Struct VirtualFs 

pub struct VirtualFs { /* private fields */ }

A sandboxed virtual filesystem backed by CowFile instances.

Provides file access for emulated .NET code (e.g., FileStream, File.Exists) without touching the real filesystem. Each entry is a CowFile that can be read via the existing stream/BinaryReader hooks.

Implementations

impl VirtualFs

pub fn new() -> Self

Creates an empty virtual filesystem with no mapped files.

pub fn map_cow(&mut self, vfs_path: &str, cow: CowFile)

Maps a virtual file by taking ownership of an existing CowFile.

For mmap-backed CowFiles (loaded from disk), the entry shares OS pages with the source. Pending writes on the source are not carried over.

Arguments

• vfs_path - Virtual path to register (normalized: case-insensitive, slash-normalized)
• cow - The CowFile instance to store

pub fn map_disk_file( &mut self, vfs_path: &str, disk_path: &Path, ) -> Result<(), Error>

Maps a virtual file from a disk path (mmap’d directly).

The file is opened via CowFile::open, which creates a MAP_PRIVATE mmap. Reads share physical pages with the OS cache; writes are copy-on-write.

Arguments

• vfs_path - Virtual path to register
• disk_path - Path to the file on disk

Errors

Returns an error if the file cannot be opened or memory-mapped.

pub fn map_data(&mut self, vfs_path: &str, data: Vec<u8>)

Maps a virtual file from in-memory data.

Creates a vec-backed CowFile from the provided data. Unlike mmap-backed entries, forking a vec-backed entry clones the data.

Arguments

• vfs_path - Virtual path to register
• data - File contents to store

pub fn get(&self, vfs_path: &str) -> Option<&CowFile>

Looks up a virtual file by path (case-insensitive, slash-normalized).

First tries an exact (normalized) match. If that fails, falls back to matching by filename component only, which handles cases where .NET code uses a full path like C:\Windows\assembly.exe but the file was mapped under just assembly.exe.

Arguments

• vfs_path - Path to look up (any format — Windows, Unix, or bare filename)

Returns

A reference to the CowFile if found, or None.

pub fn exists(&self, vfs_path: &str) -> bool

Returns true if a virtual file exists at the given path.

Uses the same lookup logic as get, including filename-only fallback matching.

pub fn is_empty(&self) -> bool

Returns true if the filesystem has no entries.

pub fn len(&self) -> usize

Returns the number of entries in the virtual filesystem.

pub fn paths(&self) -> Vec<&str>

Returns the normalized paths of all entries.

pub fn fork(&self) -> Result<VirtualFs, Error>

Forks the virtual filesystem, creating an independent copy.

Each entry uses CowFile::fork():

• Mmap-backed entries re-open the same file (zero-copy OS CoW)
• Vec-backed entries clone the data
• Pending writes are not carried over — the fork starts clean

Errors

Returns an error if any mmap-backed entry fails to re-open its file (e.g., the file was deleted since original mapping).

Trait Implementations

impl Default for VirtualFs

fn default() -> Self

Returns the “default value” for a type.