Tolerate backup attempts when flash drive is not plugged in

Also remove hardcoding of PACKAGE_MANAGER_SENTINEL constant

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

@@ -1,6 +1,7 @@
 package com.stevesoltys.backup
 
 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
@@ -33,4 +34,6 @@ class Backup : Application() {
 
 }
 
+const val MAGIC_PACKAGE_MANAGER = PACKAGE_MANAGER_SENTINEL
+
 fun isDebugBuild() = Build.TYPE == "userdebug"

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

@@ -68,7 +68,7 @@ class NotificationBackupObserver(context: Context, private val userInitiated: Bo
 }
 
 fun getAppName(pm: PackageManager, packageId: String): CharSequence {
-    if (packageId == "@pm@") return packageId
+    if (packageId == MAGIC_PACKAGE_MANAGER) return packageId
     val appInfo = pm.getApplicationInfo(packageId, 0)
     return pm.getApplicationLabel(appInfo)
 }

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

@@ -8,6 +8,7 @@ import android.os.UserHandle
 import android.util.Log
 import com.google.android.collect.Sets.newArraySet
 import com.stevesoltys.backup.Backup
+import com.stevesoltys.backup.MAGIC_PACKAGE_MANAGER
 import java.util.*
 
 private val TAG = PackageService::class.java.simpleName
@@ -49,7 +50,7 @@ class PackageService {
 
             // add magic @pm@ package (PACKAGE_MANAGER_SENTINEL) which holds package manager data
             val packageArray = eligibleApps.toMutableList()
-            packageArray.add("@pm@")
+            packageArray.add(MAGIC_PACKAGE_MANAGER)
 
             return packageArray.toTypedArray()
         }

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

@@ -2,6 +2,8 @@ package com.stevesoltys.backup.settings
 
 import android.content.ContentResolver
 import android.provider.Settings
+import java.util.concurrent.TimeUnit
+import java.util.concurrent.TimeUnit.DAYS
 
 private val SETTING = Settings.Secure.BACKUP_MANAGER_CONSTANTS
 private const val DELIMITER = ','
@@ -11,13 +13,19 @@ private const val FULL_BACKUP_INTERVAL_MILLISECONDS = "full_backup_interval_mill
 
 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 = Long.MAX_VALUE
+        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")

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

@@ -1,16 +1,16 @@
 package com.stevesoltys.backup.transport.backup
 
-import android.app.backup.BackupTransport.TRANSPORT_ERROR
+import android.app.backup.BackupTransport.*
-import android.app.backup.BackupTransport.TRANSPORT_OK
 import android.content.Context
 import android.content.pm.PackageInfo
 import android.os.ParcelFileDescriptor
 import android.util.Log
 import com.stevesoltys.backup.BackupNotificationManager
+import com.stevesoltys.backup.MAGIC_PACKAGE_MANAGER
 import com.stevesoltys.backup.metadata.MetadataWriter
 import com.stevesoltys.backup.settings.SettingsManager
 import java.io.IOException
-import java.util.concurrent.TimeUnit.MINUTES
+import java.util.concurrent.TimeUnit.DAYS
 
 private val TAG = BackupCoordinator::class.java.simpleName
 
@@ -63,7 +63,8 @@ class BackupCoordinator(
             TRANSPORT_OK
         } catch (e: IOException) {
             Log.e(TAG, "Error initializing device", e)
-            nm.onBackupError()
+            // Show error notification if we were ready for backups
+            if (getBackupBackoff() == 0L) nm.onBackupError()
             TRANSPORT_ERROR
         }
     }
@@ -101,6 +102,12 @@ class BackupCoordinator(
     }
 
     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
@@ -194,7 +201,7 @@ class BackupCoordinator(
 
     private fun getBackupBackoff(): Long {
         val noBackoff = 0L
-        val defaultBackoff = MINUTES.toMillis(10)
+        val defaultBackoff = DAYS.toMillis(30)
 
         // back off if there's no storage set
         val storage = settingsManager.getStorage() ?: return defaultBackoff

app/src/main/java/com/stevesoltys/backup/transport/backup/plugins/DocumentsProviderBackupPlugin.kt

@@ -42,7 +42,7 @@ class DocumentsProviderBackupPlugin(
     }
 
     override val providerPackageName: String? by lazy {
-        val authority = storage.rootBackupDir?.uri?.authority ?: return@lazy null
+        val authority = storage.getAuthority() ?: return@lazy null
         val providerInfo = packageManager.resolveContentProvider(authority, 0) ?: return@lazy null
         providerInfo.packageName
     }

app/src/main/java/com/stevesoltys/backup/transport/backup/plugins/DocumentsStorage.kt

@@ -72,6 +72,8 @@ class DocumentsStorage(private val context: Context, private val settingsManager
         }
     }
 
+    fun getAuthority(): String? = storage?.uri?.authority
+
     fun getSetDir(token: Long = currentToken): DocumentFile? {
         if (token == currentToken) return currentSetDir
         return rootBackupDir?.findFile(token.toString())

app/src/test/java/com/stevesoltys/backup/transport/backup/BackupCoordinatorTest.kt

@@ -2,8 +2,12 @@ package com.stevesoltys.backup.transport.backup
 
 import android.app.backup.BackupTransport.TRANSPORT_ERROR
 import android.app.backup.BackupTransport.TRANSPORT_OK
+import android.net.Uri
+import androidx.documentfile.provider.DocumentFile
 import com.stevesoltys.backup.BackupNotificationManager
+import com.stevesoltys.backup.getRandomString
 import com.stevesoltys.backup.metadata.MetadataWriter
+import com.stevesoltys.backup.settings.Storage
 import io.mockk.Runs
 import io.mockk.every
 import io.mockk.just
@@ -40,8 +44,11 @@ internal class BackupCoordinatorTest: BackupTest() {
     }
 
     @Test
-    fun `device initialization fails`() {
+    fun `error notification when device initialization fails`() {
+        val storage = Storage(Uri.EMPTY, getRandomString(), false)
+
         every { plugin.initializeDevice() } throws IOException()
+        every { settingsManager.getStorage() } returns storage
         every { notificationManager.onBackupError() } just Runs
 
         assertEquals(TRANSPORT_ERROR, backup.initializeDevice())
@@ -54,6 +61,27 @@ internal class BackupCoordinatorTest: BackupTest() {
         }
     }
 
+    @Test
+    fun `no error notification when device initialization fails on unplugged USB storage`() {
+        val storage = mockk<Storage>()
+        val documentFile = mockk<DocumentFile>()
+
+        every { plugin.initializeDevice() } throws IOException()
+        every { settingsManager.getStorage() } returns storage
+        every { storage.isUsb } returns true
+        every { storage.getDocumentFile(context) } returns documentFile
+        every { documentFile.isDirectory } returns false
+
+        assertEquals(TRANSPORT_ERROR, backup.initializeDevice())
+
+        // finish will only be called when TRANSPORT_OK is returned, so it should throw
+        every { kv.hasState() } returns false
+        every { full.hasState() } returns false
+        assertThrows(IllegalStateException::class.java) {
+            backup.finishBackup()
+        }
+    }
+
     @Test
     fun `getBackupQuota() delegates to right plugin`() {
         val isFullBackup = Random.nextBoolean()