From 2dab009e761edf8a2e56c2a2138f21e3600b22f1 Mon Sep 17 00:00:00 2001
From: Leonid Yuriev <leo@yuriev.ru>
Date: Wed, 25 Nov 2020 10:49:39 +0300
Subject: [PATCH] mdbx-windows: handling `EXCEPTION_POSSIBLE_DEADLOCK`.

Change-Id: If42c7833e9c4e02fef25634e69c0bd2e926686c1
---
 .github/actions/spelling/expect.txt |  1 +
 ChangeLog.md                        |  1 +
 src/lck-windows.c                   | 10 +++++++++-
 src/ntdll.def                       |  2 ++
 src/osal.c                          | 10 +++++++++-
 src/osal.h                          |  1 +
 6 files changed, 23 insertions(+), 2 deletions(-)

diff --git a/.github/actions/spelling/expect.txt b/.github/actions/spelling/expect.txt
index 435f969b..75cdff13 100644
--- a/.github/actions/spelling/expect.txt
+++ b/.github/actions/spelling/expect.txt
@@ -447,6 +447,7 @@ EWOULDBLOCK
 Exa
 exactkey
 exactp
+excpt
 exe
 exename
 exherbo
diff --git a/ChangeLog.md b/ChangeLog.md
index e7cf7953..90cd7f04 100644
--- a/ChangeLog.md
+++ b/ChangeLog.md
@@ -58,6 +58,7 @@ Fixes:
  - Fixed large pages checking (for compatibility and to avoid false-positive errors from `mdbx_chk`).
  - Added workaround for Wine (https://github.com/miranda-ng/miranda-ng/issues/1209).
  - Fixed `ERROR_NOT_SUPPORTED` while opening DB by UNC pathnames (https://github.com/miranda-ng/miranda-ng/issues/2627).
+ - Added handling `EXCEPTION_POSSIBLE_DEADLOCK` condition for Windows.
 
 
 ## v0.9.1 2020-09-30
diff --git a/src/lck-windows.c b/src/lck-windows.c
index 0ddd8c7d..3bcf347d 100644
--- a/src/lck-windows.c
+++ b/src/lck-windows.c
@@ -144,7 +144,15 @@ int mdbx_txn_lock(MDBX_env *env, bool dontwait) {
     if (!TryEnterCriticalSection(&env->me_windowsbug_lock))
       return MDBX_BUSY;
   } else {
-    EnterCriticalSection(&env->me_windowsbug_lock);
+    __try {
+      EnterCriticalSection(&env->me_windowsbug_lock);
+    }
+    __except ((GetExceptionCode() ==
+                 0xC0000194 /* STATUS_POSSIBLE_DEADLOCK / EXCEPTION_POSSIBLE_DEADLOCK */)
+                    ? EXCEPTION_EXECUTE_HANDLER
+                    : EXCEPTION_CONTINUE_SEARCH) {
+      return ERROR_POSSIBLE_DEADLOCK;
+    }
   }
 
   if ((env->me_flags & MDBX_EXCLUSIVE) ||
diff --git a/src/ntdll.def b/src/ntdll.def
index e3a6e33c..f974ea63 100644
--- a/src/ntdll.def
+++ b/src/ntdll.def
@@ -1242,3 +1242,5 @@ wcsstr
 wcstol
 wcstombs
 wcstoul
+__C_specific_handler
+_except_handler4_common
diff --git a/src/osal.c b/src/osal.c
index f263346b..da99e618 100644
--- a/src/osal.c
+++ b/src/osal.c
@@ -492,7 +492,15 @@ MDBX_INTERNAL_FUNC int mdbx_fastmutex_destroy(mdbx_fastmutex_t *fastmutex) {
 
 MDBX_INTERNAL_FUNC int mdbx_fastmutex_acquire(mdbx_fastmutex_t *fastmutex) {
 #if defined(_WIN32) || defined(_WIN64)
-  EnterCriticalSection(fastmutex);
+  __try {
+    EnterCriticalSection(fastmutex);
+  } __except (
+      (GetExceptionCode() ==
+       0xC0000194 /* STATUS_POSSIBLE_DEADLOCK / EXCEPTION_POSSIBLE_DEADLOCK */)
+          ? EXCEPTION_EXECUTE_HANDLER
+          : EXCEPTION_CONTINUE_SEARCH) {
+    return ERROR_POSSIBLE_DEADLOCK;
+  }
   return MDBX_SUCCESS;
 #else
   return pthread_mutex_lock(fastmutex);
diff --git a/src/osal.h b/src/osal.h
index 3212976a..a1c8c1f6 100644
--- a/src/osal.h
+++ b/src/osal.h
@@ -146,6 +146,7 @@ __extern_C key_t ftok(const char *, int);
 #ifndef WIN32_LEAN_AND_MEAN
 #define WIN32_LEAN_AND_MEAN
 #endif
+#include <excpt.h>
 #include <tlhelp32.h>
 #include <windows.h>
 #include <winnt.h>