fix(shell): prevent hang when ShellTool.Kill fails with Win32Exception#1021
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Aaronontheweb merged 1 commit intoMay 16, 2026
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ShellTool's cancellation handler assumes process.Kill() always succeeds. When Kill() throws Win32Exception (OS refuses the kill), the code logged the error and immediately awaited ReadToEndAsync on both pipes. If the child process is still alive and holding stdout/stderr open, those reads never hit EOF — recreating the exact hung-tool-call failure mode this PR was meant to fix. Fix: close StandardOutput/StandardError in the Win32Exception path so pipe reads drain immediately instead of blocking forever. Also tighten the regression test to spawn a child-process tree (Unix: 'sleep 120 & wait') so it actually exercises the entireProcessTree kill path rather than a lone sleep.
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Summary
PR #1019 fixed the
shell_executeorphaned-subprocess hang by moving toWaitForExitAsyncand handling outer cancellation. One gap remains: ifprocess.Kill(entireProcessTree: true)throwsWin32Exception(the OS refuses the kill), the handler logs the error and then immediatelyawaitsTask.WhenAll(stdoutTask, stderrTask). Since the process may still be alive and holding the pipes open, thoseReadToEndAsynccalls never hit EOF — recreating the exact hung-tool-call failure mode.Changes
ShellTool.cs— in theWin32Exceptionpath, disposeStandardOutput/StandardErrorso the pipe reads complete promptly instead of blocking forever; wrapTask.WhenAllin a catch for the expectedIOException/ObjectDisposedException.ShellToolTests.cs— tighten theCaller_cancellation_*test to spawn a child-process tree (sleep 120 & waiton Unix) so it actually exercises theentireProcessTreekill path and would hang if the tree-kill regressed.Test plan
dotnet test ShellTool— 23/23 passdotnet slopwatch analyze— 0 issues