app.portBindings and newManifest.tcpPorts may be null

src/progress.js

@@ -0,0 +1,47 @@
+/* jslint node: true */
+
+'use strict';
+
+exports = module.exports = {
+    set: set,
+    clear: clear,
+    get: get,
+
+    UPDATE: 'update',
+    BACKUP: 'backup'
+};
+
+var assert = require('assert'),
+    debug = require('debug')('box:progress');
+
+// if progress.update or progress.backup are object, they will contain 'percent' and 'message' properties
+// otherwise no such operation is currently ongoing
+var progress = {
+    update: null,
+    backup: null
+};
+
+function set(tag, percent, message) {
+    assert(tag === exports.UPDATE || tag === exports.BACKUP);
+    assert.strictEqual(typeof percent, 'number');
+    assert.strictEqual(typeof message, 'string');
+
+    progress[tag] = {
+        percent: percent,
+        message: message
+    };
+
+    debug('%s: %s %s', tag, percent, message);
+}
+
+function clear(tag) {
+    assert(tag === exports.UPDATE || tag === exports.BACKUP);
+
+    progress[tag] = null;
+
+    debug('clearing %s', tag);
+}
+
+function get() {
+    return progress;
+}