Unable to zip symlinks that link to directories Zip4j

Question

With Zip4j, I've been able to successfully zip symlinks that link to regular files correctly. However, symlinks that link to directories aren't working for me. Keep in mind that I'm trying to mirror the following shell command from Info-ZIP: zip -yr someDirectory.

Toy example:

I created one directory with a symlink to it and a regular file with a symlink to it like so:

$ mkdir tmp
$ cd tmp
$ mkdir a; ln -s a b; touch c; ln -s c d
$ cd ..
$ tree tmp
tmp
├── a
├── b -> a
├── c
└── d -> c

Ideally what would happen is the following:

$ zip -yr tmp.zip tmp
$ unzip tmp.zip -d newtmp
Archive:  tmp.zip
   creating: newtmp/tmp/
   creating: newtmp/tmp/a/
 extracting: newtmp/tmp/c            
    linking: newtmp/tmp/d            -> c 
    linking: newtmp/tmp/b            -> a 
finishing deferred symbolic links:
  newtmp/tmp/d           -> c
  newtmp/tmp/b           -> a
$ tree newtmp 
newtmp
└── tmp
    ├── a
    ├── b -> a
    ├── c
    └── d -> c

I then attempted to use Zip4j to zip these files.

For symlinks, I call setSymbolicLinkAction with INCLUDE_LINK_ONLY and manually set CompressionLevel.NO_COMPRESSION and CompressionMethod.STORE. I also set the filename for directories such that they are appended with a /.

import net.lingala.zip4j.ZipFile;
import net.lingala.zip4j.exception.ZipException;
import net.lingala.zip4j.model.ZipParameters;
import net.lingala.zip4j.model.enums.CompressionLevel;
import net.lingala.zip4j.model.enums.CompressionMethod;

import java.io.IOException;
import java.nio.file.Files;
import java.nio.file.Path;
import java.nio.file.Paths;
import java.util.stream.Stream;

public class ZipTest {
    public static void main(String[] args) throws IOException {
        try (ZipFile zipFile = new ZipFile("test.zip");
             Stream<Path> paths = Files.walk(Paths.get("tmp"))) {
            paths.forEach(path -> {
                ZipParameters zp = new ZipParameters();
                if ((!Files.isSymbolicLink(path)) && Files.isDirectory(path)) {
                    zp.setFileNameInZip(path + "/");
                } else {
                    zp.setFileNameInZip(path.toString());
                }
                if (Files.isSymbolicLink(path)) {
                    zp.setSymbolicLinkAction(ZipParameters.SymbolicLinkAction.INCLUDE_LINK_ONLY);
                    zp.setCompressionLevel(CompressionLevel.NO_COMPRESSION);
                    zp.setCompressionMethod(CompressionMethod.STORE);
                }
                try {
                    zipFile.addFile(path.toFile(), zp);
                } catch (ZipException e) {
                    throw new RuntimeException(e);
                }
            });
        }
    }
}

Unzipping output:

$ unzip test.zip -d test   
Archive:  test.zip
   creating: test/tmp/
   creating: test/tmp/a/
 extracting: test/tmp/c              
    linking: test/tmp/d              -> c 
 extracting: test/tmp/b              
finishing deferred symbolic links:
  test/tmp/d             -> c

That didn't work. The symlink b to directory a did not stay a symlink. I've also tried:

• allowing symlinks identified as directories to have / in their file name.
• zip parameters without setting compression
• calling the addFolder API on just the input directory

and nothing has worked so far.

Answer 1

This is now a known bug in Zip4j. See https://github.com/srikanth-lingala/zip4j/issues/486.