Unity Package Extractor. Extract your .unitypackage with .net C#

.Unity Package Extractor

Use the command line to extract the package.

program.exe packagePath outputPath extractMetaFiles

program.exe "d:\dir\package.unitypackage" "d:\outputDir" "true"

Program.cs

using System.Diagnostics;
using System.IO.Compression;
using System.Text;
using ICSharpCode.SharpZipLib.Tar; //nuget package SharpZipLib

var packagePath = args.Length >= 1 ? args[0] : null;
var outputPath = args.Length >= 2 ? args[1] : null;
var extractMetaFiles = args.Length < 3 || Convert.ToBoolean(args[2]);
        
if (string.IsNullOrEmpty(packagePath))
    throw new ArgumentException("No .unitypackage path was given. \n\nUSAGE: program.exe \"XXX.unitypackage\" \"optional\\output\\path\" \"optional extractMetaFiles(true or false)\" \nprogram.exe \"d:\\dir\\package.unitypackage\" \"d:\\outputDir\" \"true\"\n");

var startTime = Stopwatch.StartNew();

UnityPackageExtractor.ExtractPackage(packagePath, outputPath, extractMetaFiles);

startTime.Stop();
Console.WriteLine($"--- Finished in {startTime.Elapsed.TotalSeconds} seconds ---");

internal static class UnityPackageExtractor
{
    public static void ExtractPackage(string packagePath, string? outputPath, bool extractMetaFiles)
    {
        outputPath ??= Directory.GetCurrentDirectory();

        using var tmpDir = new TemporaryDirectory();
        ExtractTarGz(packagePath, tmpDir.Path);

        Directory.EnumerateDirectories(tmpDir.Path)
                 .ToList()
                 .ForEach(dirEntry =>
                 {
                     var assetEntryDir = Path.Combine(tmpDir.Path, dirEntry);
            
                     if (!File.Exists(Path.Combine(assetEntryDir, "pathname")) ||
                         !File.Exists(Path.Combine(assetEntryDir, "asset")))
                         return;

                     using var reader = new StreamReader(Path.Combine(assetEntryDir, "pathname"));
                     var pathname = reader.ReadLine();
            
                     if (string.IsNullOrEmpty(pathname)) return;
            
                     pathname = pathname.TrimEnd('\n');
            
                     var name = Path.GetFileName(pathname);
                     var path = pathname[..^name.Length];
            
                     name = string.Join("_", name.Split(Path.GetInvalidFileNameChars()));
                     path = string.Join("_", path.Split(Path.GetInvalidPathChars()));
                     pathname = path + name;
            
                     var assetOutPath = Path.Combine(outputPath, pathname);
                     if (!Path.GetFullPath(assetOutPath).StartsWith(Path.GetFullPath(outputPath)))
                     {
                         Console.WriteLine($"WARNING: Skipping '{dirEntry}' as '{assetOutPath}' is outside of '{outputPath}'.");
                         return;
                     }

                     Console.WriteLine($"Extracting '{dirEntry}' as '{pathname}'");
                     Directory.CreateDirectory(Path.GetDirectoryName(assetOutPath));
                     File.Move(Path.Combine(assetEntryDir, "asset"), assetOutPath);
                     if (extractMetaFiles) File.Move(Path.Combine(assetEntryDir, "asset.meta"), assetOutPath + ".meta");
                 });
    }

    private static void ExtractTarGz(string filename, string outputDir)
    {
        using var fs = new FileStream(filename, FileMode.Open, FileAccess.Read);
        using var gzipStream = new GZipStream(fs, CompressionMode.Decompress);
        using var tarArchive = TarArchive.CreateInputTarArchive(gzipStream, Encoding.UTF8);
        tarArchive.ExtractContents(outputDir);
    }

    private class TemporaryDirectory : IDisposable
    {
        public string Path { get; }

        public TemporaryDirectory()
        {
            Path = System.IO.Path.Combine(System.IO.Path.GetTempPath(), System.IO.Path.GetRandomFileName());
            Directory.CreateDirectory(Path);
        }

        public void Dispose()
        {
            if (Directory.Exists(Path)) Directory.Delete(Path, true);
        }
    }
}