From f314cd6b922ba4370a51d71adb22c091df1e4d10 Mon Sep 17 00:00:00 2001
From: Leo Yuriev <leo@yuriev.ru>
Date: Fri, 15 Jun 2018 02:54:41 +0300
Subject: [PATCH] mdbx: windows - fix truncation race while unmap.

Change-Id: I93983d100c78aa3e57c5a7ebd9d5bf2a96081ed7
---
 src/mdbx.c |  5 +++++
 src/osal.c | 12 +++++-------
 2 files changed, 10 insertions(+), 7 deletions(-)

diff --git a/src/mdbx.c b/src/mdbx.c
index e4c5248c..18be2e55 100644
--- a/src/mdbx.c
+++ b/src/mdbx.c
@@ -2041,6 +2041,11 @@ static int mdbx_mapresize(MDBX_env *env, const pgno_t size_pgno,
 
 bailout:
   if (rc == MDBX_SUCCESS) {
+#if defined(_WIN32) || defined(_WIN64)
+    assert(size_bytes == env->me_dxb_mmap.current);
+    assert(size_bytes <= env->me_dxb_mmap.filesize);
+    assert(limit_bytes == env->me_dxb_mmap.length);
+#endif
     env->me_dbgeo.now = size_bytes;
     env->me_dbgeo.upper = limit_bytes;
     if (env->me_txn) {
diff --git a/src/osal.c b/src/osal.c
index f079bb96..6fda36a2 100644
--- a/src/osal.c
+++ b/src/osal.c
@@ -892,11 +892,6 @@ int mdbx_munmap(mdbx_mmap_t *map) {
   if (!NT_SUCCESS(rc))
     ntstatus2errcode(rc);
 
-  if (map->filesize != map->current &&
-      mdbx_filesize(map->fd, &map->filesize) == MDBX_SUCCESS &&
-      map->filesize != map->current)
-    (void)mdbx_ftruncate(map->fd, map->current);
-
   map->length = 0;
   map->current = 0;
   map->address = nullptr;
@@ -922,8 +917,11 @@ int mdbx_mresize(int flags, mdbx_mmap_t *map, size_t size, size_t limit) {
     /* growth rw-section */
     SectionSize.QuadPart = size;
     status = NtExtendSection(map->section, &SectionSize);
-    if (NT_SUCCESS(status))
-      map->filesize = map->current = size;
+    if (NT_SUCCESS(status)) {
+      map->current = size;
+      if (map->filesize < size)
+        map->filesize = size;
+    }
     return ntstatus2errcode(status);
   }