Yet another way of encoding an arbitrary amount of data

[tux2603]

The #line preprocessor directive allows you to modify the line number and file name reported by exceptions, but since it's handled by the preprocessor the tokenization script never counts it. As a result, you can embed a string variable of an arbitrary length into the stack trace of an exception and then extract it using a simple substring. This is already covered by the "You may not store data inside the name of a variable/function/class etc" rule, so I didn't think it needs a full-blown issue opened, but I still wanted to share what I found.

Here's an example where five full paragraphs of Lorem Ipsum are printed out any time a new MyBot object is created:

using ChessChallenge.API;

public class MyBot : IChessBot
{
    private byte[] rawChars;


    public MyBot() 
    {
        // Load in the rawChars from the file name embedded in the stack trace
        try 
        {
            ThrowrawCharsError();
        }

        catch (System.Exception e)
        {
            int startIdx = e.StackTrace.IndexOf("^") + 1;
            rawChars = System.Convert.FromBase64String(e.StackTrace.Substring(startIdx, e.StackTrace.IndexOf("$") - startIdx));  
        }

        // Write all of the rawChars as chacrters to the console
        foreach (byte b in rawChars)
        {
            System.Console.Write((char)b);
        }
    }

    public Move Think(Board board, Timer timer)
    {
        Move[] moves = board.GetLegalMoves();
        return moves[0];
    }

    public void ThrowrawCharsError()
    {
        // Base64 encoded string containing five paragraphs of Lorem Ipsum
        #line 1 "^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$"
        throw new System.Exception();
    }
}

[SebLague]

I've never heard of that before, cool idea!