patch-cms

Documentation

A Rust reimplementation of the IBM VM/CMS environment — XEDIT editor, CMS file system, REXX scripting, spool subsystem, Hartmann pipelines, and VM inter-machine messaging.

Overview

VM/CMS was IBM's interactive mainframe operating system — a single-user virtual machine with a powerful command environment, a programmable full-screen editor (XEDIT), and REXX as its scripting language. This project recreates those semantics in modern Rust as a set of embeddable libraries with a terminal UI.

The REXX interpreter lives in a companion project, patch-rexx.

See ROADMAP.md for the full vision and current progress.

Workspace Structure

patch-cms/
├── crates/
│   ├── xedit-core/          # Editor model — pure logic, no I/O dependencies
│   ├── xedit-tui/           # Terminal UI — 3270-style block-mode rendering
│   ├── cms-core/            # CMS file system (fn ft fm), commands, EXEC processor
│   ├── cms-spool/           # Reader/punch/printer spool subsystem
│   ├── cms-pipelines/       # Hartmann pipelines
│   ├── vm-iucv/             # Inter-machine messaging (actor framework)
│   └── cms-machine/         # Interactive CMS machine binary

xedit-core is a standalone library with zero I/O dependencies. The editor is a pure state machine driven by commands, making it embeddable in other applications. With the rexx feature enabled, macros can query and drive the editor via EXTRACT variables and ADDRESS XEDIT commands.

xedit-tui provides the interactive terminal experience: prefix area editing, command line, PF keys, and screen editing with overtype/insert modes.

cms-core implements the CMS file system (fn ft fm naming), command processor with IBM-style abbreviation matching, GLOBALV variable storage, and EXEC resolution. Trait seams (ExecHandler, SmsgSender, ExtCommandHandler) decouple it from the REXX interpreter, actor framework, and extension commands.

cms-spool provides virtual reader/punch/printer queues with SPOOL, QUERY, PURGE, SENDFILE, and RECEIVE commands.

cms-pipelines implements Hartmann pipelines — the PIPE command with built-in stages (literal, console, locate, nlocate) and a two-pass executor.

vm-iucv is a Tokio-based actor framework modeled after VM/CMS inter-machine communication: Supervisor lifecycle management, SMSG messaging, and IUCV bidirectional data paths.

cms-machine wires everything together into an interactive CMS console with REXX scripting, spool commands, and pipelines — all programmable from the REPL.

Building and Running

# Build the workspace
cargo build --workspace

# Run the TUI editor
cargo run -p xedit-tui -- <filename>

# Run the interactive CMS machine
cargo run -p cms-machine -- --userid ALICE --disk /tmp/cms

# Run all tests
cargo test --workspace

CI

CI runs on Forgejo Actions (.forgejo/workflows/ci-linux.yml) for pull requests to main. The workflow's only job is just ci, so the justfile is the single source of truth for build/lint/test — local dev and CI run the same recipes.

Run the full CI check locally before pushing:

just ci    # fmt-check + lint (clippy -D warnings) + test + build

The Rust toolchain is pinned in rust-toolchain.toml and must match the toolchain: input in the CI workflow.

Current Status

906 tests passing, zero clippy warnings.

Phases 1-13 complete. The editor is fully functional with REXX macros, CMS file system, spool subsystem, Hartmann pipelines, actor-based inter-machine messaging, and an interactive CMS console. Everything is programmable from REXX/REPL.

License

MIT — Ed Sweeney, 2026