PR Summary

This pull request improves the robustness and security of the Cabinet extraction and Updatable Help code in PowerShell. The changes focus on better error handling for file operations, stricter validation of CAB entry paths, and defensive checks on module names to prevent issues with excessively long file paths.

Error handling and robustness improvements:

• Added specific exception handling (e.g., UnauthorizedAccessException, ArgumentException, NotSupportedException, SecurityException) in FdiOpen to ensure that no exceptions escape into native code; instead, a failure is signaled with a return value, matching the existing IOException handling.
• Improved FdiClose to handle invalid pointers and catch IOException, returning error codes instead of throwing exceptions.
• In the FDI notification handler, now checks the result of FdiClose and aborts extraction if closing the file fails, preventing corrupt or truncated files from being reported as successfully extracted.
• Corrected the check for valid file handles after CreateFile, ensuring that INVALID_HANDLE_VALUE is properly recognized as a failure.
• Added explicit handling for the FdintNEXT_CABINET notification, returning an error code since only single-cabinet updates are supported.

Security and validation enhancements:

• Strengthened path validation for CAB extraction: now rejects empty entry names and entries that resolve to the help directory root, preventing potential directory traversal or overwrite issues. [1] [2]

Defensive checks and user feedback:

• Introduced a maximum module name length (MaxModuleNameLength = 128) to prevent excessively long module names from causing path or file name issues.
• Added a user-facing error message and check in ProcessSingleModuleObject to reject modules with names exceeding the maximum length, with a localized error message in the resource file. [1] [2]

PR Context

PR Checklist

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• Breaking changes
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  • Experimental feature(s) needed
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• User-facing changes
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  • Documentation needed
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• Testing - New and feature
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  • Make sure you've added a new test if existing tests do not effectively test the code changed