AdaCore Blog

16 entries tagged with #strings

by Martyn Pike

An Expedition into Libadalang

I’ve been telling Ada developers for a while now that Libadalang will open up the possibility of more-easily writing Ada source code analysis tools. (You can read more about Libadalang here and here and can also access the project on Github.)

by Joffrey Huguet, Johannes Kanig

Proving a simple program doing I/O ... with SPARK

The functionality of many security-critical programs is directly related to Input/Output (I/O). This includes command-line utilities such as gzip, which might process untrusted data downloaded from the internet, but also any servers that are directly connected to the internet, such as webservers, DNS servers and so on. In this blog post we show an approach that deals with error handling and reasoning about content, and demonstrate the approach using the cat command line utility.

#Formal Verification #SPARK

by Claire Dross

Using Pointers in SPARK

In this blog post, I will present one of the most interesting additions to the community 2019 version of SPARK: pointer support. One of the core assumption in SPARK has always been the absence of aliasing, so adding pointers without breaking this assumption was quite a challenge. I will explain how this was achieved using an ownership model for pointers (like is done in Rust) through small examples.

#VerificationTools

by Rob Tice

SPARKZumo Part 1: Ada and SPARK on Any Platform

So you want to use SPARK for your next microcontroller project? Great choice! All you need is an Ada 2012 ready compiler and the SPARK tools. But what happens when an Ada 2012 compiler isn’t available for your architecture?

#CCG #SPARK #Arduino #RISC V #embedded

by Yannick Moy

Tokeneer Fully Verified with SPARK 2014

Tokeneer is a software for controlling physical access to a secure enclave by means of a fingerprint sensor. This software was created by Altran (Praxis at the time) in 2003 using the previous generation of SPARK language and tools, as part of a project commissioned by the NSA to investigate the rigorous development of critical software using formal methods. The project artefacts, including the source code, were released as open source in 2008. Tokeneer was widely recognized as a milestone in industrial formal verification. We recently transitioned this software to SPARK 2014, and it allowed us to go beyond what was possible with the previous SPARK technology. We have also shown how security vulnerabilities introduced in the code can be detected by formal verification.

#SPARK #Formal Methods

by Felix Krause

The Road to a Thick OpenGL Binding for Ada: Part 2

This blog post is part two of a tutorial based on the OpenGLAda project and will cover implementation details such as a type system for interfacing with C, error handling, memory management, and loading functions.

#OpenGL #Binding

by Lionel Matias

Leveraging Ada Run-Time Checks with Fuzz Testing in AFL

Fuzzing is a very popular bug finding method. The concept, very simple, is to continuously inject random (garbage) data as input of a software component, and wait for it to crash. If, like me, you find writing robustness test tedious and not very efficient in finding bugs, you might want to try fuzzing your Ada code. Here's a recipe to fuzz-test your Ada code, using American Fuzzy Lop and all the runtime checks your favorite Ada compiler can provide. Let's see (quickly) how AFL works, then jump right into fuzzing 3 open-source Ada libraries: ZipAda, AdaYaml, and GNATCOLL.JSON.

#Testing #Ada #VerificationTools

by Pierre-Marie de Rodat

Pretty-Printing Ada Containers with GDB Scripts

When things don’t work as expected, developers usually do one of two things: either add debug prints to their programs, or run their programs under a debugger. Today we’ll focus on the latter activity.

by Yannick Moy

Applied Formal Logic: Searching in Strings

A friend pointed me to recent posts by Tommy M. McGuire, in which he describes how Frama-C can be used to functionally prove a brute force version of string search, and to find a previously unknown bug in a faster version of string search called quick search. Frama-C and SPARK share similar history, techniques and goals. So it was tempting to redo the same proofs on equivalent code in SPARK, and completing them with a functional proof of the fixed version of quick search. This is what I'll present in this post.

#Dev Projects #Formal Verification #SPARK

by Emmanuel Briot

User-friendly strings API

User friendly strings API In a previous post, we described the design of a new strings package, with improved performance compared to the standard Ada unbounded strings implementation. That post focused on various programming techniques used to make that package as fast as possible.

by Emmanuel Briot

New strings package in GNATCOLL

This post describes the new GNATCOLL.Strings package, and the various optimizations it performs to provide improved performance.

#gnatcoll #strings #Ada

by Fabien Chouteau, Arnaud Charlet, Yannick Moy

SPARK Tetris on the Arduboy

One of us got hooked on the promise of a credit-card-size programmable pocket game under the name of Arduboy and participated in its kickstarter in 2015. The kickstarter was successful (but late) and delivered the expected working board in mid 2016. Of course, the idea from the start was to program it in Ada , but this is an 8-bits AVR microcontroller (the ATmega32u4 by Atmel) not supported anymore by GNAT Pro. One solution would have been to rebuild our own GNAT compiler for 8-bit AVR from the GNAT FSF repository and use the AVR-Ada project. Another solution, which we explore in this blog post, is to use the SPARK-to-C compiler that we developed at AdaCore to turn our Ada code into C and then use the Arduino toolchain to compile for the Arduboy board.

by Florian Schanda

SPARKSMT - An SMTLIB Processing Tool Written in SPARK - Part I

Today I will write the first article in a short series about the development of an SMTLIB processing tool in SPARK. Instead of focusing on features, I intend to focus on the how I have proved absence of run-time errors in the name table and lexer. I had two objectives: show absence of run-time errors, and do not write useless defensive code. Today's blog will be about the name table, a data structure found in many compilers that can map strings to a unique integer and back. The next blog post will talk about the lexical analyzer.

#Dev Projects #Formal Verification #SPARK

by Maxim Reznik, Nicolas Setton

Using reference types to handle persistent objects

The Ada 2012 standard introduced user-defined references. The main idea behind this is simplifying the access to elements in a container. But you can use them to control the life-circle of your persistent objects. Let's see how it could work.

#Ada 2012 #Persistent Objects #Programming

by Emmanuel Briot

Traits-Based Containers

This post describes the design of a new containers library. It highlights some of the limitations of the standard Ada containers, and proposes a new approach using generic packages as formal parameters to make these new containers highly configurable at compile time.

#Ada #Containers #Generics

by Johannes Kanig

A Little Exercise With Strings

I recently looked at string manipulation functions in a library and tried to prove absence of run-time errors of one of them. Although the function and it's proof are quite simple in the end, the process of obtaining the correct code and the proof was interesting enough to write this blog post.

#Formal Verification #SPARK