Use unmodified QtSingleApplication on Windows.

Get running application instance PID without QtSingleApplication
modification.

src/app/application.cpp

@@ -32,6 +32,10 @@
 #include <QLocale>
 #include <QLibraryInfo>
 #include <QSysInfo>
+#ifdef Q_OS_WIN
+#include <Windows.h>
+#include <QSharedMemory>
+#endif
 
 #if (!defined(DISABLE_GUI) && defined(Q_OS_MAC))
 #include <QFont>
@@ -41,11 +45,7 @@
 #include "preferences.h"
 
 Application::Application(const QString &id, int &argc, char **argv)
-#ifndef DISABLE_GUI
-    : SessionApplication(id, argc, argv)
-#else
-    : QtSingleCoreApplication(id, argc, argv)
-#endif
+    : BaseApplication(id, argc, argv)
 {
 #if defined(Q_OS_MACX) && !defined(DISABLE_GUI)
     if (QSysInfo::MacintoshVersion > QSysInfo::MV_10_8) {
@@ -62,6 +62,33 @@ Application::Application(const QString &id, int &argc, char **argv)
 #endif
 }
 
+#ifdef Q_OS_WIN
+bool Application::isRunning()
+{
+    bool running = BaseApplication::isRunning();
+    QSharedMemory *sharedMem = new QSharedMemory(id() + QLatin1String("-shared-memory-key"), this);
+    if (!running) {
+        // First instance creates shared memory and store PID
+        if (sharedMem->create(sizeof(DWORD)) && sharedMem->lock()) {
+            *(static_cast<DWORD*>(sharedMem->data())) = ::GetCurrentProcessId();
+            sharedMem->unlock();
+        }
+    }
+    else {
+        // Later instances attach to shared memory and retrieve PID
+        if (sharedMem->attach() && sharedMem->lock()) {
+            ::AllowSetForegroundWindow(*(static_cast<DWORD*>(sharedMem->data())));
+            sharedMem->unlock();
+        }
+    }
+
+    if (!sharedMem->isAttached())
+        qWarning() << "Failed to initialize shared memory: " << sharedMem->errorString();
+
+    return running;
+}
+#endif
+
 void Application::initializeTranslation()
 {
     Preferences* const pref = Preferences::instance();
@@ -72,10 +99,10 @@ void Application::initializeTranslation()
         pref->setLocale(locale);
     }
 
-    if (qtTranslator_.load(
+    if (m_qtTranslator.load(
 #if (QT_VERSION >= QT_VERSION_CHECK(5, 0, 0))
             QString::fromUtf8("qtbase_") + locale, QLibraryInfo::location(QLibraryInfo::TranslationsPath)) ||
-        qtTranslator_.load(
+        m_qtTranslator.load(
 #endif
             QString::fromUtf8("qt_") + locale, QLibraryInfo::location(QLibraryInfo::TranslationsPath))) {
             qDebug("Qt %s locale recognized, using translation.", qPrintable(locale));
@@ -83,15 +110,15 @@ void Application::initializeTranslation()
     else {
         qDebug("Qt %s locale unrecognized, using default (en).", qPrintable(locale));
     }
-    installTranslator(&qtTranslator_);
+    installTranslator(&m_qtTranslator);
 
-    if (translator_.load(QString::fromUtf8(":/lang/qbittorrent_") + locale)) {
+    if (m_translator.load(QString::fromUtf8(":/lang/qbittorrent_") + locale)) {
         qDebug("%s locale recognized, using translation.", qPrintable(locale));
     }
     else {
         qDebug("%s locale unrecognized, using default (en).", qPrintable(locale));
     }
-    installTranslator(&translator_);
+    installTranslator(&m_translator);
 
 #ifndef DISABLE_GUI
     if (locale.startsWith("ar") || locale.startsWith("he")) {

src/app/application.h

@@ -35,23 +35,24 @@
 
 #ifndef DISABLE_GUI
 #include "sessionapplication.h"
+typedef SessionApplication BaseApplication;
 #else
 #include "qtsinglecoreapplication.h"
+typedef QtSingleCoreApplication BaseApplication;
 #endif
 
-class Application
-#ifndef DISABLE_GUI
-    : public SessionApplication
-#else
-    : public QtSingleCoreApplication
-#endif
+class Application : public BaseApplication
 {
 public:
     Application(const QString &id, int &argc, char **argv);
 
+#ifdef Q_OS_WIN
+    bool isRunning();
+#endif
+
 private:
-    QTranslator qtTranslator_;
-    QTranslator translator_;
+    QTranslator m_qtTranslator;
+    QTranslator m_translator;
 
     void initializeTranslation();
 };

src/app/main.cpp

@@ -90,10 +90,6 @@ public:
 
 #include "main.moc"
 
-#if defined(Q_OS_WIN) && !defined(QBT_HAS_GETCURRENTPID)
-#error You seem to have updated QtSingleApplication without porting our custom QtSingleApplication::getRunningPid() function. Please see previous version to understate how it works.
-#endif
-
 // Signal handlers
 #if defined(Q_OS_UNIX) || defined(STACKTRACE_WIN)
 void sigintHandler(int);
@@ -217,14 +213,8 @@ int main(int argc, char *argv[])
 #else
         qDebug("qBittorrent is already running for this user.");
 #endif
+
         misc::msleep(300);
-#ifdef Q_OS_WIN
-        DWORD pid = (DWORD)app->getRunningPid();
-        if (pid > 0) {
-            BOOL b = AllowSetForegroundWindow(pid);
-            qDebug("AllowSetForegroundWindow() returns %s", b ? "TRUE" : "FALSE");
-        }
-#endif
         if (!params.torrents.isEmpty()) {
             QString message = params.torrents.join("|");
             qDebug("Passing program parameters to running instance...");

src/app/qtsingleapplication/qtlocalpeer.cpp

@@ -195,56 +195,9 @@ void QtLocalPeer::receiveConnection()
         return;
     }
     QString message(QString::fromUtf8(uMsg));
-#ifdef Q_OS_WIN
-    if (message == "qbt://pid") {
-      qint64 pid = GetCurrentProcessId();
-      socket->write((const char *)&pid, sizeof pid);
-    } else {
     socket->write(ack, qstrlen(ack));
-    }
-#else
-    socket->write(ack, qstrlen(ack));
-#endif
     socket->waitForBytesWritten(1000);
     socket->waitForDisconnected(1000); // make sure client reads ack
     delete socket;
-#ifdef Q_OS_WIN
-    if (message == "qbt://pid")
-      return;
-#endif
     emit messageReceived(message); //### (might take a long time to return)
 }
-
-#ifdef Q_OS_WIN
-qint64 QtLocalPeer::getRunningPid() {
-  if (!isClient())
-      return 0;
-
-  QLocalSocket socket;
-  bool connOk = false;
-  for (int i = 0; i < 2; i++) {
-      // Try twice, in case the other instance is just starting up
-      socket.connectToServer(socketName);
-      connOk = socket.waitForConnected(5000/2);
-      if (connOk || i)
-          break;
-      Sleep(250);
-  }
-  if (!connOk) return -1;
-
-  const char* msg = "qbt://pid";
-  QDataStream ds(&socket);
-  ds.writeBytes(msg, qstrlen(msg));
-  bool res = socket.waitForBytesWritten(5000) && socket.waitForReadyRead(5000);
-  if (!res) return -1;
-
-  DWORD pid;
-  qint64 pid_size = sizeof pid;
-  while (socket.bytesAvailable() < pid_size)
-      socket.waitForReadyRead();
-  if (socket.read((char *)&pid, pid_size) < pid_size)
-      return -1;
-
-  return pid;
-}
-#endif

src/app/qtsingleapplication/qtlocalpeer.h

@@ -57,9 +57,6 @@ public:
     bool sendMessage(const QString &message, int timeout);
     QString applicationId() const
         { return id; }
-#ifdef Q_OS_WIN
-    qint64 getRunningPid();
-#endif
 
 Q_SIGNALS:
     void messageReceived(const QString &message);

src/app/qtsingleapplication/qtsingleapplication.cpp

@@ -345,9 +345,3 @@ void QtSingleApplication::activateWindow()
 
     \obsolete
 */
-
-#ifdef Q_OS_WIN
-qint64 QtSingleApplication::getRunningPid() {
-  return peer->getRunningPid();
-}
-#endif

src/app/qtsingleapplication/qtsingleapplication.h

@@ -86,10 +86,6 @@ public:
     // Obsolete:
     void initialize(bool dummy = true)
         { isRunning(); Q_UNUSED(dummy) }
-#ifdef Q_OS_WIN
-#define QBT_HAS_GETCURRENTPID
-    qint64 getRunningPid();
-#endif
 
 public Q_SLOTS:
     bool sendMessage(const QString &message, int timeout = 5000);