SafeHandle / CriticalHandle / SafeBuffer / derived types

I feel I’m going to open the Pandora’s box for you. Let’s talk about special types: SafeHandle, CriticalHandle and their derived types.

This is the last thing about the pattern of a type that gives access to an unmanaged resource. But first, let’s list everything we usually get from unmanaged world:

The first and obvious thing is handles. This may be an meaningless word for a .NET developer, but it is a very important component of the operating system world. A handle is a 32- or 64-bit number by nature. It designates an opened session of interaction with an operating system. For example, when you open a file you get a handle from the WinApi function. Then you can work with it and do Seek, Read or Write operations. Or, you may open a socket for network access. Again an operating system will pass you a handle. In .NET handles are stored as IntPtr type;

This chapter was translated from Russian jointly by author and by professional translators. You can help us with translation from Russian or English into any other language, primarily into Chinese or German.

Also, if you want thank us, the best way you can do that is to give us a star on github or to fork repository github/sidristij/dotnetbook.

^{Source: The online counterfeit economy: consumer electronics, a report made by CSC in 2017}

Over the past 10 years, the number of fake goods in the world has doubled. This data has been published in the latest Year-End Intellectual Property Rights Review by the US Department of Homeland Security in 2016 (the most current year tracked). A lot of the counterfeiting comes from China (56%), Hong Kong (36%) and Singapore (2%). The manufacturers of original goods suffer serious losses, some of which occur on the electronics market.

Many modern products contain electronic components: clothes, shoes, watches, jewellery, cars.
Last year, direct losses from the illegal copying of consumer electronics and electronic components in the composition of other goods were about $0.5 trillion.

How to solve this problem?

This article is about the interrupt delivery process from external devices in the x86 system. It tries to answer questions such as:

• What is PIC and what is it for?
• What is APIC and what is it for? What is the purpose of LAPIC and I/O APIC?
• What are the differences between APIC, xAPIC, and x2APIC?
• What is MSI? What are the differences between MSI and MSI-X?
• What is the role of the $PIR, MPtable, and ACPI tables?

If you want to know the answer for one of these questions, or if you simply want to know about interrupt controller evolution, please, welcome.

Русская версия этой статьи.
Modern PC motherboards' firmware follow UEFI specification since 2010. In 2013, a new technology called Secure Boot appeared, intended to prevent bootkits from being installed and run. Secure Boot prevents the execution of unsigned or untrusted program code (.efi programs and operating system boot loaders, additional hardware firmware like video card and network adapter OPROMs).
Secure Boot can be disabled on any retail motherboard, but a mandatory requirement for changing its state is physical presence of the user at the computer. It is necessary to enter UEFI settings when the computer boots, and only then it's possible to change Secure Boot settings.

Most motherboards include only Microsoft keys as trusted, which forces bootable software vendors to ask Microsoft to sign their bootloaders. This process include code audit procedure and justification for the need to sign their file with globally trusted key if they want the disk or USB flash to work in Secure Boot mode without adding their key on each computer manually.
Linux distributions, hypervisors, antivirus boot disks, computer recovery software authors all have to sign their bootloaders in Microsoft.

I wanted to make a bootable USB flash drive with various computer recovery software that would boot without disabling Secure Boot. Let's see how this can be achieved.

This week we issue a really huge selection of all the essential news you might have missed on Front-end development. Make sure to check the latest updates on CSS, HTML, and JavaScript.

We’re currently experimenting with Flutter while developing our side project for step challenges with colleagues. This side project should also be considered as a playground, where we can check if we can use Flutter in more serious projects. That’s why we want to use some approaches there that can look like an over-engineering for such a small project.

So one of the first questions was what can we use for dependency injection. A quick search in the internet revealed 2 libraries with positive reviews: get_it and kiwi. As get_it turned out to be a Service Locator (and I’m not a fan of this pattern), I was going to play with kiwi, which looked more promising, but then I’ve found another one library: inject.dart. It is heavily inspired by Dagger library, and as we use the latest one in our other Android projects, I’ve decided to dig into it.

Technology and markets are going hand in hand today. It's going so close that any whiff of a tech headway and social media is going up in a frenzy about it. Writers are filling pages after pages as if it's already here. Shares ride bull or bear, and newspapers print a string of capital letters.

The PVS-Studio team has been keeping the blog about the checks of open-source projects by the same-name static code analyzer for many years. To date, more than 300 projects have been checked, the base of errors contains more than 12000 cases. Initially the analyzer was implemented for checking C and C++ code, support of C# was added later. Therefore, from all checked projects the majority (> 80%) accounts for C and C++. Quite recently Java was added to the list of supported languages, which means that there is now a whole new open world for PVS-Studio, so it's time to complement the base with errors from Java projects.

The Java world is vast and varied, so one doesn't even know where to look first when choosing a project to test the new analyzer. Ultimately, the choice fell on the full-text search and analytical engine Elasticsearch. It is quite a successful project, and it's even especially pleasant to find errors in significant projects. So, what defects did PVS-Studio for Java manage to detect? Further talk will be right about the results of the check.

Static analysis methodology involves various technologies. One of them is preprocessing files right before analyzing them. Preprocessed files are created by the compiler that runs in a special working mode. Unfortunately, our long-standing experience of developing a static analyzer shows that this mode is not great for testing. In this note, I'll give the example of a fresh bug in the C++ compiler from Microsoft.

As Senior Software Engineer at company building messaging platform for healthcare industry I am responsible, including other duties, for performance of our application. We develop pretty standard web-service using Ruby on Rails application for business logic and API, React + Redux for users' facing single page application, as database we use PostgreSQL. Common reasons for performance problems in similar stacks are heavy queries to database and I would like to tell the story how we applied non-standard but fairly simple optimisations to improve performance.

Our business operates in US, so we have to be HIPAA compliant and follow certain security policies, security audit is something that we are always prepared for. To reduce risks and costs we rely on a special cloud provider to run our applications and databases, very similar to what Heroku does. On one hand it allows us to focus on building our platform but on the other hand it adds an additional limitation to our infrastructure. Talking shortly — we cannot scale up infinitely. As a successful startup we double number of users every few month and one day our monitoring told us that we were exceeding disk IO quota on the database server. Underlying AWS started throttling which was resulting in a significant performance degradation. Ruby application was not capable to serve all incoming traffic because Unicorn workers were spending too much time awaiting for database's response, customers were unhappy.

Dmitry Pichulin, known under the nick «deemru», won the game Fhloston Paradise, developed by Tradisys on the Waves blockchain.

The winner of Fhloston Paradise was supposed to be the player paying the very last stake during a 60-block period, before any other player could pay their stake and reset the counter to zero. The winner would collect all stakes paid by other players.

Dmitry's winning recipe was the bot Patrollo, which he created. The bot paid just eight 1 WAVES stakes for Dmitry and eventually won him 4,700 WAVES ($13,100). In this interview, Dmitry discusses his bot and prospects of blockchain games.

Disposable pattern (Disposable Design Principle)

I guess almost any programmer who uses .NET will now say this pattern is a piece of cake. That it is the best-known pattern used on the platform. However, even the simplest and well-known problem domain will have secret areas which you have never looked at. So, let’s describe the whole thing from the beginning for the first-timers and all the rest (so that each of you could remember the basics). Don’t skip these paragraphs — I am watching you!

If I ask what is IDisposable, you will surely say that it is

public interface IDisposable
{
    void Dispose();
}

What is the purpose of the interface? I mean, why do we need to clear up memory at all if we have a smart Garbage Collector that clears the memory instead of us, so we even don’t have to think about it. However, there are some small details.

This chapter was translated from Russian jointly by author and by professional translators. You can help us with translation from Russian or English into any other language, primarily into Chinese or German.

Also, if you want thank us, the best way you can do that is to give us a star on github or to fork repository github/sidristij/dotnetbook.

• First of all, you can read this article in russian here.

One evening, I was reading Mastering regular expressions by Jeffrey Friedl , I realized that even if you have all the documentation and a lot of experience, there could be a lot of tricks developed by different people and imprisoned for themselves. All people are different. And techniques that are obvious for certain people may not be obvious to others and look like some kind of weird magic to third person. By the way, I already described several such moments here (in russian) .

For the administrator or the user the command line is not only a tool that can do everything, but also a highly customized tool that could be develops forever. Recently there was a translated article about some useful tricks in CLI. But I feel that the translator do not have enough experience with CLI and didn't follow the tricks described, so many important things could be missed or misunderstood.

Under the cut — a dozen tricks in Linux shell from my personal experience.

As many of our readers know, Qrator.Radar is constantly researching global BGP connectivity, as well as regional. Since the Internet stands for “Interconnected Networks,” to ensure the best possible quality and speed the interconnectivity of individual networks should be rich and diverse, with their growth motivated on a sound competitive basis.

The fault-resistance of an internet connection in any given region or country is tied to the number of alternate routes between ASes. Though, as we stated before in our Internet Segments Reliability reports, some paths are obviously more critical compared to the others (for example, the paths to the Tier-1 transit ISPs or autonomous systems hosting authoritative DNS servers), which means that having as many reachable routes as possible is the only viable way to ensure adequate system scalability, stability and robustness.

This time, we are going to have a closer look at the Russian Federation internet segment. There are reasons to keep an eye on that segment: according to the numbers provided by the RIPE database, there are 6183 autonomous systems in Russia, out of 88664 registered worldwide, which stands for 6.87% of total.

This percentage puts Russia on a second place in the world, right after the USA (30.08% of registered ASes) and before Brazil, owning 6.34% of all autonomous systems. Effects of changes in the Russian connectivity could be observed across many other countries dependant on or adjacent to that connectivity, and ultimately by almost any ISP in the world.

It has been three months since 2018 had ended. For many, it has just flew by, but for us, PVS-Studio developers, it was quite an eventful year. We were working up a sweat, fearlessly competing for spreading the word about static analysis and were searching for errors in open source projects, written in C, C++, C#, and Java languages. In this article, we gathered the top 10 most interesting of them right for you!

What's new in CUBA 7

Three years ago we announced the second publicly available major version of the framework. CUBA 6 was the game-changing version — the licensing was turned from proprietary to Apache 2.0. Those days we couldn't even guess where it was going to bring the framework in long term. CUBA community started to grow exponentially, so we have learned a lot of possible (and sometimes impossible) ways of how developers use the framework. Now we are happy to announce CUBA 7, which, we hope, will make development more coherent and joyful for all community members from those just starting their journey in CUBA and Java to skilled enterprise developers and Java experts.

It is new selection of tips and tricks about Python and programming from my Telegram-channel @pythonetc.

Previous publications.

Structures comparing

Sometimes you want to compare complex structures in tests ignoring some values. Usually, it can be done by comparing particular values with the structure:

For Russian speaking posted translated version here.

This is how Alex Viscreanu’s talk on Moscow Python Conf++ named. Now it's two weeks till before the conference, but of course, I've already heard what Alex will speak about. Find below some spoilers and talk preparing backstage: what kind of an open source Zoo developed in Kiwi, how it tests Python code and what’s the difference between The Zoo and for example mypy.

— Tell us a bit about Kiwi, yourself and what is your work within a company?

Kiwi.com is an online travel agency based in Czech Republic. We aim to make travelling as simple and accessible as possible. The company was founded in 2012 as Skypicker, and since then it has become one of the five biggest online sellers of airline tickets in Europe. It was renamed to Kiwi.com in 2016.

The special feature that we, at Kiwi.com, offer is the virtual interlining, which allows us to connect flights from companies that don’t usually cooperate together, and we are covering the possible connection issues caused by delayed flights.

Some of the numbers that we manage at Kiwi.com include 90 000 000+ daily searches, 25 000 seats sold daily, and a total of 15 000 000 000+ flight combinations available.

Here we are, continuing to explore the code of calculators! Today we are going to take a look at the project called SpeedCrunch, the second most popular free calculator.

Introduction

SpeedCrunch is a high-precision scientific calculator featuring a fast, keyboard-driven user interface. It is free and open-source software, licensed under the GPL and running on Windows, Linux, and macOS.

The source code is available on BitBucket. I was somewhat disappointed by the build documentation, which could be more detailed. It says that you need «Qt 5.2 or later» to build the project, but it actually required a few specific packages, which wasn't easy to figure out from the CMake log. By the way, it is considered a good practice nowadays to include a Dockerfile into the project to make it easier for the user to set up the development environment.

I’m an active user of Google Chrome. That’s why I’ve come up with this list of useful extensions that will help English learners to enhance writing, spelling, listening skills, and extend their vocabulary.