Disable automatic backups when a removable USB flash drive is used

as storage location.

The backup backoff time is not reliable for this as the system still
attempts to backup the magic @pm@ package without checking for the
backoff value.

app/src/main/AndroidManifest.xml

@@ -19,6 +19,11 @@
         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:allowBackup="false"

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

@@ -50,7 +50,7 @@ class RestoreProgressFragment : Fragment() {
                 // success
                 currentPackageView.text = getString(R.string.restore_finished_success)
                 val settingsManager = (requireContext().applicationContext as Backup).settingsManager
-                warningView.text = if (settingsManager.getStorage()?.ejectable == true) {
+                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)

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

@@ -0,0 +1,30 @@
+package com.stevesoltys.backup.settings
+
+import android.content.ContentResolver
+import android.provider.Settings
+
+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 {
+
+    fun enableAutomaticBackups(resolver: ContentResolver) {
+        // setting this to null will cause the BackupManagerConstants to use default values
+        setSettingValue(resolver, null)
+    }
+
+    fun disableAutomaticBackups(resolver: ContentResolver) {
+        val value = Long.MAX_VALUE
+        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/backup/settings/SettingsManager.kt

@@ -9,7 +9,7 @@ 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_EJECTABLE = "storageEjectable"
+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"
@@ -28,7 +28,7 @@ class SettingsManager(context: Context) {
         prefs.edit()
                 .putString(PREF_KEY_STORAGE_URI, storage.uri.toString())
                 .putString(PREF_KEY_STORAGE_NAME, storage.name)
-                .putBoolean(PREF_KEY_STORAGE_EJECTABLE, storage.ejectable)
+                .putBoolean(PREF_KEY_STORAGE_IS_USB, storage.isUsb)
                 .apply()
     }
 
@@ -36,8 +36,8 @@ class SettingsManager(context: Context) {
         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()
-        val ejectable = prefs.getBoolean(PREF_KEY_STORAGE_EJECTABLE, false)
+        val isUsb = prefs.getBoolean(PREF_KEY_STORAGE_IS_USB, false)
-        return Storage(uri, name, ejectable)
+        return Storage(uri, name, isUsb)
     }
 
     fun setFlashDrive(usb: FlashDrive?) {
@@ -86,9 +86,9 @@ class SettingsManager(context: Context) {
     /**
      * Sets the last backup time to "now".
      */
-    fun saveNewBackupTime() {
+    fun saveNewBackupTime(millis: Long = Date().time) {
         prefs.edit()
-                .putLong(PREF_KEY_BACKUP_TIME, Date().time)
+                .putLong(PREF_KEY_BACKUP_TIME, millis)
                 .apply()
     }
 
@@ -118,7 +118,7 @@ class SettingsManager(context: Context) {
 data class Storage(
         val uri: Uri,
         val name: String,
-        val ejectable: Boolean) {
+        val isUsb: Boolean) {
     fun getDocumentFile(context: Context) = DocumentFile.fromTreeUri(context, uri)
             ?: throw AssertionError("Should only happen on API < 21.")
 }

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

@@ -199,7 +199,7 @@ class BackupCoordinator(
         // 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.ejectable || storage.getDocumentFile(context).isDirectory) noBackoff
+        return if (!storage.isUsb || storage.getDocumentFile(context).isDirectory) noBackoff
         // otherwise back off
         else defaultBackoff
     }

app/src/main/java/com/stevesoltys/backup/ui/storage/StorageRootFetcher.kt

@@ -33,7 +33,7 @@ data class StorageRoot(
         internal val title: String,
         internal val summary: String?,
         internal val availableBytes: Long?,
-        internal val supportsEject: Boolean,
+        internal val isUsb: Boolean,
         internal val enabled: Boolean = true) {
 
     internal val uri: Uri by lazy {
@@ -41,7 +41,7 @@ data class StorageRoot(
     }
 
     fun isInternal(): Boolean {
-        return authority == AUTHORITY_STORAGE && !supportsEject
+        return authority == AUTHORITY_STORAGE && !isUsb
     }
 }
 
@@ -122,7 +122,6 @@ internal class StorageRootFetcher(private val context: Context) {
         if (!supportsCreate || !supportsIsChild) return null
         val rootId = cursor.getString(COLUMN_ROOT_ID)!!
         if (authority == AUTHORITY_STORAGE && rootId == ROOT_ID_HOME) return null
-        val supportsEject = flags and FLAG_SUPPORTS_EJECT != 0
         return StorageRoot(
                 authority = authority,
                 rootId = rootId,
@@ -131,13 +130,13 @@ internal class StorageRootFetcher(private val context: Context) {
                 title = cursor.getString(COLUMN_TITLE)!!,
                 summary = cursor.getString(COLUMN_SUMMARY),
                 availableBytes = cursor.getLong(COLUMN_AVAILABLE_BYTES),
-                supportsEject = supportsEject
+                isUsb = flags and FLAG_REMOVABLE_USB != 0
         )
     }
 
     private fun checkOrAddUsbRoot(roots: ArrayList<StorageRoot>) {
         for (root in roots) {
-            if (root.authority == AUTHORITY_STORAGE && root.supportsEject) return
+            if (root.authority == AUTHORITY_STORAGE && root.isUsb) return
         }
         val root = StorageRoot(
                 authority = AUTHORITY_STORAGE,
@@ -147,7 +146,7 @@ internal class StorageRootFetcher(private val context: Context) {
                 title = context.getString(R.string.storage_fake_drive_title),
                 summary = context.getString(R.string.storage_fake_drive_summary),
                 availableBytes = null,
-                supportsEject = true,
+                isUsb = true,
                 enabled = false
         )
         roots.add(root)

app/src/main/java/com/stevesoltys/backup/ui/storage/StorageViewModel.kt

@@ -15,6 +15,7 @@ import androidx.lifecycle.MutableLiveData
 import com.stevesoltys.backup.Backup
 import com.stevesoltys.backup.R
 import com.stevesoltys.backup.isMassStorage
+import com.stevesoltys.backup.settings.BackupManagerSettings
 import com.stevesoltys.backup.settings.FlashDrive
 import com.stevesoltys.backup.settings.Storage
 import com.stevesoltys.backup.transport.ConfigurableBackupTransportService
@@ -45,7 +46,7 @@ internal abstract class StorageViewModel(private val app: Application) : Android
         internal fun validLocationIsSet(context: Context): Boolean {
             val settingsManager = (context.applicationContext as Backup).settingsManager
             val storage = settingsManager.getStorage() ?: return false
-            if (storage.ejectable) return true
+            if (storage.isUsb) return true
             return storage.getDocumentFile(context).isDirectory
         }
     }
@@ -88,16 +89,20 @@ internal abstract class StorageViewModel(private val app: Application) : Android
         } else {
             root.title
         }
-        val storage = Storage(uri, name, root.supportsEject)
+        val storage = Storage(uri, name, root.isUsb)
         settingsManager.setStorage(storage)
 
         // reset time of last backup to "Never"
         settingsManager.resetBackupTime()
 
-        if (storage.ejectable) {
+        if (storage.isUsb) {
             val wasSaved = saveUsbDevice()
             // reset stored flash drive, if we did not update it
             if (!wasSaved) settingsManager.setFlashDrive(null)
+            BackupManagerSettings.disableAutomaticBackups(app.contentResolver)
+        } else {
+            settingsManager.setFlashDrive(null)
+            BackupManagerSettings.enableAutomaticBackups(app.contentResolver)
         }
 
         // stop backup service to be sure the old location will get updated
@@ -114,7 +119,7 @@ internal abstract class StorageViewModel(private val app: Application) : Android
                 return true
             }
         }
-        Log.w(TAG, "No USB device found for ejectable storage.")
+        Log.e(TAG, "No USB device found even though we were expecting one.")
         return false
     }
 

permissions_com.stevesoltys.backup.xml

@@ -3,5 +3,6 @@
     <privapp-permissions package="com.stevesoltys.backup">
         <permission name="android.permission.BACKUP"/>
         <permission name="android.permission.MANAGE_USB"/>
+        <permission name="android.permission.WRITE_SECURE_SETTINGS"/>
     </privapp-permissions>
 </permissions>