Code review request 6858865: Fix for 6728376 causes regression if the size of "data" is 0 and malloc returns Null for 0-length

[Xueming Shen]

Alan,

After staring those simple, 11 lines of change for minutes, I believe we 
should simply
go back with the original approach at

http://cr.openjdk.java.net/~sherman/6858865/webrev.00

The change in
http://cr.openjdk.java.net/~sherman/6858865/webrev.00

obviously is problematic, especially in case like in_len == 0 but 
out_len != 0 (no more,
or no more new input, but with a valid output buffer), it's definitely 
possible the
inflater/deflater might have more bites to (and should) output in this 
scenario, it's a
bug to return 0 here.

Sure it's possible to go further like

if (in_len == 0)
     return 0;
....

if (len == 0)
     ...

But given the purpose of this fix is to solve that particular 
"regression" (which actually
does not cause any regression for "mainstream" platforms), I prefer not 
take the risk
of causing another real regression/behavior change here, especially we 
got burned
couple times here in the past when tried to do better.

Agree?

-Sherman



On 11/19/2010 02:03 PM, Xueming Shen wrote:
> On 11/19/2010 01:51 PM, Alan Bateman wrote:
>> Xueming Shen wrote:
>>> :
>>> Why do you want to feed the zlib with a null buffer? :-)
>> So are you saying that if the length is 0 that it still looks at the 
>> buffer? If so, then I'm okay with the last webrev.
>>
>
> zlib does buffer null check before anything else, just like we do null 
> check/throw NPE first then
> check the offset and length.
>
> -Sherman

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