From 4384320d416aabb86e30ce07b551704f6607807c Mon Sep 17 00:00:00 2001
From: dogmaphobic <mavlink@grubba.com>
Date: Sat, 23 Jan 2016 02:19:34 -0500
Subject: [PATCH] Detect running instance and prevent loading second instance.

---
 src/main.cc | 12 ++++++++++++
 1 file changed, 12 insertions(+)

diff --git a/src/main.cc b/src/main.cc
index c71f483592..91c48eb1fd 100644
--- a/src/main.cc
+++ b/src/main.cc
@@ -35,6 +35,8 @@ This file is part of the QGROUNDCONTROL project
 
 #include "QGCApplication.h"
 
+#define  SINGLE_INSTANCE_PORT   14499
+
 #ifndef __mobile__
     #include "QGCSerialPortInfo.h"
 #endif
@@ -119,6 +121,16 @@ jint JNI_OnLoad(JavaVM* vm, void* reserved)
 int main(int argc, char *argv[])
 {
 
+#ifndef __mobile__
+    //-- Test for another instance already running. If that's the case, we simply exit.
+    QHostAddress host("127.0.0.1");
+    QUdpSocket socket;
+    if(!socket.bind(host, SINGLE_INSTANCE_PORT, QAbstractSocket::DontShareAddress)) {
+        qWarning() << "Another instance already running. Exiting.";
+        exit(-1);
+    }
+#endif
+
 #ifdef Q_OS_MAC
 #ifndef __ios__
     // Prevent Apple's app nap from screwing us over
-- 
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