GMOD Data Unpacker

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.IO;

using SevenZip;
using SevenZip.Compression.LZMA;

namespace GMODDataPack
{
    class Program
    {
        static string ReadCString(BinaryReader r)
        {
            StringBuilder sb = new StringBuilder();
            char c = r.ReadChar();
            while (c != '\0')
            {
                sb.Append(c);
                c = r.ReadChar();
            }
            return sb.ToString();
        }

        static void Main(string[] args)
        {
            if (args.Length == 0) return;

            byte[] bytes = File.ReadAllBytes(args[0]);
            BinaryReader r = new BinaryReader(new MemoryStream(bytes));

            string lzma = "" + r.ReadChar() + r.ReadChar() + r.ReadChar() + r.ReadChar();
            if(lzma != "LZMA")
                return;

            UInt32 size = r.ReadUInt32();
            UInt32 size_or = r.ReadUInt32();

            byte[] lzma_props = r.ReadBytes(5);
            byte[] dp = r.ReadBytes((int)size);

            SevenZip.Compression.LZMA.Decoder dec = new SevenZip.Compression.LZMA.Decoder();
            dec.SetDecoderProperties(lzma_props);

            MemoryStream ms = new MemoryStream(dp);
            MemoryStream msout = new MemoryStream();

            int readsize = int.MaxValue;
            while (true) // Fuck this shit, but it works
            {
                try
                {
                    dec.Code(ms, msout, size,
                        readsize, null);
                    if (readsize < 1) break;
                }
                catch
                {
                    readsize = readsize / 10;
                }
            }

            msout.Position = 0;
            r = new BinaryReader(msout);
            byte[] datapack = r.ReadBytes((int)msout.Length);//(int)size_or);

            r = new BinaryReader(new MemoryStream(datapack));
            string cats = "" + r.ReadChar() + r.ReadChar() + r.ReadChar() + r.ReadChar();
            if (cats != "CATS")
                return;

            UInt16 vers = r.ReadUInt16();
            UInt16 filecount = r.ReadUInt16();

            for (int i = 0; i < filecount; i++)
            {
                UInt32 fsizetotal = r.ReadUInt32();
                string fname = ReadCString(r);
                byte[] hash = r.ReadBytes(16);

                uint fsize = fsizetotal - (uint)(fname.Length + 1 + 16); /*+1 for \0*/

                if (fsize == 1)
                {
                    Console.WriteLine("Not writing {0} (Null)", fname);
                    r.ReadByte();
                }
                else
                {
                    byte[] filecont = r.ReadBytes((int)fsize);

                    string fnametowrite = Path.GetFileName(args[0]).Replace('.', '_') + "/" + fname;
                    Directory.CreateDirectory(Path.GetDirectoryName(fnametowrite));

                    File.WriteAllBytes(fnametowrite, filecont);
                    Console.WriteLine("Writing {0}...", fname);
                }
            }
        }
    }
}