Help Multisell Bug

[Antartico™]

If you buy any item in any multisell shop, and the amount of required adena is higher than the adena limit of interlude, you get the items, and it cost you... not 0 adena, but -1444684684 adena, you get the items, and you gain adena.

 

Example:

 

You sell 1 potion for 500kk adena, and you have 1 adena in your inventory.

Try buy 1 or 2 or 3 or 4 potions, and you get the message "you don't have enough adena".

Now try buy 5...

You get 5 potions, and maybe 2kkk adena (from 1 adena).

 

There is any chance of support from someone to fix this?

 

PD: Tested and work on aCis 360

[Tessa]

Tested on 3 RU servers, don't work on any of them

They are gods, they know how to catch integer overflow! :D

[SweeTs]

Ya, damn, they did something on their own :o

[Gam3Master]

Ya, damn, they did something on their own :o

It is very hard to fix it?

[AccessDenied]

We managed to do it, the issue comes from adena * item count. Which can overcome long easily

where is this line?

[Antartico™]

Da fak. How it come that you create English topic in GR section? Ffs.

 

Imma tell you one thing, it's current on all l2j packs. Also, gz for the topic. Now everyone will know about that issue, but from another side, shitty servers will go down :D

 

I posted it here because i sent a PM to Tryskell two weeks ago and he never answer me, then i sent you another PM and you just told me "a very nasty bug", but as you enjoy trolling noobs like me, i don't know if you was saying it seriously or just kidding.

[Reborn12]

I posted it here because i sent a PM to Tryskell two weeks ago and he never answer me, then i sent you another PM and you just told me "a very nasty bug", but as you enjoy trolling noobs like me, i don't know if you was saying it seriously or just kidding.

He is just kidding always

[SweeTs]

Meeee, nooo wai. I'm always serious  :you serious?:

 

 

:happyforever:  :you serious?:  :happyforever:  :you serious?:  :dat:  :happyforever:

[Reborn12]

True :p or not :D

[xxdem]

 

If you buy any item in any multisell shop, and the amount of required adena is higher than the adena limit of interlude, you get the items, and it cost you... not 0 adena, but -1444684684 adena, you get the items, and you gain adena.

 

Example:

 

You sell 1 potion for 500kk adena, and you have 1 adena in your inventory.

Try buy 1 or 2 or 3 or 4 potions, and you get the message "you don't have enough adena".

Now try buy 5...

You get 5 potions, and maybe 2kkk adena (from 1 adena).

 

There is any chance of support from someone to fix this?

 

PD: Tested and work on aCis 360

 

 

The fix is straight forward, cast the multiplication of count and price into an long and compare it with Integer.MAX_VALUE, I personally prefer masking it with 0xFF

[Tessa]

http://docs.oracle.com/javase/8/docs/api/java/lang/Math.html#multiplyExact-int-int-

[xxdem]

http://docs.oracle.com/javase/8/docs/api/java/lang/Math.html#multiplyExact-int-int-

 

this one is even better

[Tessa]

this one is even better

It's exactly what you suggest

/**
 * Returns the product of the arguments,
 * throwing an exception if the result overflows an {@code int}.
 *
 * @param x the first value
 * @param y the second value
 * @return the result
 * @throws ArithmeticException if the result overflows an int
 * @since 1.8
 */
public static int multiplyExact(int x, int y) {
    long r = (long)x * (long)y;
    if ((int)r != r) {
        throw new ArithmeticException("integer overflow");
    }
    return (int)r;
}

[xxdem]

 

It's exactly what you suggest

/**
 * Returns the product of the arguments,
 * throwing an exception if the result overflows an {@code int}.
 *
 * @param x the first value
 * @param y the second value
 * @return the result
 * @throws ArithmeticException if the result overflows an int
 * @since 1.8
 */
public static int multiplyExact(int x, int y) {
    long r = (long)x * (long)y;
    if ((int)r != r) {
        throw new ArithmeticException("integer overflow");
    }
    return (int)r;
}

 

ofc it is, I am veteran in OOP 

[Tessa]

Is this bug because of the overflow only, or there is something more? Because the overflow is easy to catch...

[Nik]

Fix is simple... just throw InvalidArgumentException when reducing inventory item with negative count, after that just look from where all the errors come xD Problem isnt only multisell, also bug works everywhere, except russian packs, they have this

private static long mulAndCheck(long a, long b, String msg, boolean limit) {
		long ret;
		if (a > b)
			// use symmetry to reduce boundary cases
			ret = mulAndCheck(b, a, msg, limit);
		else if (a < 0) {
			if (b < 0) {
				// check for positive overflow with negative a, negative b
				if (a >= Long.MAX_VALUE / b)
					ret = a * b;
				else if(limit)
					ret = Long.MAX_VALUE;
				else
					throw new ArithmeticException(msg);
			} else if (b > 0) {
				// check for negative overflow with negative a, positive b
				if (Long.MIN_VALUE / b <= a)
					ret = a * b;
				else if(limit)
					ret = Long.MIN_VALUE;
				else
					throw new ArithmeticException(msg);
			}
			else
				ret = 0;
		} else if (a > 0) {
			// check for positive overflow with positive a, positive b
			if (a <= Long.MAX_VALUE / b)
				ret = a * b;
			else if(limit)
				ret = Long.MAX_VALUE;
			else
				throw new ArithmeticException(msg);
		}
		else
			ret = 0;
		return ret;
	}

:D:D:D:D:D:D:D:D

Its pure govnokod though. http://govnokod.ru/java

Edited August 28, 2016 by Nik