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

[Lance Andersen]

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> 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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 <http://oracle.com/us/design/oracle-email-sig-198324.gif>Lance Andersen| Principal Member of Technical Staff | +1.781.442.2037
Oracle Java Engineering 
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Lance.Andersen at oracle.com <mailto:Lance.Andersen at oracle.com>