Fix for paths over 260 characters

[ARoese]

Hello, I believe your issue with paths over 260 characters stems from the implementation of mmio::mapped_file_source::open() in a library you use. I made an issue for this on that repo, but this is something you can work around up-stream by prefixing your paths with \\?\ before passing them into the open function.

This shouldn't be too big a refactor, since you only seem to use the library in these 3 places:
here
here
here

This issue (with the same fix) may also affect fstream, which is used here.

[ersh1]

Thanks! I was led to believe that the issue was caused by MO2. I was not aware that by default std::filesystem::path doesn't support long paths. I'll include a fix in the upcoming update.

[ARoese]

it's not that it doesn't support them, as per this thread reply, it's that it will not add them for you due to less friendly behavior incurred by using them. Specifically, you need to ensure your paths are normalized and cleaned up yourself because the underlying APIs will not do it for you if you use long paths. For example, it might not replace / with \ in paths. This means you might have to pass paths through GetFullPathName which will normalize them.

For example, I think these paths will cause problems without normalization if you add that prefix because they use / instead of \. std::filesystem::path::make_preferred will do this part of normalization which is probably the only part to worry about.

MO2 might also not handle long paths well. In that case, longer paths will cause issues for it. I haven't looked at that code to confirm, though.

[ersh1]

I've tried fixing the issue and it doesn't really seem fixable.

I've added long path prefixes, but a file with a long path (260+ characters) will either be considered as nonexistent (by functions like is_regular_file or GetFileAttributesW) or will straight up crash the game when it scans for loose files by merely being inside the Data folder (in vanilla code, even without OAR). Perhaps the first case happens because of MO2? I'm not sure.

I can't seem to even add a reliable warning when a path exceeds the 260 character limit, because the file seems to also fail to load in cases where the virtual filesystem path (from MO2) isn't too long, but the real file path is. And OAR only sees the virtual filesystem structure created by MO2, it doesn't know the actual file paths.

I'm kinda out of ideas at this point.

[MrGrymReaper]

If you add a manifest for OpenAnimationReplacer SKSE64 plugin this, can then be used with a registry tweak or group policy alteration to support the longer path.

For more information see this link - https://gearupwindows.com/unlocking-extended-file-path-support-in-windows-10-overcoming-the-260-character-limit/.