Link to issue number:

Fixes #9039

Summary of the issue:

The COM Registration Fixing Tool seems to have never worked fully on 64bit Windows, as a result of path confusion caused by the use of SysWOW64, and the executable names used.

In addition, modern browsers seem to check a typelib registration that could be damaged by certain uninstallations (e.g. older versions of MathPlayer). We didn't previously do anything about this.

Further background:

In 64 bit Windows, %WINDIR%\System32 contains 64-bit executables. Meanwhile, %WINDIR%\SysWOW64 contains 32-bit executables. That seems inverted from what it should be, but there is a good explanation here for why it's like that.

When a 32-bit application calls something in System32, SysWOW64 assumes that it wants the 32-bit version, and redirects the call to the version in the SysWOW64 directory.
If the 32-bit application really wants the 64-bit version of whatever it's calling, it has to use the virtual directory %WINDIR%\Sysnative, which SysWOW64 provides.

We were calling regedit.exe and regsvr32.exe in contexts where we assumed 32-bit, from either %WINDIR% or %WINDIR%\System32. Because NVDA is 32-bit, that would result in the 32-bit application being called. That's okay.
However when the test was made for 64-bit, executables in %WINDIR%\SysWOW64 were being used, which are also 32-bit.

At least one of those should be 64-bit for COM reregistrations, but neither are.

In no case should we ever call anything in %WINDIR%\SysWOW64 ourselves, which we currently do.

Description of how this pull request fixes the issue:

Taken from the commit that rewrites COMRegistrationFixes/__init__.py:
Repaired the COM Registration Fixing Tool so it is more effective on 64bit Windows (Partial fix of #9039).

• Problems:
  • The registerServer function called the 32-bit version of regsvr32.exe, even in 64-bit contexts.
  • The applyRegistryPatch function called the 32-bit version of regedit, even in 64-bit contexts.
  • The Win7 32-bit run did not take into account 32-bit only systems (no Program Files (x86) folder).
• Remediation:
  • Replaced applyRegistryPatch function with two new functions: apply32bitRegistryPatch and apply64bitRegistryPatch.
  • Replaced registerServer function with register32bitServer and register64bitServer, to make clear what they do.
  • The new functions don't check 32/64 bitness; they leave that to the caller and log errors on failure.
  • Updated to more descriptive error logging.
  • Adjusted the Windows 7 code to use server registration with proper bitness for each DLL.
• Path remediations:
  • Moved the OLEACC_REG_FILE_PATH constant to the top of the file with the rest.
  • Added Sysnative path to the list of path constants at the top of the file.
  • Now use Sysnative in the path for intentional 64bit calls.
  • Now use System32 in the path for 32-bit calls on either 32-bit or 64-bit systems.
  • Now use reg.exe's import option to load .reg files instead of regedit.exe.
  • Now check whether to use "Program Files" or "Program Files (x86)" on Win7.
  • Removed now unused sysWow64 path constant.
• Misc:
  • Added docstring note about 32 and 64 bit functions needing attention if NVDA goes 64-bit in the future.
  • Converted path constants to uppercase-with-underscore style, and corrected case on some Windows paths.
  • Moved comments with discussion links into module docstring, and rearranged.
  • Used subprocess.STARTUPINFO to prevent console windows from showing during executions.
  • In gui/__init__.py update the message shown on tool completion, to recommend a restart.

Separately, @michaelDCurran found a registry key that we should delete to restore browser functionality under certain circumstances. That is included as a separate joint commit.

Testing strategy:

Followed the STR in #9039 (comment).

• With current Alphas, could not restore the registry, as described in that STR.
• With these modifications, the registry key was restored, indicating that the reg patch successfully applied.
• Installed and uninstalled MathPlayer to break browsers, and used the final version of the tool to fix it.

Known issues with pull request:

Windows 7 tests would be valuable, but I can not run them.

My original refactor of this tool is still in progress, but that will now be limited to UX enhancements, since this covers the guts of the tool. These are important updates to the functionality, and imo should be accepted apart from the rest of the refactor.

Change log entries:

Bug fixes
The COM Registration Fixing Tool has been rewritten to solve more problems, and work better on 64bit Windows systems.

Changes for developers:

- In the `COMRegistrationFixes` module, the `applyRegistryPatch` function has been replaced by `apply32bitRegistryPatch` and `apply64bitRegistryPatch` functions. The `registerServer` function has been replaced by `register32bitServer` and `register64bitServer` functions.

Code Review Checklist:

• Pull Request description is up to date.
• Unit tests.
• System (end to end) tests.
• Manual testing.
• User Documentation.
• Change log entry.
• Context sensitive help for GUI changes.
• UX of all users considered:
  • Speech
  • Braille
  • Low Vision
  • Different web browsers