Provisioning a Windows 7 VM so it can be driven from the host by VBoxManage
guestcontrol takes a handful of settings that are easy to forget and easy to
get wrong, and every one of them here was learned by hitting it:
- Windows Error Reporting's dialog blocks a guestcontrol call until the host's
timeout. A harness that scores a timeout as a failure then invents bugs that
do not exist, so DontShowUI is not a nicety.
- The host watches the guest with controlvm screenshotpng, so a screen saver or
a blanked monitor makes every screenshot useless.
- Bulk transfer over the VirtualBox shared folder is far faster than a copyto
per file, but the mapping is per-user and does not survive into a new
interactive session.
The readiness report is the other half of the point. A test run against a box
with no printer, or no audio capture device, reads as "the software under test
refused" when the truth is "this VM never had one". It reports DWM composition
for the same reason: with composition off, SetWindowDisplayAffinity fails with
error 8 for every value, so anything testing screen-capture protection is
testing nothing -- and Windows 7 forces the Basic theme while the install is
not activated, which is exactly the state a throwaway test VM is usually in.
Two shapes in the DWM check are load-bearing and are commented as such. Under
guestcontrol, redirecting PowerShell's stdout to a file (or capturing it with
for /f) hangs the run until the host times out, so PowerShell prints the verdict
and the batch does not capture it. And the if/else must stay on ONE line: split
across two, PowerShell treats the file as an incomplete command and waits on
stdin forever. Two plausible cheaper checks are also wrong here, measured, and
are called out so nobody re-introduces them: dwm.exe keeps running with
composition off, and HKCU\...\DWM\Composition is the stored preference rather
than the live state. Both report ENABLED while the API returns false.
The elevated half is skipped with a notice rather than attempted, because a
guestcontrol-launched process gets a UAC-filtered token even for an account in
Administrators and cannot elevate itself.
Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01LLgzr9B13msJhCLpnmjNJS
vilimpoc.org / repos / dotfiles / commit