// 'of' can be null - in that case everyone's permissions have been requested. Otherwise only
  // single user's.
  // If the user requesting 'LIST PERMISSIONS' is not a superuser OR his username doesn't match
  // 'of', we
  // throw UnauthorizedException. So only a superuser can view everybody's permissions. Regular
  // users are only
  // allowed to see their own permissions.
  public Set<PermissionDetails> list(
      AuthenticatedUser performer, Set<Permission> permissions, IResource resource, String of)
      throws RequestValidationException, RequestExecutionException {
    if (!performer.isSuper() && !performer.getName().equals(of))
      throw new UnauthorizedException(
          String.format(
              "You are not authorized to view %s's permissions", of == null ? "everyone" : of));

    Set<PermissionDetails> details = new HashSet<PermissionDetails>();

    for (UntypedResultSet.Row row : process(buildListQuery(resource, of))) {
      if (row.has(PERMISSIONS)) {
        for (String p : row.getSet(PERMISSIONS, UTF8Type.instance)) {
          Permission permission = Permission.valueOf(p);
          if (permissions.contains(permission))
            details.add(
                new PermissionDetails(
                    row.getString(USERNAME),
                    DataResource.fromName(row.getString(RESOURCE)),
                    permission));
        }
      }
    }

    return details;
  }
 public Set<DataResource> protectedResources() {
   return ImmutableSet.of(DataResource.columnFamily(Auth.AUTH_KS, PERMISSIONS_CF));
 }