fix(windows): prevent VHF report buffer overruns - #200

Description

On affected Windows 10 systems, a DualSense pairing GetFeature callback advertises 128 bytes for a 64-byte VHF buffer. Clearing the advertised length overwrites the allocation and crashes WUDFHost; the PageHeap dump in #199 catches that write directly.

Use a shared response copier in GetFeature and GetInputReport that writes only the actual report bytes. Preserve undersized-request rejection and the optional zero ID for unnumbered input reports.

Screenshot

Issues Fixed or Closed

• Fixes Experiencing Complete Control Loss After Close/DC of Moonlight And Reconnect with DualSense #196
• Fixes Windows: driver host process crashes ~1s after DualSense virtual gamepad creation; all libvirtualhid devices become invalid until reboot #199

Roadmap Issues

Testing

• Added five regression tests covering oversized feature/input requests, optional zero IDs, short requests, and exact-size requests. Three fail with the original clearing behavior; all five pass with the fix.
• MSYS2/UCRT64: built test_libvirtualhid and gamepad_adapter; 47 focused protocol, backend, lifecycle, adapter, and native HID/SDL tests passed.
• MSVC/WDK: cmake --build cmake-build-issue199-msvc-driver --config Release --target libvirtualhid_umdf -j 4 passed.
• clang-format --dry-run --Werror on the three changed files and git diff --check passed.
• Installed-device smoke tests used the existing Windows 11 driver. The newly built driver still needs a signed build and a PageHeap retest on the affected Windows 10 system.

Type of Change

• feat: New feature (non-breaking change which adds functionality)
• fix: Bug fix (non-breaking change which fixes an issue)
• docs: Documentation only changes
• style: Changes that do not affect the meaning of the code (white-space, formatting, missing semicolons, etc.)
• refactor: Code change that neither fixes a bug nor adds a feature
• perf: Code change that improves performance
• test: Adding missing tests or correcting existing tests
• build: Changes that affect the build system or external dependencies
• ci: Changes to CI configuration files and scripts
• chore: Other changes that don't modify src or test files
• revert: Reverts a previous commit
• BREAKING CHANGE: Introduces a breaking change (can be combined with any type above)

Checklist

• Code follows the style guidelines of this project
• Code has been self-reviewed
• Code has been commented, particularly in hard-to-understand areas
• Code docstring/documentation-blocks for new or existing methods/components have been added or updated
• Tests have been added or updated for new or modified functionality, including regression tests for bug fixes

AI Usage

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• AI tools were used while preparing this PR

Generated with Codex (model: gpt-6.1-sol; thinking level: xhigh).