Overview

The cms-machine crate wires all subsystems together into an interactive CMS console. It is the top-level binary that provides a REPL where users can issue CMS commands, run REXX EXECs, use spool commands, and execute pipelines.

CmsMachineHandler

CmsMachineHandler implements the MachineHandler trait from vm-iucv, bridging the actor framework with the CMS CommandProcessor. It handles:

on_ipl – Prints the startup banner, runs PROFILE EXEC if present, and begins the command loop.
on_smsg – Dispatches incoming messages. Messages from $CON trigger command execution; messages from other machines are displayed and stored in GLOBALV (LMSGSRC, LMSGTXT).
on_logoff – Cleans up resources.

Console Architecture

The console uses a split-thread design:

stdin (blocking read)
  |
  v
cmd_tx channel ──> CmsMachineHandler
  |                      |
  +── SMSG from $CON ──> on_smsg()
                           |
                           v
                    CommandProcessor::execute()
                           |
                           v
                    output_tx channel ──> stdout

A dedicated thread reads lines from stdin and sends them via cmd_tx.
After sending a command, the thread sends an SMSG from the $CON pseudo-machine to wake the handler.
The handler receives the SMSG, pulls the command from cmd_rx, executes it, and sends output lines via output_tx.
The console thread reads output lines until it sees the BATCH_DONE sentinel, then prompts for the next command.

BATCH_DONE Sentinel

The BATCH_DONE constant is a special marker string sent after every command completes. The console thread waits for this sentinel before displaying the next prompt, ensuring output from one command is fully flushed before the next begins.

Subsystem Integration

All subsystems are available from the REPL:

Subsystem	How it connects
CMS commands	Built into `CommandProcessor` (GLOBALV, LISTFILE, etc.)
REXX EXECs	`CmsRexxExecHandlerWithSwap` – persistent state across EXECs
Spool	`CmsExtCommandHandler` routes SP/QUERY/PURGE/SENDFILE/RECEIVE
Pipelines	`CmsExtCommandHandler` routes PIPE commands to `run_pipe()`
SMSG	`ChannelSmsgSender` routes through the actor framework

The CmsRexxExecHandlerWithSwap handler swaps the file system, GLOBALV store, and SMSG sender into the REXX execution context, so REXX EXECs can issue CMS commands that modify persistent state.

CLI Usage

# Basic usage
cargo run -p cms-machine -- --userid ALICE --disk /tmp/cms

# Multiple disks (mounted as A, B, C, ...)
cargo run -p cms-machine -- --userid BOB --disk /tmp/d1 --disk /tmp/d2

The --userid flag sets the machine’s identity for SMSG routing. Each --disk path is mounted as a minidisk at successive filemode letters (A, B, C, …) in read-write mode.