On Tue, 10 Sep 2024 06:15:57 GMT, Jaikiran Pai <j...@openjdk.org> wrote:
> Can I please get a review of this change which cleans up the code in the > `java` launcher? The original motivation for the change was to prevent the > `java` launcher's C code from parsing a jar's manifest when launching an > application through `java -jar foo.jar`. The jar parsing code in C currently > doesn't have the same level of robustness and features as what's available in > the Java side implementation of `Zip/JarFile` API in `java.util.zip`. Among > them, one is the lack of ZIP64 support in the launcher's jar parsing code. > That issue was noticed in https://bugs.openjdk.org/browse/JDK-8328995 and a > PR (https://github.com/openjdk/jdk/pull/18479) was proposed to enhance this C > code in the launcher to support ZIP64 jar files. Even before the proposed > changes in that PR, there already were a few concerns about long term > maintainability of the jar parsing code in the launcher given that it > duplicates what we already do in the Java side implementation, so adding new > C code here isn't prefer able. > > The change in this current PR removes the part where the launcher's C code > was parsing the jar's manifest file to identify "Main-Class" and > "SplashScreen-Image" attributes from the manifest of the jar that was being > launched. This was being done in the C code to support a long outdated "JRE > selection" feature (mJRE https://bugs.openjdk.org/browse/JDK-8058407) which > required it to parse the jar's manifest. After that feature was removed, the > sole reason the jar's manifest was continued to be parsed in this launcher > code was for convenience. > > With the changes proposed in this PR, the launcher will use the jar parsing C > code only if the jar has a "SplashScreen-Image" in its manifest. The number > of such jars, based on an experiment against a large corpus of jar files, is > very minimal (we found just 26 jars in around 900K odd jar files with a > "SplashScreen-Image"). The updated code in this PR also delegates the > identification of the "SplashScreen-Image" attribute to the java code (in > `LauncherHelper`) thus removing the need to parse the manifest in C code. The > only time the C code will now do the jar parsing is to display a splash > screen image (if any is present) from the jar file. I think even that can be > avoided, but I haven't experimented with it and I would like to pursue that > separately in future, instead of this PR. > > Finally, a few of the utility functions that were introduced in the launcher > C code in a recent JEP to support "Implicitly Declared Classes and Instance > Main... This pull request has been closed without being integrated. ------------- PR: https://git.openjdk.org/jdk/pull/20929
