C# - Dateien mit gzip Compressen

    class gz
    {
        public static void Compress(string filename)
        {
            if (filename.IndexOf(".gz") >= 1)
            {
                return;
            }
            Console.ForegroundColor = ConsoleColor.Yellow;
            Console.WriteLine("[GZIP]compression on file {0}", filename);
            FileStream infile;
            try
            {
                infile = new FileStream(filename, FileMode.Open, FileAccess.Read, FileShare.Read);
                byte[] buffer = new byte[infile.Length];
                int count = infile.Read(buffer, 0, buffer.Length);
                if (count != buffer.Length)
                {
                    infile.Close();
                    Console.WriteLine("[GZIP]Failed: Unable to read data from file");
                    return;
                }
                infile.Close();
                FileStream fs = new FileStream(filename + ".gz", FileMode.Create, FileAccess.Write, FileShare.Write);
                GZipStream compressedzipStream = new GZipStream(fs, CompressionMode.Compress, true);
                Console.WriteLine("[GZIP]Compression");
                compressedzipStream.Write(buffer, 0, buffer.Length);
                compressedzipStream.Close();
                Console.WriteLine("[GZIP]Original size: {0}, Compressed size: {1}", buffer.Length, fs.Length);
                fs.Close();
                File.Delete(filename);
            }
            catch (InvalidDataException)
            {
                Console.WriteLine("[GZIP]Error: The file being read contains invalid data.");
            }
            catch (FileNotFoundException)
            {
                Console.WriteLine("[GZIP]Error:The file specified was not found.");
            }
            catch (ArgumentException)
            {
                Console.WriteLine("[GZIP]Error: path is a zero-length string, contains only white space, or contains one or more invalid characters");
            }
            catch (PathTooLongException)
            {
                Console.WriteLine("[GZIP]Error: The specified path, file name, or both exceed the system-defined maximum length. For example, on Windows-based platforms, paths must be less than 248 characters, and file names must be less than 260 characters.");
            }
            catch (DirectoryNotFoundException)
            {
                Console.WriteLine("[GZIP]Error: The specified path is invalid, such as being on an unmapped drive.");
            }
            catch (IOException)
            {
                Console.WriteLine("[GZIP]Error: An I/O error occurred while opening the file.");
            }
            catch (UnauthorizedAccessException)
            {
                Console.WriteLine("[GZIP]Error: path specified a file that is read-only, the path is a directory, or caller does not have the required permissions.");
            }
            catch (IndexOutOfRangeException)
            {
                Console.WriteLine("[GZIP]Error: You must provide parameters for GZIP.");
            }
            finally
            {
                Console.ForegroundColor = ConsoleColor.White;
            }
        }
    }