qemu: Implement qemuMonitorRegister()

Implement qemuMonitorRegister() as there is already a
qemuMonitorUnregister() function. This way it may be easier to
understand the code paths.

Signed-off-by: Marc Hartmayer <mhartmay@linux.vnet.ibm.com>
Reviewed-by: Bjoern Walk <bwalk@linux.vnet.ibm.com>

src/qemu/qemu_monitor.c

@@ -837,15 +837,7 @@ qemuMonitorOpenInternal(virDomainObjPtr vm,
 
 
     virObjectLock(mon);
-    virObjectRef(mon);
+    if (!qemuMonitorRegister(mon)) {
-    if ((mon->watch = virEventAddHandle(mon->fd,
-                                        VIR_EVENT_HANDLE_HANGUP |
-                                        VIR_EVENT_HANDLE_ERROR |
-                                        VIR_EVENT_HANDLE_READABLE,
-                                        qemuMonitorIO,
-                                        mon,
-                                        virObjectFreeCallback)) < 0) {
-        virObjectUnref(mon);
         virObjectUnlock(mon);
         virReportError(VIR_ERR_INTERNAL_ERROR, "%s",
                        _("unable to register monitor events"));
@@ -944,6 +936,34 @@ qemuMonitorOpenFD(virDomainObjPtr vm,
 }
 
 
+/**
+ * qemuMonitorRegister:
+ * @mon: QEMU monitor
+ *
+ * Registers the monitor in the event loop. The caller has to hold the
+ * lock for @mon.
+ *
+ * Returns true in case of success, false otherwise
+ */
+bool
+qemuMonitorRegister(qemuMonitorPtr mon)
+{
+    virObjectRef(mon);
+    if ((mon->watch = virEventAddHandle(mon->fd,
+                                        VIR_EVENT_HANDLE_HANGUP |
+                                        VIR_EVENT_HANDLE_ERROR |
+                                        VIR_EVENT_HANDLE_READABLE,
+                                        qemuMonitorIO,
+                                        mon,
+                                        virObjectFreeCallback)) < 0) {
+        virObjectUnref(mon);
+        return false;
+    }
+
+    return true;
+}
+
+
 void
 qemuMonitorUnregister(qemuMonitorPtr mon)
 {

src/qemu/qemu_monitor.h

@@ -296,6 +296,8 @@ qemuMonitorPtr qemuMonitorOpenFD(virDomainObjPtr vm,
                                  void *opaque)
     ATTRIBUTE_NONNULL(1) ATTRIBUTE_NONNULL(4);
 
+bool qemuMonitorRegister(qemuMonitorPtr mon)
+    ATTRIBUTE_NONNULL(1);
 void qemuMonitorUnregister(qemuMonitorPtr mon)
     ATTRIBUTE_NONNULL(1);
 void qemuMonitorClose(qemuMonitorPtr mon);