fun/web/documentation/extensions/kcgi/kcgi.md

layout: page published: true noToc: false noComments: false noDate: false title: Fun - KCGI extension (optional) subtitle: Documentation for KCGI (kcgi) extension (optional) description: Documentation for KCGI (kcgi) extension (optional) permalink: /documentation/extensions/kcgi/ lang: en tags:

• extension
• kcgi
• optional

---

• CMake option: FUN_WITH_KCGI=ON
• Purpose: integrate the kcgi (CGI/FastCGI) C library; provide request parsing and response helpers for building CGI apps in Fun.
• Homepage: https://kristaps.bsd.lv/kcgi/{:class="ext"}

Build notes

• Requires system kcgi development headers and libraries (pkg-config name: kcgi).
• If pkg-config is not available, build falls back to linking against libkcgi and zlib (as configured in cmake/Extensions/KCGI.cmake).

Provided helper/opcodes

• Function: kcgi_parse(data: none) -> Map | Nil. Parses the current CGI/FastCGI request via kcgi and returns a Map with keys like method, scheme, host, port, path, suffix, query, and fields (GET/POST map). Returns Nil on failure or when the extension is disabled.
• Function: kcgi_reply_start(code:int, content_type:string) -> 1/0. Starts the HTTP reply (sets Content-Type and opens the body).
• Function: kcgi_write(text:string) -> 1/0. Writes a chunk to the response body.
• Function: kcgi_end() -> 1/0. Finalizes the response and frees request resources.
• Opcodes: OP_KCGI_PARSE, OP_KCGI_REPLY_START, OP_KCGI_WRITE, OP_KCGI_END (internal mappings for the functions above).

Quickstart

• Configure: cmake -S . -B build -DFUN_WITH_KCGI=ON
• Build: cmake --build build --target fun
• Run example:
  • FUN_LIB_DIR="$(pwd)/lib" ./build/fun examples/cgi/hello_kcgi.fun

Example output

• Content-Type: text/html; charset=utf-8

• Hello, Fun!

Notes

• Running outside a real CGI/FastCGI environment may emit RFC warnings (e.g., missing REMOTE_ADDR); these are benign for local testing.
• When FUN_WITH_KCGI is OFF, the helpers behave as no-ops (returning Nil/0) to keep scripts portable.