[jdk11u-dev] RFR: 8288763: Pack200 extraction failure with invalid size

[Volker Simonis]

On Mon, 20 Jun 2022 23:03:33 GMT, Tyler Steele <tsteele at openjdk.org> wrote:

> While running some internal testing, a college has discovered a failure related to the Pack200 archive format on the zLinux platform. The problematic code was removed in the current repo by [JDK-8234596](https://bugs.openjdk.org/browse/JDK-8234596), however that change was large, and required a CSR. I feel that it would be too risky and cumbersome to backport those changes to jdk11 (and ultimately jdk8 as well), so I'd like to propose this change as a new change to jdk11 rather than via the usual backport process.
> 
> ### Testing
> These changes have been run against the failing test on zLinux and the Tier 1 tests completed successfully.

Hi @backwaterred,
Thanks for running the additional tests, really appreciated.
As I said before, I think your changes are fine and I'll approve them.

If you have some extra time to dig into this issue it would still be interesting to find out why the same zlib version 1.2.11 produces different compressed sizes on x86_64 and s390. Do you know if the native zlib on your system contains some extra changes or enhancements compared to the upstream version? And by the way, what Linux distro did you observe this issue?

One way to find this out would be to build you JDK under test with a statically linked zlib version (i.e. `--with-zlib=bundled`). This will use the original 1.2.11 zlib sources which are bundled with OpenJDK. If this statically linked JDK behaves differently this would indicate that there's some "secrete sauce" in your platforms native zlib. That doesn't mean that there's something wrong about it. It's just the JDK which is not prepared for it :)

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Marked as reviewed by simonis (Reviewer).

PR: https://git.openjdk.org/jdk11u-dev/pull/1163