lordjeb / nullfs

A null file system that does not store any data

nullFS File System

nullFS is an educational research project. It is a full implementation of a Windows installable file system that doesn't do any real work. It will allow full operation of the file system: creating files, deleting files, reading and writing data, etc. But it will not actually store the data anywhere. Read operations will be successful, but will always return zero-filled buffers. Write operations will succeed but not persist the data anywhere.

Testing Environment

1. Windows 10/11 VM (x64 only)
2. Copy files to test VM:
   • nullFS.sys
   • nullFS.inf
   • nullFSIntegrationTests.exe
   • You can use .\test\scripts\updateTestVm.ps1 to copy these files, but must set the DRIVER_DEV_VM_NAME and DRIVER_DEV_VM_PATH environment variables first.
3. Install driver by double-clicking nullFS.inf
4. Enable driver verifier
   • verifier.exe /flags standard /driver nullFS.sys
5. Restart VM
6. Attach a kernel debugger
7. [Optional] Enable wmitrace output to debugger
   • !wmitrace.enable nullFS 4FE5B599-1715-4296-B97E-FE7EB2E28FC3 -level 5
   • !wmitrace.start nullFS
   • !wmitrace.kdtracing nullFS 1
8. Run tests
   • nullFSIntegrationTests.exe --gtest_filter=*

Future work items

1. Create a debugger extension to dump the file system state