Add close() methods throughout the SecureJar->JarContents chain to allow closing the backing file systems

src/main/java/cpw/mods/jarhandling/JarContents.java

@@ -2,6 +2,7 @@
 
 import org.jetbrains.annotations.ApiStatus;
 
+import java.io.IOException;
 import java.net.URI;
 import java.nio.file.Path;
 import java.util.Collection;
@@ -18,7 +19,7 @@
  * Convert to a full jar with {@link SecureJar#from(JarContents)}.
  */
 @ApiStatus.NonExtendable
-public interface JarContents {
+public interface JarContents extends AutoCloseable {
     /**
      * @see SecureJar#getPrimaryPath()
      */
@@ -69,4 +70,10 @@ static JarContents of(Path fileOrFolder) {
     static JarContents of(Collection<Path> filesOrFolders) {
         return new JarContentsBuilder().paths(filesOrFolders.toArray(new Path[0])).build();
     }
+
+    /**
+     * Closes the underlying resources.
+     */
+    @Override
+    void close() throws IOException;
 }

src/main/java/cpw/mods/jarhandling/SecureJar.java

@@ -17,10 +17,6 @@
 import java.security.CodeSigner;
 import java.util.List;
 import java.util.Optional;
-import java.util.Set;
-import java.util.function.BiPredicate;
-import java.util.function.Function;
-import java.util.function.Supplier;
 import java.util.jar.Attributes;
 import java.util.jar.Manifest;
 
@@ -86,6 +82,12 @@ static SecureJar from(JarContents contents, JarMetadata metadata) {
      */
     Path getRootPath();
 
+    /**
+     * Closes the underlying file system resources (if any).
+     * Renders this object unusable.
+     */
+    void close() throws IOException;
+
     /**
      * All the functions that are necessary to turn a {@link SecureJar} into a module.
      */

src/main/java/cpw/mods/jarhandling/VirtualJar.java

@@ -4,6 +4,7 @@
 import cpw.mods.niofs.union.UnionFileSystemProvider;
 import org.jetbrains.annotations.Nullable;
 
+import java.io.IOException;
 import java.io.InputStream;
 import java.lang.module.ModuleDescriptor;
 import java.net.URI;
@@ -106,6 +107,11 @@ public Path getRootPath() {
         return dummyFileSystem.getRoot();
     }
 
+    @Override
+    public void close() throws IOException {
+        dummyFileSystem.close();
+    }
+
     private class VirtualJarModuleDataProvider implements ModuleDataProvider {
         @Override
         public String name() {

src/main/java/cpw/mods/jarhandling/impl/Jar.java

@@ -3,10 +3,10 @@
 import cpw.mods.jarhandling.JarMetadata;
 import cpw.mods.jarhandling.SecureJar;
 import cpw.mods.niofs.union.UnionFileSystem;
-import cpw.mods.niofs.union.UnionPathFilter;
 import cpw.mods.util.LambdaExceptionUtils;
 import org.jetbrains.annotations.Nullable;
 
+import java.io.IOException;
 import java.io.InputStream;
 import java.lang.module.ModuleDescriptor;
 import java.net.URI;
@@ -104,6 +104,11 @@ public Path getRootPath() {
         return filesystem.getPath("");
     }
 
+    @Override
+    public void close() throws IOException {
+        contents.close();
+    }
+
     @Override
     public String toString() {
         return "Jar[" + getURI() + "]";

src/main/java/cpw/mods/jarhandling/impl/JarContentsImpl.java

@@ -218,4 +218,9 @@ public List<SecureJar.Provider> getMetaInfServices() {
         }
         return this.providers;
     }
+
+    @Override
+    public void close() throws IOException {
+        filesystem.close();
+    }
 }

src/main/java/cpw/mods/niofs/union/UnionFileSystem.java

@@ -155,8 +155,23 @@ public UnionFileSystemProvider provider() {
     }
 
     @Override
-    public void close() {
+    public void close() throws IOException {
         provider().removeFileSystem(this);
+        IOException closeException = null;
+        for (var embeddedFs : embeddedFileSystems.values()) {
+            try {
+                embeddedFs.fs.close();
+            } catch (IOException e) {
+                if (closeException != null) {
+                    closeException.addSuppressed(e);
+                } else {
+                    closeException = e;
+                }
+            }
+        }
+        if (closeException != null) {
+            throw closeException;
+        }
     }
 
     @Override

src/test/java/cpw/mods/jarhandling/impl/TestDummyJarProvider.java

@@ -13,11 +13,9 @@
 import java.lang.module.Configuration;
 import java.lang.module.ModuleDescriptor;
 import java.lang.module.ModuleFinder;
-import java.lang.module.ResolvedModule;
 import java.net.URI;
 import java.nio.file.Path;
 import java.security.CodeSigner;
-import java.util.Arrays;
 import java.util.List;
 import java.util.Optional;
 import java.util.Set;
@@ -133,5 +131,9 @@ public Path getPath(final String first, final String... rest) {
         public Path getRootPath() {
             return null;
         }
+
+        @Override
+        public void close() {
+        }
     }
 }

src/test/java/cpw/mods/jarhandling/impl/TestMetadata.java

@@ -70,5 +70,9 @@ public Set<String> getPackagesExcluding(String... excludedRootPackages) {
         public List<SecureJar.Provider> getMetaInfServices() {
             return List.of();
         }
+
+        @Override
+        public void close() {
+        }
     }
 }