Using a generic stream to create a zipped file with SharpCompress

Question

Since System.IO.Compression seems to be out of reach for now if I want to use both dotnet core + net461, I've tried with SharpCompress.

The "read zip" part was easy, but I am having trouble finding out how to write to a zip stream.

The wiki of the project is a bit outdated. This is the only example that I've found that applies to writing to streams. I've tried to follow it and adapt it to my needs, but I am stuck at the exception it throws:

using Microsoft.VisualStudio.TestTools.UnitTesting;
using SharpCompress.Common;
using SharpCompress.Compressors.Deflate;
using SharpCompress.Writers;
using System;
using System.IO;

namespace DbManager.DjdbCore.Tests
{
    [TestClass]
    public class ZipTests
    {
        public ZipTests()
        {
            Directory.SetCurrentDirectory(AppContext.BaseDirectory);
        }

        [TestMethod]
        public void Test()
        {            
            var zip = File.OpenWrite(@"..\..\..\..\..\test-resources\zip_file_test.zip");
            var writerOptions = new WriterOptions(CompressionType.Deflate);
            var zipWriter = WriterFactory.Open(zip, ArchiveType.Zip, writerOptions);            

            var memoryStream = new MemoryStream();            
            var binaryWriter = new BinaryWriter(memoryStream);
            binaryWriter.Write("Test string inside binary file - text to fill it up: qoiwjqefñlawijfñlaskdjfioqwjefñalskvndñaskvnqo`wiefowainvñaslkfjnwpowiqjfeopwiqjnfjñlaskdjfñlasdfjiowiqjefñaslkdjfñalskjfpqwoiefjqw");

            var deflateStream = new DeflateStream(memoryStream, SharpCompress.Compressors.CompressionMode.Compress);
            deflateStream.Write(memoryStream.ToArray(), 0, Convert.ToInt32(memoryStream.Length));

            // EXCEPTION: SharpCompress.Compressors.Deflate.ZlibException: 'Cannot Read after Writing.'
            // Source code: if (_streamMode != StreamMode.Reader) { throw new ZlibException("Cannot Read after Writing."); }
            zipWriter.Write("test_file_inside_zip.bin", deflateStream, DateTime.Now);                         

            zip.Flush();

            zipWriter.Dispose();
            zip.Dispose();            
        }

    }
}

In case it helps, this is what I used (and it worked, but only in dotnet core) using the library System.IO.Compression:

private void WriteAsZipBinary()
{
    //Open the zip file if it exists, else create a new one 
    var zip = ZipPackage.Open(this.FileFullPath, FileMode.OpenOrCreate, FileAccess.ReadWrite);

    var zipStream = ZipManager.GetZipWriteStream(zip, nameOfFileInsideZip);

    var memoryStream = new MemoryStream();
    var binaryWriter = new BinaryWriter(memoryStream);

    // Here is where strings etc are written to the binary file:
    WriteStuffInBinaryStream(ref binaryWriter);

    //Read all of the bytes from the file to add to the zip file 
    byte[] bites = new byte[Convert.ToInt32(memoryStream.Length - 1) + 1];
    memoryStream.Position = 0;
    memoryStream.Read(bites, 0, Convert.ToInt32(memoryStream.Length));

    binaryWriter.Dispose();
    binaryWriter = null;

    memoryStream.Dispose();
    memoryStream = null;

    zipStream.Position = 0;
    zipStream.Write(bites, 0, bites.Length);

    zip.Close();

}   

public static Stream GetZipWriteStream(Package zip, string renamedFileName)
{

    //Replace spaces with an underscore (_) 
    string uriFileName = renamedFileName.Replace(" ", "_");

    //A Uri always starts with a forward slash "/" 
    string zipUri = string.Concat("/", Path.GetFileName(uriFileName));

    Uri partUri = new Uri(zipUri, UriKind.Relative);
    string contentType = "Zip"; // System.Net.Mime.MediaTypeNames.Application.Zip;

    //The PackagePart contains the information: 
    // Where to extract the file when it's extracted (partUri) 
    // The type of content stream (MIME type):  (contentType) 
    // The type of compression:  (CompressionOption.Normal)   
    PackagePart pkgPart = zip.CreatePart(partUri, contentType, CompressionOption.Normal);

    //Compress and write the bytes to the zip file 
    return pkgPart.GetStream();

}

Answer 1

I'll post here the answer on github from @adamhathcock (the owner of the project):

[TestMethod]
public void Test()
{            

    var writerOptions = new WriterOptions(CompressionType.Deflate);
    using(var zip = File.OpenWrite(@"..\..\..\..\..\test-resources\zip_file_test.zip"))
    using(var zipWriter = WriterFactory.Open(zip, ArchiveType.Zip, writerOptions))
    {
        var memoryStream = new MemoryStream();            
        var binaryWriter = new BinaryWriter(memoryStream);
        binaryWriter.Write("Test string inside binary file - text to fill it up: qoiwjqefñlawijfñlaskdjfioqwjefñalskvndñaskvnqo`wiefowainvñaslkfjnwpowiqjfeopwiqjnfjñlaskdjfñlasdfjiowiqjefñaslkdjfñalskjfpqwoiefjqw");

        memoryStream.Position = 0;
        zipWriter.Write("test_file_inside_zip.bin", memoryStream, DateTime.Now);                          
    }
}

2 things:

1. You forgot to reset the MemoryStream after writing to it so it can be read.

2. You don't need to manually use the DeflateStream. You've told the ZipWriter what compression to use. If it worked, you would have double compressed the bytes which would be garbage really.