Fixes COUCHDB-640 - Reset views with invalid update seqs.

If a database is restored to a previous version, and the view files
are not updated appropriately they will contain data from the database
after the reverted-to-update_seq. This patch checks that the update
sequence recorded in a view is less than or equal to the update
sequence of the database.

Patch is by Filipe Manana. Execellent work once again.



git-svn-id: https://svn.apache.org/repos/asf/couchdb/trunk@911544 13f79535-47bb-0310-9956-ffa450edef68

2 files changed, 33 insertions, 13 deletions

diff --git a/src/couchdb/couch_view.erl b/src/couchdb/couch_view.erl
index f80ce434..cbbbd4ac 100644
--- a/src/couchdb/couch_view.erl
+++ b/src/couchdb/couch_view.erl
@@ -284,6 +284,15 @@ handle_call({get_group_server, DbName,
         {ok, NewPid} ->
             add_to_ets(NewPid, DbName, Sig),
             {reply, {ok, NewPid}, Server};
+        {error, invalid_view_seq} ->
+            do_reset_indexes(DbName, Root),
+            case (catch couch_view_group:start_link({Root, DbName, Group})) of
+            {ok, NewPid} ->
+                add_to_ets(NewPid, DbName, Sig),
+                {reply, {ok, NewPid}, Server};
+            Error ->
+                {reply, Error, Server}
+            end;
         Error ->
             {reply, Error, Server}
         end;
@@ -292,6 +301,10 @@ handle_call({get_group_server, DbName,
     end.
 
 handle_cast({reset_indexes, DbName}, #server{root_dir=Root}=Server) ->
+    do_reset_indexes(DbName, Root),
+    {noreply, Server}.
+
+do_reset_indexes(DbName, Root) ->
     % shutdown all the updaters and clear the files, the db got changed
     Names = ets:lookup(couch_groups_by_db, DbName),
     lists:foreach(
@@ -304,8 +317,7 @@ handle_cast({reset_indexes, DbName}, #server{root_dir=Root}=Server) ->
             end
         end, Names),
     delete_index_dir(Root, DbName),
-    file:delete(Root ++ "/." ++ binary_to_list(DbName) ++ "_temp"),
-    {noreply, Server}.
+    file:delete(Root ++ "/." ++ ?b2l(DbName) ++ "_temp").
 
 handle_info({'EXIT', FromPid, Reason}, Server) ->
     case ets:lookup(couch_groups_by_updater, FromPid) of
diff --git a/src/couchdb/couch_view_group.erl b/src/couchdb/couch_view_group.erl
index 6589bc6a..8439304d 100644
--- a/src/couchdb/couch_view_group.erl
+++ b/src/couchdb/couch_view_group.erl
@@ -78,17 +78,25 @@ start_link(InitArgs) ->
 init({InitArgs, ReturnPid, Ref}) ->
     process_flag(trap_exit, true),
     case prepare_group(InitArgs, false) of
-    {ok, #group{db=Db, fd=Fd}=Group} ->
-        couch_db:monitor(Db),
-        Owner = self(),
-        Pid = spawn_link(fun()-> couch_view_updater:update(Owner, Group) end),
-        {ok, RefCounter} = couch_ref_counter:start([Fd]),
-        {ok, #group_state{
-                db_name=couch_db:name(Db),
-                init_args=InitArgs,
-                updater_pid = Pid,
-                group=Group,
-                ref_counter=RefCounter}};
+    {ok, #group{db=Db, fd=Fd, current_seq=Seq}=Group} ->
+        case Seq > couch_db:get_update_seq(Db) of
+        true ->
+            ReturnPid ! {Ref, self(), {error, invalid_view_seq}},
+            ignore;
+        _ ->
+            couch_db:monitor(Db),
+            Owner = self(),
+            Pid = spawn_link(
+                fun()-> couch_view_updater:update(Owner, Group) end
+            ),
+            {ok, RefCounter} = couch_ref_counter:start([Fd]),
+            {ok, #group_state{
+                    db_name=couch_db:name(Db),
+                    init_args=InitArgs,
+                    updater_pid = Pid,
+                    group=Group,
+                    ref_counter=RefCounter}}
+        end;
     Error ->
         ReturnPid ! {Ref, self(), Error},
         ignore