Verify database version before import

app/src/main/java/de/danoeh/antennapod/fragment/preferences/ImportExportPreferencesFragment.java

@@ -216,8 +216,8 @@ public class ImportExportPreferencesFragment extends PreferenceFragmentCompat {
 
     private void showExportErrorDialog(final Throwable error) {
         progressDialog.dismiss();
-        final AlertDialog.Builder alert = new AlertDialog.Builder(getContext())
+        final AlertDialog.Builder alert = new AlertDialog.Builder(getContext());
-                .setNeutralButton(android.R.string.ok, (dialog, which) -> dialog.dismiss());
+        alert.setPositiveButton(android.R.string.ok, (dialog, which) -> dialog.dismiss());
         alert.setTitle(R.string.export_error_label);
         alert.setMessage(error.getMessage());
         alert.show();

core/src/main/java/de/danoeh/antennapod/core/storage/DatabaseExporter.java

@@ -1,6 +1,8 @@
 package de.danoeh.antennapod.core.storage;
 
 import android.content.Context;
+import android.database.sqlite.SQLiteDatabase;
+import android.database.sqlite.SQLiteException;
 import android.net.Uri;
 import android.os.ParcelFileDescriptor;
 import android.util.Log;
@@ -14,21 +16,10 @@ import java.io.FileOutputStream;
 import java.io.IOException;
 import java.io.InputStream;
 import java.nio.channels.FileChannel;
-import java.util.Arrays;
 
 public class DatabaseExporter {
     private static final String TAG = "DatabaseExporter";
-    private static final byte[] SQLITE3_MAGIC = "SQLite format 3\0".getBytes();
+    private static final String TEMP_DB_NAME = PodDBAdapter.DATABASE_NAME + "_tmp";
-
-    public static boolean validateDB(Uri inputUri, Context context) throws IOException {
-        try (InputStream inputStream = context.getContentResolver().openInputStream(inputUri)) {
-            byte[] magicBuf = new byte[SQLITE3_MAGIC.length];
-            if (inputStream.read(magicBuf) == magicBuf.length) {
-                return Arrays.equals(SQLITE3_MAGIC, magicBuf);
-            }
-        }
-        return false;
-    }
 
     public static void exportToDocument(Uri uri, Context context) throws IOException {
         ParcelFileDescriptor pfd = null;
@@ -78,14 +69,21 @@ public class DatabaseExporter {
     public static void importBackup(Uri inputUri, Context context) throws IOException {
         InputStream inputStream = null;
         try {
-            if (!validateDB(inputUri, context)) {
+            File tempDB = context.getDatabasePath(TEMP_DB_NAME);
-                throw new IOException(context.getString(R.string.import_bad_file));
+            inputStream = context.getContentResolver().openInputStream(inputUri);
+            FileUtils.copyInputStreamToFile(inputStream, tempDB);
+
+            SQLiteDatabase db = SQLiteDatabase.openDatabase(tempDB.getAbsolutePath(),
+                    null, SQLiteDatabase.OPEN_READONLY);
+            if (db.getVersion() > PodDBAdapter.VERSION) {
+                throw new IOException(context.getString(R.string.import_no_downgrade));
             }
+            db.close();
 
             File currentDB = context.getDatabasePath(PodDBAdapter.DATABASE_NAME);
-            inputStream = context.getContentResolver().openInputStream(inputUri);
+            currentDB.delete();
-            FileUtils.copyInputStreamToFile(inputStream, currentDB);
+            FileUtils.moveFile(tempDB, currentDB);
-        } catch (IOException e) {
+        } catch (IOException | SQLiteException e) {
             Log.e(TAG, Log.getStackTraceString(e));
             throw e;
         } finally {

core/src/main/java/de/danoeh/antennapod/core/storage/PodDBAdapter.java

@@ -48,6 +48,7 @@ public class PodDBAdapter {
 
     private static final String TAG = "PodDBAdapter";
     public static final String DATABASE_NAME = "Antennapod.db";
+    public static final int VERSION = 1090000;
 
     /**
      * Maximum number of arguments for IN-operator.
@@ -1336,8 +1337,6 @@ public class PodDBAdapter {
      * Helper class for opening the Antennapod database.
      */
     private static class PodDBHelper extends SQLiteOpenHelper {
-        private static final int VERSION = 1090000;
-
         /**
          * Constructor.
          *
@@ -1345,8 +1344,7 @@ public class PodDBAdapter {
          * @param name    Name of the database
          * @param factory to use for creating cursor objects
          */
-        public PodDBHelper(final Context context, final String name,
+        public PodDBHelper(final Context context, final String name, final CursorFactory factory) {
-                           final CursorFactory factory) {
             super(context, name, factory, VERSION, new PodDbErrorHandler());
         }
 
@@ -1369,10 +1367,8 @@ public class PodDBAdapter {
         }
 
         @Override
-        public void onUpgrade(final SQLiteDatabase db, final int oldVersion,
+        public void onUpgrade(final SQLiteDatabase db, final int oldVersion, final int newVersion) {
-                              final int newVersion) {
+            Log.w("DBAdapter", "Upgrading from version " + oldVersion + " to " + newVersion + ".");
-            Log.w("DBAdapter", "Upgrading from version " + oldVersion + " to "
-                    + newVersion + ".");
             DBUpgrader.upgrade(db, oldVersion, newVersion);
         }
     }

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

@@ -572,6 +572,7 @@
     <string name="opml_import_ask_read_permission">Access to external storage is required to read the OPML file</string>
     <string name="import_select_file">Select file to import</string>
     <string name="import_ok">Import successful.\n\nPlease press OK to restart AntennaPod</string>
+    <string name="import_no_downgrade">This database was exported with a newer version of AntennaPod. Your current installation does not yet know how to handle this file.</string>
 
     <!-- Sleep timer -->
     <string name="set_sleeptimer_label">Set sleep timer</string>
@@ -768,7 +769,6 @@
     <string name="cast_failed_to_play">Failed to start the playback of media</string>
     <string name="cast_failed_to_stop">Failed to stop the playback of media</string>
     <string name="cast_failed_to_pause">Failed to pause the playback of media</string>
-    <!--<string name="cast_failed_to_connect">Could not connect to the device</string>-->
     <string name="cast_failed_setting_volume">Failed to set the volume</string>
     <string name="cast_failed_no_connection">No connection to the cast device is present</string>
     <string name="cast_failed_no_connection_trans">Connection to the cast device has been lost. Application is trying to re-establish the connection, if possible. Please wait for a few seconds and try again.</string>
@@ -786,7 +786,6 @@
     <string name="notification_channel_playing_description">Allows to control playback. This is the main notification you see while playing a podcast.</string>
     <string name="notification_channel_error">Errors</string>
     <string name="notification_channel_error_description">Shown if something went wrong, for example if download or gpodder sync fails.</string>
-    <string name="import_bad_file">Invalid/corrupt file</string>
 
     <!-- Widget settings -->
     <string name="widget_settings">Widget settings</string>