KUKURUKU HUB

Writing a File System in Linux Kernel

Written by kmu1990

Who This Article is for There are no complex or difficult concepts in this article, all required is a basic knowledge of the command line, the C language, Makefile and a general understanding about file systems. In this article I am going to describe the components necessary for development inside the Linux kernel, then we’ll write the simplest loadable kernel module and, finally, write a framework for the future file system. It’s a module that will register quite a useful (for now) file system in the kernel. The ones familiar with development inside Linux kernel may not find anything interesting here. Introduction A file system is one of the central OS subsystems. File systems continue to develop as operating systems evolve. Currently we have an entire heterogenetic zoo of file systems, from the old “classic” UFS , to the new exotic NILFS (though this idea isn’t new at all,

Brain Overclock or Internal Virtualization of Consciousness

Written by leon_3

Do you remember this movie? What is it doing here? Why the hell is such post on Kukuruku? I guess, because I think that the main component of IT is human, or rather our brain. I’ll tell you about another possibility of using your brain a bit more effectively. Everything described here has been tried out by me. It’s important to note that I’ll highlight if I haven’t tried something. I didn’t use any drugs or devices. Popular methods have only been used. And yes, it’s devastatingly realistic. Having tried it once, you'll never resist spreading the word. To avoid unnecessary cries in comments, I’m asking all staunch defenders of any religion or faith, and all the esoteric representatives to down-vote me and stop reading further. You’ll find no philosophy and great universal mysteries in this article. The rest of you are welcome — I’ll try to tell you about

J Can be Readable

Written by AraneusAdoro

You must be kidding me! It’s like programming using regular expressions… You’ll never make me do that again! I’m looking at the code and feel like an idiot. Isn’t it really an esoteric language like brain fuck? Does anyone really use it? And such programs can be read afterwards? quicksort=: (($:@(<#[), (=#[), $:@(>#[)) ({~ ?@#)) ^: (1<#) Perl is a trifle against it. About J language J — is a Korean of programming languages (may look confusing). It’s an explosion in reserved characters factory. Plenty of brackets, periods, slashes and it even works. It must be magic or something. Wanting to be short or just having been carried away some people writing on J forget even simple rules of any code writing. These rules aren’t new but they acquire a critical meaning as applied to APL similar languages. As when reading ((]i.~[:{.[){([:{:[),]`([:<[$:[:>])@.([:32&=[:3!:0[:>]))«2 0 construction even a trained brain is at

Running and Software Development

Written by Michael Dubakov

What can running and software development have in common? Nothing special at fist glance. A sweaty and slender runner totally differs from a flabby, bent by scoliosis programmer. Stadiums don’t applaud to developers and no one gives them the country flag for the lap of honor round the office after some release. Nevertheless, running and development do have many things in common. I have read a very difficult book — Surfaces and Essences . Douglas Hofstadter had a blast and I didn’t want to read the book after the first 50 pages. I literally forced myself to read few dozens of pages per week until I read till the third book – then I loved it. This book is about the way people think. They think in terms of analogies. Using millions of examples, Hofstadter and Sander quite clearly bring out the way analogies work and the things you can

Using Go to Execute Commands on Hundreds of Servers with SSH

Written by youROCK

In this article we’re going to write a simple program on Go (100 lines), which will execute commands via SSH protocol on hundreds of servers, and will do it quite efficiently. It will be implemented with the help of go.crypto/ssh , which is SSH protocol implementation by authors of Go. More “advanced” version of the program written in this article is available on github: GoSSHa (Go SSH agent). Introduction The company I work for has more than one server and in order to keep the work efficient libpssh library on the basis of libssh2 has been written. This library was written on C with libevent use many years ago, and it still copes with its tasks. One thing is that it’s quite complicate to maintain it. Go language from Google is getting more popular, as well as within our company. So I decided to rewrite libpssh with Go and fix

JavaScript optimization challenge

Written by Няша Няшная

Hi, we're hosting the JS optimization challenge right now, with cash prizes and all. Link to full rules. The challenge: make JS strftime function very fast, and beat the performance of GNU libc's strftime . The slower code that can be used as a base for optimizations is here: github.com/mvasilkov/strftime You're free to use that source as the base of your solution. To make things interesting, we're not providing the reference benchmark. The benchmark will run on V8 (Node.js) engine. Send your solutions to [email protected] (as attachments, GitHub gists or whatever). Last date for submission is June 22, 2014. Winners will be announced on June 29.

Introduction to Writing Tests with ScalaTest

Written by Kukuruku Hub

To be able to quickly start visualizing some of the tests that can be written with ScalaTest, we can take advantage of the test-patterns-scala template from the Typesafe Activator . It consists of a number of examples that essentially target the ScalaTest framework. The easiest way to get the code is to download the template bundle for test-patterns-scala. An archive contains a bootstrap script that can simplify our life's by starting Activator automatically. Setting up the test-patterns-scala activator project only requires you to go to the directory where you installed the Typesafe Activator and then, either start the GUI through the > activator ui command, or type > activator new to create a new project and select the appropriate template when prompted. Download the bundle Extract the downloaded zip file `cd` to test-patterns-scala directory from your console Run ./activator ui You can also generate the project by running: ./activator new

Mobile Typography

Written by Kukuruku Hub

As a designer you are probably keenly aware that more often than not, your dream font is not available on every device and every browser. Whether this knowledge is founded in the experience of designing and developing a site yourself, or from a horrifying experience such as your developer showing you the implementation of your design and feeling the special tug on your soul as part of you dies when viewing your original font choice rendered down into an abomination that makes comic-sans look vaguely desirable. Previously you may have even decided to give up the fight of using the perfect font for the entire site and opted to use it only on special portions of the design as an image. This, you tell yourself, will help you sleep at night and fix all the problems in the world as they can see the effort you have put into product

Browser Extension to Extract the Text from Images

Written by alizar

Naptha — is a very useful Chrome extension. It automatically recognizes text of all the images that are downloaded by the browser. With the help of this extension you can edit images text, select, copy and translate it. This extension is indispensable for copying the text from the document scans, photographs, posters, diagrams, charts, screenshots and even memes. The idea to create this extension was born on the basis of xkcd meme. It showed the websites, which didn’t allow selecting the text at their web-pages. Ironically, xkcd website can also be referred to “violators” as it doesn’t allow selecting the text inside the memes. Naptha extension fixes this drawback. Developers say that the Stroke Width Transform algorithm, which is used in the extension, can recognize a text even of incoherent flourishes. This peculiarity can be considered as a bug or a feature. By the way, Naptha works for any

Lytro Company Announced a Plenoptic Camera of the Second Generation

Written by ilya42

Lytro Company, founded by Ren Ng from Stanford University, is commercializing plenoptic photography. It’s a photo of the light field when matrix with the help of micro lens system fixes not a 2D image but full information of the scene light field — you can focus such images right after the shooting, and photos taken by this camera allow you to get a stereo image. The first Lytro camera looked more like a cute toy and shots quality was not that high. After rendering it into a 2D image its resolution was just a few mega pixels. The second generation camera, named Lytro Illym , looks much more like a real camera in both appearance and features. The size of the sensor has been increased from 1/3" to 1", images resolution is 40 Megaray (it’s the measurement for plenoptic cameras) compared to 11 in the first Lytro. 2D images

How I Found the Best Programming Language in the World. Part 1

Written by Andrey Platov

Since I’m going to provoke trolls on the subject of programming languages, and even name the best one in the world (I mean absolutely the best, for sure), I recommend all of them to check out my previous post “ Choosing a Programming Language ”. Everything mentioned there is still up-to-date, and I wouldn’t’ like to repeat myself here. Read it? Good. Today I am going to talk about the best programming language in the world , and I’ll name it closer to the end of this post. Three days ago I didn’t even think that unicorns existed, as each language sucks in this way or another, and each one does it in its own way (actually, there are some languages that always suck, but we won’t talk about them). As an engineer, I totally understood that the language question was impossible without various trade offs, starting from garbage

Asynchronous Programming: Back to the Future

Written by Grigory Demchenko

Asynchronous programming… Hearing these words, programmers’ eyes begin to shine, breathing becomes shallow, hands are shaking and the brain is drawing multiple levels of abstraction… Managers’ eyes become wide, sounds become inarticulate, fists are clenched, and the voice switches to overtones. The only thing that unites these two groups of people is a rapid pulse. However, there are different reasons. While programmers are eager for the fight, managers are trying to look into the crystal ball and realize the risks, frantically trying to come up with reasons to extend the deadlines as mush as they can. Later, when the most part of the code is already written, programmers begin to realize and experience the bitterness of asynchronous programming, spending endless nights in a debugger, desperately trying to understand what is actually happening… That's exactly what my inflamed imagination draws when hearing “asynchronous programming”. Of course, all of it is

Why Using Finalizers Is a Bad Idea

Written by Sofi Fateeva

Not so long ago we worked on a diagnostic rule related to the finalizer check. This provoked an argument on the details of the garbage collector work and the finalization of objects. Although we have been programming in C# for more than 5 years, we haven't achieved any consensus as regards this question, so I decided to study it more thoroughly. Introduction Usually .NET developers encounter a finalizer when they need to free an unmanaged resource. That's when a programmer has to think about a specific question: should we implement in our class IDisposable , or add a finalizer? Then he goes to StackOverflow, for example, and reads answers to questions like the Finalize/Dispose pattern in C# where he sees a classic pattern of IDisposable implementation, and the definition of the finalizer. The same pattern can be found in the MSDN description of the IDisposable interface. Some consider it

Choosing a Programming Language

Written by Andrey Platov

Frankly speaking, I never faced the question of choosing a programming language. In other words, this choice has always been obvious for me. I never took part in holy wars like C++ vs. Java that used to be so popular at the end of 1990s. When you see a huge growth of productivity with your own eyes, any discussions become meaningless. I've also noticed that only people who've seen just one side of the given discussion usually take part in it. This may be a good idea when it comes to gay marriages. But it’s very unprofessional in the world of programming. Perhaps, that’s the reason why all informal parties of programmers in the alco-holy war format have failed. It’s hard to gather professionals in such a way. Anyway, I’ve been thinking about the choice of a programming language for a week. However, it was the first time I

Complementing Unit Testing with Static Analysis, with NUnit as an Example

Written by Alex Astva

When discussing static analysis tools for C# projects, programmers will often deny the necessity of static analysis arguing that most errors can be caught through unit testing. So, I decided to find out how well one of the most popular unit-testing frameworks, NUnit, was tested and see if our analyzer could find anything of interest there. Introduction NUnit is a popular unit-testing library for .NET projects ported from Java to C#. Its code is open and can be downloaded from the project website http://www.nunit.org/ . It should be noted that JUnit — the project that NUnit was ported from — was created by such renowned programmers as Erich Gamma, a co-author of the textbook on object-oriented design patterns, and Kent Beck, the creator of the test-driven development and extreme programming methodologies. I recall reading his book Test Driven Development By Example once, where he explains test-driven development by the

Why we need novel authentication schemes?

Written by Cossack Labs

Revealing security holes in 5 main methods of authentication Introduction: A Word To Pass Passwords are ultimate keepers of diversity and security. Since Ancient Roman times until now, they are used for one to prove being worthy to get some privilege others do not possess, however strongly desire to obtain. A “magic word”, which one knows and others don’t, opens the door for an opportunity and diversifies an individual selecting them from an enormous crowd. We can say that password is the oldest and the most widely used pillar of authentication, which is extensively used in 21st century Internet. Its importance is even greater than before, because nowadays more and more people are communicating remotely without seeing or hearing each other, using remote means to gain access to automated systems. Therefore, they have to rely only on passwords to verify remote party and prove their own identity. Just getting

Building secure end-to-end webchat with Themis

Written by Cossack Labs

Intro While developing components of our products, we love to explore use cases and usability through creating real-world test stands. 0fc is a side-product of WebThemis research: while doing some protocol design for front-end clients with WebThemis services, we wanted to try it in a real-world situation. We've set ourselves a novel idea: end-to-end encrypted webchat, inclined towards client anonymity, giving zero trust to the server, built only with typical Themis primitives. Always seeking real-world testing of any interesting models and ideas we stumble, we've created a simple web application for Absolutely Discrete Communications :) With 0fc, you: don't need client apps (web client app is loaded the first time you connect to host) don't need static keys are able to receive temporary invitation key by any channel are authenticated only by knowledge of this invitation key, which is being issued by chatroom owner 0fc can run on any

Introducing Themis

Written by Cossack Labs

What is Themis? Themis is a high-level cryptographic services library: a library providing easy to use, highly abstracted set of functions to solve real-world security problems. We would like you to focus on building your software with security taken care of by professionals, instead of scrupulously assembling building blocks into cryptosystems yourself, resolving implementations, platform availability, vulnerabilities and performance contstraints yourself. Themis is designed to provide complicated cryptosystems in an easy-to-use developer infrastructure, suitable for modern rapid development. It is an Open Source, Apache 2.0 licensed product that you can use free-of-charge, contribute code to or use in your own work. Themis will provide a wide set of security instruments. The first three of which that are implemented in the current, 0.9 release are: Secure Message : a simple encrypted messaging solution applicable to a wide range of applications. Secure Session: a safer, session-oriented messaging solution with better security

Releasing Themis into public: usability testing

Written by Cossack Labs

Experiment: developers with no Themis experience building an application with use of it in 6 hours. Being ready to release Themis, we’ve gathered a few colleagues and decided to make a test run on unsuspecting developers, how would the library blend into their workflows? 1. Introduction While usability testing for user-centric applications has it’s own distinct techniques, standards and frameworks, this is not so typical for a relatively complex and technical library aimed at developers and spanning multiple languages and platforms. As noted here , Themis started as an internal project, designed to meet our needs for future products. Themis is set to provide secure messaging and cryptography to third party apps in a very convenient and easy to use package, yet providing highest security levels. The decision to make Themis an open source project brought with it the need to provide not just source code but also a

SMS Gateway API: start sending and receiving text messages

Written by TextMagic

TextMagic SMS API is a platform for building your own messaging app using our messaging infrastructure. It allows you to send and receive SMS text messages, query information about inbound and outbound messages, manage contacts, create templates (i.e. message formats and static texts) and schedule recurrent SMS messages as well as process bulk SMS messages. We have created a set of client libraries for the most popular programming languages (such as REST API Java and REST API PHP). These libraries allow you to integrate our API into your code in minutes. Just choose your preferred language to get started.

Celebrating 30th Anniversary of The First C++ Compiler: Let's Find Bugs in It

Written by Marina Makarova

This article was originally published at viva64.com . Republished by the authors' permission. Cfront is a C++ compiler which came into existence in 1983 and was developed by Bjarne Stroustrup. At that time it was known as «C with Classes». Cfront had a complete parser, symbol tables, and built a tree for each class, function, etc. Cfront was based on CPre. Cfront defined the language until circa 1990. Many of the obscure corner cases in C++ are related to the Cfront implementation limitations. The reason is that Cfront performed translation from C++ to C. In short, Cfront is a sacred artifact for a C++ programmer. So I just couldn't help checking such a project.  Introduction  The idea to check Cfront occurred to me after reading an article, devoted to the 30-th anniversary of the first Release version of this compiler: " 30 YEARS OF C++ ". I contacted Bjarne

Competing With Amazon: How to Improve Your Car Parts Store

Written by Alexander Lashkov

Going online allows you to significantly expand your customer base and auto parts stores are not an exception. There are multiple ways to buy a car, parts or potential substitutes and it’s really challenging to compete with giants like Amazon or eBay. Here’s our take on what can be possibly done in order to make your car parts store more efficient. The problem: Car parts search There is an average of 14,000 parts in a car (and it may go up to 30k) so it’s a quite a problem to look up some parts for your particular car brand and model. Offline stores usually have around 5k parts in inventory and people tend to flock to marketplaces, especially online aggregators like Amazon, that provide more options with detailed descriptions. Looking it up all by yourself is even more challenging as you have to dig into catalogs, VINs and diagrams

How to take screenshots correctly: some practical tips

Written by Kirill Kliushkin

If you have ever made a help file or user manual for your app, you’re sure to have noticed the unexpected amount of time and effort producing screenshots takes. You’d think a screenshot was “a second’s work, Alt+PrintScreen and Ctrl+V!”. Some clients are surprised to hear that a screenshot in a user manual can cost $2 or even $5. In this article, I’ll advise you on how to take screenshots correctly, why they’re not just “two clicks” and what pitfalls an inexperienced screenshotter may meet. See it as a checklist or a list of practical tips for those who write software documentation. I hope it will help you avoid disappointments, and delight your users with beautiful, easy-to-understand images. What Needs a Screenshot? Needs a screenshot: Layout of the main elements and areas of the interface with captions. For example, the toolbar, status bar, main menu, pop-up menu. This avoids

Introduction to J Programming Language [2004]

Written by Dr. K. L. Metlov

Take a look at the brief introduction to the J programming language . It took me two days to write the article. I got familiar with this language a little more than a month ago, when looking for a convenient way for programming on the Pocket PC. All this month, I read books and articles about J, K and APL. I also tried out programs of other developers, wrote some trivial ones of my own and recently wrote my first, non-trivial program, which I improved and described in this article. My overall impression of J programming language is admiration. You’re welcome to read my article and share your thoughts about any mistakes or ambiguities found in it. Introduction Evolutionary Branches In these days of universal computer literacy, it’s difficult to find an active person, who has no idea of programming languages that allow to control the computer. But even

Lock-Free Data Structures. Exploring Queues

Written by Max Khiszinsky

It was long ago since the last time we talked about lock free containers. I was planning to quickly write another article about queues, but there was one problem. I knew what I wanted to write about, but I had no implementation of those methods in C++. It was wrong to write about something I did not try out myself. That’s how I tried to implement new queue algorithms in libcds . So now I can continue the series. This article is going to be the last one in the series about queues. Last time we spoke about them, we considered some interesting algorithms of lock free queues and provided their operation results in some synthetic tests. To sum up, it was really bad. Our hopes that the lock free approach on the magic compare-and-swap (CAS) would give us at least any, if not linear, performance gain with the

Short Story on Scaling an NLP Problem without Using a Ton of Hardware

Written by eandrawos

The cornerstone of the small work done for getting the info for these great charts with IEPY , was to be able to catch mentioned companies. The basic idea of relation extraction is to be able to detect mentioned things in text (so called Mentions, or Entity-Occurrences), and later decide if in the text is expressed or not the target relation between each couple of those things. In our case, we needed to find where companies were mentioned, and later determine if in a given sentence it was said that Company-A was funding Company-B or not. In order to detect those funding we needed to be sure of capturing every mention of a company. And although the NER used catched most of them, there are always some folks that name their company #waywire or 8th Story, words that are not very easily trackable with a NER. A good solution

Everything You Wanted to Know about USB Type-C, but did not Ask

Written by MVideo

Dear %username%, Have you heard of the new USB Type-C? The one double-sided, fast and fancy. It can charge the new MacBook and promises to become a new standard for the next ten years? So, first of all, it is a type of connector, and not a new standard. The standard is called USB 3.1. Secondly, we should talk about the new standard of USB, while Type-C is a nice bonus. Let’s find out the difference and what things are behind USB 3.1 and Type C. We will also learn how to charge a laptop with a USB-cable and see what else can be done with the new USB Type-C. Fast Facts As a standard, USB appeared almost twenty years ago. The first specifications for the USB 1.0 appeared in 1994 and solved three key problems: unification of a connector, simplicity for users, high speed data transfer to and