InfoBroker: add initial meta table.

This particular table contains information about the currently running 
systemquery instance.

TODO: Add other interesting things such as # of connected peers etc.

src/lib/core/InfoBroker.mjs

@@ -1,14 +1,23 @@
 "use strict";
 
+import path from 'path';
+import fs from 'fs';
+
 import sysinfo from 'systeminformation';
 
 import log from '../../lib/io/NamespacedLog.mjs'; const l = log("infobroker");
 
+// HACK: Make sure __dirname is defined when using es6 modules. I forget where I found this - a PR with a source URL would be great :D
+const __dirname = import.meta.url.slice(7, import.meta.url.lastIndexOf("/"));
+
+
 class InfoBroker {
 	constructor() {
+		this.sym_meta = Symbol("____meta_info____")
 		this.allowed_tables = {
 			// name → sysinfo name
 			cpu: "cpu",
+			meta: this.sym_meta
 		};
 	}
 	
@@ -16,6 +25,16 @@ class InfoBroker {
 		return Object.keys(this.allowed_tables).includes(name);
 	}
 	
+	async make_table_meta() {
+		return {
+			version: JSON.parse(fs.promises.readFile(path.resolve(__dirname, "../../../package.json"), "utf-8")).version,
+			versions_env: process.versions,
+			pid: process.pid,
+			uptime: process.uptime(),
+			memory: process.memoryUsage(),
+		};
+	}
+	
 	async fetch_table(name) {
 		if(!(typeof name === "string"))
 			throw new Exception(`Error: Expected name to be of type string, but received value of type ${typeof name} instead.`);
@@ -25,7 +44,11 @@ class InfoBroker {
 			return null;
 		}
 		
-		return await sysinfo[this.allowed_tables[name]]();
+		let name_translated = this.allowed_tables[name];
+		if(name_translated === this.sym_meta)
+			return await this.make_table_meta();
+		
+		return await sysinfo[name_translated]();
 	}
 }