support for symbolic links

bundler/src/main/java/io/ib67/sfcraft/bundler/BundleEntry.java

@@ -15,5 +15,6 @@ public record BundleEntry(
         String name
 ) {
     public static short ATTR_REASSEMBLE = 1;
+    public static short ATTR_SYMLINK = 2;
     public static short MAGIC = (short) 0xA2E3;
 }

bundler/src/main/java/io/ib67/sfcraft/bundler/BundleReader.java

@@ -16,21 +16,24 @@ import java.util.HashMap;
 public class BundleReader {
     protected final long maxTime;
     protected final long minTime;
+    protected final boolean linkSymbol;
     private final byte[] buffer = new byte[4096];
     protected final boolean skipOldEntry;
     protected final ByteBufAllocator allocator;
     protected final byte[] dict;
 
     @Builder
-    public BundleReader(long maxTime, long minTime, boolean skipOldEntry, ByteBufAllocator allocator, byte[] dict) {
+    public BundleReader(long maxTime, long minTime, boolean linkSymbol, boolean skipOldEntry, ByteBufAllocator allocator, byte[] dict) {
         this.maxTime = maxTime == 0 ? Long.MAX_VALUE : maxTime;
         this.minTime = minTime;
+        this.linkSymbol = linkSymbol;
         this.skipOldEntry = skipOldEntry;
         this.allocator = allocator == null ? ByteBufAllocator.DEFAULT : allocator;
         this.dict = dict;
     }
 
     public void extract(Path bundle, Path destination) throws IOException {
+        var symbolsToLink = new HashMap<String, String>();
         var readMaps = new HashMap<String, Long>();
         try (var zstd = new ZstdInputStreamNoFinalizer(Files.newInputStream(bundle, StandardOpenOption.READ));
              var in = new EntryInputStream(zstd)) {
@@ -52,7 +55,14 @@ public class BundleReader {
                 var path = destination.resolve(entry.name()); // todo prevent path underflow
                 var parentDir = path.getParent();
                 if (Files.notExists(parentDir)) Files.createDirectories(parentDir);
-                if ((entry.attribute() & BundleEntry.ATTR_REASSEMBLE) != 0) {
+                if ((entry.attribute() & BundleEntry.ATTR_SYMLINK) != 0) {
+                    var toRead = (int) entry.length();
+                    var strArr = new byte[toRead];
+                    while ((toRead -= in.read(strArr, (int) (entry.length() - toRead), toRead)) > 0) ;
+                    var target = new String(strArr);
+                    var targetPath = Path.of(target);
+                    Files.createSymbolicLink(targetPath, path);
+                } else if ((entry.attribute() & BundleEntry.ATTR_REASSEMBLE) != 0) {
                     var entryData = allocator.buffer();
                     var toRead = entry.length();
                     var buffer = this.buffer;

bundler/src/main/java/io/ib67/sfcraft/bundler/BundleWriter.java

@@ -12,6 +12,7 @@ import lombok.Builder;
 import lombok.SneakyThrows;
 
 import java.io.*;
+import java.nio.charset.StandardCharsets;
 import java.nio.file.Files;
 import java.nio.file.Path;
 import java.util.*;
@@ -142,6 +143,11 @@ public class BundleWriter implements Closeable {
     }
 
     public void write(Path path, boolean suggestGunzip) throws IOException {
+        if(Files.isDirectory(path)) return;
+        if(Files.isSymbolicLink(path)) {
+            writeSymbol(path);
+            return;
+        }
         if (suggestGunzip && allowReassemble) {
             //todo size limit
             writeReassembleInMem(path);
@@ -150,6 +156,22 @@ public class BundleWriter implements Closeable {
         writePlain(path);
     }
 
+    private void writeSymbol(Path path) throws IOException {
+        if (!Files.isSymbolicLink(path)) return;
+        var target = Files.readSymbolicLink(path);
+        var rPath = relativeRoot.toAbsolutePath().relativize(path.toAbsolutePath());
+        String linkTarget;
+        try{
+            linkTarget = relativeRoot.relativize(target).toString();
+        } catch (Exception e) {
+            linkTarget = target.toAbsolutePath().toString();
+        }
+        var targetBytes = linkTarget.getBytes(StandardCharsets.UTF_8);
+
+        this.outputStream.writeEntryHeader(rPath.toString(), BundleEntry.ATTR_SYMLINK,targetBytes.length, System.currentTimeMillis());
+        this.outputStream.write(targetBytes);
+    }
+
     @SneakyThrows
     private void writeReassembleInMem(Path path) {
         if (!"region".equals(path.getParent().toString()) && !path.toString().endsWith(".mca")) { // todo use pattern matcher

bundler/src/main/java/io/ib67/sfcraft/bundler/Main.java

@@ -31,7 +31,7 @@ public class Main {
         var out = opts.string("out", "Output. Can be jpack bundle or directory", null);
         var help = opts.bool("help", false);
         var allowGunzip = opts.bool("reasm", "Should we reassemble NBT files for maximum compression rate", true);
-
+        var linkSymbol = opts.bool("link","Should we store/decompress symbol links? This may set you vulnerable if you're decompressing a malformed archive.", true);
         // useless parallel
         var parallel = opts.bool("parallel", "Use parallelized bundler. This conflicts with compress options", false);
         var parallelThreshold = opts.integer("threshold", "The threshold of parallel bundling", 512);
@@ -82,7 +82,7 @@ public class Main {
         }
 
         if (in.endsWith(".swb.zst")) {
-            BundleReader.builder().build().extract(inPath, outPath);
+            BundleReader.builder().linkSymbol(linkSymbol).build().extract(inPath, outPath);
         } else if (out.endsWith(".swb.zst")) {
             UnaryOperator<BundleWriter.BundleWriterBuilder> cfg = it -> it
                     .allowGunzip(allowGunzip)