Narcissistic program challenge

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Narcissistic program challenge

Last post 07-08-2008 10:50 AM by rdrunner. 28 replies.

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03-31-2008 1:57 PM

zzo38
Joined on 02-10-2008
Posts 154

Narcissistic program challenge

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Write a narcissistic program. Which means it takes the input and if it matches the program code you output 1, if it doesn't you output 0. Do not cheat by accessing the program's source code.

: IF COMPILE ?-GOTO COMPILE-HERE ; IMMEDIATE
: THEN HERE SWAP ! ; IMMEDIATE
: ELSE COMPILE GOTO COMPILE-HERE SWAP HERE SWAP ! ; IMMEDIATE

03-31-2008 2:12 PM In reply to

Lingerance
Joined on 07-24-2007
Posts 857

Re: Narcissistic program challenge

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So basically this is a bizarre reverse-quine? WFT.

irc://irc.slashnet.org/#TDWTF
"You acquaint the SURLY THUGS with your brand of diplomacy."

Filed under: WFT

03-31-2008 2:32 PM In reply to

Faxmachinen
Joined on 03-19-2007
Posts 191

Re: Narcissistic program challenge

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// narc.cpp

#include <cstdio>

int main()
{
	FILE narc = fopen("narc.cpp", "w+");

	for (int ch = getchar(); ch != EOF; ch = getchar())
		fputc(ch, narc);

	fclose(narc);

	puts("1");

	return 0;
}

rpar PROTON all

Filed under: it worked the first time

03-31-2008 2:39 PM In reply to

Faxmachinen
Joined on 03-19-2007
Posts 191

Re: Narcissistic program challenge

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I have another solution too, but it involves you not being able to see the source.

rpar PROTON all

03-31-2008 4:44 PM In reply to

ComputerForumUser
Joined on 02-15-2007
Posts 72

Re: Narcissistic program challenge

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It's not even so much of a reverse quine - any quine that builds a string of its code can do a comparison between that and the input:

<?php $str = '<?php $str = \'X\'; echo substr_replace($str, addslashes($str), 14, 1); ?>'; echo substr_replace($str, addslashes($str), 14, 1); ?>

... becomes ...

<?php $str = '<?php $str = \'O\'; $prog = substr_replace($str, addslashes($str), 14, 1); if (!strcmp($argv[\'input\'], $prog)) echo \'1\'; else echo \'0\'; ?>'; $prog = substr_replace($str, addslashes($str), 14, 1); if (!strcmp($_GET['input'], $prog)) echo '1'; else echo '0'; ?>

Briefcase is Lord!

03-31-2008 5:09 PM In reply to

dextron
Joined on 02-05-2008
Posts 11

Re: Narcissistic program challenge

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Here's a Ruby solution....

cmd=<<EOF
def do_compare(testFile,cmdString)
    cmdArr=cmdString.to_a.each {|l| l.chomp!}
    cmdArr[0,0]= "cmd=<<EOF"
    cmdArr.push "EOF","eval cmd","do_compare(ARGV[0],cmd)"
    testArr=File.open(testFile).collect.each {|l| l.chomp!}
    puts "1" if cmdArr==testArr
    puts "0" unless cmdArr==testArr
end
EOF
eval cmd
do_compare(ARGV[0],cmd)

Filed under: Ruby, non-poignant

04-01-2008 10:39 AM In reply to

zentar
Joined on 04-01-2008
Posts 3

Re: Narcissistic program challenge

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This is the closest I could come up with, in a bash shell script:


#!/bin/bash


diff $0 $1 1> /dev/null 2>&1


if [ $? -eq 0 ]; then

    echo 1

else

    echo 0

fi

04-02-2008 6:27 AM In reply to

flop
Joined on 04-27-2007
Posts 51

Re: Narcissistic program challenge

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If it must not access its own source code, there are two solutions: Either it accesses a copy of its own source code, or it uses another way to know whether it found it.

Using a CRC32 would have too many false positives, so I settled for MD5 ... but my machine is too slow, I only have 14 of 32 characters matching: b452cdaf2785e22fb69cbb078cbafa80 vs. be32ca183785e22db6cbb52a18b528e0.

#!/bin/sh

CONSTANT=b452cdaf2785e22fb69cbb078cbafa80
if [[ `md5sum < "$1" | cut -f1 -d" "` eq $CONSTANT ]]
then
  echo 1
else
  echo 0
fi

Please note that an empty line must be included at the end.

04-02-2008 8:15 AM In reply to

flop
Joined on 04-27-2007
Posts 51

Re: Narcissistic program challenge

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What I forgot to mention: Yes, I know about hashclash (http://www.win.tue.nl/hashclash/), and yes, I'm hoping for the best.

Just a quick-and-dirty solution (try) ... If I'd replace all but 31 characters in the constant by ? I'd even have a match now. (Still standing at 14.)

04-29-2008 8:59 PM In reply to

BeenThere
Joined on 04-11-2008
Posts 131

Re: Narcissistic program challenge

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Here's one in JavaScript. Doesn't access any files, and takes the Script tags into account. or input, just use any old textarea and paste it in, and onclick the value to the function:

<script language='javascript'>
function narcissistic(input) {
	var narcissist = "%3Cscript%20language%3D%27javascript%27%3E%0Afunction%20narcissistic%28input%29%20%7B%0A%09var%20narcissist%20%3D%20%22%22%3B%0A%09var%20narcissist2%20%3D%20narcissist.substr%280%2C119%29+escape%28narcissist%29+narcissist.substr%28119%29%3B%0A%09if%20%28input%20%3D%3D%20unescape%28narcissist2%29%29%20return%20true%3B%0A%09return%20false%3B%0A%7D%0A%3C/script%3E";
	var narcissist2 = narcissist.substr(0,119)+escape(narcissist)+narcissist.substr(119);
	if (input == unescape(narcissist2)) return true;
	return false;
}
</script>

It's 'sourcecode pattern' var uses the pattern of the primary program without the escaped source put into it (just "" if unescaped), then drops it in programmatically on the next line.

That way it can "know what it looks like when it knows what it looks like"

but hell - it works without cheating!

The mind boggles,
And yet the goggles,
They do nothing.

04-29-2008 9:10 PM In reply to

BeenThere
Joined on 04-11-2008
Posts 131

Re: Narcissistic program challenge

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Whole HTML if anyone cares:

<html>
<head>
<script language='javascript'>
function narcissistic(input) {
	var narcissist = "%3Cscript%20language%3D%27javascript%27%3E%0Afunction%20narcissistic%28input%29%20%7B%0A%09var%20narcissist%20%3D%20%22%22%3B%0A%09var%20narcissist2%20%3D%20narcissist.substr%280%2C119%29+escape%28narcissist%29+narcissist.substr%28119%29%3B%0A%09if%20%28input%20%3D%3D%20unescape%28narcissist2%29%29%20return%20true%3B%0A%09return%20false%3B%0A%7D%0A%3C/script%3E";
	var narcissist2 = narcissist.substr(0,119)+escape(narcissist)+narcissist.substr(119);
	if (input == unescape(narcissist2)) return true;
	return false;
}
</script>
</head>
<body>
<form name="mainform">
<textarea name="inputdata" cols="400" rows="20" ></textarea><br>
<input type="button"name="btn" value="test" onclick="alert(narcissistic(document.mainform.inputdata.value));">
</form>
</body>
</html>

It goes off the page to the right, but will show up if you copy/paste. The program is considered from "<script..." to "...</script>" without the following linebreak.

The mind boggles,
And yet the goggles,
They do nothing.

04-30-2008 9:30 PM In reply to

The Enterpriser
Joined on 04-30-2008
Posts 12

Re: Narcissistic program challenge

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unless I'm mistaken, this isn't much of a challenge right..?

pseudo code:

String programCode = "all the code in this file" ;

if(input.equals(programCode)

return 1;

return 0;

A more enjoyable solution would be to read the program from memory and work from there.. although you would only find out if the logic was the same, not the code itself.

05-01-2008 1:28 AM In reply to

ammoQ
Joined on 04-13-2005
Vienna.Austria.Europe.Earth
Posts 3,332

Re: Narcissistic program challenge

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The Enterpriser:
unless I'm mistaken, this isn't much of a challenge right..?

pseudo code:

String programCode = "all the code in this file" ;

if(input.equals(programCode)

return 1;

return 0;

I'm not sure whether or not this post is for real, so just in case you really mean it:

You will soon find out that the "all the code in this file" part is really hard.

Because it's impossible even in pseudocode (linebreaks removed and escaping ommited for clarity):

String programCode = "String programCode = "all the code in this file" ; if(input.equals(programCode)) return 1; return 0;" ;

if(input.equals(programCode))

return 1;

return 0;

You can repeat that ad infinitum without getting anywhere.

beanbag girl 4ever

05-01-2008 3:35 AM In reply to

The Enterpriser
Joined on 04-30-2008
Posts 12

Re: Narcissistic program challenge

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fair enough, for those of us who are too lazy to type to infinity...

I'd go with the hash solution. Although finding out the hash of the source code where the source code includes said hash, sounds like a fun problem in itself.

05-01-2008 12:18 PM In reply to

BeenThere
Joined on 04-11-2008
Posts 131

Re: Narcissistic program challenge

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The Enterpriser:
fair enough, for those of us who are too lazy to type to infinity...

I'd go with the hash solution. Although finding out the hash of the source code where the source code includes said hash, sounds like a fun problem in itself.

The only way is to construct the source at runtime out of data that is the source without the "source var" populated. A hash could work if it was reverseable, because you'll need to manipulate the sourcecode var at runtime. I went with escaping the source to a hex string because you can still perform string parsing on the whole variable without corrupting the value.

The mind boggles,
And yet the goggles,
They do nothing.

05-01-2008 1:12 PM In reply to

ammoQ
Joined on 04-13-2005
Vienna.Austria.Europe.Earth
Posts 3,332

Re: Narcissistic program challenge

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Time to post a really working solution that perfectly matches the challenge...

Edit: Oops, I haven't seen until now that BeenThere seems to have solved the challenge, too, one day before me...

#include <stdio.h>
int main(int argc, char **argv ) { char b[999]; char f[999]; char *s="#include <stdio.h>%cint main(int argc, char **argv ) { char b[999]; char f[999]; char *s=%c%s%c; sprintf(b,s,10,34,s,34,10); fread(f,1,451,stdin); putc(48+(feof(stdin) && !memcmp(f,b,450)),stdout); putc(10,stdout); return 0; }%c"; sprintf(b,s,10,34,s,34,10); fread(f,1,451,stdin); putc(48+(feof(stdin) && !memcmp(f,b,450)),stdout); putc(10,stdout); return 0; }

Runs on Linux, because it depends on LF as line delimiters (as opposed to CR LF on Windows). But you Windows users can easily change that, can you?

[erich@iTux ~]$ ./narcist <narcist.c
1
[erich@iTux ~]$ ls -l narcist.c
-rw-r--r-- 1 erich erich 450 Mai  1 19:11 narcist.c
[erich@iTux ~]$

Make sure the source is exactly 450 bytes long, no extra linefeeds etc. allowed...

Readable (but non-working b/c of the extra whitespace) version of the source code:

#include <stdio.h>
int main(int argc, char **argv ) { char b[999]; char f[999];
  char *s="#include <stdio.h>%cint main(int argc, char **argv ) { char b[999]; char f[999]; char *s=%c%s%c; sprintf(b,s,10,34,s,34,10); fread(f,1,451,stdin); putc(48+(feof(stdin) && !memcmp(f,b,450)),stdout); putc(10,stdout); return 0; }%c";
  sprintf(b,s,10,34,s,34,10);
  fread(f,1,451,stdin);
  putc(48+(feof(stdin) && !memcmp(f,b,450)),stdout);
  putc(10,stdout);
  return 0;
}

beanbag girl 4ever

05-01-2008 10:50 PM In reply to

The Enterpriser
Joined on 04-30-2008
Posts 12

Re: Narcissistic program challenge

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Shameful cheating I know...

open(PROGRAM,">>narc.pl");
$input = $ARGV[0];
$input =~ s/\W//g;
print PROGRAM "#" . $input;
close PROGRAM;
print 0;

05-02-2008 6:43 PM In reply to

BeenThere
Joined on 04-11-2008
Posts 131

Re: Narcissistic program challenge

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The Enterpriser:
Shameful cheating I know...
open(PROGRAM,">>narc.pl");
$input = $ARGV[0];
$input =~ s/\W//g;
print PROGRAM "#" . $input;
close PROGRAM;
print 0;

You do realize that "cheat" method has been posted several times over in this very thread, right? Basically, that's plagerism off a "fail" which...I can't begin to quite understand...

The mind boggles,
And yet the goggles,
They do nothing.

05-03-2008 6:52 AM In reply to

The Enterpriser
Joined on 04-30-2008
Posts 12

Re: Narcissistic program challenge

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You do realize that "cheat" method has been posted several times over in this very thread, right? Basically, that's plagerism off a "fail" which...I can't begin to quite understand...

No, where?

05-05-2008 5:14 PM In reply to

omega0
Joined on 04-26-2007
Posts 57

Re: Narcissistic program challenge

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Three perl solutions, they grown scarier (but also cheat more) as you go

print <<'' x 2 . "\n" eq join'',<STDIN>
print <<'' x 2 . "\n" eq join'',<STDIN>

use B::Deparse;sub x{
    undef $/;
    print 'use B::Deparse;sub x' . 'B::Deparse'->new->coderef2text(\&x) . "x;\n" eq <STDIN>;
}x;

#!perl
$ENV{PERL5DB}='*DB::DB=sub{}';exec"$^X -d -0777 $0"if!$^P;
binmode STDIN;print <STDIN>eq join'',@{"_<$0"}[1..3];

05-05-2008 9:52 PM In reply to

omega0
Joined on 04-26-2007
Posts 57

Re: Narcissistic program challenge

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The Enterpriser:
I'd go with the hash solution. Although finding out the hash of the source code where the source code includes said hash, sounds like a fun problem in itself.

Since you know exactly what the line containing the hash looks like, just keep it out of the hash:

uuse Digest::MD5;
$hash = '83b099b39b1679357ceebe2dc394f0ed';
@data = ;
$removed = splice @data, 1, 1;
$result = Digest::MD5::md5_hex( join "", @data );
print $result eq $hash and $removed eq "\$hash = '$hash';";

05-06-2008 2:32 AM In reply to

flop
Joined on 04-27-2007
Posts 51

Re: Narcissistic program challenge

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omega0:
Since you know exactly what the line containing the hash looks like, just keep it out of the hash:

Nice trick. But I think you forgot the \\n in the $hash-comparision... and @data seems a bit destroyed, too. "uuse" is good as well ;-)

05-07-2008 3:33 PM In reply to

too_many_usernames
Joined on 12-09-2005
(0,0,0) in local frame
Posts 146

Re: Narcissistic program challenge

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Attempting for worse abuse of the rules:

#include <stdio.h>

int main(int argc,char**argv)

{

/* since all inputs which could be passed to this program would be copies, rather than the original code itself, nothing matches. */

return 0;

}

05-08-2008 4:31 PM In reply to

Faxmachinen
Joined on 03-19-2007
Posts 191

Re: Narcissistic program challenge

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You could also read in a string, and put a null character somewhere in the source.

rpar PROTON all

05-08-2008 4:51 PM In reply to

ammoQ
Joined on 04-13-2005
Vienna.Austria.Europe.Earth
Posts 3,332

Re: Narcissistic program challenge

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It's actually not that very difficult to solve that challenge. Just take any one of the quine-type self-replicating programs that are available in large numbers, and redirect the output to a buffer that is finally compared against the input. Adjust the quine part, done.

beanbag girl 4ever

05-29-2008 5:45 PM In reply to

terminus
Joined on 05-29-2008
Posts 3

Re: Narcissistic program challenge

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#include <stdio.h>
#include <stdlib.h>
#include <string.h>

char out[ 16000 ];
int j = 0;

const char* fmt = "#include <stdio.h>\n#include <stdlib.h>\n#include <string.h>\n\nchar out[ 16000 ];\nint j = 0;\n\nconst char* fmt = \"?\";\n\nint main( int chg )\n{\n    int i;\n    int len = strlen( fmt );\n\n    for ( i = 0; i < len; i++ )\n    {\n        if ( chg > 0 )\n        {\n            if ( fmt[ i ] == \'\\x3f\' )\n               {\n                   main( 0 );\n               }\n               else\n               {\n                   out[ j++ ] = fmt[ i ];\n               }\n               continue;\n         }\n\n         switch ( fmt[ i ] )\n