🛡️ Sentinel: [HIGH] Fix Process() pipe buffer deadlock in AutomationExecutor

[NSEvent]

🛡️ Sentinel: [HIGH] Fix Process() pipe buffer deadlock in AutomationExecutor

🚨 Severity: HIGH
💡 Vulnerability: AutomationExecutor was calling process.waitUntilExit() before reading the output from the pipe.
🎯 Impact: If a child process output exceeds the OS pipe buffer size (~64KB), the child blocks on writing to the pipe. If the parent calls waitUntilExit() while the child is blocked on writing, both processes wait on each other indefinitely (a deadlock/DoS condition).
🔧 Fix: Swapped the order to read pipe data (readDataToEndOfFile()) before invoking process.waitUntilExit() in runProcess and childPIDs.
✅ Verification: Code statically validated and Code Review passed.

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PR created automatically by Jules for task 12717234424937094384 started by @NSEvent

Summary by CodeRabbit

• Bug Fixes

  • Prevented process execution from hanging when command output exceeds the pipe buffer.
  • Improved reliability when retrieving child process information by reading command output before completion checks.
  • Process lookup failures now return an empty result safely.

• Documentation

  • Added guidance on avoiding pipe-related deadlocks when working with subprocesses.

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Review details

⚙️ Run configuration

Configuration used: defaults

Review profile: CHILL

Plan: Pro Plus

Run ID: dd27fe69-7364-44f9-a03f-26b859a4908a

📥 Commits

Reviewing files that changed from the base of the PR and between 539ef46 and 6904bd9.

📒 Files selected for processing (2)

• TriggerKit/Sources/TriggerKitRuntime/AutomationExecutor.swift
• TriggerKit/Tests/TriggerKitRuntimeTests/AutomationExecutorTests.swift

📝 Walkthrough

Walkthrough

Changes

Process pipe safety

Layer / File(s)	Summary
Process execution output ordering TriggerKit/Sources/TriggerKitRuntime/AutomationExecutor.swift, .Jules/sentinel.md	runProcess consumes pipe output before waiting for process termination, and documentation records the pipe-buffer deadlock scenario and mitigation.
Child-process discovery output ordering TriggerKit/Sources/TriggerKitRuntime/AutomationExecutor.swift	childPIDs(of:) reads pgrep output before waiting and returns an empty list immediately when execution fails.

Estimated code review effort: 2 (Simple) | ~10 minutes

🚥 Pre-merge checks | ✅ 4 | ❌ 1

❌ Failed checks (1 warning)

Check name	Status	Explanation	Resolution
Docstring Coverage	⚠️ Warning	Docstring coverage is 50.00% which is insufficient. The required threshold is 80.00%.	Write docstrings for the functions missing them to satisfy the coverage threshold.

✅ Passed checks (4 passed)

Check name	Status	Explanation
Description Check	✅ Passed	Check skipped - CodeRabbit’s high-level summary is enabled.
Title check	✅ Passed	The title clearly describes the main fix: preventing a Process pipe-buffer deadlock in AutomationExecutor.
Linked Issues check	✅ Passed	Check skipped because no linked issues were found for this pull request.
Out of Scope Changes check	✅ Passed	Check skipped because no linked issues were found for this pull request.

✨ Finishing Touches

🧪 Generate unit tests (beta)

• Create PR with unit tests
• Commit unit tests in branch sentinel-fix-process-deadlock-12717234424937094384

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