Fix detection of JSON when restarting libvirtd

The XML XPath for detecting JSON in the running VM statefile was
wrong causing all VMs to get JSON mode enabled at libvirtd restart.

In addition if a VM was running a JSON enabled QEMU once, and then
altered to point to a non-JSON enabled QEMU later the 'monJSON'
flag would not get reset to 0.

* src/qemu/qemu_driver.c: Fix setting/detection of JSON mode

src/qemu/qemu_driver.c

@@ -221,8 +221,11 @@ static int qemuDomainObjPrivateXMLParse(xmlXPathContextPtr ctxt, void *data)
         priv->monConfig->type = VIR_DOMAIN_CHR_TYPE_PTY;
     VIR_FREE(tmp);
 
-    if (virXPathBoolean(NULL, "int(./monitor[1]/@json)", ctxt))
+    if (virXPathBoolean(NULL, "count(./monitor[@json = '1']) > 0", ctxt)) {
         priv->monJSON = 1;
+    } else {
+        priv->monJSON = 0;
+    }
 
     switch (priv->monConfig->type) {
     case VIR_DOMAIN_CHR_TYPE_PTY:
@@ -2440,7 +2443,9 @@ static int qemudStartVMDaemon(virConnectPtr conn,
 #if HAVE_YAJL
     if (qemuCmdFlags & QEMUD_CMD_FLAG_MONITOR_JSON)
         priv->monJSON = 1;
+    else
 #endif
+        priv->monJSON = 0;
 
     if ((ret = virFileDeletePid(driver->stateDir, vm->def->name)) != 0) {
         virReportSystemError(conn, ret,