Begin to implement CLI: implement listing, add help, add create stub

src/cli_create.cpp

@@ -0,0 +1,50 @@
+// Copyright (c) Vitaliy Filippov, 2019+
+// License: VNPL-1.1 (see README.md for details)
+
+#include "cli.h"
+#include "cluster_client.h"
+#include "base64.h"
+
+// Create an image, snapshot or clone
+//
+// Snapshot creation does a etcd transaction which:
+// - Changes the name of old inode to the name of the snapshot (say, testimg -> testimg@0)
+// - Sets the readonly flag for the old inode
+// - Creates a new inode with the same name pointing to the old inode as parent
+// - Adjusts /index/image/*
+//
+// The same algorithm can be easily implemented in any other language or even via etcdctl,
+// however we have it here for completeness
+struct image_creator_t
+{
+    cli_tool_t *parent;
+
+    int state = 0;
+
+    bool is_done()
+    {
+        return true;
+    }
+
+    void loop()
+    {
+        return;
+    }
+};
+
+std::function<bool(void)> cli_tool_t::start_create(json11::Json cfg)
+{
+    json11::Json::array cmd = cfg["command"].array_items();
+    auto image_creator = new image_creator_t();
+    image_creator->parent = this;
+    return [image_creator]()
+    {
+        image_creator->loop();
+        if (image_creator->is_done())
+        {
+            delete image_creator;
+            return true;
+        }
+        return false;
+    };
+}