Function addUserFilterToFilter

edgraph/access.go:1279–1310

* addUserFilterToFilter makes sure that user can't misue filters to access other user's info. If the *filter* have type(dgraph.type.Group) or type(dgraph.type.User) functions, it generate a *newFilter* with function like eq(dgraph.xid, userId) or eq(dgraph.xid,groupId...) and return a filter

(filter *dql.FilterTree, userId string,
	groupIds []string)

			}
*/
func addUserFilterToFilter(filter *dql.FilterTree, userId string,
	groupIds []string) *dql.FilterTree {

	if filter == nil {
		return nil
	}

	if filter.Func != nil && filter.Func.Name == "type" {

		// type function supports only one argument
		if len(filter.Func.Args) != 1 {
			return nil
		}
		arg := filter.Func.Args[0]
		var newFilter *dql.FilterTree
		switch arg.Value {
		case "dgraph.type.User":
			newFilter = userFilter(userId)
		case "dgraph.type.Group":
			newFilter = groupFilter(groupIds)
		}

		// If filter have function, it can't have children.
		return parentFilter(newFilter, filter)
	}

	for idx, child := range filter.Child {
		filter.Child[idx] = addUserFilterToFilter(child, userId, groupIds)
	}

	return filter
}

// removePredsFromQuery removes all the predicates in blockedPreds
// from all the queries in gqs.