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CoccinelleJump to section titled Coccinelle

Coccinelle is a program matching tool which allows programmers to easily write some complex style-preserving source-to-source transformations on C source code, for instance, code refactoring. There are useful online resources which document this tool very well, however it is slightly difficult for a beginner to understand these concepts through these materials. So this is my attempt to explain the details of this tool in more convenient way.

About CoccinelleJump to section titled About Coccinelle

Coccinelle is a program matching and transformation engine for C code. It works by providing a language SmPL (semantic patch language) for specifying desired matches and transformations in C code. initially, Coccinelle was initially targeted towards performing collateral evolutions in Linux, but it can be applied on any other C code.

Goals of CoccinelleJump to section titled Goals of Coccinelle

  • Automatically find code containing bugs or requiring collateral evolution.

  • Automatically fix bugs and perform collateral evolution.

  • Provide a system that is accessible to software developers.

Getting started with coccinelleJump to section titled Getting started with coccinelle

It is always helpful to learn via examples. So I will try to cover a set of examples which will help to understand every element of coccinelle tools in a very applied way. So to get started with coccinelle, let us work out with the following steps:

  • Step 1: Download coccinelle and install it. The Coccinelle binary is called spatch. For linux, you can do it via following command:

sudo apt-get install coccinelle

  • Step-2: As we have discussed coccinelle utilizes semantic patch language. Lets consider a problem where we want to add parantheses over statement like !E & C so that it would become !(E & C). To solve this type of issue, make a file say ex1.cocci which contains:
@@
expression E;
constant C;
@@
- !E & C
+ !(E & C)
  • Step -3 : Save the above code, then work out with following commands in your working directory.

$ spatch --sp-file ex1.cocci --no-includes --dir /drivers/staging > ret.out.

Did you find any satisfactory result? if yes, then submit some of the patches. Some of my accepted patches in linux foundation are here

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