GZipStream not reading the whole file

Question

I have some code that downloads gzipped files, and decompresses them. The problem is, I can't get it to decompress the whole file, it only reads the first 4096 bytes and then about 500 more.

Byte[] buffer = new Byte[4096];
int count = 0;
FileStream fileInput = new FileStream("input.gzip", FileMode.Open, FileAccess.Read, FileShare.Read);
FileStream fileOutput = new FileStream("output.dat", FileMode.Create, FileAccess.Write, FileShare.None);
GZipStream gzipStream = new GZipStream(fileInput, CompressionMode.Decompress, true);

// Read from gzip steam
while ((count = gzipStream.Read(buffer, 0, buffer.Length)) > 0)
{
    // Write to output file
    fileOutput.Write(buffer, 0, count);
}

// Close the streams
...

I've checked the downloaded file; it's 13MB when compressed, and contains one XML file. I've manually decompressed the XML file, and the content is all there. But when I do it with this code, it only outputs the very beginning of the XML file.

Anyone have any ideas why this might be happening?

Answer 1

I ended up using a gzip executable to do the decompression instead of a GZipStream. It can't handle the file for some reason, but the executable can.

Answer 2

EDIT

Try not leaving the GZipStream open:

GZipStream gzipStream = new GZipStream(fileInput, CompressionMode.Decompress,  
                                                                         false);

or

GZipStream gzipStream = new GZipStream(fileInput, CompressionMode.Decompress);

Answer 3

Are you calling Close or Flush on fileOutput? (Or just wrap it in a using, which is recommended practice.) If you don't the file might not be flushed to disk when your program ends.

Answer 4

Same thing happened to me. In my case only reads up to 6 lines and then reached end of file. So I realized that although the extension is gz, it was compressed by another algorithm not supported by GZipStream. So I used SevenZipSharp library and it worked. This is my code

You can use SevenZipSharp library

using (var input = File.OpenRead(lstFiles[0]))
{
    using (var ds = new SevenZipExtractor(input))
    {
        //ds.ExtractionFinished += DsOnExtractionFinished;

        var mem = new MemoryStream();
        ds.ExtractFile(0, mem);

        using (var sr = new StreamReader(mem))
        {
            var iCount = 0;
            String line;
            mem.Position = 0;
            while ((line = sr.ReadLine()) != null && iCount < 100)
            {
                iCount++;
                LstOutput.Items.Add(line);
            }

        }
    }
}