[couchdb] 01/01: Validate the result from collate_fun

[rn...@apache.org]

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rnewson pushed a commit to branch prototype/fdb-layer-ebtree-collate-validate
in repository https://gitbox.apache.org/repos/asf/couchdb.git

commit 44564eb7ef9ba2051c96520d8180d39fb35f2e1d
Author: Robert Newson <rn...@apache.org>
AuthorDate: Tue Aug 4 21:28:58 2020 +0100

    Validate the result from collate_fun
---
 src/ebtree/src/ebtree.erl | 13 ++++++++++++-
 1 file changed, 12 insertions(+), 1 deletion(-)

diff --git a/src/ebtree/src/ebtree.erl b/src/ebtree/src/ebtree.erl
index bae0ff3..36d3c47 100644
--- a/src/ebtree/src/ebtree.erl
+++ b/src/ebtree/src/ebtree.erl
@@ -918,7 +918,13 @@ collate(#tree{} = _Tree, _A, ?MAX) ->
 
 collate(#tree{} = Tree, A, B) ->
     #tree{collate_fun = CollateFun} = Tree,
-    CollateFun(A, B).
+    Result = CollateFun(A, B),
+    case lists:member(Result, [lt, eq, gt]) of
+        true ->
+            Result;
+        false ->
+            throw(invalid_collation_result)
+    end.
 
 
 collate(#tree{} = Tree, A, B, Allowed) ->
@@ -1090,6 +1096,11 @@ collation_fun_test_() ->
     ].
 
 
+collate_validation_test() ->
+    Tree = #tree{collate_fun = fun(_A, _B) -> foo end},
+    ?assertThrow(invalid_collation_result, collate(Tree, 1, 2)).
+
+
 lookup_test() ->
     Db = erlfdb_util:get_test_db([empty]),
     Tree = open(Db, <<1,2,3>>, 4),