4 files changed, 38 insertions, 11 deletions

diff --git a/src/plugins/platforms/xcb/qxcbconnection.h b/src/plugins/platforms/xcb/qxcbconnection.h
index f31ecf8e03..7286b6b89b 100644
--- a/src/plugins/platforms/xcb/qxcbconnection.h
+++ b/src/plugins/platforms/xcb/qxcbconnection.h
@@ -471,6 +471,7 @@ public:
 
     QXcbEventReader *eventReader() const { return m_reader; }
 
+    bool canGrab() const { return m_canGrabServer; }
 protected:
     bool event(QEvent *e) Q_DECL_OVERRIDE;
 
diff --git a/src/plugins/platforms/xcb/qxcbintegration.cpp b/src/plugins/platforms/xcb/qxcbintegration.cpp
index 52269bafea..cace087613 100644
--- a/src/plugins/platforms/xcb/qxcbintegration.cpp
+++ b/src/plugins/platforms/xcb/qxcbintegration.cpp
@@ -92,11 +92,11 @@
 
 QT_BEGIN_NAMESPACE
 
-#if defined(QT_DEBUG) && defined(Q_OS_LINUX)
 // Find out if our parent process is gdb by looking at the 'exe' symlink under /proc,.
 // or, for older Linuxes, read out 'cmdline'.
 static bool runningUnderDebugger()
 {
+#if defined(QT_DEBUG) && defined(Q_OS_LINUX)
     const QString parentProc = QLatin1String("/proc/") + QString::number(getppid());
     const QFileInfo parentProcExe(parentProc + QLatin1String("/exe"));
     if (parentProcExe.isSymLink())
@@ -113,12 +113,15 @@ static bool runningUnderDebugger()
             s += c;
     }
     return s == "gdb";
-}
+#else
+    return false;
 #endif
+}
 
 QXcbIntegration::QXcbIntegration(const QStringList &parameters, int &argc, char **argv)
     : m_services(new QGenericUnixServices)
     , m_instanceName(0)
+    , m_canGrab(true)
 {
     qRegisterMetaType<QXcbWindow*>();
 #ifdef XCB_USE_XLIB
@@ -126,16 +129,10 @@ QXcbIntegration::QXcbIntegration(const QStringList &parameters, int &argc, char
 #endif
     m_nativeInterface.reset(new QXcbNativeInterface);
 
-    bool canGrab = true;
-    #if defined(QT_DEBUG) && defined(Q_OS_LINUX)
-    canGrab = !runningUnderDebugger();
-    #endif
-    static bool canNotGrabEnv = qgetenv("QT_XCB_NO_GRAB_SERVER").length();
-    if (canNotGrabEnv)
-        canGrab = false;
-
     // Parse arguments
     const char *displayName = 0;
+    bool noGrabArg = false;
+    bool doGrabArg = false;
     if (argc) {
         int j = 1;
         for (int i = 1; i < argc; i++) {
@@ -146,13 +143,35 @@ QXcbIntegration::QXcbIntegration(const QStringList &parameters, int &argc, char
                 displayName = argv[++i];
             else if (arg == "-name" && i < argc - 1)
                 m_instanceName = argv[++i];
+            else if (arg == "-nograb")
+                noGrabArg = true;
+            else if (arg == "-dograb")
+                doGrabArg = true;
             else
                 argv[j++] = argv[i];
         }
         argc = j;
     } // argc
 
-    m_connections << new QXcbConnection(m_nativeInterface.data(), canGrab, displayName);
+    bool underDebugger = runningUnderDebugger();
+    if (noGrabArg && doGrabArg && underDebugger) {
+        qWarning() << "Both -nograb and -dograb command line arguments specified. Please pick one. -nograb takes prcedence";
+        doGrabArg = false;
+    }
+
+#if defined(QT_DEBUG)
+    if (!noGrabArg && !doGrabArg && underDebugger) {
+        qDebug("Qt: gdb: -nograb added to command-line options.\n"
+               "\t Use the -dograb option to enforce grabbing.");
+    }
+#endif
+    m_canGrab = (!underDebugger && noGrabArg) || (underDebugger && doGrabArg);
+
+    static bool canNotGrabEnv = qEnvironmentVariableIsSet("QT_XCB_NO_GRAB_SERVER");
+    if (canNotGrabEnv)
+        m_canGrab = false;
+
+    m_connections << new QXcbConnection(m_nativeInterface.data(), m_canGrab, displayName);
 
     for (int i = 0; i < parameters.size() - 1; i += 2) {
 #ifdef Q_XCB_DEBUG
diff --git a/src/plugins/platforms/xcb/qxcbintegration.h b/src/plugins/platforms/xcb/qxcbintegration.h
index ffb068ecb3..db6ad541ea 100644
--- a/src/plugins/platforms/xcb/qxcbintegration.h
+++ b/src/plugins/platforms/xcb/qxcbintegration.h
@@ -117,6 +117,7 @@ private:
 
     mutable QByteArray m_wmClass;
     const char *m_instanceName;
+    bool m_canGrab;
 };
 
 QT_END_NAMESPACE
diff --git a/src/plugins/platforms/xcb/qxcbwindow.cpp b/src/plugins/platforms/xcb/qxcbwindow.cpp
index 5d3206b097..85af8ee1d2 100644
--- a/src/plugins/platforms/xcb/qxcbwindow.cpp
+++ b/src/plugins/platforms/xcb/qxcbwindow.cpp
@@ -2170,6 +2170,9 @@ void QXcbWindow::updateSyncRequestCounter()
 
 bool QXcbWindow::setKeyboardGrabEnabled(bool grab)
 {
+    if (grab && !connection()->canGrab())
+        return false;
+
     if (!grab) {
         xcb_ungrab_keyboard(xcb_connection(), XCB_TIME_CURRENT_TIME);
         return true;
@@ -2185,6 +2188,9 @@ bool QXcbWindow::setKeyboardGrabEnabled(bool grab)
 
 bool QXcbWindow::setMouseGrabEnabled(bool grab)
 {
+    if (grab && !connection()->canGrab())
+        return false;
+
     if (!grab) {
         xcb_ungrab_pointer(xcb_connection(), XCB_TIME_CURRENT_TIME);
         return true;