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  ______\ \_\\_______________________\///__________________________//_/ /______
  \___\                                                                   /___/
   | .__                                 __                                  |
   | |                   ___  __________/  |________                         |
   |                     \  \/  / ____/\   __\_  __ \                        |
   ;                      >    < <_|  | |  |  |  | \/                        ;
   :                     /__/\_ \__   | |__|  |__|                           :
   .                           \/  |__|                                      .
   .                                                                         .
   :           H/Q Another Droid BBS - andr01d.zapto.org:9999                :
   ;                                                                         ;
   + --- --  -   .     -        ---    ---    ---        -     .    - -- --- +
   :                                                                         :
   |                     Check files for included files                      |
   :                                                                         :
   ` --- --  -   .     -        ---    ---    ---        -     .    - -- --- '

   Its a common practice in the demoscene and not only, to include files, 
   like music, art, text inside the main executable of an app/demo or in 
   a separate .data file. The same practice i use for NULL. All music and 
   files are included in the main executable.
   
   Back then, when you listen to a good song from a demo, there were some 
   utilities called "rippers" that could extract the included files. Some 
   of them were damn good and you could find all sort of files in emags 
   and demos, like .gif, .mod, .s3m, .pcx, .bmp etc. PC games also were 
   "targets" of file ripping. This way you could have an awesome 
   wallpaper for your Win3.11 machine from your favorite game.
   
   But how those ripping utils work? First you have to identify that the 
   target file has a file you want to extract. Almost all file formats 
   have a unique id, which we can search for and identify them. This id 
   can be a series of bytes or a string with fixed values or in more 
   complex occasions can be bytes with calculated values in predefined 
   positions, even worst... the file format can not be identified.
   
   So lets write a simple program to search for S3M files, which is a 
   format for track music. First we check the file format. You can find 
   the format specs here: 
            https://github.com/lclevy/unmo3/blob/master/spec/s3m.txt
            
   As we see, this file format, has a fixed id in position 45d. So if we 
   search for this ID in the target file and find we know for sure  (or 
   99%) that a S3M file is included.
   
   Below is a simple Pascal program to search for the ID of the S3M file 
   format. Instead of searching for the whole 4 byte ID, we search first 
   to match the first byte, if we find it, check if the second matches 
   etc. Its more simple this way, instead of reading 4 bytes at once, 
   check the values, go back to the original position, cause by reading 4 
   bytes we changed it by 4... etc. etc. etc.
   
   If you compile the program and check the second issue of NULL you will 
   find a match ;)
   
   + --- --  - CUT HERE -       ---    ---    ---        -     .    - -- --- '
   
   program filetype;

    uses 
      crt,
      sysutils;

    var
      b:byte;
      f:file;
      
    begin
      assign(f,paramstr(1));
      reset(f,1);
      while not eof(f) do begin
        blockread(f,b,1);
        if chr(b)='S' then begin
          blockread(f,b,1);
          if chr(b)='C' then begin
            blockread(f,b,1);
            if chr(b)='R' then begin
              blockread(f,b,1);
                if chr(b)='M' then begin
                  writeln('S3M ID found in Position: '+inttostr(filepos(f)-3))
                end;
            end;
          end;
        end;
      
      end;  
      close(f);
    end.

   + --- --  -   .     -        ---    ---    ---        -     .    - -- --- '
         _____         _   _              ____          _   _ 
        |  _  |___ ___| |_| |_ ___ ___   |    \ ___ ___|_|_| |        8888
        |     |   | . |  _|   | -_|  _|  |  |  |  _| . | | . |     8 888888 8
        |__|__|_|_|___|_| |_|_|___|_|    |____/|_| |___|_|___|     8888888888
                                                                   8888888888
                DoNt Be aNoTHeR DrOiD fOR tHe SySteM               88 8888 88
                                                                   8888888888
 /: HaM RaDiO   /: ANSi ARt!     /: MySTiC MoDS   /: DooRS         '88||||88'
 /: NeWS        /: WeATheR       /: FiLEs         /: SPooKNet       ''8888"'
 /: GaMeS       /: TeXtFiLeS     /: PrEPardNeSS   /: FsxNet            88
 /: TuTors      /: bOOkS/PdFs    /: SuRVaViLiSM   /: ArakNet    8 8 88888888888
                                                              888 8888][][][888
   TeLNeT : andr01d.zapto.org:9999 [UTC 11:00 - 20:00]          8 888888##88888
   SySoP  : xqtr                   eMAiL: xqtr@gmx.com          8 8888.####.888
   DoNaTe : https://paypal.me/xqtr                              8 8888##88##888


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