vfs #

vfs is a pure Dart virtual file system with an int file-descriptor boundary and a Preview1-oriented host API.

This package is designed for code that wants a small, testable VFS with Unix-style descriptor operations such as open, read, write, seek, and close, while also supporting preopened directories and path-based operations such as pathOpen and pathFilestatGet.

Features #

• fixed stdio descriptors: 0, 1, 2
• in-memory file and directory storage
• preopened directories and dirfd-relative path resolution
• int fd operations for open, read, write, seek, and close
• descriptor metadata via fdFdstatGet, fdFilestatGet, and fdPrestatGet
• typed VFSFile and VFSDirectory accessors
• structured VFSException errors
• pure Dart with no platform dependencies

Getting started #

Add the package:

dependencies:
  vfs: ^0.0.1-alpha

Usage #

import 'dart:convert';
import 'dart:typed_data';

import 'package:vfs/vfs.dart';

void main() {
  final vfs = MemoryVFS(stdin: utf8.encode('hello'));
  vfs.mountPreopen(fd: 3, guestPath: '/sandbox');

  vfs.file('/sandbox/data.txt').write(utf8.encode('abc'));

  final fd = vfs.pathOpen(3, 'data.txt', mode: VFSOpenMode.readWrite);
  final buffer = Uint8List(3);
  vfs.read(fd, buffer);
  vfs.seek(fd, 0, whence: VFSWhence.end);
  vfs.write(fd, utf8.encode('def'));
  vfs.close(fd);

  print(utf8.decode(vfs.file('/sandbox/data.txt').read())); // abcdef
}

Status #

This is an early prerelease focused on a minimal in-memory backend and a Preview1-oriented descriptor surface. Additional backends and richer semantics may be added later.