From dfc3020426265b343804319f8bcb380920a702b4 Mon Sep 17 00:00:00 2001
From: Leo Yuriev <leo@yuriev.ru>
Date: Mon, 17 Apr 2017 19:35:36 +0300
Subject: [PATCH] mdbx: fix mdbx_canary_put().

---
 mdbx.h     | 2 +-
 src/mdbx.c | 7 +++++++
 2 files changed, 8 insertions(+), 1 deletion(-)

diff --git a/mdbx.h b/mdbx.h
index 75688438..2af8b66f 100644
--- a/mdbx.h
+++ b/mdbx.h
@@ -1725,7 +1725,7 @@ typedef int MDBX_pgvisitor_func(size_t pgno, unsigned pgnumber, void *ctx,
 LIBMDBX_API int mdbx_env_pgwalk(MDB_txn *txn, MDBX_pgvisitor_func *visitor,
                                 void *ctx);
 
-typedef struct mdbx_canary { size_t x, y, z, v; } mdbx_canary;
+typedef struct mdbx_canary { uint64_t x, y, z, v; } mdbx_canary;
 
 LIBMDBX_API int mdbx_canary_put(MDB_txn *txn, const mdbx_canary *canary);
 LIBMDBX_API size_t mdbx_canary_get(MDB_txn *txn, mdbx_canary *canary);
diff --git a/src/mdbx.c b/src/mdbx.c
index 19424aba..eb29d3ab 100644
--- a/src/mdbx.c
+++ b/src/mdbx.c
@@ -9841,15 +9841,22 @@ int mdbx_canary_put(MDB_txn *txn, const mdbx_canary *canary) {
   if (unlikely(txn->mt_signature != MDBX_MT_SIGNATURE))
     return MDBX_EBADSIGN;
 
+  if (unlikely(txn->mt_flags & MDB_TXN_BLOCKED))
+    return MDB_BAD_TXN;
+
   if (unlikely(F_ISSET(txn->mt_flags, MDB_TXN_RDONLY)))
     return EACCES;
 
   if (likely(canary)) {
+    if (txn->mt_canary.x == canary->x && txn->mt_canary.y == canary->y &&
+        txn->mt_canary.z == canary->z && txn->mt_canary.v == canary->v)
+      return MDB_SUCCESS;
     txn->mt_canary.x = canary->x;
     txn->mt_canary.y = canary->y;
     txn->mt_canary.z = canary->z;
   }
   txn->mt_canary.v = txn->mt_txnid;
+  txn->mt_flags |= MDB_TXN_DIRTY;
 
   return MDB_SUCCESS;
 }