SharpZipLib - ZipException “System.ArgumentOutOfRangeException” - Why am I getting this exception?

Question

I'm using SharpZipLib to unzip files. My code has been working nicely for all zipfiles except the zip file what i am extracting now...

Got this exception:

System.ArgumentOutOfRangeException: Specified argument was out of the range of valid values.
Parameter name: length

The exception is being thrown at size = s.Read(data, 0, data.Length);

Hereb is my code...

 public static void UnzipFile(string sourcePath, string targetDirectory)
     {
        try
        {
            using (ZipInputStream s = new ZipInputStream(File.OpenRead(sourcePath)))
            {
                ZipEntry theEntry;
                while ((theEntry = s.GetNextEntry()) != null)
                {
                    //string directoryName = Path.GetDirectoryName(theEntry.Name);
                    string fileName = Path.GetFileName(theEntry.Name);

                    if (targetDirectory.Length > 0)
                    {
                        Directory.CreateDirectory(targetDirectory);
                    }

                    if (fileName != String.Empty)
                    {
                        using (FileStream streamWriter = File.Create(targetDirectory + fileName))
                        {
                            int size = 2048;
                            byte[] data = new byte[2048];
                            while (true)
                            {
                                size = s.Read(data, 0, data.Length);
                                if (size > 0)
                                {
                                    streamWriter.Write(data, 0, size);
                                }
                                else
                                {
                                    break;
                                }
                            }
                        }
                    }
                }
            }
        }
        catch (Exception ex)
        {
            throw new Exception("Error unzipping file \"" + sourcePath + "\"", ex);
        }
    }

Answer 1

Looks like a bug to me. Fortunately, you have access to the code, so you should be able to see exactly where it's going wrong. I suggest you build a debug version of SharpZipLib, break on the line which is throwing the exception, and have a look at what it's actually testing.

It should be fine to read into a 2K buffer even if there's not 2K of data left.

(I wouldn't actually write the code quite how you have, but that's a different matter. I'd also move it into its own utility method - the act of copying all the data from one stream to another is pretty common. There's no need to tie it to zip.)

Answer 2

Looking at the code, you are reading the same set of bytes again (and advancing the position).

size = s.Read(data, 0, data.Length);

An example from here shows that the 2nd argument should be a moving position & not a fixed number.

Answer 3

Change your code int size = 2048; to int size = data.Length;. You won't take OutOfRange exception.

 using (FileStream streamWriter = File.Create(targetDirectory + fileName))
    {
       int size = data.Length;
       byte[] data = new byte[size];
       while (true)
       {
            size = s.Read(data, 0, data.Length);
            if (size > 0)
            {
                streamWriter.Write(data, 0, size);
            }
            else
            {
               break;
            }
       }
    }