qemuMonitorJSONDelDevice: Return -2 on DeviceNotFound error

A caller might be interested in differentiating the cause for
error, especially if DeviceNotFound error occurred.
Signed-off-by: NMichal Privoznik <mprivozn@redhat.com>
ACKed-by: NPeter Krempa <pkrempa@redhat.com>

src/qemu/qemu_monitor.c

@@ -3008,6 +3008,16 @@ qemuMonitorDriveDel(qemuMonitorPtr mon,
 }
 
 
+/**
+ * @mon: monitor object
+ * @devalias: alias of the device to detach
+ *
+ * Sends device detach request to qemu.
+ *
+ * Returns: 0 on success,
+ *         -2 if DeviceNotFound error encountered (error NOT reported)
+ *         -1 otherwise (error reported)
+ */
 int
 qemuMonitorDelDevice(qemuMonitorPtr mon,
                      const char *devalias)

src/qemu/qemu_monitor_json.c

@@ -4191,6 +4191,11 @@ int qemuMonitorJSONDelDevice(qemuMonitorPtr mon,
     if (qemuMonitorJSONCommand(mon, cmd, &reply) < 0)
         goto cleanup;
 
+    if (qemuMonitorJSONHasError(reply, "DeviceNotFound")) {
+        ret = -2;
+        goto cleanup;
+    }
+
     if (qemuMonitorJSONCheckError(cmd, reply) < 0)
         goto cleanup;