Gapotchenko.FX.IO.FileSystems.MSCfb 2026.7.2

Overview

This module implements the MS-CFB (Compound File Binary Format) file system and integrates it with the virtual file system (VFS) abstraction layer, allowing compound files to be accessed and manipulated using a unified file system interface.

Overview

MS-CFB is a structured storage format that embeds a complete file system within a single file. It underpins a variety of widespread file formats, such as Microsoft Office binary documents, .msi files, and many others.

Gapotchenko.FX.IO.FileSystems.MSCfb exposes a compound file via MSCfbFileSystem class, which implements the usual VFS surface (IVirtualFileSystem / IFileSystemView), including streams, directories, enumeration, and timestamps.

Paths in MSCfbFileSystem are case-insensitive in accordance with the format specification.

Conceptually, the MS-CFB format can be viewed as a compact, portable, and standardized file system encapsulated within a single file, similar in spirit to FAT12 or FAT16.

MSCfbFileSystem

MSCfbFileSystem class is the primary entry point for working with a compound file. It can be instantiated directly over an existing System.IO.Stream, or accessed via MSCfbFileSystem.Storage property to open or create a compound file on disk (or any other backing store exposed through VfsLocation or VfsReadOnlyLocation).

Opening from a stream

For a compound file you already have as a stream (for example from a network or an in-memory buffer):

using Gapotchenko.FX.IO.FileSystems.MSCfb;
using Gapotchenko.FX.IO.Vfs;

void ReadFromStream(Stream stream)
{
    using var vfs = new MSCfbFileSystem(stream);

    if (vfs.FileExists("README.txt"))
    {
        string text = vfs.ReadAllFileText("README.txt");
        // ...
    }
}

Use the constructor overloads when you need a writable file system, leave-open behavior, or MSCfbFileSystemOptions. There is also MSCfbFileSystem.CreateAsync for asynchronous construction.

Opening or creating a file via storage

MSCfbFileSystem.Storage property implements IFileSystemStorage<IMSCfbFileSystem, MSCfbFileSystemOptions> interface and follows the same patterns as other mountable VFS types: read-only open, create/overwrite, and full OpenFile/WriteFile/ReadFile semantics via extension methods provided byGapotchenko.FX.IO.Vfs module.

using Gapotchenko.FX.IO.FileSystems.MSCfb;
using Gapotchenko.FX.IO.Vfs;

// Open an existing compound file for reading (from a local path)
using var cfb = MSCfbFileSystem.Storage.ReadFile("document.cfb");

// Create a new compound file (or truncate an existing one)
using var newCfb = MSCfbFileSystem.Storage.CreateFile("new.cfb");
newCfb.WriteAllFileText("README.txt", "Hello from MS-CFB");

VfsReadOnlyLocation and VfsLocation accept implicit conversions from string (paths on the host file system) or you can specify a custom IFileSystemView to open storage from a non-local backend.

Related Modules

• Gapotchenko.FX.IO.Vfs - Provides the virtual file system abstraction layer
• Gapotchenko.FX.IO.FileSystems - Provides base functionality for file system implementations

Other Modules

Let's continue with a look at some other modules provided by Gapotchenko.FX:

• Gapotchenko.FX
• Gapotchenko.FX.AppModel.Information
• Gapotchenko.FX.Collections
• Gapotchenko.FX.Console
• Gapotchenko.FX.Data
• Gapotchenko.FX.Diagnostics
• Gapotchenko.FX.IO
  • Gapotchenko.FX.IO.FileSystems
    • ➴ Gapotchenko.FX.IO.FileSystems.MSCfb
  • Gapotchenko.FX.IO.Vfs
• Gapotchenko.FX.Linq
• Gapotchenko.FX.Math
• Gapotchenko.FX.Memory
• Gapotchenko.FX.Security.Cryptography
• Gapotchenko.FX.Text
• Gapotchenko.FX.Threading
• Gapotchenko.FX.Tuples
• Gapotchenko.FX.Versioning

Or look at the full list of modules.