[windows][cws] Add api for killing a process.

[derekwbrown]

Adds api (not called anywhere by this PR) to kill a process by its pid.

Testing instructions will be included in the PR which consumes this API.

Motivation

Additional Notes

[agent-platform-auto-pr]

[Fast Unit Tests Report]

On pipeline 33461694 (CI Visibility). The following jobs did not run any unit tests:

Jobs:

• tests_deb-arm64-py3
• tests_deb-x64-py3
• tests_flavor_dogstatsd_deb-x64
• tests_flavor_heroku_deb-x64
• tests_flavor_iot_deb-x64
• tests_rpm-arm64-py3
• tests_rpm-x64-py3

If you modified Go files and expected unit tests to run in these jobs, please double check the job logs. If you think tests should have been executed reach out to #agent-developer-experience

[pr-commenter]

Test changes on VM

Use this command from test-infra-definitions to manually test this PR changes on a VM:

inv create-vm --pipeline-id=33461694 --os-family=ubuntu

[richl-dd]

Understanding this is a draft PR, we might want to consider this section of the docs for TerminateProcess:

When a process terminates itself, TerminateProcess stops execution of the calling thread and does not return. Otherwise, TerminateProcess is asynchronous; it initiates termination and returns immediately. If you need to be sure the process has terminated, call the WaitForSingleObject function with a handle to the process.

Since this is for CWS, we might want to be sure the process is actually terminated. Maybe a timeout or something otherwise since the function returns right away, we might think we terminated it when we didn't. Something to think about?

[derekwbrown]

Agreed, and noted
https://github.com/DataDog/datadog-agent/pull/25311/files#diff-dc0948c7849fc8f9538fdd3eea18265e9e0088217942d99429a870f2892fd7b5R426

if we think we need some sort of completion notification (either make this call synchronous or have some sort of async callback mechanism when the process has actually been stopped), that would be additional scope.

[safchain]

On linux we use the exit event with a timeout to report that the process has actually been killed. I'll try to use this with the common part on the agent handling the kill action

[richl-dd]

@derekwbrown , whoops I missed the comment - my bad. In that case, I think that if this function returns nil, then to the caller that should be made clear that the process termination was successfully initiated, and not that it was actually terminated.

@safchain using the exit event is probably a good indicator that it was successfully terminated.

@derekwbrown @safchain - is this function planned to be called from security agent or system probe?

[derekwbrown]

This will only work from system probe; if you call it without admin rights you can only termination your own processes.

[pr-commenter]

Regression Detector

Regression Detector Results

Run ID: 56d91628-e2ca-4ba2-8220-8bec749fa77b
Baseline: e3b2bc7
Comparison: 79c355d

Performance changes are noted in the perf column of each table:

• ✅ = significantly better comparison variant performance
• ❌ = significantly worse comparison variant performance
• ➖ = no significant change in performance

No significant changes in experiment optimization goals

Confidence level: 90.00%
Effect size tolerance: |Δ mean %| ≥ 5.00%

There were no significant changes in experiment optimization goals at this confidence level and effect size tolerance.

Experiments ignored for regressions

Regressions in experiments with settings containing erratic: true are ignored.

perf	experiment	goal	Δ mean %	Δ mean % CI
❌	file_to_blackhole	% cpu utilization	+37.16	[+31.53, +42.79]

Fine details of change detection per experiment

perf	experiment	goal	Δ mean %	Δ mean % CI
❌	file_to_blackhole	% cpu utilization	+37.16	[+31.53, +42.79]
➖	pycheck_1000_100byte_tags	% cpu utilization	+3.41	[-1.42, +8.25]
➖	basic_py_check	% cpu utilization	+1.62	[-1.07, +4.31]
➖	file_tree	memory utilization	+1.10	[+0.95, +1.25]
➖	otel_to_otel_logs	ingress throughput	+0.06	[-0.33, +0.45]
➖	tcp_dd_logs_filter_exclude	ingress throughput	+0.01	[-0.04, +0.05]
➖	trace_agent_msgpack	ingress throughput	+0.00	[-0.00, +0.00]
➖	trace_agent_json	ingress throughput	+0.00	[-0.01, +0.01]
➖	uds_dogstatsd_to_api	ingress throughput	-0.01	[-0.21, +0.20]
➖	process_agent_real_time_mode	memory utilization	-0.01	[-0.06, +0.04]
➖	process_agent_standard_check_with_stats	memory utilization	-0.11	[-0.17, -0.05]
➖	uds_dogstatsd_to_api_cpu	% cpu utilization	-0.42	[-3.25, +2.42]
➖	idle	memory utilization	-0.46	[-0.49, -0.42]
➖	process_agent_standard_check	memory utilization	-0.57	[-0.63, -0.51]
➖	tcp_syslog_to_blackhole	ingress throughput	-2.59	[-23.81, +18.63]

Explanation

A regression test is an A/B test of target performance in a repeatable rig, where "performance" is measured as "comparison variant minus baseline variant" for an optimization goal (e.g., ingress throughput). Due to intrinsic variability in measuring that goal, we can only estimate its mean value for each experiment; we report uncertainty in that value as a 90.00% confidence interval denoted "Δ mean % CI".

For each experiment, we decide whether a change in performance is a "regression" -- a change worth investigating further -- if all of the following criteria are true:

1. Its estimated |Δ mean %| ≥ 5.00%, indicating the change is big enough to merit a closer look.

2. Its 90.00% confidence interval "Δ mean % CI" does not contain zero, indicating that if our statistical model is accurate, there is at least a 90.00% chance there is a difference in performance between baseline and comparison variants.

3. Its configuration does not mark it "erratic".

[derekwbrown]

included in #25513