gnucobol: Instructions file for Claude Code

CLAUDE.md

This file provides guidance to Claude Code (claude.ai/code) when working with code in this repository.

Project Overview

This is a Docker containerization wrapper for GnuCOBOL (GNU COBOL compiler). It maintains build and deployment configurations for multiple GnuCOBOL versions (3.0, 3.1, 3.2, 4.0) as Docker containers, with actual GnuCOBOL source distributed as tarballs.

Repository Structure

gnucobol/
├── 3.0/, 3.1/, 3.2/, 4.0/  # Version-specific directories
│   ├── builder/             # Docker build env with Dockerfile and tarball
│   ├── hello/               # Test program container
│   ├── runtime/             # Runtime container
│   └── daily.sh             # Version build script
└── daily.sh                  # Main build orchestration script

Build Commands

Docker Images

Build all containers for a version (uses podman):

cd 4.0 && ./daily.sh

This builds three images: gnucobol:4.0-builder, gnucobol:4.0-runtime, gnucobol:4.0-hello

Build individual container:

cd 4.0/builder && podman build -t gnucobol:4.0-builder .

The root daily.sh and update.sh scripts are primarily reference automation for release/update flow. Prefer editing the versioned Dockerfiles directly when making repository changes.

COBOL Compilation Commands

Compile COBOL to executable:

cobc -x program.cob

GnuCOBOL 4.0 Bug Fix

The Dockerfiles are pinned to alpine:3.20 for stability.

The builder Dockerfile includes a patch for a NULL pointer dereference bug in libcob/common.c (function cob_setup_env). At line 2652, strrchr() can return NULL if the path has no slash character, but line 2653 dereferences p+1 without checking for NULL. The sed commands add the missing NULL check:

// Before (buggy):
p = strrchr (binpath, SLASH_CHAR);
if (memcmp (p+1, "bin", 3) == 0
 || memcmp (p+1, "lib", 3) == 0) {

// After (fixed):
p = strrchr (binpath, SLASH_CHAR);
if (p && (memcmp (p+1, "bin", 3) == 0
 || memcmp (p+1, "lib", 3) == 0)) {