LTRData.ExFat.DiscUtils 1.0.16

ExFat

An exFAT accessor library.

Fork

This fork is LTRData.ExFat.

This is a fork of ExFat.DiscUtils. The main goal of this fork is more efficient, safer and faster code at the cost of dropping support for some old versions of .NET Framework. It depends of LTRData.DiscUtils fork of DiscUtils instead of the upstream DiscUtils.DiscUtils, to get better performance in asynchronous calls and Span<byte>-based calls.

Summary

ExFat allows to manipulate an exFAT formatted partition (provided as a System.IO.Stream). It comes with two packages:

• The core package ExFat.Core available from NuGet, which allows simple exFAT management at three different levels (partition, entry and path).
• The DiscUtils package ExFat.DiscUtils available from NuGet, which depends on DiscUtils package.

Currently, ExFat.Core does what it says: files/directories manipulation at any level. DiscUtils support is on its way and should be released in the very next few days.

ExFat.Core works at three levels:

1. Lowest level: partition access. This allows to manipulate clusters, allocation bitmap, directory entries and clusterr streams.
2. Middle level: entry access. Files/directories can be used to read/write content.
3. High level: path access. This works as you would expect using file paths.

ExFat.DiscUtils is also a high-level access (using paths) with implementation for DiscUtils.

Because it is still under development, you can see pending features state here.

Samples

All examples assume you have a Stream containing an exFAT partition.

// Access at partition-level. Most efficient, most dangerous.
// Integrity is not guaranteed at this level, 
// user needs to make all neceassary operations in right order.
using(var partition = new ExFatPartition(partitionStream))
{
    // returns all entries (including bitmap, volume label, etc.) from root directory
    var entries = partition.GetEntries(partition.RootDirectoryDataDescriptor);

    // returns all files/directories meta entries
    var metaEntries = partition.GetMetaEntries(partition.RootDirectoryDataDescriptor);

    // assuming there is one, of course (but we're in a sample)
    var someDirectory = metaEntries.First(e => e.IsDirectory);
    var directoryMetaEntries = partition.GetMetaEntries(someDirectory.DataDescriptor);

    var someFile = metaEntries.First(e => !e.IsDirectory);
    using(var dataStream = partition.OpenDataStream(someFile.DataDescriptor, FileAccess.Read))
    { }
}

// Access at entry level. Quite fast, since user has to track entries.
// Integrity is guaranteed. File attributes are not honored (maybe one day...)
using(var entryFilesystem = new ExFatEntryFilesystem(partitionStream))
{
    var someFileEntry = entryFilesystem.FindChild(filesystem.RootDirectory, "someFile");
    using(var fileStream = entryFilesystem.OpenFile(someFileEntry, FileAccess.Read)
    { }

    // finding one file in a directory requires two steps
    var someDirectoryEntry = entryFilesystem.FindChild(filesystem.RootDirectory, "someDirectory");
    var someChildFileEntry = entryFilesystem.FindChild(someDirectoryEntry, "someDirectory");
}

// Access at path level. Uses a path cache to retrieve entries, 
// so speed is not as good (but not that bad either)
// since there is not drive, paths only specify the directory chain
// (so "a\b\c" for example)
using(var pathFilesystem = new ExFatPathFilesystem(partitionStream))
{
    var rootEntries = pathFilesystem.EnumerateEntries("\"); // "" works too for root
    var childEntries = pathFilesystem.EnumerateEntries(@"\somedir"); // "somedir" works too
    using(var s = pathFilesystem.Open(@"a\b\c", FileMode.Open, FileAccess.Read)
    { }
}

Current build status (for people who care... If you ever meet one):