FileProvider: attempt to work with sd cards

src/main/java/eu/siacs/conversations/persistance/FileBackend.java

@@ -515,7 +515,7 @@ public class FileBackend {
 				return FileProvider.getUriForFile(context, packageId + FILE_PROVIDER, file);
 			} catch(IllegalArgumentException e) {
 				if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.N) {
-					throw new SecurityException();
+					throw new SecurityException(e);
 				} else {
 					return Uri.fromFile(file);
 				}

src/main/java/eu/siacs/conversations/ui/adapter/MessageAdapter.java

@@ -22,6 +22,7 @@ import android.text.style.RelativeSizeSpan;
 import android.text.style.StyleSpan;
 import android.text.util.Linkify;
 import android.util.DisplayMetrics;
+import android.util.Log;
 import android.view.ActionMode;
 import android.view.Menu;
 import android.view.MenuItem;
@@ -967,6 +968,7 @@ public class MessageAdapter extends ArrayAdapter<Message> implements CopyTextVie
 		try {
 			uri = FileBackend.getUriForFile(activity, file);
 		} catch (SecurityException e) {
+			Log.d(Config.LOGTAG,"No permission to access "+file.getAbsolutePath(),e);
 			Toast.makeText(activity, activity.getString(R.string.no_permission_to_access_x, file.getAbsolutePath()), Toast.LENGTH_SHORT).show();
 			return;
 		}

src/main/res/xml/file_paths.xml

@@ -1,8 +1,21 @@
 <?xml version="1.0" encoding="utf-8"?>
 <paths>
-    <external-path name="external" path="/"/>
-    <files-path path="Images/" name="pictures" />
-    <files-path path="Videos" name="videos"/>
-    <files-path path="Files/" name="files" />
-    <cache-path path="Camera/" name="camera" />
+    <external-path
+        name="external"
+        path="/"/>
+    <root-path
+        name="storage"
+        path="/storage/"/>
+    <files-path
+        name="pictures"
+        path="Images/"/>
+    <files-path
+        name="videos"
+        path="Videos"/>
+    <files-path
+        name="files"
+        path="Files/"/>
+    <cache-path
+        name="camera"
+        path="Camera/"/>
 </paths>