From 72fdb2fb8870f49cb066eca754e87e7b7e5d82d9 Mon Sep 17 00:00:00 2001
From: Magnus Ahltorp <map@kth.se>
Date: Tue, 18 Nov 2014 17:06:53 +0100
Subject: Make ht load tree and verify root hash before updating tree size

---
 src/ht.erl | 15 ++++++++++++++-
 1 file changed, 14 insertions(+), 1 deletion(-)

(limited to 'src/ht.erl')

diff --git a/src/ht.erl b/src/ht.erl
index b4c7401..4b08e34 100644
--- a/src/ht.erl
+++ b/src/ht.erl
@@ -28,7 +28,7 @@
 -module(ht).
 -behaviour(gen_server).
 
--export([reset_tree/1, size/0, leaf_hash/1]).
+-export([reset_tree/1, load_tree/1, size/0, leaf_hash/1]).
 -export([add/1, root/0, root/1, path/2, consistency/2]).
 -export([start_link/0, start_link/1, stop/0]).
 -export([init/1, handle_call/3, terminate/2, handle_cast/2, handle_info/2,
@@ -53,6 +53,8 @@ start_link(NEntries) ->
     gen_server:start_link({local, ?MODULE}, ?MODULE, [NEntries], []).
 reset_tree(Arg) ->
     call(?MODULE, {reset_tree, Arg}).
+load_tree(Version) ->
+    call(?MODULE, {load_tree, Version}).
 stop() ->
     call(?MODULE, stop).
 size() ->
@@ -93,6 +95,9 @@ terminate(_Reason, _State) ->
 handle_call({reset_tree, Arg}, _From, _State) ->
     NewTree = new(Arg),
     {reply, NewTree, NewTree};
+handle_call({load_tree, Version}, _From, State) ->
+    {Reply, NewTree} = read_new_entries(State, Version),
+    {reply, Reply, NewTree};
 handle_call(stop, _From, State) ->
     {stop, normal, stopped, State};
 handle_call(size, _From, State) ->
@@ -256,6 +261,14 @@ first_left_node(Layer, Index, BAL) ->
 add(Tree = #tree{version = V, store = Store}, Hash) ->
     Tree#tree{version = V + 1, store = ts:add(Store, 0, Hash)}.
 
+read_new_entries(State, Version) when is_integer(Version) ->
+    NewEntries = db:get_by_indices(State#tree.version + 1, Version, {sorted, true}),
+    NewState = foldl(fun(Hash, Tree) ->
+                             add(Tree, Hash)
+                     end, State, [H || {_I, H, _E} <-
+                                           NewEntries]),
+    {ok, NewState}.
+
 %% @doc Return a new tree.
 -spec new(list()) -> tree().
 new([]) ->
-- 
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