From 24a8bdec49ee360bf0412631ff8931de91e109fc Mon Sep 17 00:00:00 2001
From: Leo Yuriev <leo@yuriev.ru>
Date: Wed, 20 Dec 2017 14:22:37 +0300
Subject: [PATCH] mdbx: fix SIGSEGV in case mdbx_env_close_ex() called without
 mdbx_env_open().

---
 src/mdbx.c | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/src/mdbx.c b/src/mdbx.c
index 6d25c03d..3d435ca2 100644
--- a/src/mdbx.c
+++ b/src/mdbx.c
@@ -5387,8 +5387,9 @@ int __cold mdbx_env_close_ex(MDBX_env *env, int dont_sync) {
   if (unlikely(env->me_signature != MDBX_ME_SIGNATURE))
     return MDBX_EBADSIGN;
 
-  if ((env->me_flags & MDBX_RDONLY) == 0) {
-    if (env->me_txn0->mt_owner && env->me_txn0->mt_owner != mdbx_thread_self())
+  if (env->me_lck && (env->me_flags & MDBX_RDONLY) == 0) {
+    if (env->me_txn0 && env->me_txn0->mt_owner &&
+        env->me_txn0->mt_owner != mdbx_thread_self())
       return MDBX_BUSY;
     if (!dont_sync)
       rc = mdbx_env_sync(env, true);