Catch error when loading snapshots for app checking

app/src/main/java/com/stevesoltys/seedvault/repo/Checker.kt

@@ -49,20 +49,25 @@ internal class Checker(
         private set
 
     @WorkerThread
-    suspend fun getBackupSize(): Long {
+    suspend fun getBackupSize(): Long? {
         // get all snapshots
         val folder = TopLevelFolder(crypto.repoId)
         val handles = mutableListOf<AppBackupFileType.Snapshot>()
-        backendManager.backend.list(folder, AppBackupFileType.Snapshot::class) { fileInfo ->
+        try {
-            handles.add(fileInfo.fileHandle as AppBackupFileType.Snapshot)
+            backendManager.backend.list(folder, AppBackupFileType.Snapshot::class) { fileInfo ->
+                handles.add(fileInfo.fileHandle as AppBackupFileType.Snapshot)
+            }
+            val snapshots = snapshotManager.onSnapshotsLoaded(handles)
+            this.snapshots = snapshots // remember loaded snapshots
+            this.handleSize = handles.size // remember number of snapshot handles we had
+        } catch (e: Exception) {
+            log.error(e) { "Error loading snapshots: " }
+            // we swallow this exception, because an error will be shown in the next step
+            return null
         }
-        val snapshots = snapshotManager.onSnapshotsLoaded(handles)
-        this.snapshots = snapshots // remember loaded snapshots
-        this.handleSize = handles.size // remember number of snapshot handles we had
-
         // get total disk space used by snapshots
         val sizeMap = mutableMapOf<String, Int>()
-        snapshots.forEach { snapshot ->
+        snapshots?.forEach { snapshot ->
             // add sizes to a map first, so we don't double count
             snapshot.blobsMap.forEach { (chunkId, blob) -> sizeMap[chunkId] = blob.length }
         }
@@ -73,7 +78,12 @@ internal class Checker(
     suspend fun check(percent: Int) {
         check(percent in 0..100) { "Percent $percent out of bounds." }
 
-        if (snapshots == null) getBackupSize() // just get size again to be sure we get snapshots
+        if (snapshots == null) try {
+            getBackupSize() // just get size again to be sure we get snapshots
+        } catch (e: Exception) {
+            nm.onCheckFinishedWithError(0, 0)
+            checkerResult = CheckerResult.GeneralError(e)
+        }
         val snapshots = snapshots ?: error("Snapshots still null")
         val handleSize = handleSize ?: error("Handle size still null")
         check(handleSize >= snapshots.size) {

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

@@ -50,9 +50,11 @@ class AppCheckFragment : Fragment() {
         }
 
         viewModel.backupSize.observe(viewLifecycleOwner) {
-            slider.labelBehavior = LABEL_VISIBLE
+            if (it != null) {
-            slider.invalidate()
+                slider.labelBehavior = LABEL_VISIBLE
-            onSliderChanged(slider.value)
+                slider.invalidate()
+                onSliderChanged(slider.value)
+            }
             // we can stop observing as the loaded size won't change again
             viewModel.backupSize.removeObservers(viewLifecycleOwner)
         }

app/src/main/java/com/stevesoltys/seedvault/ui/check/AppCheckResultActivity.kt

@@ -56,9 +56,14 @@ class AppCheckResultActivity : BackupActivity() {
             is CheckerResult.Success -> onSuccess(result)
             is CheckerResult.Error -> onError(result)
             is CheckerResult.GeneralError, null -> {
-                // TODO
+                if (result == null) {
-                if (result == null) log.error { "No more result" }
+                    val str = getString(R.string.backup_app_check_error_no_result)
-                else log.info((result as CheckerResult.GeneralError).e) { "Error: " }
+                    val e = NullPointerException(str)
+                    val r = CheckerResult.GeneralError(e)
+                    onGeneralError(r)
+                } else {
+                    onGeneralError(result as CheckerResult.GeneralError)
+                }
             }
         }
         checker.clear()
@@ -98,14 +103,8 @@ class AppCheckResultActivity : BackupActivity() {
                 R.string.backup_app_check_error_only_broken_snapshots,
                 result.existingSnapshots,
             )
-        } else if (result.existingSnapshots > result.snapshots.size) {
-            getString(
-                R.string.backup_app_check_error_some_snapshots,
-                result.existingSnapshots,
-                result.snapshots.size,
-            )
         } else {
-            getString(R.string.backup_app_check_error_read_all_snapshots, result.snapshots.size)
+            getString(R.string.backup_app_check_error_has_snapshots, result.existingSnapshots)
         }
         requireViewById<TextView>(R.id.introView).text = intro
 
@@ -121,4 +120,16 @@ class AppCheckResultActivity : BackupActivity() {
         )
     }
 
+    private fun onGeneralError(result: CheckerResult.GeneralError) {
+        setContentView(R.layout.activity_check_result)
+        requireViewById<ImageView>(R.id.imageView).setImageResource(R.drawable.ic_cloud_error)
+        requireViewById<TextView>(R.id.titleView).setText(R.string.backup_app_check_error_title)
+
+        requireViewById<TextView>(R.id.introView).text =
+            getString(R.string.backup_app_check_error_no_snapshots)
+
+        requireViewById<TextView>(R.id.disclaimerView).text =
+            "${result.e.localizedMessage}\n\n${result.e}"
+    }
+
 }

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

@@ -196,12 +196,12 @@
     <string name="notification_checking_action">Details</string>
 
     <string name="backup_app_check_success_intro">%1$d snapshots were found and %2$d%% of their data (%3$s) successfully verified:</string>
-    <string name="backup_app_check_success_disclaimer">Note: We can not verify whether apps include all of their data in the backup.</string>
+    <string name="backup_app_check_success_disclaimer">Note: we cannot verify whether individual apps include all of their user data in the backup.</string>
     <string name="backup_app_check_error_title">@string/notification_checking_error_title</string>
     <string name="backup_app_check_error_no_snapshots">We could not find any backup. Please run a successful backup first and then try checking again.</string>
     <string name="backup_app_check_error_only_broken_snapshots">We found %1$d backup snapshots. However, all of them were corrupted. Please run a successful backup and then try checking again.</string>
-    <string name="backup_app_check_error_some_snapshots">We found %1$d backup snapshots. However, we could only read the following %2$d snapshots.</string>
+    <string name="backup_app_check_error_has_snapshots">We found %1$d backup snapshots, some of them are corrupt or have errors. Below are the backups that could be restored.</string>
-    <string name="backup_app_check_error_read_all_snapshots">We found %1$d backup snapshots. However, some had errors and can not be fully restored.</string>
+    <string name="backup_app_check_error_no_result">We lost the detailed results. Did a long time pass since running the check? Try running again.</string>
 
     <!-- App Backup and Restore State -->
 
@@ -235,7 +235,7 @@
     <string name="restore_restore_set_apps_no_size">Has user data for <xliff:g example="42" id="apps">%1$d</xliff:g> apps</string>
     <string name="restore_restore_set_apks">Contains <xliff:g example="42" id="apps">%1$d</xliff:g> apps (<xliff:g example="1 GB" id="size">%2$s</xliff:g>)</string>
     <string name="restore_restore_set_apks_no_size">Contains <xliff:g example="42" id="apps">%1$d</xliff:g> apps</string>
-    <string name="restore_restore_set_can_not_get_restored">Can not be (fully) restored.</string>
+    <string name="restore_restore_set_can_not_get_restored">This backup has some errors. You may be able to restore it partly.</string>
     <string name="restore_skip">Don\'t restore</string>
     <string name="restore_skip_apps">Skip restoring apps</string>
     <string name="restore_invalid_location_title">No backups found</string>