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diff --git a/libs/usvfs/README.md b/libs/usvfs/README.md new file mode 100644 index 0000000..1167810 --- /dev/null +++ b/libs/usvfs/README.md @@ -0,0 +1,59 @@ +# USVFS + +[](http://www.gnu.org/licenses/gpl-3.0.en.html) +[](https://github.com/ModOrganizer2/usvfs/actions) + +USVFS (short for User Space Virtual File System) aims to allow windows applications to +create file or directory links that are visible to only a select set of processes. +It does so by using api hooking to fool file access functions into discovering/opening +files that are in fact somewhere else. + +## Current state + +USVFS is work in progress and should be considered in alpha state. +It is a core component of Mod Organizer v2 <https://github.com/ModOrganizer2/modorganizer> +and thus receives serious real world testing. + +## Building + +You will need `cmake`, Python 3+ and `vcpkg` to build USVFS: + +```pwsh +cmake --preset vs2022-windows-x64 +cmake --build --preset vs2022-windows-x64 --config Release + +# only if you need to hook x86 applications +cmake --preset vs2022-windows-x86 +cmake --build --preset vs2022-windows-x86 --config Release +``` + +## Comparison to symbolic links + +The following is based on the final goal for USVFS and doesn't necessary reflect the +current development state. + +Unlike symbolic file links provided by NTFS + +- links aren't visible to all applications but only to those the caller chooses +- links disappear when the "session ends" +- doesn't require write access to the link destination +- doesn't require administrator rights (neither for installation nor for use) +- links are filesystem independent so you can create links on fat32 drives, read-only media and network drives +- can link multiple directories on top of a single destination (overlaying) +- can also "virtually" unlink files, thus make them invisible to processes or replace existing files + +There are of course drawbacks + +- will always impose a memory and cpu overhead though hopefully those will be marginal +- becomes active only during the initialization phase of each process so it may not be active at the time dependent dlls are loaded +- introduces a new source of bugs that can cause hard to diagnose problems in affected processes +- may rub antivirus software the wrong way as the used techniques are similar to what some malware does. + +## License + +USVFS is currently licensed under the GPLv3 but this may change in the future. + +## Contributing + +Contributions are very welcome but please notice that since I'm still undecided on +licensing I have to ask all contributors to agree to future licensing changes. |