RFR: 8343839: Detect patched modules and abort run-time image link early

[Alan Bateman]

On Tue, 12 Nov 2024 11:00:36 GMT, Severin Gehwolf <sgehwolf at openjdk.org> wrote:

> Please review this fix to how patched modules are being handled when linking from the run-time image. During review of [JDK-8311302](https://bugs.openjdk.org/browse/JDK-8311302) it was pointed out that module patching should be detected earlier and the link should get aborted in that case.
> 
> This patch implements it, by looking at the `jdk.module.patch.0` property like [other code in the JDK](https://github.com/openjdk/jdk/blob/2c1e4c381615ce52276f4bf331a1e7a845af4b6e/src/hotspot/share/cds/cdsConfig.cpp#L282) does. After this patch module patching is being detected before any archives are being read or the actual linking process starts (contrary to the previous solution).
> 
> Testing:
> - [x] GHA testing (mac aarch64 test failures are infra related)
> - [x] Local testing of existing test, which covers it
> 
> Thoughts?

src/jdk.jlink/share/classes/jdk/tools/jlink/internal/JlinkTask.java line 625:

> 623:             // Do not permit linking from run-time image when the current image
> 624:             // is being patched
> 625:             if (jdk.internal.misc.VM.getSavedProperties().get("jdk.module.patch.0") != null) {

I don't think we should introduce this dependency. Instead, I think we should look at adding a property such as jdk.patched, with a boolean value, to indicate if the current runtime is patched or not. This could be useful for java -XshowSettings output too.

src/jdk.jlink/share/classes/jdk/tools/jlink/resources/jlink.properties line 128:

> 126: \ --keep-packaged-modules is not supported
> 127: err.runtime.link.modified.file={0} has been modified
> 128: err.runtime.link.patched.module=The current runtime includes module patches.\

Not sure about "module patches", its more that the current runtime has been patched with --patch-module.

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PR Review Comment: https://git.openjdk.org/jdk/pull/22037#discussion_r1837935419
PR Review Comment: https://git.openjdk.org/jdk/pull/22037#discussion_r1837936172