From 6d438605dd0d7bf3947e49a6e98b33115460dbd1 Mon Sep 17 00:00:00 2001
From: Leonid Yuriev <leo@yuriev.ru>
Date: Fri, 24 Aug 2018 04:00:59 +0300
Subject: [PATCH] mdbx: backport - check comparator for MDBX_GET_BOTH and
 MDBX_GET_BOTH_RANGE.

---
 src/mdbx.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/src/mdbx.c b/src/mdbx.c
index d1567925..ea2c6619 100644
--- a/src/mdbx.c
+++ b/src/mdbx.c
@@ -7130,9 +7130,11 @@ set1:
       MDBX_val olddata;
       if (unlikely((rc = mdbx_node_read(mc, leaf, &olddata)) != MDBX_SUCCESS))
         return rc;
+      if (unlikely(mc->mc_dbx->md_dcmp == NULL))
+        return MDBX_EINVAL;
       rc = mc->mc_dbx->md_dcmp(data, &olddata);
       if (rc) {
-        if (op == MDBX_GET_BOTH || rc > 0)
+        if (op != MDBX_GET_BOTH_RANGE || rc > 0)
           return MDBX_NOTFOUND;
         rc = 0;
       }