Thank you Andrew!
The multiplier 6 was pre-existent, and I don't really want to change
behavior in this legacy class.
The high limit of (Integer.MAX_VALUE - 20) was arbitrarily chosen.
I don't think it matters much in this case, but I can change it to
(Integer.MAX_VALUE - 8), which is used in several other places.
I've just updated the code in-place to make the intent of the fix more
clear.
Could you please check it if it looks better now?
http://cr.openjdk.java.net/~igerasim/8225397/00/webrev/
Thanks in advance!
Ivan
On 6/6/19 3:57 AM, Andrew Haley wrote:
On 6/6/19 10:18 AM, Ivan Gerasimov wrote:
Hello!
It is yet another instance of integer overflow under certain extreme
circumstances.
This time it is when calculating the initial capacity of a StringBuilder
in BitSet.toString.
If there are too many elements in the set, we can't do much anyway.
The best effort is to avoid confusing NegativeArraySizeException and let
the method throw OOM.
Would you please help review the fix?
BUGURL: https://bugs.openjdk.java.net/browse/JDK-8225397
WEBREV: http://cr.openjdk.java.net/~igerasim/8225397/00/webrev/
@@ -1184,7 +1184,9 @@
int numBits = (wordsInUse > 128) ?
cardinality() : wordsInUse * BITS_PER_WORD;
- StringBuilder b = new StringBuilder(6*numBits + 2);
+ int sizeHint = (numBits <= (Integer.MAX_VALUE - 22) / 6) ?
+ 6 * numBits + 2 : Integer.MAX_VALUE - 20;
+ StringBuilder b = new StringBuilder(sizeHint);
b.append('{');
int i = nextSetBit(0);
This needs a comment. What is significant about 6 and 22?
--
With kind regards,
Ivan Gerasimov
