Development

This document outlines how to contribute code to the CNDP project.

Getting the code

The CNDP code can be cloned from the repository on GitHub:

git clone https://github.com/CloudNativeDataPlane/cndp.git

Submitting Patches

Use Github Pull requests to change CNDP.

Coding Guidelines

C code should follow the CNDP coding standards.

A .clang-format is available in the CNDP repo and can be run with clang-format or ninja clang-format. A pre-commit hook is also available and can be used to apply the clang format to modified files in a commit. The pre-commit hook also runs gofmt for modified .go files, and runs tools/check_json.py for modified .jsonc files.

Install the clang-format:

sudo apt-get install -y clang-format

If committing changes to the .go or .jsonc files:

sudo apt-get -y golang
pip install jsonc-parser jsonschema

Install the pre-commit hook before committing changes:

cp .githooks/pre-commit .git/hooks/
chmod +x .git/hooks/pre-commit

Guidelines for public or private APIs is to hide as much of the internal API from the developer. Which means we need to label function prototypes as public using the CNDP_API macro. The macro is defined as

#define CNDP_API __attribute__((visibility("default")))

And used in this way:

CNDP_API int cne_init();

We also use function versioning macros to allow for build time function linking using the following APIs:

#ifdef CNE_BUILD_SHARED_LIBS
#define FUNCTION_VERSION(internal, api, ver) __asm__(".symver " #internal ", " #api "@" #ver)
#define DEFAULT_VERSION(internal, api, ver)  __asm__(".symver " #internal ", " #api "@@" #ver)
#else
#define FUNCTION_VERSION(internal, api, ver)
#define DEFAULT_VERSION(internal, api, ver)
#endif

To hide internal APIs we have public and private headers. The public headers are installed in the system, but the private headers are not. The public headers should use typedefs to hide the internal structures by:

typedef void foo_t;
foo_t *foo;

where the structure may be

struct foo {
  int bar;
};

Do not hide the ‘*’ type inside the typedef.

This requires the public APIs to only return void pointers and the public functions are passed these void types and must cast the void pointer into the private structure pointer i.e.

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int foobar(foo_t *foo) {
    struct foo *f = foo;    // Cast of foo is not required as *foo is a void *

    return 0;
}

Naming header files as xyz_private.h and cne_xyz.h is preferred. The .c files should be named xyz.c or cne_xyz.c.