SharpZipLib VS ZipWrapper

SharpZipLib

• Best practice to generate ZIP file for client side download?
  2 projects | /r/Blazor | 1 Aug 2022

  public class DownloadStreamedZippedFilesActionResult : FileResult { private const int Zip64CentralDirectoryRecordSize = 56; private const int Zip64CentralDirectoryLocatorSize = 20; /// /// This was obtained by debugging DotNetZip. It might change in newer versions of the library. The size is hardcoded with no constant available, not even a private one. /// private const int DotNetZipLocalFileHeaderExtraFieldLength = 20; private const int DotNetZipCentralDirectoryHeaderExtraFieldLength = 32; private const string ZipExtension = ".zip"; private static readonly ILogger Logger = ApplicationLogging.CreateLogger(); private readonly IReadOnlyCollection files; private readonly CancellationToken cancellationToken; public DownloadStreamedZippedFilesActionResult(string fileName, IEnumerable files, CancellationToken cancellationToken) : base(MediaTypeConverter.GetMimeType(ZipExtension)) { this.files = files.ToArray(); FileDownloadName = fileName + ZipExtension; this.cancellationToken = cancellationToken; } public DownloadStreamedZippedFilesActionResult(string fileName, IEnumerable files) : this(fileName, files, new CancellationToken(false)) { } public override Task ExecuteResultAsync(ActionContext context) { var response = context.HttpContext.Response; response.OnStarting(() => { var contentDisposition = new ContentDispositionHeaderValue("attachment"); contentDisposition.SetHttpFileName(FileDownloadName); response.Headers.Add("access-control-expose-headers", new[] { "content-disposition", "content-length" }); response.Headers.Add("content-disposition", contentDisposition.ToString()); response.Headers.ContentLength = CalculateContentLength(); return Task.FromResult(0); }); var callback = GetCallback(); return callback(response.Body); } private Func GetCallback() { return async (outputStream) => { byte[] buffer = new byte[4096]; try { var countingStream = new CountingStream(outputStream); using (outputStream) using (var zipStream = new Ionic.Zip.ZipOutputStream(countingStream, true)) { zipStream.CompressionLevel = Ionic.Zlib.CompressionLevel.Level0; zipStream.CompressionMethod = Ionic.Zip.CompressionMethod.None; zipStream.EnableZip64 = Zip64Option.Always; foreach (var file in files) { using (var fileContent = await file.GetContentAsync()) { zipStream.PutNextEntry(file.Name); StreamUtils.Copy(fileContent, zipStream, buffer); zipStream.Flush(); outputStream.Flush(); } cancellationToken.ThrowIfCancellationRequested(); } zipStream.Flush(); zipStream.Close(); outputStream.Flush(); } } catch (Exception e) { Logger.LogError(e, "Unexpected error streaming {FileName}", FileDownloadName); throw; } }; } private long CalculateContentLength() { /* ZIP file size constants according to the specification https://users.cs.jmu.edu/buchhofp/forensics/formats/pkzip.html and https://pkware.cachefly.net/webdocs/casestudies/APPNOTE.TXT * Please note this only works with compression type 0 (store, no compression). * This formula also takes into account the additional content DotNetZip adds in the extra fields. It might be different for other zip providers. * ZIP constants come from SharpZipLib https://github.com/icsharpcode/SharpZipLib/blob/master/src/ICSharpCode.SharpZipLib/Zip/ZipConstants.cs */ return files.Count * (ZipConstants.LocalHeaderBaseSize + ZipConstants.Zip64DataDescriptorSize + ZipConstants.CentralHeaderBaseSize + DotNetZipLocalFileHeaderExtraFieldLength + DotNetZipCentralDirectoryHeaderExtraFieldLength) + 2 * files.Sum(f => f.Name.Length) + files.Sum(f => f.Size) + ZipConstants.EndOfCentralRecordBaseSize + Zip64CentralDirectoryRecordSize + Zip64CentralDirectoryLocatorSize; } } public record class StreamedFile { private readonly Func> fileFunc; public StreamedFile(string name, long size, Func> fileFunc) { this.fileFunc = fileFunc; Name = name; Size = size; } public string Name { get; } public long Size { get; } /// /// Callback to get the file from S3, Azure Storage or wherever /// public Task GetContentAsync() => fileFunc(); }

• Process StandardOutput misses lines when compared with direct CMD output (.NET 6)
  1 project | /r/dotnet | 20 May 2022
• Package to open/extract a DEB archive in C#
  1 project | /r/csharp | 23 Apr 2022
• Problem exporting to CBZ (maybe Windows 11 problem)
  1 project | /r/comicrackusers | 6 Dec 2021
• Malware downloaded from PyPI 41,000 times was surprisingly stealthy
  2 projects | /r/programming | 20 Nov 2021

  Not python but I have story of team that depended on a C# library for saving zip files (SharpZipLib); turns out SharpZipLib had an issue: it could corrupt zip files ( https://github.com/icsharpcode/SharpZipLib/issues/391 ). This was a desktop app and reports from users came pouring in about they not being able to open their files. In response the company had to first manually recover their user's data; and nowadays they stress test sharpziplib to make sure it does not produce corrupted files in newer versions.

ZipWrapper

We haven't tracked posts mentioning ZipWrapper yet.
Tracking mentions began in Dec 2020.