e)
+            return TRANSPORT_ERROR
+        }
+        try {
+            full.clearBackupData(packageInfo)
+        } catch (e: IOException) {
+            Log.w(TAG, "Error clearing full backup data for $packageName", e)
+            return TRANSPORT_ERROR
+        }
+        calledClearBackupData = true
+        return TRANSPORT_OK
+    }
+
+    fun finishBackup(): Int = when {
+        kv.hasState() -> {
+            check(!full.hasState()) { "K/V backup has state, but full backup has dangling state as well" }
+            kv.finishBackup()
+        }
+        full.hasState() -> {
+            check(!kv.hasState()) { "Full backup has state, but K/V backup has dangling state as well" }
+            full.finishBackup()
+        }
+        calledInitialize || calledClearBackupData -> {
+            calledInitialize = false
+            calledClearBackupData = false
+            TRANSPORT_OK
+        }
+        else -> throw IllegalStateException("Unexpected state in finishBackup()")
+    }
+
+    @Throws(IOException::class)
+    private fun writeBackupMetadata(token: Long) {
+        val outputStream = plugin.getMetadataOutputStream()
+        metadataWriter.write(outputStream, token)
+    }
+
+    private fun getBackupBackoff(): Long {
+        val noBackoff = 0L
+        val defaultBackoff = DAYS.toMillis(30)
+
+        // back off if there's no storage set
+        val storage = settingsManager.getStorage() ?: return defaultBackoff
+        // don't back off if storage is not ejectable or available right now
+        return if (!storage.isUsb || storage.getDocumentFile(context).isDirectory) noBackoff
+        // otherwise back off
+        else defaultBackoff
+    }
+
+}

app/src/main/java/com/stevesoltys/seedvault/transport/backup/BackupModule.kt

@@ -0,0 +1,11 @@
+package com.stevesoltys.seedvault.transport.backup
+
+import org.koin.android.ext.koin.androidContext
+import org.koin.dsl.module
+
+val backupModule = module {
+    single { InputFactory() }
+    single { KVBackup(get<BackupPlugin>().kvBackupPlugin, get(), get(), get()) }
+    single { FullBackup(get<BackupPlugin>().fullBackupPlugin, get(), get(), get()) }
+    single { BackupCoordinator(androidContext(), get(), get(), get(), get(), get(), get()) }
+}

app/src/main/java/com/stevesoltys/seedvault/transport/backup/BackupPlugin.kt

@@ -0,0 +1,34 @@
+package com.stevesoltys.seedvault.transport.backup
+
+import java.io.IOException
+import java.io.OutputStream
+
+interface BackupPlugin {
+
+    val kvBackupPlugin: KVBackupPlugin
+
+    val fullBackupPlugin: FullBackupPlugin
+
+    /**
+     * Initialize the storage for this device, erasing all stored data.
+     */
+    @Throws(IOException::class)
+    fun initializeDevice()
+
+    /**
+     * Returns an [OutputStream] for writing backup metadata.
+     */
+    @Throws(IOException::class)
+    fun getMetadataOutputStream(): OutputStream
+
+    /**
+     * Returns the package name of the app that provides the backend storage
+     * which is used for the current backup location.
+     *
+     * Plugins are advised to cache this as it will be requested frequently.
+     *
+     * @return null if no package name could be found
+     */
+    val providerPackageName: String?
+
+}

app/src/main/java/com/stevesoltys/seedvault/transport/backup/FullBackup.kt

@@ -0,0 +1,186 @@
+package com.stevesoltys.seedvault.transport.backup
+
+import android.app.backup.BackupTransport.*
+import android.content.pm.PackageInfo
+import android.os.ParcelFileDescriptor
+import android.util.Log
+import com.stevesoltys.seedvault.crypto.Crypto
+import com.stevesoltys.seedvault.header.HeaderWriter
+import com.stevesoltys.seedvault.header.VersionHeader
+import libcore.io.IoUtils.closeQuietly
+import org.apache.commons.io.IOUtils
+import java.io.IOException
+import java.io.InputStream
+import java.io.OutputStream
+
+private class FullBackupState(
+        internal val packageInfo: PackageInfo,
+        internal val inputFileDescriptor: ParcelFileDescriptor,
+        internal val inputStream: InputStream,
+        internal val outputStream: OutputStream) {
+    internal val packageName: String = packageInfo.packageName
+    internal var size: Long = 0
+}
+
+const val DEFAULT_QUOTA_FULL_BACKUP = (2 * (25 * 1024 * 1024)).toLong()
+
+private val TAG = FullBackup::class.java.simpleName
+
+internal class FullBackup(
+        private val plugin: FullBackupPlugin,
+        private val inputFactory: InputFactory,
+        private val headerWriter: HeaderWriter,
+        private val crypto: Crypto) {
+
+    private var state: FullBackupState? = null
+
+    fun hasState() = state != null
+
+    fun getQuota(): Long = plugin.getQuota()
+
+    fun checkFullBackupSize(size: Long): Int {
+        Log.i(TAG, "Check full backup size of $size bytes.")
+        return when {
+            size <= 0 -> TRANSPORT_PACKAGE_REJECTED
+            size > plugin.getQuota() -> TRANSPORT_QUOTA_EXCEEDED
+            else -> TRANSPORT_OK
+        }
+    }
+
+    /**
+     * Begin the process of sending a packages' full-data archive to the backend.
+     * The description of the package whose data will be delivered is provided,
+     * as well as the socket file descriptor on which the transport will receive the data itself.
+     *
+     * If the package is not eligible for backup,
+     * the transport should return [TRANSPORT_PACKAGE_REJECTED].
+     * In this case the system will simply proceed with the next candidate if any,
+     * or finish the full backup operation if all apps have been processed.
+     *
+     * After the transport returns [TRANSPORT_OK] from this method,
+     * the OS will proceed to call [sendBackupData] one or more times
+     * to deliver the packages' data as a streamed tarball.
+     * The transport should not read() from the socket except as instructed to
+     * via the [sendBackupData] method.
+     *
+     * After all data has been delivered to the transport, the system will call [finishBackup].
+     * At this point the transport should commit the data to its datastore, if appropriate,
+     * and close the socket that had been provided in [performFullBackup].
+     *
+     * If the transport returns [TRANSPORT_OK] from this method,
+     * then the OS will always provide a matching call to [finishBackup]
+     * even if sending data via [sendBackupData] failed at some point.
+     *
+     * @param targetPackage The package whose data is to follow.
+     * @param socket The socket file descriptor through which the data will be provided.
+     * If the transport returns [TRANSPORT_PACKAGE_REJECTED] here,
+     * it must still close this file descriptor now;
+     * otherwise it should be cached for use during succeeding calls to [sendBackupData],
+     * and closed in response to [finishBackup].
+     * @param flags [FLAG_USER_INITIATED] or 0.
+     * @return [TRANSPORT_PACKAGE_REJECTED] to indicate that the package is not to be backed up;
+     * [TRANSPORT_OK] to indicate that the OS may proceed with delivering backup data;
+     * [TRANSPORT_ERROR] to indicate an error that precludes performing a backup at this time.
+     */
+    fun performFullBackup(targetPackage: PackageInfo, socket: ParcelFileDescriptor, @Suppress("UNUSED_PARAMETER") flags: Int = 0): Int {
+        if (state != null) throw AssertionError()
+        Log.i(TAG, "Perform full backup for ${targetPackage.packageName}.")
+
+        // get OutputStream to write backup data into
+        val outputStream = try {
+            plugin.getOutputStream(targetPackage)
+        } catch (e: IOException) {
+            Log.e(TAG, "Error getting OutputStream for full backup of ${targetPackage.packageName}", e)
+            return backupError(TRANSPORT_ERROR)
+        }
+
+        // create new state
+        val inputStream = inputFactory.getInputStream(socket)
+        state = FullBackupState(targetPackage, socket, inputStream, outputStream)
+
+        // store version header
+        val state = this.state ?: throw AssertionError()
+        val header = VersionHeader(packageName = state.packageName)
+        try {
+            headerWriter.writeVersion(state.outputStream, header)
+            crypto.encryptHeader(state.outputStream, header)
+        } catch (e: IOException) {
+            Log.e(TAG, "Error writing backup header", e)
+            return backupError(TRANSPORT_ERROR)
+        }
+        return TRANSPORT_OK
+    }
+
+    /**
+     * Method to reset state,
+     * because [finishBackup] is not called
+     * when we don't return [TRANSPORT_OK] from [performFullBackup].
+     */
+    private fun backupError(result: Int): Int {
+        Log.i(TAG, "Resetting state because of full backup error.")
+        state = null
+        return result
+    }
+
+    fun sendBackupData(numBytes: Int): Int {
+        val state = this.state
+                ?: throw AssertionError("Attempted sendBackupData before performFullBackup")
+
+        // check if size fits quota
+        state.size += numBytes
+        val quota = plugin.getQuota()
+        if (state.size > quota) {
+            Log.w(TAG, "Full backup of additional $numBytes exceeds quota of $quota with ${state.size}.")
+            return TRANSPORT_QUOTA_EXCEEDED
+        }
+
+        Log.i(TAG, "Send full backup data of $numBytes bytes.")
+
+        return try {
+            val payload = IOUtils.readFully(state.inputStream, numBytes)
+            crypto.encryptSegment(state.outputStream, payload)
+            TRANSPORT_OK
+        } catch (e: IOException) {
+            Log.e(TAG, "Error handling backup data for ${state.packageName}: ", e)
+            TRANSPORT_ERROR
+        }
+    }
+
+    fun clearBackupData(packageInfo: PackageInfo) {
+        plugin.removeDataOfPackage(packageInfo)
+    }
+
+    fun cancelFullBackup() {
+        Log.i(TAG, "Cancel full backup")
+        val state = this.state ?: throw AssertionError("No state when canceling")
+        clearState()
+        try {
+            plugin.removeDataOfPackage(state.packageInfo)
+        } catch (e: IOException) {
+            Log.w(TAG, "Error cancelling full backup for ${state.packageName}", e)
+        }
+        // TODO roll back to the previous known-good archive
+    }
+
+    fun finishBackup(): Int {
+        Log.i(TAG, "Finish full backup of ${state!!.packageName}.")
+        return clearState()
+    }
+
+    private fun clearState(): Int {
+        val state = this.state ?: throw AssertionError("Trying to clear empty state.")
+        return try {
+            state.outputStream.flush()
+            closeQuietly(state.outputStream)
+            closeQuietly(state.inputStream)
+            closeQuietly(state.inputFileDescriptor)
+            TRANSPORT_OK
+        } catch (e: IOException) {
+            Log.w(TAG, "Error when clearing state", e)
+            TRANSPORT_ERROR
+        } finally {
+            this.state = null
+        }
+    }
+
+}

app/src/main/java/com/stevesoltys/seedvault/transport/backup/FullBackupPlugin.kt

@@ -0,0 +1,21 @@
+package com.stevesoltys.seedvault.transport.backup
+
+import android.content.pm.PackageInfo
+import java.io.IOException
+import java.io.OutputStream
+
+interface FullBackupPlugin {
+
+    fun getQuota(): Long
+
+    // TODO consider using a salted hash for the package name to not leak it to the storage server
+    @Throws(IOException::class)
+    fun getOutputStream(targetPackage: PackageInfo): OutputStream
+
+    /**
+     * Remove all data associated with the given package.
+     */
+    @Throws(IOException::class)
+    fun removeDataOfPackage(packageInfo: PackageInfo)
+
+}

app/src/main/java/com/stevesoltys/seedvault/transport/backup/InputFactory.kt

@@ -0,0 +1,21 @@
+package com.stevesoltys.seedvault.transport.backup
+
+import android.app.backup.BackupDataInput
+import android.os.ParcelFileDescriptor
+import java.io.FileInputStream
+import java.io.InputStream
+
+/**
+ * This class exists for easier testing, so we can mock it and return custom data inputs.
+ */
+internal class InputFactory {
+
+    fun getBackupDataInput(inputFileDescriptor: ParcelFileDescriptor): BackupDataInput {
+        return BackupDataInput(inputFileDescriptor.fileDescriptor)
+    }
+
+    fun getInputStream(inputFileDescriptor: ParcelFileDescriptor): InputStream {
+        return FileInputStream(inputFileDescriptor.fileDescriptor)
+    }
+
+}

app/src/main/java/com/stevesoltys/seedvault/transport/backup/KVBackup.kt

@@ -0,0 +1,194 @@
+package com.stevesoltys.seedvault.transport.backup
+
+import android.app.backup.BackupTransport.*
+import android.content.pm.PackageInfo
+import android.os.ParcelFileDescriptor
+import android.util.Log
+import com.stevesoltys.seedvault.crypto.Crypto
+import com.stevesoltys.seedvault.encodeBase64
+import com.stevesoltys.seedvault.header.HeaderWriter
+import com.stevesoltys.seedvault.header.VersionHeader
+import libcore.io.IoUtils.closeQuietly
+import java.io.IOException
+
+class KVBackupState(internal val packageName: String)
+
+const val DEFAULT_QUOTA_KEY_VALUE_BACKUP = (2 * (5 * 1024 * 1024)).toLong()
+
+private val TAG = KVBackup::class.java.simpleName
+
+internal class KVBackup(
+        private val plugin: KVBackupPlugin,
+        private val inputFactory: InputFactory,
+        private val headerWriter: HeaderWriter,
+        private val crypto: Crypto) {
+
+    private var state: KVBackupState? = null
+
+    fun hasState() = state != null
+
+    fun getQuota(): Long = plugin.getQuota()
+
+    fun performBackup(packageInfo: PackageInfo, data: ParcelFileDescriptor, flags: Int): Int {
+        val isIncremental = flags and FLAG_INCREMENTAL != 0
+        val isNonIncremental = flags and FLAG_NON_INCREMENTAL != 0
+        val packageName = packageInfo.packageName
+
+        when {
+            isIncremental -> {
+                Log.i(TAG, "Performing incremental K/V backup for $packageName")
+            }
+            isNonIncremental -> {
+                Log.i(TAG, "Performing non-incremental K/V backup for $packageName")
+            }
+            else -> {
+                Log.i(TAG, "Performing K/V backup for $packageName")
+            }
+        }
+
+        // initialize state
+        if (this.state != null) throw AssertionError()
+        this.state = KVBackupState(packageInfo.packageName)
+
+        // check if we have existing data for the given package
+        val hasDataForPackage = try {
+            plugin.hasDataForPackage(packageInfo)
+        } catch (e: IOException) {
+            Log.e(TAG, "Error checking for existing data for ${packageInfo.packageName}.", e)
+            return backupError(TRANSPORT_ERROR)
+        }
+        if (isIncremental && !hasDataForPackage) {
+            Log.w(TAG, "Requested incremental, but transport currently stores no data $packageName, requesting non-incremental retry.")
+            return backupError(TRANSPORT_NON_INCREMENTAL_BACKUP_REQUIRED)
+        }
+
+        // TODO check if package is over-quota
+
+        if (isNonIncremental && hasDataForPackage) {
+            Log.w(TAG, "Requested non-incremental, deleting existing data.")
+            try {
+                clearBackupData(packageInfo)
+            } catch (e: IOException) {
+                Log.w(TAG, "Error clearing backup data for ${packageInfo.packageName}.", e)
+            }
+        }
+
+        // ensure there's a place to store K/V for the given package
+        try {
+            plugin.ensureRecordStorageForPackage(packageInfo)
+        } catch (e: IOException) {
+            Log.e(TAG, "Error ensuring storage for ${packageInfo.packageName}.", e)
+            return backupError(TRANSPORT_ERROR)
+        }
+
+        // parse and store the K/V updates
+        return storeRecords(packageInfo, data)
+    }
+
+    private fun storeRecords(packageInfo: PackageInfo, data: ParcelFileDescriptor): Int {
+        // apply the delta operations
+        for (result in parseBackupStream(data)) {
+            if (result is Result.Error) {
+                Log.e(TAG, "Exception reading backup input", result.exception)
+                return backupError(TRANSPORT_ERROR)
+            }
+            val op = (result as Result.Ok).result
+            try {
+                if (op.value == null) {
+                    Log.e(TAG, "Deleting record with base64Key ${op.base64Key}")
+                    plugin.deleteRecord(packageInfo, op.base64Key)
+                } else {
+                    val outputStream = plugin.getOutputStreamForRecord(packageInfo, op.base64Key)
+                    val header = VersionHeader(packageName = packageInfo.packageName, key = op.key)
+                    headerWriter.writeVersion(outputStream, header)
+                    crypto.encryptHeader(outputStream, header)
+                    crypto.encryptMultipleSegments(outputStream, op.value)
+                    outputStream.flush()
+                    closeQuietly(outputStream)
+                }
+            } catch (e: IOException) {
+                Log.e(TAG, "Unable to update base64Key file for base64Key ${op.base64Key}", e)
+                return backupError(TRANSPORT_ERROR)
+            }
+        }
+        return TRANSPORT_OK
+    }
+
+    /**
+     * Parses a backup stream into individual key/value operations
+     */
+    private fun parseBackupStream(data: ParcelFileDescriptor): Sequence<Result<KVOperation>> {
+        val changeSet = inputFactory.getBackupDataInput(data)
+
+        // Each K/V pair in the restore set is kept in its own file, named by the record key.
+        // Wind through the data file, extracting individual record operations
+        // and building a sequence of all the updates to apply in this update.
+        return generateSequence {
+            // read the next header or end the sequence in case of error or no more headers
+            try {
+                if (!changeSet.readNextHeader()) return@generateSequence null  // end the sequence
+            } catch (e: IOException) {
+                Log.e(TAG, "Error reading next header", e)
+                return@generateSequence Result.Error(e)
+            }
+            // encode key
+            val key = changeSet.key
+            val base64Key = key.encodeBase64()
+            val dataSize = changeSet.dataSize
+
+            // read value
+            val value = if (dataSize >= 0) {
+                Log.v(TAG, "  Delta operation key $key   size $dataSize   key64 $base64Key")
+                val bytes = ByteArray(dataSize)
+                val bytesRead = try {
+                    changeSet.readEntityData(bytes, 0, dataSize)
+                } catch (e: IOException) {
+                    Log.e(TAG, "Error reading entity data for key $key", e)
+                    return@generateSequence Result.Error(e)
+                }
+                if (bytesRead != dataSize) {
+                    Log.w(TAG, "Expecting $dataSize bytes, but only read $bytesRead.")
+                }
+                bytes
+            } else null
+            // add change operation to the sequence
+            Result.Ok(KVOperation(key, base64Key, value))
+        }
+    }
+
+    @Throws(IOException::class)
+    fun clearBackupData(packageInfo: PackageInfo) {
+        plugin.removeDataOfPackage(packageInfo)
+    }
+
+    fun finishBackup(): Int {
+        Log.i(TAG, "Finish K/V Backup of ${state!!.packageName}")
+        state = null
+        return TRANSPORT_OK
+    }
+
+    /**
+     * Method to reset state,
+     * because [finishBackup] is not called when we don't return [TRANSPORT_OK].
+     */
+    private fun backupError(result: Int): Int {
+        Log.i(TAG, "Resetting state because of K/V Backup error of ${state!!.packageName}")
+        state = null
+        return result
+    }
+
+    private class KVOperation(
+            internal val key: String,
+            internal val base64Key: String,
+            /**
+             * value is null when this is a deletion operation
+             */
+            internal val value: ByteArray?
+    )
+
+    private sealed class Result<out T> {
+        class Ok<out T>(val result: T) : Result<T>()
+        class Error(val exception: Exception) : Result<Nothing>()
+    }
+
+}

app/src/main/java/com/stevesoltys/seedvault/transport/backup/KVBackupPlugin.kt

@@ -0,0 +1,49 @@
+package com.stevesoltys.seedvault.transport.backup
+
+import android.content.pm.PackageInfo
+import java.io.IOException
+import java.io.OutputStream
+
+interface KVBackupPlugin {
+
+    /**
+     * Get quota for key/value backups.
+     */
+    fun getQuota(): Long
+
+    // TODO consider using a salted hash for the package name (and key) to not leak it to the storage server
+    /**
+     * Return true if there are records stored for the given package.
+     */
+    @Throws(IOException::class)
+    fun hasDataForPackage(packageInfo: PackageInfo): Boolean
+
+    /**
+     * This marks the beginning of a backup operation.
+     *
+     * Make sure that there is a place to store K/V pairs for the given package.
+     * E.g. file-based plugins should a create a directory for the package, if none exists.
+     */
+    @Throws(IOException::class)
+    fun ensureRecordStorageForPackage(packageInfo: PackageInfo)
+
+    /**
+     * Return an [OutputStream] for the given package and key
+     * which will receive the record's encrypted value.
+     */
+    @Throws(IOException::class)
+    fun getOutputStreamForRecord(packageInfo: PackageInfo, key: String): OutputStream
+
+    /**
+     * Delete the record for the given package identified by the given key.
+     */
+    @Throws(IOException::class)
+    fun deleteRecord(packageInfo: PackageInfo, key: String)
+
+    /**
+     * Remove all data associated with the given package.
+     */
+    @Throws(IOException::class)
+    fun removeDataOfPackage(packageInfo: PackageInfo)
+
+}