Database downloader changes

- Store the new database separately and move into place
- Check for network connection before trying to download
- Don't immediately delete the database on download start
- Only delete new database on download failure
- Wait until all downloads complete before attempting reload

Signed-off-by: Tad <tad@spotco.us>

app/build.gradle

@@ -6,8 +6,8 @@ android {
         applicationId "us.spotco.malwarescanner"
         minSdkVersion 19
         targetSdkVersion 32
-        versionCode 112
-        versionName "2.35"
+        versionCode 113
+        versionName "2.36"
         resConfigs 'en', 'af', 'de', 'el', 'es', 'fi', 'fr', 'it', 'pl', 'pt', 'ru', 'tr', 'zh-rCN'
     }
     buildTypes {

app/src/main/AndroidManifest.xml

@@ -2,6 +2,7 @@
 <manifest xmlns:android="http://schemas.android.com/apk/res/android"
     package="us.spotco.malwarescanner">
 
+    <uses-permission android:name="android.permission.ACCESS_NETWORK_STATE" />
     <uses-permission android:name="android.permission.FOREGROUND_SERVICE" />
     <uses-permission android:name="android.permission.INTERNET" />
     <uses-permission android:name="android.permission.MANAGE_EXTERNAL_STORAGE" />

app/src/main/java/us/spotco/malwarescanner/Database.java

@@ -53,6 +53,8 @@ class Database {
 
     private static final DateFormat dateFormat = DateFormat.getDateInstance();
 
+    private static final ConcurrentLinkedQueue<AsyncTask<?, ?, ?>> downloadFutures = new ConcurrentLinkedQueue<>();
+
     public Database(TextView log) {
         Database.log = log;
     }
@@ -62,7 +64,15 @@ class Database {
     }
 
     public static boolean isDatabaseLoaded() {
-        return areDatabasesAvailable() && databaseFullyLoaded;
+        return areDatabasesAvailable() && !isDatabaseLoading();
+    }
+
+    public static boolean isDatabaseLoading() {
+        return !databaseFullyLoaded && databaseCurrentlyLoading;
+    }
+
+    public static boolean hasDownloadsRunning() {
+        return downloadFutures.size() > 0;
     }
 
     public static void updateDatabase(Context context, ConcurrentLinkedQueue<SignatureDatabase> signatureDatabases) {
@@ -106,7 +116,7 @@ class Database {
                     try {
                         boolean validated = verifier.verify(databaseLocation, databaseSigLocation, publicKey);
                         if (validated) {
-                            Log.d("Hypatia", "Successfully validated database");
+                            Log.d("Hypatia", "Successfully validated database: " + databaseLocation.getName());
                             FileInputStream databaseLoading = new FileInputStream(databaseLocation);
                             switch (databaseLocation.getName()) {
                                 case "hypatia-md5-bloom.bin":
@@ -139,13 +149,29 @@ class Database {
     }
 
     public static class Downloader extends AsyncTask<Object, String, String> {
+        @Override
+        protected void onPreExecute() {
+            Database.downloadFutures.add(this);
+            super.onPreExecute();
+        }
+
+        @Override
+        protected void onPostExecute(String s) {
+            Database.downloadFutures.remove(this);
+            super.onPostExecute(s);
+        }
+
         @Override
         protected String doInBackground(Object... objects) {
             boolean onionRouting = (boolean) objects[0];
             String url = (String) objects[1];
             File out = new File((String) objects[2]);
+            File outNew = new File((String) objects[2] + ".new");
             String baseURL = (String) objects[3];
             try {
+                if(outNew.exists()) {
+                    outNew.delete();
+                }
                 HttpURLConnection connection;
                 if (onionRouting) {
                     Utils.waitUntilOrbotIsAvailable();
@@ -167,10 +193,7 @@ class Database {
                 int res = connection.getResponseCode();
                 if (res != 304) {
                     if (res == 200) {
-                        if (out.exists()) {
-                            out.delete();
-                        }
-                        FileOutputStream fileOutputStream = new FileOutputStream(out);
+                        FileOutputStream fileOutputStream = new FileOutputStream(outNew);
 
                         final byte[] data = new byte[1024];
                         int count;
@@ -179,6 +202,8 @@ class Database {
                         }
 
                         fileOutputStream.close();
+                        outNew.renameTo(out); //Move the new file into place
+
                         publishProgress(url.replaceAll(baseURL, "")
                                 + "\n\t" + Utils.getContext().getString(R.string.main_database_download_success)
                                 + "\n\t" + Utils.getContext().getString(R.string.main_database_released_on, lastModifiedServer) + "\n");
@@ -193,7 +218,9 @@ class Database {
                 connection.disconnect();
             } catch (Exception e) {
                 e.printStackTrace();
-                out.delete();
+                if(outNew.exists()) {
+                    outNew.delete();
+                }
                 publishProgress(url.replaceAll(baseURL, "")
                         + "\n" + Utils.getContext().getString(R.string.main_database_download_error_logcat) + "\n");
             }

app/src/main/java/us/spotco/malwarescanner/MainActivity.java

@@ -35,6 +35,7 @@ import android.os.Environment;
 import android.provider.Settings;
 import android.text.InputType;
 import android.text.method.ScrollingMovementMethod;
+import android.util.Log;
 import android.view.Menu;
 import android.view.MenuItem;
 import android.view.WindowManager;
@@ -152,6 +153,8 @@ public class MainActivity extends Activity {
             case R.id.mnuUpdateDatabase:
                 if (malwareScanner.running) {
                     logView.append(getString(R.string.lblScanRunning) + "\n");
+                } else if (!Utils.isNetworkAvailable(this)) {
+                    logView.append(getString(R.string.lblNoNetwork) + "\n");
                 } else {
                     if (prefs.getBoolean("ONION_ROUTING", false)) {
                         Utils.requestStartOrbot(this);
@@ -276,9 +279,27 @@ public class MainActivity extends Activity {
 
     private void updateDatabase() {
         new Database(findViewById(R.id.txtLogOutput));
-        Database.updateDatabase(this, Database.signatureDatabases);
+        if(!Database.isDatabaseLoading()) {
+            Database.updateDatabase(this, Database.signatureDatabases);
+        } else {
+            Log.w("Hypatia", "Database is loading, not downloading!");
+        }
         if (Database.isDatabaseLoaded()) {
-            Utils.getThreadPoolExecutor().execute(() -> Database.loadDatabase(getApplicationContext(), true, Database.signatureDatabases));
+            Utils.getThreadPoolExecutor().execute(() -> {
+                try {
+                    Thread.sleep(500);
+                    Log.w("Hypatia", "Invoking database reload!");
+                    while (Database.hasDownloadsRunning()) {
+                        Thread.sleep(500);
+                        Log.w("Hypatia", "Download in progress, waiting!");
+
+                    }
+                } catch (InterruptedException e) {
+                    throw new RuntimeException(e);
+                }
+                Log.w("Hypatia", "Really reloading database!");
+                Database.loadDatabase(getApplicationContext(), true, Database.signatureDatabases);
+            });
         }
     }
 

app/src/main/java/us/spotco/malwarescanner/Utils.java

@@ -22,6 +22,8 @@ import android.content.Context;
 import android.content.Intent;
 import android.content.SharedPreferences;
 import android.content.pm.PackageManager;
+import android.net.ConnectivityManager;
+import android.net.NetworkInfo;
 import android.os.Build;
 
 import java.io.File;
@@ -169,6 +171,13 @@ class Utils {
         }
     }
 
+    //Credit: https://stackoverflow.com/a/4239019
+    public static boolean isNetworkAvailable(Context context) {
+        ConnectivityManager connectivityManager = (ConnectivityManager) context.getSystemService(Context.CONNECTIVITY_SERVICE);
+        NetworkInfo activeNetworkInfo = connectivityManager != null ? connectivityManager.getActiveNetworkInfo() : null;
+        return activeNetworkInfo != null && activeNetworkInfo.isConnected();
+    }
+
     public static Context getContext() {
         return context;
     }

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

@@ -62,4 +62,5 @@
     <string name="scan_control">Scan Control</string>
     <string name="lblScanRunning">Skipping action, a scan is running!</string>
     <string name="lblSigningKey">Database signing key</string>
+    <string name="lblNoNetwork">No network connected!</string>
 </resources>