Revert "Replace RunGuard with SingleApplication"

This reverts commit d105ff6.

src/CMakeLists.txt

@@ -128,14 +128,11 @@ if(ANDROID)
 
     target_include_directories(QGC PUBLIC ${CMAKE_SOURCE_DIR}/android/src)
 else()
-    set(QAPPLICATION_CLASS QApplication CACHE STRING "Inheritance class for SingleApplication" FORCE)
-    FetchContent_Declare(SingleApplication
-        GIT_REPOSITORY https://github.com/itay-grudev/SingleApplication
-        GIT_TAG v3.5.1
-        GIT_SHALLOW TRUE
+    target_sources(QGC
+        PRIVATE
+            RunGuard.cc
+            RunGuard.h
     )
-    FetchContent_MakeAvailable(SingleApplication)
-    target_link_libraries(QGC PUBLIC SingleApplication::SingleApplication)
 endif()
 
 target_precompile_headers(QGC PRIVATE ${CMAKE_SOURCE_DIR}/src/pch.h)

src/QGCApplication.cc

@@ -137,7 +137,7 @@ static QObject* shapeFileHelperSingletonFactory(QQmlEngine*, QJSEngine*)
 }
 
 QGCApplication::QGCApplication(int &argc, char* argv[], bool unitTesting)
-    : QGCAPPLICATION_CLASS(argc, argv)
+    : QApplication(argc, argv)
     , _runningUnitTests(unitTesting)
 {
     _msecsElapsedTime.start();

src/QGCApplication.h

@@ -23,13 +23,6 @@
 #include <QtCore/private/qthread_p.h>
 #include <QtCore/private/qobject_p.h>
 
-#if defined(Q_OS_ANDROID) || defined(Q_OS_IOS)
-    #define QGCAPPLICATION_CLASS QApplication
-#else
-    #include <SingleApplication>
-    #define QGCAPPLICATION_CLASS SingleApplication
-#endif
-
 // Work around circular header includes
 class QQmlApplicationEngine;
 class QGCToolbox;
@@ -63,7 +56,7 @@ class QGCApplication;
 **/
 
 // TODO: Use QtGraphs to convert to QGuiApplication
-class QGCApplication : public QGCAPPLICATION_CLASS
+class QGCApplication : public QApplication
 {
     Q_OBJECT
 public:

src/RunGuard.cc

@@ -0,0 +1,87 @@
+/****************************************************************************
+ *
+ * (c) 2009-2020 QGROUNDCONTROL PROJECT <http://www.qgroundcontrol.org>
+ *
+ * QGroundControl is licensed according to the terms in the file
+ * COPYING.md in the root of the source code directory.
+ *
+ ****************************************************************************/
+
+#include "RunGuard.h"
+
+#include <QtCore/QCryptographicHash>
+
+namespace
+{
+
+QString generateKeyHash( const QString& key, const QString& salt )
+{
+    QByteArray data;
+
+    data.append( key.toUtf8() );
+    data.append( salt.toUtf8() );
+    data = QCryptographicHash::hash( data, QCryptographicHash::Sha1 ).toHex();
+
+    return data;
+}
+
+}
+
+RunGuard::RunGuard( const QString& key )
+    : key( key )
+    , memLockKey( generateKeyHash( key, "_memLockKey" ) )
+    , sharedmemKey( generateKeyHash( key, "_sharedmemKey" ) )
+    , sharedMem( sharedmemKey )
+    , memLock( memLockKey, 1 )
+{
+    memLock.acquire();
+    {
+        QSharedMemory fix( sharedmemKey );    // Fix for *nix: http://habrahabr.ru/post/173281/
+        fix.attach();
+    }
+    memLock.release();
+}
+
+RunGuard::~RunGuard()
+{
+    release();
+}
+
+bool RunGuard::isAnotherRunning()
+{
+    if ( sharedMem.isAttached() )
+        return false;
+
+    memLock.acquire();
+    const bool isRunning = sharedMem.attach();
+    if ( isRunning )
+        sharedMem.detach();
+    memLock.release();
+
+    return isRunning;
+}
+
+bool RunGuard::tryToRun()
+{
+    if ( isAnotherRunning() )   // Extra check
+        return false;
+
+    memLock.acquire();
+    const bool result = sharedMem.create( sizeof( quint64 ) );
+    memLock.release();
+    if ( !result )
+    {
+        release();
+        return false;
+    }
+
+    return true;
+}
+
+void RunGuard::release()
+{
+    memLock.acquire();
+    if ( sharedMem.isAttached() )
+        sharedMem.detach();
+    memLock.release();
+}

src/RunGuard.h

@@ -0,0 +1,36 @@
+/****************************************************************************
+ *
+ * (c) 2009-2020 QGROUNDCONTROL PROJECT <http://www.qgroundcontrol.org>
+ *
+ * QGroundControl is licensed according to the terms in the file
+ * COPYING.md in the root of the source code directory.
+ *
+ ****************************************************************************/
+
+#pragma once
+
+
+#include <QtCore/QObject>
+#include <QtCore/QSharedMemory>
+#include <QtCore/QSystemSemaphore>
+
+class RunGuard
+{
+public:
+    RunGuard( const QString& key );
+    ~RunGuard();
+
+    bool isAnotherRunning();
+    bool tryToRun();
+    void release();
+
+private:
+    const QString key;
+    const QString memLockKey;
+    const QString sharedmemKey;
+
+    QSharedMemory sharedMem;
+    QSystemSemaphore memLock;
+
+    Q_DISABLE_COPY( RunGuard )
+};

src/main.cc

@@ -17,6 +17,10 @@
 #include "QGC.h"
 #include "AppMessages.h"
 
+#ifndef __mobile__
+    #include "RunGuard.h"
+#endif
+
 #ifdef Q_OS_ANDROID
     #include "AndroidInterface.h"
 #endif
@@ -78,6 +82,24 @@ void sigHandler(int s)
 
 int main(int argc, char *argv[])
 {
+#ifndef __mobile__
+    // We make the runguard key different for custom and non custom
+    // builds, so they can be executed together in the same device.
+    // Stable and Daily have same QGC_APP_NAME so they would
+    // not be able to run at the same time
+    const QString runguardString = QString("%1 RunGuardKey").arg(QGC_APP_NAME);
+
+    RunGuard guard(runguardString);
+    if (!guard.tryToRun()) {
+        // QApplication is necessary to use QMessageBox
+        QApplication errorApp(argc, argv);
+        QMessageBox::critical(nullptr, QObject::tr("Error"),
+            QObject::tr("A second instance of %1 is already running. Please close the other instance and try again.").arg(QGC_APP_NAME)
+        );
+        return -1;
+    }
+#endif
+
 #ifdef Q_OS_LINUX
 #ifndef Q_OS_ANDROID
     if (getuid() == 0) {