tristantarrant/jar-cloner

A little cli util that can recreate jar files byte of byte after they are unpacked.

jar-cloner

Build it with:

./mvnw clean package

Using

You first extract the structure/metadata of the jar file into a yaml file:

java -jar cli/target/quarkus-app/quarkus-run.jar extract some.jar contents.yaml

The contents.yaml file will look something like this:

---
comment: "PACK200"
entries:
- name: "META-INF/MANIFEST.MF"
  time: 1689775860000
  extra: !!binary |-
    /soAAA==
  method: 8
  crc: 3483357844
  size: 434231
- name: "/org/example/Main.class"
  time: 1689775674000
  method: 8
  crc: 1044789276
  size: 1881

You can now use this contents.yaml file to create a new jar file with the same structure. If the files being added to the new jar file are the same as the original jar file, the new jar file will be byte for byte identical as the original jar file.

The following command will create the new.jar using the data in the directory directoryWithFiles and the metadata in the contents.yaml file.

java -jar cli.target/quarkus-app/quarkus-run.jar create -C directoryWithFiles contents.yaml new.jar 

Maven Plugin

To use with maven, first run the following to extract the metadata from a some.jar file:

mvn io.github.chirino:jar-cloner-maven-plugin:1.0.0-SNAPSHOT:extract -D jar-cloner.jar=some.jar

It will generate a src/main/jar-cloner.yaml file.

After that, assuming your target/classes directory contains the files you want to package into a new jar file, you can run:

mvn io.github.chirino:jar-cloner-maven-plugin:1.0.0-SNAPSHOT:repackage