From 40c7008d1aea56cdf80b5ec3e21b50d72d679851 Mon Sep 17 00:00:00 2001
From: Joerg Henning <henning.joerg@gmail.com>
Date: Thu, 29 Sep 2016 10:48:57 +0530
Subject: [PATCH] Proper, node-js style error handling for set_crontab

It's a start...
---
 app.js              | 34 +++++++++++++++++++++++++++-------
 crontab.js          | 29 ++++++++++++++++++++---------
 public/js/script.js | 11 +++++++++++
 3 files changed, 58 insertions(+), 16 deletions(-)

diff --git a/app.js b/app.js
index 113fbf8..3087b38 100755
--- a/app.js
+++ b/app.js
@@ -72,9 +72,11 @@ app.post(routes.remove, function(req, res) {
 	crontab.remove(req.body._id);
 	res.end();
 });
-app.get(routes.crontab, function(req, res) {
-	crontab.set_crontab(req.query.env_vars);
-	res.end();
+app.get(routes.crontab, function(req, res, next) {
+	crontab.set_crontab(req.query.env_vars, function(err) {
+		if (err) next(err);
+		else res.end();
+	});
 });
 
 app.get(routes.backup, function(req, res) {
@@ -127,8 +129,8 @@ app.post(routes.import, function(req, res) {
 		fstream.on('close', function () {
 			crontab.reload_db();
 			res.redirect(routes.root);
-        	});
-    	});
+		});
+	});
 });
 
 app.get(routes.import_crontab, function(req, res) {
@@ -145,6 +147,24 @@ app.get(routes.logger, function(req, res) {
 		res.end("No errors logged yet");
 });
 
-app.listen(app.get('port'), function() {
-  	console.log("Crontab UI is running at http://localhost:" + app.get('port'));
+// error handler
+app.use(function(err, req, res, next) {
+	var data = {};
+	var statusCode = err.statusCode || 500;
+
+	data.message = err.message || 'Internal Server Error';
+
+	if (process.env.NODE_ENV === 'development' && err.stack) {
+		data.stack = err.stack
+	}
+
+	if (parseInt(data.statusCode) >= 500) {
+		console.error(err);
+	}
+
+	res.status(statusCode).json(data);
+});
+
+app.listen(app.get('port'), function() {
+	console.log("Crontab UI is running at http://localhost:" + app.get('port'));
 });
diff --git a/crontab.js b/crontab.js
index 253c760..b6f743f 100644
--- a/crontab.js
+++ b/crontab.js
@@ -1,8 +1,11 @@
 //load database
 var Datastore = require('nedb');
 var db = new Datastore({ filename: __dirname + '/crontabs/crontab.db' });
+
 db.loadDatabase(function (err) {
+	if (err) throw err; // no hope, just terminate
 });
+
 var exec = require('child_process').exec;
 var fs = require('fs');
 var cron_parser = require("cron-parser");
@@ -52,32 +55,40 @@ exports.crontabs = function(callback){
 		callback(docs);
 	});
 };
-exports.set_crontab = function(env_vars){
+exports.set_crontab = function(env_vars, callback){
 	exports.crontabs( function(tabs){
 		var crontab_string = "";
 		if (env_vars) {
 			crontab_string = env_vars + "\n";
 		}
 		tabs.forEach(function(tab){
-			if(!tab.stopped){
-				if (tab.logging && tab.logging == "true"){
+			if(!tab.stopped) {
+				if (tab.logging && tab.logging == "true") {
 					tmp_log = "/tmp/" + tab._id + ".log";
 					log_file = exports.log_folder + "/" + tab._id + ".log";
 					if(tab.command[tab.command.length-1] != ";") // add semicolon
 						tab.command +=";";
 					//{ command; } 2>/tmp/<id>.log|| {if test -f /tmp/<id>; then date >> <log file>; cat /tmp/<id>.log >> <log file>; rm /tmp<id>.log }
 					crontab_string += tab.schedule + " { " + tab.command + " } 2> " + tmp_log +"; if test -f " + tmp_log +"; then date >> " + log_file + "; cat " + tmp_log + " >> " + log_file + "; rm " + tmp_log + "; fi \n";
-					}
-				else
+				}
+				else {
 					crontab_string += tab.schedule + " " + tab.command + "\n";
+				}
 			}
 		});
 
-		fs.writeFile(exports.env_file, env_vars);
-		fs.writeFile("/tmp/crontab", crontab_string, function(err) {
-			exec("crontab /tmp/crontab");
-		});
+		fs.writeFile(exports.env_file, env_vars, function(err) {
+			if (err) callback(err);
 
+			fs.writeFile("/tmp/crontab", crontab_string, function(err) {
+				if (err) return callback(err);
+
+				exec("crontab /tmp/crontab", function(err) {
+					if (err) return callback(err);
+					else callback();
+				});
+			});
+		});
 	});
 };
 
diff --git a/public/js/script.js b/public/js/script.js
index c704a95..174b2d3 100644
--- a/public/js/script.js
+++ b/public/js/script.js
@@ -6,6 +6,15 @@ function infoMessageBox(message, title){
 	$("#info-title").html(title);
 	$("#info-popup").modal('show');
 }
+// like info, but for errors.
+function errorMessageBox(message) {
+	var msg =
+		"Operation failed: " + message + ". " +
+		"Please see error log for details.";
+	$("#info-body").html(msg);
+	$("#info-title").html("Error");
+	$("#info-popup").modal('show');
+}
 // modal with full control
 function messageBox(body, title, ok_text, close_text, callback){
 	$("#modal-body").html(body);
@@ -50,6 +59,8 @@ function setCrontab(){
 		$.get(routes.crontab, { "env_vars": $("#env_vars").val() }, function(){
 			// TODO show only if success
 			infoMessageBox("Successfuly set crontab file!","Information");
+		}).fail(function(response) {
+			errorMessageBox(response.statusText,"Error");
 		});
 	});
 }