c-systems
Installation
SKILL.md
C Systems & Native Code
Covers C11 and later for libraries, systems code, and native extensions. For C++ (RAII, templates, move semantics), see the ia-cpp-systems skill.
Repo conventions outrank this skill
Read the repo's AGENTS.md/CLAUDE.md, its public headers, and two adjacent .c files before writing anything. Where they conflict with the rules below, they win, and the diff carries no note about it.
This gate is load-bearing. Established C codebases sanction idioms these rules would otherwise flag:
| Local idiom | Where it is correct |
|---|---|
| Tab indentation | php-src and its extensions, Linux kernel |
goto cleanup / goto err |
Kernel, OpenSSL, curl, php-src: the dominant multi-resource release idiom |
Macros containing return |
RETURN_*/RETVAL_* in PHP extensions, Py_RETURN_* in CPython |
| Project status types | zend_result, CURLcode, int plus errno: do not invent a parallel enum beside one |
Never widen a scoped task into a repo-wide restyle because adjacent untouched C predates a rule here.