GZipStream not working as expected on compress.

[jgauffin]

I'm using .NET standard and had ported some code from .NET 4.5.2.

Expected outcome:

Dispose() or Flush() should be enough for the compressed contents to get copied to the inner stream.

Actual outcome

Both Flush and Dispose are required to get the correct amount of bytes back from the gzipstream:

using (var gzip = new GZipStream(ms, CompressionLevel.Optimal, true))
{
    gzip.Write(jsonBytes, 0, jsonBytes.Length);
    gzip.Flush();
}
buffer = ms.ToArray();

With just flush, I get 190 instead of 200 bytes:

using (var gzip = new GZipStream(ms, CompressionLevel.Optimal))
{
    gzip.Write(jsonBytes, 0, jsonBytes.Length);
    gzip.Flush();
    buffer = ms.ToArray();
}

With only Dispose i get 194 of the 200 expected bytes:

using (var gzip = new GZipStream(ms, CompressionLevel.Optimal, true))
{
    gzip.Write(jsonBytes, 0, jsonBytes.Length);
}
buffer = ms.ToArray();

[Petermarcu]

I am assuming you are trying to run the library on .NET Core? We need to get this bug to whichever implementation of .NET Standard you are running on.

[jgauffin]

The .NET library is compiled as .NET standard. I discovered the error in a .NET ASP.NET Core MVC application and reproduced it in a .NET Core console application.

[Petermarcu]

Great. Yeah, it will be compiled against .NET Standard but will run on an implementation of .NET Standard in one of the implementations. Sounds like this one is in .NET Core. I'm going to move this issue to the repo that has the Compression code for .NET Core.

[Petermarcu]

Issue moved to dotnet/corefx #24920 via ZenHub

[jgauffin]

Thank you for your help