Blog articles

  • 20th January 2018

How to dismantle a compiler bomb

bombCmemory

main[-1u]={1};

You have heard of "zip bombs" (a tiny ZIP file that decompresses to multiple gigabytes) and "XML bombs" (small XML file abusing the entities to consume lots of memory), and now there is a "compiler bomb" to follow suit.  The idea is quite similar -- the source code is only 14 bytes, but the generated executable will be over 16 GB in size…

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  • 25th October 2017

Namaste India

CIndiaobfuscated

This obfuscated piece of C code prints the map of India to the standard output.

#include <stdio.h>
main()
{
    int a,b,c;
    int count = 1;
    for (b=c=10;a="- FIGURE?, UMKC,XYZHello Folks,\
    TFy!QJu ROo TNn(ROo)SLq SLq ULo+\
    UHs UJq TNn*RPn/QPbEWS_JSWQAIJO^\
    NBELPeHBFHT}TnALVlBLOFAkHFOuFETp\
    HCStHAUFAgcEAelclcn^r^r\\tZvYxXy\
    T|S~Pn SPm SOn TNn ULo0ULo#ULo-W\
    Hq!WFs XDt!" [b+++21]; )
    for(; a-- > 64 ; )
    putchar ( ++c=='Z' ? c = c/ 9:33^b&1);
    return 0;
}
…
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  • 7th October 2017

Regex prime checker

JavaPerlregex

This Java snippet uses a regular expression for something way different than they were designed for: a primality check.

public static boolean prime(int n) {
    return !new String(new char[n]).matches(".?|(..+?)\\1+");
}
…
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  • 11th September 2017

Quine - a self-replicating program

CPython 3Quineself-replicating

Quines are computer programs that accept no input and write its own source code on the standard output.  This entry was taken from the Jargon File, the author is unknown.

char*f="char*f=%c%s%c;main()
{printf(f,34,f,34,10);}%c";
main(){printf(f,34,f,34,10);}
…
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  • 27th August 2017

Underscore Pi

CIOCCC

This clever program written by Brian Westley calculates π by looking at its own area.  It is one of the winning entries of IOCCC in 1988.

#define _ -F<00||--F-OO--;
int F=00,OO=00;main(){F_OO();printf("%1.3f\n",4.*-F/OO/OO);}F_OO()
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