Riven
« League of Dukes » JGO Kernel  Posts: 5871 Medals: 255
Hand over your head.
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on:
2007-10-27 18:12:04 » |
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I'm tempted to host some silly competion thingy about writing the smallest code to perform some I/O task. I coded some really silly task, and I'd like you guys to check out whether there is anything dangerous possible. If so, I'd be very grateful if you'd let me know as fast as possible. I'm renting this server, and I wouldn't really like to get my account suspended. I tried to isolate the running of tasks as much as possible, within the current JVM, but I might have to resort launching a new JVM to avoid any corruption of the HTTP-server-instance hosting this. http://213.247.55.3:8484/compileandrun/A (naive) solution for the task would be: 1
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| while(true)
{
int a = in.read();
int b = in.read();
if((a|b)<0) break;
out.write(b);
out.write(a);
} |
108 bytes, linebreaks don't count (for readability reasons), but spaces do Beat that! I didn't really raise the bar very high, did I..  Anyway, give it a try, and tell me if there's something I need to know.  |
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Riven
« League of Dukes » JGO Kernel Posts: 5871 Medals: 255
Hand over your head.
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Reply #1 on:
2007-10-27 18:20:50 » |
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Beat 62 bytes, and don't forget to be naughty.
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Riven
« League of Dukes » JGO Kernel Posts: 5871 Medals: 255
Hand over your head.
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Reply #2 on:
2007-10-27 18:52:37 » |
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I disabled uppercase characters... to catch the casual tester This worked though: Gimme your tricks.. |
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Games published by our own members! Go get 'em! 
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kappa
« League of Dukes » JGO Kernel Posts: 2360 Medals: 59
★★★★★
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Reply #3 on:
2007-10-27 20:12:51 » |
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ewww, no uppercase characters  , pretty much ends it for me. |
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Riven
« League of Dukes » JGO Kernel Posts: 5871 Medals: 255
Hand over your head.
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Reply #4 on:
2007-10-27 20:35:24 » |
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Hey... how else would I keep it secure... and... why would you need Classes in such tasks? I'm glad you tried it though |
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Abuse
JGO Kernel  Posts: 1866 Medals: 5
falling into the abyss of reality
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Reply #5 on:
2007-10-27 20:36:35 » |
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Beat 62 bytes, and don't forget to be naughty.
Got to 64bytes so far.... |
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Riven
« League of Dukes » JGO Kernel Posts: 5871 Medals: 255
Hand over your head.
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Reply #6 on:
2007-10-27 20:40:28 » |
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Way to go!
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kappa
« League of Dukes » JGO Kernel Posts: 2360 Medals: 59
★★★★★
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Reply #7 on:
2007-10-27 20:42:59 » |
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and... why would you need Classes in such tasks?
ah sorry my mistake, thought the task was to break the program |
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Riven
« League of Dukes » JGO Kernel Posts: 5871 Medals: 255
Hand over your head.
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Reply #8 on:
2007-10-27 20:45:07 » |
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That too...  and that stops like 99.9999% of all attacks. |
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Abuse
JGO Kernel Posts: 1866 Medals: 5
falling into the abyss of reality
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Reply #9 on:
2007-10-27 21:53:23 » |
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Got to 64bytes so far....
Haha, I'm such a muppet - that 64byte solution was actually 62bytes =) I hadn't removed the declaration of the now unused b integer  Can't see a way of beating 62 though... atleast not yet =) |
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Games published by our own members! Go get 'em! 
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Riven
« League of Dukes » JGO Kernel Posts: 5871 Medals: 255
Hand over your head.
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Reply #10 on:
2007-10-27 21:56:23 » |
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Darn.
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Riven
« League of Dukes » JGO Kernel Posts: 5871 Medals: 255
Hand over your head.
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Reply #11 on:
2007-10-27 22:21:05 » |
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A dead end... but I love it! 1
| for(byte[]b={0,0,1};in.read(b,b[2]++&1,1)>0;out.write(b,0,b[2]*2&2)); |
(69 bytes) |
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Abuse
JGO Kernel Posts: 1866 Medals: 5
falling into the abyss of reality
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Reply #12 on:
2007-10-27 22:56:17 » |
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A dead end... but I love it! 1
| for(byte[]b={0,0,1};in.read(b,b[2]++&1,1)>0;out.write(b,0,b[2]*2&2)); |
(69 bytes) If you are going to break the defined contract of InputStream.read(byte[],int,int), by only checking for ">0" on the return type, then the 62 byte solution mentioned earlier can be trimmed to 61 bytes =) (presumably your own 6[1/2] byte solution is exactly the same as mine?) 1
| for(int a;(a=in.read())>0;out.write(in.read()),out.write(a)); |
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Riven
« League of Dukes » JGO Kernel Posts: 5871 Medals: 255
Hand over your head.
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Reply #13 on:
2007-10-27 22:59:37 » |
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>0 is not breaking the contract of InputStream.read(byte[],int,int) This method blocks until input data is available, end of file is detected, or an exception is thrown. it will never ever return 0. Unless your set the thrid argument to 0  |
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noblemaster
JGO Ninja Posts: 730 Medals: 6
Age of Conquest makes your day!
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Reply #14 on:
2007-10-27 23:00:35 » |
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actually, I got 1 byte less ( 60 bytes): 1
| for(int a;(a=in.read())>0;out.write(a))out.write(in.read()); |
ditto Abuse it's 61 bytes if you use >=0... |
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Riven
« League of Dukes » JGO Kernel Posts: 5871 Medals: 255
Hand over your head.
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Reply #15 on:
2007-10-27 23:02:53 » |
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I guess this is good enough to turn into a bigger project I wrote the http-server myself, so pretty much everything is possible. Again, don't forget to mention the security-holes. Thank you.
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Riven
« League of Dukes » JGO Kernel Posts: 5871 Medals: 255
Hand over your head.
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Reply #16 on:
2007-10-27 23:04:44 » |
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1
| for(int a;(a=in.read())>0;out.write(a))out.write(in.read()); |
I totally love the simplicity. |
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Abuse
JGO Kernel Posts: 1866 Medals: 5
falling into the abyss of reality
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Reply #17 on:
2007-10-27 23:06:57 » |
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oh yeah, nice spot |
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Abuse
JGO Kernel Posts: 1866 Medals: 5
falling into the abyss of reality
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Reply #18 on:
2007-10-27 23:08:38 » |
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I totally love the simplicity.
I still think your 69byte solution is by far the most complicated =S |
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Matzon
« League of Dukes » JGO Kernel Posts: 1805 Medals: 8
I'm gonna wring your pants!
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Reply #19 on:
2007-10-28 03:52:32 » |
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isn't this flawed, since it only checks the validity of the first in.read?
-edit- ok, the string has pairs of bytes.
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Riven
« League of Dukes » JGO Kernel Posts: 5871 Medals: 255
Hand over your head.
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Reply #20 on:
2007-10-28 11:07:04 » |
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Riven
« League of Dukes » JGO Kernel Posts: 5871 Medals: 255
Hand over your head.
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Reply #21 on:
2007-10-28 12:28:15 » |
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I'm adding a database now, to make accounts, and compete against eachother...
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markush
Jr. Member Posts: 52
Plöp!
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Reply #22 on:
2007-10-28 15:04:40 » |
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72 bytes! muhahaha To achieve it, you can replace the only space with a line break, and since that doesn't count its one byte off |
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Riven
« League of Dukes » JGO Kernel Posts: 5871 Medals: 255
Hand over your head.
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«
Reply #23 on:
2007-10-28 15:12:55 » |
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Hehe... then I get 72 bytes too... and I got 2 solutions: 1
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| for(int
r=0,i=0,b=0;r>-1;b=b<<1|(r=in.read())&1)
if(i++%8==0)out.write(b); |
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| for(int
r,i=0,b=0;(r=in.read())>0;)
{
b=b<<1|r&1;
if(++i%8==0)out.write(b);
} |
The first is extremely not-done. |
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Riven
« League of Dukes » JGO Kernel Posts: 5871 Medals: 255
Hand over your head.
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«
Reply #24 on:
2007-10-28 15:15:33 » |
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It's a nice loophole though, and I'll make sure I'll 'fix' that.
Like... only linebreaks allowed after a '{'
Could you show me your solution?
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markush
Jr. Member Posts: 52
Plöp!
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Reply #25 on:
2007-10-28 15:24:54 » |
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Hehe... then I get 72 bytes too... and I got 2 solutions: 1
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| for(int
r=0,i=0,b=0;r>-1;b=b<<1|(r=in.read())&1)
if(i++%8==0)out.write(b); |
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| for(int
r,i=0,b=0;(r=in.read())>0;)
{
b=b<<1|r&1;
if(++i%8==0)out.write(b);
} |
The first is extremely not-done. My is a bit different: 1
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| for(int
c=0,i=0,x;(x=in.read())>0;c<<=1){
c|=x&1;
if(++i%8<1)out.write(c);
} |
And 71 bytes with that: 1
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| for(int
r=1,i=0,b=0;r>0;b=b<<1|(r=in.read())&1)
if(i++%8==0)out.write(b); |
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Abuse
JGO Kernel Posts: 1866 Medals: 5
falling into the abyss of reality
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Reply #26 on:
2007-10-28 15:56:46 » |
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erm, am I missing something? 2 of the solutions above don't work? They output a leading 0 to the output stream. 1
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| for(int
r=1,i=0,b=0;r>0;b=b<<1|(r=in.read())&1)
if(i++%8==0)out.write(b); |
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| for(int
r=0,i=0,b=0;r>-1;b=b<<1|(r=in.read())&1)
if(i++%8==0)out.write(b); |
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Martin Strand
Jr. Member Posts: 60
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Reply #27 on:
2007-10-28 16:13:20 » |
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This doesn't output a leading zero but all ascii values are 0x100 too high. It looks ok on that web page though. (70 bytes) 1
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| for(int
r=1,b=1;
r>0;
b=b<<1|(r=in.read())&1)
if(b>255)
{
out.write(b);
b=1;
} |
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Abuse
JGO Kernel Posts: 1866 Medals: 5
falling into the abyss of reality
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«
Reply #28 on:
2007-10-28 16:29:01 » |
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This doesn't output a leading zero but all ascii values are 0x100 too high. It looks ok on that web page though. (70 bytes) 1
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| for(int
r=1,b=1;
r>0;
b=b<<1|(r=in.read())&1)
if(b>255)
{
out.write(b);
b=1;
} |
That's perfectly ok - the contract of OutputStream.write(int) dictates that only the bottom 8 bits are used anyway, so using the upper bits for signalling is pretty damn clever =) |
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Abuse
JGO Kernel Posts: 1866 Medals: 5
falling into the abyss of reality
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Reply #29 on:
2007-10-28 16:37:19 » |
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An adaption of the above (66 bytes!) :- for(int
b=1;
(b=b<<1|(in.read()-48))>0;)
if(b>255){
out.write(b);
b=1;
} And there is even a redundant ';' in the for, which I'm sure can be optimised away with some restructuring? |
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