Prevent inherited input stream from being closed on Windows (fixes #1115)

[gnodet]

This PR fixes issue #1115 where the inherited input stream is closed when a subprocess terminates on Windows.

The problem occurs because ProcessBuilder.inheritIO() causes the subprocess to inherit all standard streams (stdin, stdout, stderr) from the parent process. When the subprocess terminates, it closes these streams, which can cause issues if the parent process still needs to use them.

This fix modifies the isPosixSystemStream and systemStreamName methods in ExecTerminalProvider to handle Windows differently:

1. For isPosixSystemStream:

   • On Windows:
     • For SystemStream.Output and SystemStream.Error, we use explicit redirects to avoid inheriting stdin
     • For SystemStream.Input, we use isWindowsSystemStream which is safer on Windows
   • On non-Windows platforms, we continue to use inheritIO() as it works fine there

2. For systemStreamName:

   • On Windows, for SystemStream.Input, we use System.console() to check if stdin is a terminal without using ProcessBuilder
   • For all other cases, we use the original approach

This approach is targeted and minimally invasive, focusing only on fixing the Windows-specific issue while leaving the behavior unchanged for other platforms.

[gnodet]

augment review

[augmentcode]

🤖 Augment PR Summary

Summary: Prevents a Windows-specific issue where probing system streams via subprocesses could close the parent process’s inherited stdin.

Changes:

• Refactors ExecTerminalProvider.isPosixSystemStream to avoid inheritIO() on Windows by selectively inheriting only the stream being tested.
• Updates systemStreamName to avoid inheriting stdin on Windows when checking SystemStream.Input, using System.console() instead.

Technical Notes: Non-Windows behavior remains unchanged, while Windows uses explicit ProcessBuilder redirects to reduce risk of closing inherited streams.

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[augmentcode]

Review completed. 1 suggestions posted.

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[augmentcode]

On Cygwin/MSYS terminals (which this provider explicitly supports in winSysTerminal), System.console() is commonly null even when stdin is a tty; returning null here may make isSystemStream(Input) false and prevent TerminalBuilder from creating a system terminal in those environments.

Severity: high

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