Extract tar.gz-archives with tar-cs library

Let’s implement the code to demonstrate how to extract files and directories from tar.gz-archives.

The code:

using System;
using System.IO;
using System.IO.Compression;
using tar_cs;

/// <summary>
/// Example of tar-cs library usage to extract tar.gz-archives.
/// Please use the latest version (from trunk) of the library.
/// </summary>
public static class TarGZip
{
    public static void Extract(string inputFile, string outputDirectory)
    {
        using (FileStream inputStream = File.OpenRead(inputFile))
        using (Stream tarStream = UnGZipSteam(inputStream))
        {
            var tarReader = new TarReader(tarStream);
            while (tarReader.MoveNext(false)) // Moves pointer to the next file in the tar archive.
            {
                ExtractTarEntry(tarReader, outputDirectory);
            }
        }
    }

    /// <summary>
    /// Since GZipStream.Position Property is not implemented,
    /// it is necessary to use MemoryStream as intermediate storage.
    /// </summary>
    /// <param name="inputStream">The input stream.</param>
    /// <returns>Un-gzipped stream.</returns>
    private static Stream UnGZipSteam(Stream inputStream)
    {
        using (GZipStream gZipStream = new GZipStream(inputStream, CompressionMode.Decompress))
        {
            MemoryStream memoryStream = new MemoryStream();
            gZipStream.CopyTo(memoryStream);
            memoryStream.Position = 0;
            return memoryStream;
        }
    }

    private static void ExtractTarEntry(TarReader tarReader, string outputDirectory)
    {
        string relativePath = tarReader.FileInfo.FileName;

        // Relative path can contain slash, not backslash.
        // Use Path.GetFullPath() method to convert path.
        string fullPath = Path.GetFullPath(Path.Combine(outputDirectory, relativePath));

        switch (tarReader.FileInfo.EntryType)
        {
            case EntryType.File:
            case EntryType.FileObsolete:
                using (FileStream outputStream = File.Create(fullPath))
                {
                    // Read data from a current file to a Stream.
                    tarReader.Read(outputStream);
                }
                break;
            case EntryType.Directory:
                Directory.CreateDirectory(fullPath);
                break;
            default:
                throw new NotSupportedException("Not supported entry type: " + tarReader.FileInfo.EntryType);
        }
    }
}

Please note that since GZipStream.Position Property is not implemented, it is necessary to use MemoryStream as intermediate storage or implement GZipStream wrapper with Position property support.

Leave a Reply (Markdown is enabled)

Your email address will not be published. Required fields are marked *