qemu: Introduce nbd-server-add command

This will be used with new migration scheme.
This patch creates basically just monitor stub
functions. Wiring them into something useful
is done in later patches.

src/qemu/qemu_monitor.c

@@ -3485,3 +3485,25 @@ int qemuMonitorNBDServerStart(qemuMonitorPtr mon,
 
     return qemuMonitorJSONNBDServerStart(mon, host, port);
 }
+
+int qemuMonitorNBDServerAdd(qemuMonitorPtr mon,
+                            const char *deviceID,
+                            bool writable)
+{
+    VIR_DEBUG("mon=%p deviceID=%s",
+              mon, deviceID);
+
+    if (!mon) {
+        virReportError(VIR_ERR_INVALID_ARG, "%s",
+                       _("monitor must not be NULL"));
+        return -1;
+    }
+
+    if (!mon->json) {
+        virReportError(VIR_ERR_OPERATION_UNSUPPORTED, "%s",
+                       _("JSON monitor is required"));
+        return -1;
+    }
+
+    return qemuMonitorJSONNBDServerAdd(mon, deviceID, writable);
+}

src/qemu/qemu_monitor.h

@@ -679,6 +679,9 @@ char *qemuMonitorGetTargetArch(qemuMonitorPtr mon);
 int qemuMonitorNBDServerStart(qemuMonitorPtr mon,
                               const char *host,
                               unsigned int port);
+int qemuMonitorNBDServerAdd(qemuMonitorPtr mon,
+                            const char *deviceID,
+                            bool writable);
 /**
  * When running two dd process and using <> redirection, we need a
  * shell that will not truncate files.  These two strings serve that

src/qemu/qemu_monitor_json.c

@@ -4663,3 +4663,28 @@ cleanup:
     virJSONValueFree(data);
     return ret;
 }
+
+int
+qemuMonitorJSONNBDServerAdd(qemuMonitorPtr mon,
+                            const char *deviceID,
+                            bool writable)
+{
+    int ret = -1;
+    virJSONValuePtr cmd;
+    virJSONValuePtr reply = NULL;
+
+    if (!(cmd = qemuMonitorJSONMakeCommand("nbd-server-add",
+                                           "s:device", deviceID,
+                                           "b:writable", writable,
+                                           NULL)))
+        return ret;
+
+    ret = qemuMonitorJSONCommand(mon, cmd, &reply);
+
+    if (ret == 0)
+        ret = qemuMonitorJSONCheckError(cmd, reply);
+
+    virJSONValueFree(cmd);
+    virJSONValueFree(reply);
+    return ret;
+}

src/qemu/qemu_monitor_json.h

@@ -337,4 +337,7 @@ char *qemuMonitorJSONGetTargetArch(qemuMonitorPtr mon);
 int qemuMonitorJSONNBDServerStart(qemuMonitorPtr mon,
                                   const char *host,
                                   unsigned int port);
+int qemuMonitorJSONNBDServerAdd(qemuMonitorPtr mon,
+                                const char *deviceID,
+                                bool writable);
 #endif /* QEMU_MONITOR_JSON_H */