How do I use GZipStream with System.IO.MemoryStream?

Question

I am having an issue with this test function where I take an in memory string, compress it, and decompress it. The compression works great, but I can\'t seem to get the dec

Answer 1

I had an issue where *.CopyTo(stream)* would end up with a byte[0] result. The solution was to add .Position=0 before calling .CopyTo(stream) Answered here

I also use a BinaryFormatter that would throw an 'End of stream encountered before parsing was completed' exception if position was not set to 0 before deserialization. Answered here

This is the code that worked for me.

 public static byte[] SerializeAndCompressStateInformation(this IPluginWithStateInfo plugin, Dictionary stateInfo)
    {
        byte[] retArr = new byte[] { byte.MinValue };
        try
        {
            using (MemoryStream msCompressed = new MemoryStream())//what gzip writes to
            {
                using (GZipStream gZipStream = new GZipStream(msCompressed, CompressionMode.Compress))//setting up gzip
                using (MemoryStream msToCompress = new MemoryStream())//what the settings will serialize to
                {
                    BinaryFormatter formatter = new BinaryFormatter();
                    //serialize the info into bytes
                    formatter.Serialize(msToCompress, stateInfo);
                    //reset to 0 to read from beginning byte[0] fix.
                    msToCompress.Position = 0;
                    //this then does the compression
                    msToCompress.CopyTo(gZipStream);
                }
                //the compressed data as an array of bytes
                retArr = msCompressed.ToArray();
            }
        }
        catch (Exception ex)
        {
            Logger.Error(ex.Message, ex);
            throw ex;
        }
        return retArr;
    }


    public static Dictionary DeserializeAndDecompressStateInformation(this IPluginWithStateInfo plugin, byte[] stateInfo)
    {
        Dictionary settings = new Dictionary();
        try
        {

            using (MemoryStream msDecompressed = new MemoryStream()) //the stream that will hold the decompressed data
            {
                using (MemoryStream msCompressed = new MemoryStream(stateInfo))//the compressed data
                using (GZipStream gzDecomp = new GZipStream(msCompressed, CompressionMode.Decompress))//the gzip that will decompress
                {
                    msCompressed.Position = 0;//fix for byte[0]
                    gzDecomp.CopyTo(msDecompressed);//decompress the data
                }
                BinaryFormatter formatter = new BinaryFormatter();
                //prevents 'End of stream encountered' error
                msDecompressed.Position = 0;
                //change the decompressed data to the object
                settings = formatter.Deserialize(msDecompressed) as Dictionary;
            }
        }
        catch (Exception ex)
        {
            Logger.Error(ex.Message, ex);
            throw ex;
        }
        return settings;
    }