restart file observer when permisson are granted

src/main/java/eu/siacs/conversations/services/XmppConnectionService.java

@@ -9,6 +9,7 @@ import android.content.Context;
 import android.content.Intent;
 import android.content.IntentFilter;
 import android.content.SharedPreferences;
+import android.content.pm.PackageManager;
 import android.database.ContentObserver;
 import android.graphics.Bitmap;
 import android.media.AudioManager;
@@ -29,6 +30,7 @@ import android.security.KeyChain;
 import android.support.annotation.BoolRes;
 import android.support.annotation.IntegerRes;
 import android.support.v4.app.RemoteInput;
+import android.support.v4.content.ContextCompat;
 import android.text.TextUtils;
 import android.util.DisplayMetrics;
 import android.util.Log;
@@ -64,6 +66,7 @@ import java.util.concurrent.atomic.AtomicLong;
 import javax.security.auth.callback.Callback;
 
 import eu.siacs.conversations.Config;
+import eu.siacs.conversations.Manifest;
 import eu.siacs.conversations.R;
 import eu.siacs.conversations.crypto.OmemoSetting;
 import eu.siacs.conversations.crypto.PgpDecryptionService;
@@ -970,7 +973,10 @@ public class XmppConnectionService extends Service {
 		restoreFromDatabase();
 
 		getContentResolver().registerContentObserver(ContactsContract.Contacts.CONTENT_URI, true, contactObserver);
+		if (Build.VERSION.SDK_INT < Build.VERSION_CODES.M || ContextCompat.checkSelfPermission(this, android.Manifest.permission.WRITE_EXTERNAL_STORAGE) == PackageManager.PERMISSION_GRANTED) {
+			Log.d(Config.LOGTAG,"starting file observer");
 			new Thread(fileObserver::startWatching).start();
+		}
 		if (Config.supportOpenPgp()) {
 			this.pgpServiceConnection = new OpenPgpServiceConnection(this, "org.sufficientlysecure.keychain", new OpenPgpServiceConnection.OnBound() {
 				@Override
@@ -1024,6 +1030,11 @@ public class XmppConnectionService extends Service {
 		super.onDestroy();
 	}
 
+	public void restartFileObserver() {
+		Log.d(Config.LOGTAG,"restarting file observer");
+		new Thread(fileObserver::restartWatching).start();
+	}
+
 	public void toggleScreenEventReceiver() {
 		if (awayWhenScreenOff() && !manuallyChangePresence()) {
 			final IntentFilter filter = new IntentFilter(Intent.ACTION_SCREEN_ON);

src/main/java/eu/siacs/conversations/ui/ConversationFragment.java

@@ -499,6 +499,15 @@ public class ConversationFragment extends XmppFragment implements EditMessage.Ke
 		return true;
 	}
 
+	private static boolean writeGranted(int[] grantResults, String[] permission) {
+		for(int i = 0; i < grantResults.length; ++i) {
+			if (Manifest.permission.WRITE_EXTERNAL_STORAGE.equals(permission[i])) {
+				return grantResults[i] == PackageManager.PERMISSION_GRANTED;
+			}
+		}
+		return false;
+	}
+
 	private static String getFirstDenied(int[] grantResults, String[] permissions) {
 		for (int i = 0; i < grantResults.length; ++i) {
 			if (grantResults[i] == PackageManager.PERMISSION_DENIED) {
@@ -1343,7 +1352,7 @@ public class ConversationFragment extends XmppFragment implements EditMessage.Ke
 
 	@Override
 	public void onRequestPermissionsResult(int requestCode, @NonNull String permissions[], @NonNull int[] grantResults) {
-		if (grantResults.length > 0)
+		if (grantResults.length > 0) {
 			if (allGranted(grantResults)) {
 				if (requestCode == REQUEST_START_DOWNLOAD) {
 					if (this.mPendingDownloadableMessage != null) {
@@ -1369,6 +1378,12 @@ public class ConversationFragment extends XmppFragment implements EditMessage.Ke
 				Toast.makeText(getActivity(), res, Toast.LENGTH_SHORT).show();
 			}
 		}
+		if (writeGranted(grantResults, permissions)) {
+			if (activity != null && activity.xmppConnectionService != null) {
+				activity.xmppConnectionService.restartFileObserver();
+			}
+		}
+	}
 
 	public void startDownloadable(Message message) {
 		if (!hasPermissions(REQUEST_START_DOWNLOAD, Manifest.permission.WRITE_EXTERNAL_STORAGE)) {

src/main/java/eu/siacs/conversations/utils/ConversationsFileObserver.java

@@ -75,6 +75,11 @@ public abstract class ConversationsFileObserver {
 
     abstract public void onEvent(int event, String path);
 
+    public void restartWatching() {
+        stopWatching();
+        startWatching();
+    }
+
     private class SingleFileObserver extends FileObserver {
         private final String path;