[tgross]

On Windows, the os.Process.Signal method returns an error when sending os.Interrupt (SIGINT) because it isn't implemented. This causes test servers in the testutil packages to break on Windows. Use the platform specific syscalls to generate the SIGINT instead.

The agent's signal handler also did not correctly handle the Ctrl-C because we were masking os.Interrupt instead of SIGINT.

Fixes: #26775

Contributor Checklist

• Changelog Entry If this PR changes user-facing behavior, please generate and add a
  changelog entry using the make cl command.
  • no changelog, as this is a test-only fix
• Testing Please add tests to cover any new functionality or to demonstrate bug fixes and
  ensure regressions will be caught.
• Documentation If the change impacts user-facing functionality such as the CLI, API, UI,
  and job configuration, please update the Nomad website documentation to reflect this. Refer to
  the website README for docs guidelines. Please also consider whether the
  change requires notes within the upgrade guide.

Reviewer Checklist

• Backport Labels Please add the correct backport labels as described by the internal
  backporting document.
• Commit Type Ensure the correct merge method is selected which should be "squash and merge"
  in the majority of situations. The main exceptions are long-lived feature branches or merges where
  history should be preserved.
• Enterprise PRs If this is an enterprise only PR, please add any required changelog entry
  within the public repository.

• If a change needs to be reverted, we will roll out an update to the code within 7 days.

Changes to Security Controls

Are there any changes to security controls (access controls, encryption, logging) in this pull request? If so, explain.

[tgross]

I've been doing some testing and discovered that on Windows the signal handler is also ignoring os.Interrupt, so I've had to switch it out for syscall.SIGINT just to get it to catch the signal at all. But the tests still reporting failure and I can't yet figure out why:

==> Starting Nomad agent...
==> Nomad agent configuration:

       Advertise Addrs: HTTP: 172.31.25.30:50317; RPC: 172.31.25.30:50318; Serf: 172.31.25.30:50319
            Bind Addrs: HTTP: [0.0.0.0:50317]; RPC: 0.0.0.0:50318; Serf: 0.0.0.0:50319
                Client: false
             Log Level: ERROR
               Node Id: b9dfa3a1-ddc3-743e-ff7c-a02c42d2c79b
                Region: global (DC: dc1)
                Server: true
               Version: 1.10.6-dev

==> Nomad agent started! Log data will stream in below:

2025-09-16T20:04:00.543Z [ERROR] failed to send event to windows eventlog, timed out: event="&{2  1}"
=== RUN   TestVariables_SimpleCRUD/1_fail_create_when_no_items
=== RUN   TestVariables_SimpleCRUD/2_create_sv1
=== RUN   TestVariables_SimpleCRUD/2_create_sv2
=== RUN   TestVariables_SimpleCRUD/4_update_sv1
=== RUN   TestVariables_SimpleCRUD/5_list_vars
=== RUN   TestVariables_SimpleCRUD/5a_list_vars_opts
=== RUN   TestVariables_SimpleCRUD/5b_prefixlist
=== RUN   TestVariables_SimpleCRUD/6_delete_sv1
=== RUN   TestVariables_SimpleCRUD/7_list_vars_after_delete
==> Caught signal: interrupt
2025-09-16T20:04:02.709Z [ERROR] failed to send event to windows eventlog, timed out: event="&{3  1}"
FAIL    github.com/hashicorp/nomad/api  3.102s

If we call s.cmd.Process.Kill() instead of sending the SIGINT, the tests do get marked as passing, so there's definitely something specific to this problem going on here.

[tgross]

@chrisroberts discovered that we needed to call SetConsoleCtrlHandler as well, so this is now working as expected.

[jrasell]

LGTM and although the Windows stuff looks a little magical to me, it seems to track given what I've read in this PR, the issue, and on the Microsoft learn website about the functions.

[github-actions]

I'm going to lock this pull request because it has been closed for 120 days ⏳. This helps our maintainers find and focus on the active contributions.
If you have found a problem that seems related to this change, please open a new issue and complete the issue template so we can capture all the details necessary to investigate further.