Discard stdin a command does not read instead of failing on WSManFault 232 (#183)

[bertysentry]

Closes #183.

Problem

When a command exits without reading its standard input, or before the input arrives, the server answers the WSMan Send with fault 232, "The pipe is being closed". WsmanClient.RemoteCommand.send(...) turned it into a WinRMFaultException, so execute() and start() failed and lost the command's output and exit code. The CLI failed the same way whenever input was piped into such a command (echo x | … exec hostname, exit 70).

Fix

RemoteCommand.send(...) treats fault 232 like a broken pipe on a local java.lang.Process: it stops sending, discards the rest of the input, and the Receive loop goes on, so the caller gets the command's actual output and exit code. Any other fault still fails.

Every stdin path goes through that method, so the fix covers them all:

• pre-supplied input (stdin(String|Path|InputStream)) with execute() and start();
• RemoteProcess.stdin(): flush() and close() stay silent for input the command does not read. A Process pipe would throw an IOException here, but whether the input beats the command's exit varies from host to host (every time on 2008 R2, never in five runs on 2019), and a failure would too. The output and exit code tell the caller how the command went.

The CLI's interactive shell pump also writes through RemoteProcess.stdin(). Input it sends after the remote cmd.exe exited should therefore no longer fail the session. That follows from the code path; I didn't reproduce it live, because the timing window is narrow there.

Tests

Four new FakeWsmanServer tests in CommandStdinTest:

• execute(), where the first of three read buffers is refused with fault 232: the output and exit code are returned, and nothing more is sent;
• start() with pre-supplied input, refused the same way;
• RemoteProcess.stdin(): the refused flush(), a later write and close() don't fail and send nothing more, and the output and exit code (1) are read normally;
• any other fault on a Send still fails execute() with a WinRMFaultException.

Without the fix, the three fault-232 tests fail with Send failed: HTTP 500 (WSManFault 232): The pipe is being closed. mvn clean verify site passes.

Live check: anaxagore, Windows Server 2008 R2

• Before: echo x | java -cp target/classes org.metricshub.winrm.cli.WinRmCli -h anaxagore … exec hostname printed winrm-java: Send failed: HTTP 500 (WSManFault 232): The pipe is being closed. and exited 70.
• After: 3 of 3 runs print ANAXAGORE and exit 0.
• API probe:
  • stdin("x\n").execute() and stdin("x\n").start() both return ANAXAGORE with exit code 0.
  • A write through RemoteProcess.stdin() 3 s after cmd /c echo early& exit 3 exited doesn't fail, and early and exit code 3 are reported.
  • 1 MB of input to hostname completes in 124 ms.
  • sort still gets its input.

Docs

• The "Standard input" section of commands.md, and the stdin forwarding paragraph of cli.md: input the command does not read is discarded.
• Javadoc of CommandRequest.stdin(String) (which the other stdin(...) variants refer to), RemoteProcess.stdin() and CommandCursor.send(...).

Known limit

After the refusal, pre-supplied input from a stream is still read to its end, although nothing more is sent. An endless producer (yes | … exec hostname) therefore runs until the timeout. Stopping the read would require CommandCursor.send(...) to report the refusal, which changes a public interface released since 2.0.00, so it is left out.

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Codex Review Summary

This comment shows the latest Codex review activity on this pull request.

Review	Status	Commit	Review trigger
📝 Code Review	✅ Completed 2026-09-27T23:24:32.703682Z	679cef6	PR opened

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