delete rootWindow::_NET_SUPPORTING_WM_CHECK on exit

If it remains there all Qt applications will start with a BadWindow error.

 * src/mcompositemanager_p.h:
   Added MCompositeManagerPrivate::prepared.
 * src/mcompositemanager.cpp (MCompositeManager::~MCompositeManager):
   If prepare()d delete the property.
 * mcompositor/xserverpinger.h
 * mcompositor/xserverpinger.cpp:
   Stand guard for the parent and delete the property for it if terminated
   by a SIGINT or SIGTERM.

4 files changed, 46 insertions, 1 deletions

diff --git a/mcompositor/xserverpinger.cpp b/mcompositor/xserverpinger.cpp
index 654cf39..afb00b3 100644
--- a/mcompositor/xserverpinger.cpp
+++ b/mcompositor/xserverpinger.cpp
@@ -14,11 +14,13 @@
 
 #include <signal.h>
 #include <sys/prctl.h>
+#include <sys/signalfd.h>
 
 // Ping X in @pingInterval miliseconds.
 XServerPinger::XServerPinger(int pingInterval)
 {
     Display *dpy;
+    sigset_t sigs;
 
     // Open a separate connection to X.
     dpy = XOpenDisplay(NULL);
@@ -33,6 +35,15 @@ XServerPinger::XServerPinger(int pingInterval)
     timer = new QTimer();
     connect(timer, SIGNAL(timeout()), SLOT(tick()));
     timer->start(pingInterval);
+
+    // die() if we get SIGINT or SIGTERM.
+    sigemptyset(&sigs);
+    sigaddset(&sigs, SIGINT);
+    sigaddset(&sigs, SIGTERM);
+    connect(new QSocketNotifier(signalfd(-1, &sigs, 0),
+                                QSocketNotifier::Read),
+            SIGNAL(activated(int)), SLOT(die(int)));
+    sigprocmask(SIG_BLOCK, &sigs, NULL);
 }
 
 void XServerPinger::xInput(int)
@@ -68,6 +79,22 @@ void XServerPinger::tick()
         qWarning("X is on holidays");
 }
 
+void XServerPinger::die(int)
+{
+    const char *wmcheck = "_NET_SUPPORTING_WM_CHECK";
+
+    xcb_delete_property(xcb,
+                        xcb_setup_roots_iterator(xcb_get_setup(xcb)).data->root,
+                        xcb_intern_atom_reply(xcb,
+                                              xcb_intern_atom(xcb,
+                                                              False,
+                                                              strlen(wmcheck),
+                                                              wmcheck),
+                                              NULL)->atom);
+    xcb_flush(xcb);
+    QCoreApplication::quit();
+}
+
 // Start XServerPinger in a separate process if it's not running yet.
 static void altmain() __attribute__((constructor));
 static void altmain()
@@ -82,7 +109,7 @@ static void altmain()
         return;
 
     // Die with the parent.
-    prctl(PR_SET_PDEATHSIG, SIGKILL);
+    prctl(PR_SET_PDEATHSIG, SIGTERM);
 
     int meh = 0;
     QCoreApplication app(meh, 0);
diff --git a/mcompositor/xserverpinger.h b/mcompositor/xserverpinger.h
index 6482946..8d3c52f 100644
--- a/mcompositor/xserverpinger.h
+++ b/mcompositor/xserverpinger.h
@@ -20,6 +20,7 @@ protected:
 public slots:
     void xInput(int);
     void tick();
+    void die(int);
 };
 
 #endif // ! XSERVERPINGER_H
diff --git a/src/mcompositemanager.cpp b/src/mcompositemanager.cpp
index 0f0c80a..a957e98 100644
--- a/src/mcompositemanager.cpp
+++ b/src/mcompositemanager.cpp
@@ -712,6 +712,7 @@ MCompositeManagerPrivate::MCompositeManagerPrivate(QObject *p)
       glwidget(0),
       compositing(true),
       changed_properties(false),
+      prepared(false),
       stacking_timeout_check_visibility(false),
       stacking_timeout_timestamp(CurrentTime)
 {
@@ -734,6 +735,11 @@ MCompositeManagerPrivate::MCompositeManagerPrivate(QObject *p)
 
 MCompositeManagerPrivate::~MCompositeManagerPrivate()
 {
+    if (prepared)
+        // Advertise the world we're gone.
+        XDeleteProperty(QX11Info::display(), QX11Info::appRootWindow(),
+                        ATOM(_NET_SUPPORTING_WM_CHECK));
+
     delete watch;
     delete atom;
     watch   = 0;
@@ -834,6 +840,8 @@ void MCompositeManagerPrivate::prepare()
     XSelectInput(QX11Info::display(), home_button_win,
                  ButtonReleaseMask | ButtonPressMask);
     XMapWindow(QX11Info::display(), home_button_win);
+
+    prepared = true;
 }
 
 void MCompositeManagerPrivate::loadPlugins()
@@ -3940,6 +3948,9 @@ void MCompositeManager::remoteControl(int cmdfd)
         const char **argv;
         unsigned i;
 
+        delete d;
+        XFlush(QX11Info::display());
+
         // Convert the QStringList of args into a char *[].
         i = 0;
         argv = new const char *[args.count()+1];
@@ -3953,6 +3964,8 @@ void MCompositeManager::remoteControl(int cmdfd)
         qDebug("Gothca!");
     } else if (!strcmp(cmd, "exit") || !strcmp(cmd, "quit")) {
         // exit() deadlocks, go the fast route
+        delete d;
+        XFlush(QX11Info::display());
         _exit(0);
     } else if (!strcmp(cmd, "help")) {
         qDebug("Commands i understand:");
diff --git a/src/mcompositemanager_p.h b/src/mcompositemanager_p.h
index 4179cfa..6a27174 100644
--- a/src/mcompositemanager_p.h
+++ b/src/mcompositemanager_p.h
@@ -160,6 +160,10 @@ public:
     bool changed_properties;
     MDeviceState *device_state;
 
+    // Indicates whether MCompositeManager::prepare() has finished.
+    // Used by the destructor.
+    bool prepared;
+
     xcb_connection_t *xcb_conn;
 
     // mechanism for lazy stacking