Please refer to
  https://bugs.kde.org/show_bug.cgi?id=209903

  http://www.davidfaure.fr/2009/klauncher_kioslave.diff

Index: klauncher.cpp
===================================================================
--- kdelibs-4.3.3/kinit/klauncher.cpp	(revision 1034932)
+++ kdelibs-4.3.3/kinit/klauncher.cpp	(working copy)
@@ -621,7 +621,7 @@
 void
 KLauncher::requestStart(KLaunchRequest *request)
 {
-#ifdef Q_WS_WIN
+#ifdef USE_KPROCESS_FOR_KIOSLAVES
    requestList.append( request );
    lastRequest = request;
 
@@ -1126,12 +1126,15 @@
     }
 
     QStringList arg_list;
-#ifdef Q_WS_WIN
+#ifdef USE_KPROCESS_FOR_KIOSLAVES
     arg_list << name;
     arg_list << protocol;
     arg_list << mConnectionServer.address();
     arg_list << app_socket;
     name = KStandardDirs::findExe(QLatin1String("kioslave"));
+#ifdef Q_OS_UNIX
+    QString arg1 = protocol;
+#endif
 #else
     QString arg1 = protocol;
     QString arg2 = mConnectionServer.address();
@@ -1268,7 +1268,7 @@
       slave->reparseConfiguration();
 }
 
-#ifdef Q_WS_WIN
+#ifdef USE_KPROCESS_FOR_KIOSLAVES
 void
 KLauncher::slotGotOutput()
 {
Index: klauncher.h
===================================================================
--- kdelibs-4.3.3/kinit/klauncher.h	(revision 1034932)
+++ kdelibs-4.3.3/kinit/klauncher.h	(working copy)
@@ -31,6 +31,10 @@
 #include <fixx11h.h>
 #endif
 
+#if defined(Q_WS_WIN) || defined(Q_WS_MAC)
+#define USE_KPROCESS_FOR_KIOSLAVES
+#endif
+
 #include <QtCore/QString>
 #include <QtCore/QSocketNotifier>
 #include <QtCore/QTimer>
@@ -105,7 +105,7 @@ public:
 #endif
    QStringList envs; // env. variables to be app's environment
    QString cwd;
-#ifdef Q_WS_WIN
+#ifdef USE_KPROCESS_FOR_KIOSLAVES
 protected:
    KProcess *process;
    friend class KLauncher;
@@ -286,7 +290,7 @@
    void processRequestReturn(int status, const QByteArray &requestData);
 
 protected Q_SLOTS:
-#ifdef Q_WS_WIN
+#ifdef USE_KPROCESS_FOR_KIOSLAVES
     void slotGotOutput();
     void slotFinished(int exitCode, QProcess::ExitStatus exitStatus);
 #endif