Problem with decompress, GZipStream

Question

I have problem with decomress gzip:

string fileData = string.Empty;
// byte[] starts with 31 and 139
var gzBuffer = entity.Data.Skip(pos).ToArray(); 
using (GZipStream stream = new GZipStream(new MemoryStream(gzBuffer),CompressionMode.Decompress))
{
    const int size = 4096;
    byte[] buffer = new byte[size];
    using (MemoryStream memory = new MemoryStream())
    {
        int count = 0;
        do
        {
            count = stream.Read(buffer, 0, size);
            if (count > 0)
            {
                memory.Write(buffer, 0, count);
            }
        } while (count > 0);
        fileData = Encoding.UTF8.GetString(memory.ToArray());
    }
}

In the debugger, count allways equal 0. Where is the problem?
Thanks.

How was this stream compressed? I'v also experienced this problem in the past and the error was actually in the compression logic. — Jan-Peter Vos
@Jan-Peter Vos: I can not say for sure because the message comes from the web. — user348173
Hmmm... I can't see anything obvious... "the data" is the first thing that comes to mind. Can you (for example) show what gzBuffer is? — Marc Gravell

oleksii oleksii · Accepted Answer · 2011-05-15T15:13:23

not sure if this will be of much help to you, but I will try. This is what I used in a sample project to compress/decompress files with GZIP. Maybe you can adapt this code for your needs?

public string Compress(FileInfo fi)
{
    string outPath;

    using (FileStream inFile = fi.OpenRead())
    {
        outPath = fi.FullName + ".gz";
        using (FileStream outFile = File.Create(outPath))
        {
            using (var compress = new GZipStream(outFile, 
                                                 CompressionMode.Compress))
            {
                inFile.CopyTo(compress);
            }
        }
    }

    return outPath;
}

public void Decompress(FileInfo fi)
{
    using (FileStream inFile = fi.OpenRead())
    {
        string curFile = fi.FullName;
        string origName = curFile.Remove(curFile.Length - fi.Extension.Length);

        using (FileStream outFile = File.Create(origName))
        {
            using (var decompress = new GZipStream(inFile, 
                                                   CompressionMode.Decompress))
            {
                decompress.CopyTo(outFile);
            }
        }
    }
}

Problem with decompress, GZipStream

1 Answers