OpenMcdf

OpenMcdf is a fully .NET / C# library to manipulate Compound File Binary File Format files, also known as Structured Storage.

Compound files include multiple streams of information (document summary, user data) in a single container, and is used as the bases for many different file formats:

• Microsoft Office (.doc, .xls, .ppt)
• Windows thumbnails cache files (thumbs.db)
• Outlook messages (.msg)
• Visual Studio Solution Options (.suo)
• Advanced Authoring Format (.aaf)

OpenMcdf v3 has a rewritten API and supports:

• An idiomatic dotnet API and exception hierarchy
• Fast and efficient enumeration and manipulation of storages and streams
• File sizes up to 16 TB (using major format version 4 with 4096 byte sectors)
• Transactions (i.e. commit and/or revert)
• Consolidation (i.e. reclamation of space by removing free sectors)
• Nullable attributes

Limitations:

• No support for red-black tree balancing (directory entries are stored in a tree, but are not balanced. i.e. trees are "all-black")
• No support for single writer, multiple readers

Getting started

To create a new compound file:

byte[] b = new byte[10000];

using var root = RootStorage.Create("test.cfb");
using CfbStream stream = root.CreateStream("MyStream");
stream.Write(b, 0, b.Length);