Fix #12536: Handle Ctrl+C on Windows terminals

[JackMyers001]

Summary

Fixes #12536.

On Windows, JLine handles Ctrl+C as the terminal's INT signal. Without an explicit handler, the standalone Maven JVM does not follow its normal interrupt termination path and Maven's shutdown hooks do not run, which can leave long-running child processes alive.

This change registers an INT handler for Windows terminals that exits with status 130. This triggers normal JVM shutdown and its registered cleanup hooks.

Please backport this change to maven-4.0.x.

Testing

• mvn -Prun-its verify passes
• Confirmed issue in 4.0.0-rc-5 and master on:
  • Windows 11 with PowerShell in Windows Terminal
  • Windows 11 with Git Bash in Windows Terminal
• Confirmed issue is not present in 4.0.0-rc-5 and master on:
  • macOS 26 with Fish in Ghostty
  • Arch Linux with Fish in Ghostty
• Confirmed issue is not present in 3.9.16 on all configs listed above
• Confirmed issue is not present with this patch on all configs listed above

No automated regression test is included because the failure requires a real Windows terminal running Maven and a way to send a Ctrl+C event to that console.

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[gnodet]

Code Review

Clean, minimal, and correctly scoped fix for a real Windows-specific Ctrl+C regression in Maven 4. The approach is sound and consistent with existing codebase patterns.

Key observations:

• The !context.invokerRequest.embedded() guard is essential and correctly placed — calling System.exit() from an embedded Maven invocation would terminate the host process. The doCreateTerminal method already uses the same embedded() check.
• Exit code 130 (128 + SIGINT=2) follows the Unix convention for signal-terminated processes and is properly extracted into a named constant.
• The fix is correctly gated to Windows only via OSUtils.IS_WINDOWS. On Unix/macOS, the OS delivers SIGINT to the JVM natively. On Windows, JLine puts the terminal into raw mode and consumes Ctrl+C as console input before the JVM sees it.
• System.exit() is appropriate here (vs. Thread.currentThread().interrupt() used in other handlers like EncryptInvoker/ShellInvoker) because the goal is full JVM termination with shutdown hooks for the main build invocation.

Two minor notes (non-blocking):

• The signal handler runs inside the terminalConsumer callback on the fast-terminal-thread — the handler is correctly registered on the real underlying terminal.
• The lambda parameter signal is unused (always INT), consistent with existing patterns in EncryptInvoker, UpgradeInvoker, and ShellInvoker.

This review was generated by an AI agent and may contain inaccuracies. Please verify all suggestions before applying.

Claude Code on behalf of gnodet