OneClick to Tar files

oneclick2tars.cs

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

namespace oneclick2tars {
    class Program {
        static void Main(string[] args) {
            long offset = 0;
            string file = @"c:\users\jon\desktop\SGH\SGH-I717UCLE2_74A55FA71D15964F9EC9E9489B34DE4E.exe";
			string[] files = { /*"amss.bin" , "mdm.bin",*/ /*"boot.img",*/ /*"system.img.ext4"*/ };
			 
            while(offset >= 0) {
                offset = find(file, new int[] { 0x75, 0x73, 0x74, 0x61, 0x72, 0x20, 0x20 }, offset + 1);
                if(offset > 0){
					TarFile tarFile = GetTarHeader(file, offset);
                    Console.WriteLine(tarFile);
					//if(files.Contains(tarFile.FileName)){
						Console.WriteLine("Getting file {0}", tarFile.FileName);
						GetFile(file, tarFile);
					//}
                    offset += tarFile.Size;
				}
            }
        }

        static long find(string filename, int[] needle, long offset) {
            FileStream file = File.OpenRead(filename);
            file.Seek(offset, SeekOrigin.Begin);
            long len = file.Length;

            while(offset < len) {
                int buf = file.ReadByte();
                int i = 0;
                for(; i < needle.Length; i++) {
                    if(needle[i] == buf)
                        buf = file.ReadByte();
                    else
                        break;
                }

                if(i == needle.Length)
                    return offset;
                else if(i > 0)
                    file.Seek(i * -1, SeekOrigin.Current);

                offset++;
            }

            return -1;
            
        }

        static TarFile GetTarHeader(string filename, long offset){
            FileStream file = File.OpenRead(filename);
            file.Seek(offset - 0x101, SeekOrigin.Begin);

            byte[] buf = new byte[512];
            file.Read(buf, 0, 512);

            TarFile tarFile = new TarFile();
            tarFile.FileName = GetString(buf, 0);
			tarFile.Size = Convert.ToInt64(GetString(buf, 124), 8);
			tarFile.Offset = offset - 0x101;
			tarFile.Length = (tarFile.Size % 0x200) == 0 ? (tarFile.Size + 0x200) : (((tarFile.Size / 0x200) + 1) * 0x200) + 0x200;
			
			file.Close();

            return tarFile;
        }
		
		static void GetFile(string fileName, TarFile file){
			FileStream iFile = File.OpenRead(fileName);
			FileStream oFile = File.OpenWrite(@"c:\users\jon\Desktop\oneclick2tar\" + file.FileName + ".tar");
			long written = 0;
			
			byte[] buf = new byte[512];
			iFile.Seek(file.Offset, SeekOrigin.Begin);
			iFile.Read(buf, 0, 512);
			oFile.Write(buf, 0, 512);
			
			while(written < file.Size){
				buf = new byte[512];
				iFile.Read(buf, 0, (int)Math.Min(file.Size - written, 512L));
				oFile.Write(buf, 0, 512);
				written += 512;
			}
			
			buf = new byte[512];
			oFile.Write(buf, 0, 512);
			oFile.Write(buf, 0, 512);
			
			oFile.Close();
			iFile.Close();
		}

        static string GetString(byte[] buf, int offset) {
            StringBuilder retval = new StringBuilder();

            for(int i = offset; i < buf.Length; i++) {
                if(buf[i] == 0)
                    break;
                retval.Append((char)(buf[i]));
            }

            return retval.ToString();
        }

        struct TarFile {
            public string FileName;
            public long Size;
            public long Offset;
			public long Length;

            public override string ToString() {
                return String.Format("{0}\n\tOffset: 0x{1:X10}\n\tSize:   0x{2:X10}\n\tEnd:    0x{3:X10}", FileName, Offset, Size, Offset + Length);
            }
        }
    }
}