From a89b42858645cc6565ea925ff020ed0881702ac6 Mon Sep 17 00:00:00 2001
From: Gavin Andresen <gavinandresen@gmail.com>
Date: Tue, 15 Oct 2013 15:30:20 +1000
Subject: [PATCH] Avoid core dump if rpc port is in use.

The cleanup code needs to check for NULL rpcworkers thread group.

Rebased-from: b7f6e156462a24129078252a4e957a5be622ebcc 0.8.x
---
 src/bitcoinrpc.cpp | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/src/bitcoinrpc.cpp b/src/bitcoinrpc.cpp
index 37846ffda..88df45fd5 100644
--- a/src/bitcoinrpc.cpp
+++ b/src/bitcoinrpc.cpp
@@ -852,7 +852,8 @@ void StopRPCThreads()
     if (rpc_io_service == NULL) return;
 
     rpc_io_service->stop();
-    rpc_worker_group->join_all();
+    if (rpc_worker_group != NULL)
+        rpc_worker_group->join_all();
     delete rpc_worker_group; rpc_worker_group = NULL;
     delete rpc_ssl_context; rpc_ssl_context = NULL;
     delete rpc_io_service; rpc_io_service = NULL;