JDK <= 11 tests may fail when built with "--with-zlib=system"

[Antonio Vieiro]

Hi all,

The files generated with "jar" and "pack200" may have different sizes 
depending if OpenJDK was compiled with "--with-zlib=system" or 
"--with-zlib=bundled", even though the files are correctly compressed.

As a consequence the tests "DeflateIn_InflateOut" and "PackTestZip64" in 
"java.base", which use the generated file size at different stages, may 
fail when "--with-zlib=system" is used.

This is indeed the case in Fedora 40, where tier1 tests fail [4], [5] 
because of these tests.

### DeflateIn_InflateOut

The problem with the "DeflateIn_InflateOut" test could be solved by 
backporting https://bugs.openjdk.org/browse/JDK-8240226 (which better 
handles the sizes of the generated files) to OpenJDK 11 and earlier.

### PackTestZip64

The PackTestZip64 test [2] uses the generated "pack200" tool to repack, 
pack and unpack a "golden.jar" file [3] (probably generated with 
--with-zlib=bundled), and expects that the resulting size of the file is 
equal to the original size of "golden.jar".

File sizes are indeed equal if "pack200" was compiled with 
"--with-zlib=bundled" (so the repacking, packing and unpacking produces 
the very same golden.jar file).

But when "pack200" is built with "--with-zlib=system" the repacking, 
packing and unpacking of golden.jar is being performed with the system 
library and may produce a golden.jar file that is equivalent to the 
original golden.jar file, although the length of the file is different.

## Proposed solution

To ensure that OpenJDK 11 and earlier can be tested in a variety of 
systems with "--with-zlib=system" we could backport JDK-8240226 and we 
will need to create a bug for the PackTestZip64 test.

The PackTestZip64 could be either:

- Ignored
- Updated to verify the integrity of the resulting files, instead of 
just checking the sizes of the files.

Would it be possible to open a bug for PackTestZip64 so we can fix & 
backport it?

Thanks,
Antonio

[1]
https://fedoraproject.org/wiki/Changes/ZlibNGTransition

[2]
https://github.com/openjdk/jdk11u/blob/master/test/jdk/tools/pack200/PackTestZip64.java#L116

[3]
https://github.com/openjdk/jdk11u/blob/42f70422f10472aa67ca86bfbac25a5d5c314ec2/test/jdk/tools/pack200/pack200-verifier/data/golden.jar

[4]
/home/avieirov/REPOS/OPENJDK/jdk11u-dev/build/linux-x86_64-normal-server-release/images/jdk/bin/unpack200 
tools.pack.gz tools_native.jar

Warning: The unpack200 tool is deprecated, and is planned for removal in 
a future JDK release.

STDERR:
java.io.IOException: Files are differ starting at position: 43630
	at PackTestZip64.compareTwoFiles(PackTestZip64.java:117)
	at PackTestZip64.testPacking(PackTestZip64.java:89)
	at PackTestZip64.main(PackTestZip64.java:48)
	at 
java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke0(Native 
Method)
	at 
java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
	at 
java.base/jdk.internal.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
	at java.base/java.lang.reflect.Method.invoke(Method.java:566)
	at 
com.sun.javatest.regtest.agent.MainActionHelper$AgentVMRunnable.run(MainActionHelper.java:333)
	at java.base/java.lang.Thread.run(Thread.java:829)

JavaTest Message: Test threw exception: java.io.IOException
JavaTest Message: shutting down test


TEST RESULT: Failed. Execution failed: `main' threw exception: 
java.io.IOException: Files are differ starting at position: 43630

[5]
https://bugzilla.redhat.com/show_bug.cgi?id=2280757