RFR: 8286978: SIGBUS in libz during CDS initialization [v2]

[Ioi Lam]

On Fri, 20 May 2022 05:37:27 GMT, Calvin Cheung <ccheung at openjdk.org> wrote:

>> Please review this fix to ensure all requested bytes are transferred by calling `FileChannel.transferFrom` in a loop and checking its return value.
>> 
>> Tested by running the SharedArchiveConsistency.java test on linux-aarch64 30 times on each of the following tier3 options:
>> 
>> - `-XX:+CreateCoredumpOnCrash -XX:+UseSerialGC `
>> - `-XX:+CreateCoredumpOnCrash -XX:+UseParallelGC -XX:+UseNUMA`
>
> Calvin Cheung has updated the pull request incrementally with one additional commit since the last revision:
> 
>   corrected the condition of the while loop, removed an unneeded line of code

Changes requested by iklam (Reviewer).

test/lib/jdk/test/lib/cds/CDSArchiveUtils.java line 440:

> 438:             transferFrom(inputChannel, outputChannel, 0, offset);
> 439:             outputChannel.position(offset);
> 440:             outputChannel.write(ByteBuffer.wrap(bytes));

The changes for transferFrom looks good, but we still have a problem with outputChannel.write(), which can also return fewer bytes than requested (or even zero).

For simplicity, I think it's best to ditch FileChannel and use FileOutputStream.write() instead.

test/lib/jdk/test/lib/cds/CDSArchiveUtils.java line 458:

> 456:             transferFrom(inputChannel, outputChannel, 0, offset);
> 457:             inputChannel.position(offset + nBytes);
> 458:             long length = orgSize - nBytes;

Line 458 doesn't seem to be needed.

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PR: https://git.openjdk.java.net/jdk/pull/8799