Add support for another explicit IO error event

This introduces a new event type

   VIR_DOMAIN_EVENT_ID_IO_ERROR_REASON

This event is the same as the previous VIR_DOMAIN_ID_IO_ERROR
event, but also includes a string describing the cause of
the event.

Thus there is a new callback definition for this event type

typedef void (*virConnectDomainEventIOErrorReasonCallback)(virConnectPtr conn,
                                                           virDomainPtr dom,
                                                           const char *srcPath,
                                                           const char *devAlias,
                                                           int action,
                                                           const char *reason,
                                                           void *opaque);

This is currently wired up to the QEMU block IO error events

* daemon/remote.c: Dispatch IO error events to client
* examples/domain-events/events-c/event-test.c: Watch for
  IO error events
* include/libvirt/libvirt.h.in: Define new IO error event ID
  and callback signature
* src/conf/domain_event.c, src/conf/domain_event.h,
  src/libvirt_private.syms: Extend API to handle IO error events
* src/qemu/qemu_driver.c: Connect to the QEMU monitor event
  for block IO errors and emit a libvirt IO error event
* src/remote/remote_driver.c: Receive and dispatch IO error
  events to application
* src/remote/remote_protocol.x: Wire protocol definition for
  IO error events
* src/qemu/qemu_monitor.c, src/qemu/qemu_monitor.h,
  src/qemu/qemu_monitor_json.c: Watch for BLOCK_IO_ERROR event
  from QEMU monitor

libvirt-override-virConnect.py

@@ -94,7 +94,19 @@
             cb = cbData["cb"]
             opaque = cbData["opaque"]
 
-            cb(self, virDomain(self, _obj=dom), opaque)
+            cb(self, virDomain(self, _obj=dom), srcPath, devAlias, opaque)
+            return 0
+        except AttributeError:
+            pass
+
+    def dispatchDomainEventIOErrorReasonCallback(self, dom, srcPath, devAlias, action, reason, cbData):
+        """Dispatches events to python user domain IO error event callbacks
+        """
+        try:
+            cb = cbData["cb"]
+            opaque = cbData["opaque"]
+
+            cb(self, virDomain(self, _obj=dom), srcPath, devAlias, action, reason, opaque)
             return 0
         except AttributeError:
             pass

libvirt-override.c

@@ -3207,6 +3207,58 @@ libvirt_virConnectDomainEventIOErrorCallback(virConnectPtr conn ATTRIBUTE_UNUSED
     return ret;
 }
 
+static int
+libvirt_virConnectDomainEventIOErrorReasonCallback(virConnectPtr conn ATTRIBUTE_UNUSED,
+                                                   virDomainPtr dom,
+                                                   const char *srcPath,
+                                                   const char *devAlias,
+                                                   int action,
+                                                   const char *reason,
+                                                   void *opaque)
+{
+    PyObject *pyobj_cbData = (PyObject*)opaque;
+    PyObject *pyobj_dom;
+    PyObject *pyobj_ret;
+    PyObject *pyobj_conn;
+    PyObject *dictKey;
+    int ret = -1;
+
+    LIBVIRT_ENSURE_THREAD_STATE;
+
+    /* Create a python instance of this virDomainPtr */
+    virDomainRef(dom);
+    pyobj_dom = libvirt_virDomainPtrWrap(dom);
+    Py_INCREF(pyobj_cbData);
+
+    dictKey = libvirt_constcharPtrWrap("conn");
+    pyobj_conn = PyDict_GetItem(pyobj_cbData, dictKey);
+    Py_DECREF(dictKey);
+
+    /* Call the Callback Dispatcher */
+    pyobj_ret = PyObject_CallMethod(pyobj_conn,
+                                    (char*)"dispatchDomainEventIOErrorCallback",
+                                    (char*)"OssisO",
+                                    pyobj_dom,
+                                    srcPath, devAlias, action, reason,
+                                    pyobj_cbData);
+
+    Py_DECREF(pyobj_cbData);
+    Py_DECREF(pyobj_dom);
+
+    if(!pyobj_ret) {
+#if DEBUG_ERROR
+        printf("%s - ret:%p\n", __FUNCTION__, pyobj_ret);
+#endif
+        PyErr_Print();
+    } else {
+        Py_DECREF(pyobj_ret);
+        ret = 0;
+    }
+
+    LIBVIRT_RELEASE_THREAD_STATE;
+    return ret;
+}
+
 static int
 libvirt_virConnectDomainEventGraphicsCallback(virConnectPtr conn ATTRIBUTE_UNUSED,
                                               virDomainPtr dom,
@@ -3345,6 +3397,9 @@ libvirt_virConnectDomainEventRegisterAny(ATTRIBUTE_UNUSED PyObject * self,
     case VIR_DOMAIN_EVENT_ID_IO_ERROR:
         cb = VIR_DOMAIN_EVENT_CALLBACK(libvirt_virConnectDomainEventIOErrorCallback);
         break;
+    case VIR_DOMAIN_EVENT_ID_IO_ERROR_REASON:
+        cb = VIR_DOMAIN_EVENT_CALLBACK(libvirt_virConnectDomainEventIOErrorReasonCallback);
+        break;
     case VIR_DOMAIN_EVENT_ID_GRAPHICS:
         cb = VIR_DOMAIN_EVENT_CALLBACK(libvirt_virConnectDomainEventGraphicsCallback);
         break;