RFR: JDK-8232879: (zipfs) Writing out data with ZipFileSystem leads to a CRC failure in the generated jar file

[Jaikiran Pai]

Thank you Lance.

-Jaikiran

On 24/10/19 1:17 AM, Lance Andersen wrote:
> Hi Jaikiran,
>
> I will take a look and once we are good with the review, I can sponsor it.
>
> Best
> Lance
>> On Oct 23, 2019, at 7:24 AM, Jaikiran Pai <jai.forums2013 at gmail.com
>> <mailto:jai.forums2013 at gmail.com>> wrote:
>>
>> Can I please get a review and a sponsor for a potential fix for
>> JDK-8232879[1]? The patch is available as a webrev at [2].
>>
>> What's happening in there is that the
>> jdk.nio.zipfs.ZipFileSystem.DeflatingEntryOutputStream is overriding the
>> one arg write(byte b) method and calling the super.write(b) and then
>> doing a crc.update. The super.write(b)
>> (java.util.zip.DeflaterOutputStream in this case) actually internally
>> calls the 3 arg write(b, offset, length) which is overriding by this
>> jdk.nio.zipfs.ZipFileSystem.DeflatingEntryOutputStream. In its
>> implementation of write(b, offset, length), in addition to (rightly)
>> calling super.write(b, offset, length), this method also updates the CRC
>> (again). So this ends up updating the CRC multiple times when the single
>> arg write is invoked.
>>
>> The patch now removes this overridden implementation of write(b) in the
>> DeflatingEntryOutputStream so that the call is handled by the
>> java.util.zip.DeflaterOutputStream. Although there's no @implNote on
>> java.util.zip.DeflaterOutputStream#write(byte b) static that it's
>> (always) going to call the 3 arg write(b, offset, length) method, the
>> implementation as of now does indeed do that. So I guess, its probably
>> OK to rely on that knowledge and get rid of this overridden write(b)
>> method instead of coming up with a bit more complicated fix.
>>
>> The patch also includes a jtreg testcase which reproduces this issues
>> and verifies the fix.
>>
>> [1] https://bugs.openjdk.java.net/browse/JDK-8232879
>>
>> [2] https://cr.openjdk.java.net/~jpai/webrev/8232879/1/webrev/
>>
>> -Jaikiran
>>
>>
>
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