winevfs

Please don't use this unless you need to. USVFS/ModOrganizer 2 should work out of the box under wine now.

Winevfs was an earlier attempt to allow Bethesda games modding to work under linux, but it's quite buggy and slow. Notably, programs such as Nemesis don't work at all when using winevfs.

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This is a virtual filesystem for wine, written primarily as a native linux alternative to Mod Organizer's USVFS (which is currently broken under wine).

It works by replacing various standard system library functions using LD_PRELOAD, similar to how USVFS works under Windows.

Although this might also work for some Linux programs, it might not work with all (notably find from findutils), as it only replaces functions, rather than the actual syscalls. It also contains a few wine-specific hacks to either ensure it works, or try to improve performance.

Among the hacks are:

• Everything is treated case-insensitive (using a cached algorithm)
• fork() is currently intentionally not properly handled, as overriding setsid() works just as well, while keeping performance by not duplicating reading the VFS
• It pretends to be CIOPFS, which will sometimes prevent wine from running its own case-insensitive algorithm.

There are also a number of limitations that may or may not be addressed in future versions:

• Deleting files only somewhat works. Deleting a directory, or files that lay outside of the VFS, may not be properly registered
• Performance is currently not as good as it could be. There are some ways it can be improved, including better caching and a few executable-specific hacks. These are planned for a future version.
  • This has been partly fixed through the ?full= option (allowing certain whitelisted executables to read the entire VFS before loading)
• This has only been tested with Bethesda games, and a few tools related to them.
• wineserver must not be already running prior to this, as it needs to hook LD_PRELOAD into it in order to function.
  • Make sure the hooked wineserver is killed before running a program without winevfs! If you don't, the program will fail, some in more disasterous ways than others.
    • Mod Organizer will clear your entire profile.
• The case-insensitive string comparison only supports ASCII, it needs to support the full Unicode specification to be correct.
• It works using a path cache instead of a node tree. What originally started out as an optimization ended up making the codebase significantly more complex and slower in some cases. Fixing this would require rewriting a significant amount of the code.

Programs that currently work (tested):

• Skyrim (LE)
• Fallout 4
• Fallout NV
• FNIS (requires dotnet40 to work)
• Bodyslide

Programs that do not work (yet):

• Nemesis Unlimited Behavior Engine (requires wine-mono to work, it fails under dotnet40)
  • It's a heavily multithreaded application, which currently fails due to a few thread races
  • I'm currently trying to fix it

Usage

Winevfs is primarily intended to be used with movfs4l.py, but it can also be run manually if needed.

It reads a VFS information file that contains a list of every file or directory that will be redirected, in this format:

R
/path/to/virtual/file1
/path/to/real/file1
R
/path/to/virtual/folder1
/path/to/real/folder1
W
/path/to/virtual/folder1
/path/to/real/folder2

When reading /path/to/virtual/file, winevfs will silently redirect the call to /path/to/real/file1 instead. /path/to/virtual/folder1 will contain every file/folder (recursively) from /path/to/real/folder1 and /path/to/real/folder2, in that order. When writing to /path/to/virtual/folder1, if the file/folder does not already exist, it will create a new entry in /path/to/real/folder2.

Running winevfs requires you to specify the VFS information file in the WINEVFS_VFSFILE environment variable:

WINEVFS_VFSFILE=/path/to/vfsinfo ./bin/winevfs wine SomeApp.exe

Depending on your system, you may need to rename lib to lib64, and lib32 to lib. Refer to your /usr folder to see how it should be organized.