SapMachine #2218: Add method to check if a path in zipfs is a symbolic link

Author: schmelter-sap

src/java.base/share/classes/jdk/internal/access/JdkNioZipfsAccess.java

@@ -0,0 +1,37 @@
+/*
+ * Copyright (c) 2026 SAP SE. All rights reserved.
+ * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
+ *
+ * This code is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License version 2 only, as
+ * published by the Free Software Foundation.  Oracle designates this
+ * particular file as subject to the "Classpath" exception as provided
+ * by Oracle in the LICENSE file that accompanied this code.
+ *
+ * This code is distributed in the hope that it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
+ * version 2 for more details (a copy is included in the LICENSE file that
+ * accompanied this code).
+ *
+ * You should have received a copy of the GNU General Public License version
+ * 2 along with this work; if not, write to the Free Software Foundation,
+ * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
+ *
+ * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
+ * or visit www.oracle.com if you need additional information or have any
+ * questions.
+ */
+
+package jdk.internal.access;
+
+import java.nio.file.Path;
+
+/**
+ * SharedSecrets interface used for the access from jdk.nio.zipfs
+ */
+
+public interface JdkNioZipfsAccess {
+
+    public boolean isSymbolicLink(Path path);
+}

src/java.base/share/classes/jdk/internal/access/SharedSecrets.java

@@ -109,6 +109,8 @@ public class SharedSecrets {
     @Stable private static JavaxCryptoSealedObjectAccess javaxCryptoSealedObjectAccess;
     @Stable private static JavaxCryptoSpecAccess javaxCryptoSpecAccess;
     @Stable private static JavaxSecurityAccess javaxSecurityAccess;
+	// SapMachine 2026-04-14: Support for symlink detection in zipfs.
+	@Stable private static JdkNioZipfsAccess jdkNioZipfsAccess;
 
     public static void setJavaUtilCollectionAccess(JavaUtilCollectionAccess juca) {
         javaUtilCollectionAccess = juca;
@@ -537,4 +539,14 @@ private static void ensureClassInitialized(Class<?> c) {
             MethodHandles.lookup().ensureInitialized(c);
         } catch (IllegalAccessException e) {}
     }
+
+    // SapMachine 2026-04-14
+    public static void setJdkNioZipfsAccess(JdkNioZipfsAccess access) {
+        jdkNioZipfsAccess = access;
+    }
+
+    // SapMachine 2026-04-14
+    public static JdkNioZipfsAccess getJdkNioZipfsAccess() {
+        return jdkNioZipfsAccess;
+    }
 }

src/java.base/share/classes/module-info.java

@@ -167,6 +167,8 @@
         jdk.net,
         // SapMachine 2024-06-12: process group extension
         jdk.sapext,
+        // SapMachine 2026-04-13: symlink support for zipfs entries in sapext.
+        jdk.zipfs,
         jdk.sctp,
         jdk.crypto.cryptoki;
     exports jdk.internal.classfile.components to

src/jdk.sapext/share/classes/com/sap/jdk/ext/util/ZipfsUtils.java

@@ -0,0 +1,54 @@
+/*
+ * Copyright (c) 2026 SAP SE. All rights reserved.
+ * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
+ *
+ * This code is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License version 2 only, as
+ * published by the Free Software Foundation.  Oracle designates this
+ * particular file as subject to the "Classpath" exception as provided
+ * by Oracle in the LICENSE file that accompanied this code.
+ *
+ * This code is distributed in the hope that it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
+ * version 2 for more details (a copy is included in the LICENSE file that
+ * accompanied this code).
+ *
+ * You should have received a copy of the GNU General Public License version
+ * 2 along with this work; if not, write to the Free Software Foundation,
+ * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
+ *
+ * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
+ * or visit www.oracle.com if you need additional information or have any
+ * questions.
+ */
+ package com.sap.jdk.ext.util;
+
+import java.nio.file.Path;
+
+import jdk.internal.access.JdkNioZipfsAccess;
+import jdk.internal.access.SharedSecrets;
+ 
+public class ZipfsUtils {
+
+    // Silence warning about implicit ctor.
+    private ZipfsUtils() {
+    }
+
+    /**
+     * Returns <code>true</code> if the given path is a <code>jdk.nio.zipfs.ZipPath</code> which
+     * represents a symbolic link.
+     *
+     * @param path The path in the zipfs.
+     * @return <code>true</code> if the path represents a symbolic link.
+     */
+    public static boolean isSymbolicLink(Path path) {
+        JdkNioZipfsAccess access = SharedSecrets.getJdkNioZipfsAccess();
+
+        if (access == null) {
+            return false;
+        }
+
+        return access.isSymbolicLink(path);
+    }
+}

src/jdk.zipfs/share/classes/jdk/nio/zipfs/ZipFileSystem.java

@@ -3649,4 +3649,17 @@ public boolean equals(Object other) {
                                  oname, 0, oname.length);
         }
     }
+
+    // SapMachine 2026-04-14: Returns true if the resolved path points to a symnbolic link.
+    boolean isSymlink(byte[] path) {
+        IndexNode inode = getInode(path);
+
+        if ((inode != null) && (inode.pos != -1)) {
+            long attrEx = ZipConstants.CENATX(cen, inode.pos);
+
+            return (attrEx & 0xF0000000L) ==  0xA0000000L;
+        }
+
+        return false;
+    }
 }

src/jdk.zipfs/share/classes/jdk/nio/zipfs/ZipPath.java

@@ -62,6 +62,25 @@ final class ZipPath implements Path {
     private volatile int[] offsets;
     private int hashcode = 0;  // cached hashcode (created lazily)
 
+    // SapMachine 2026-04-14: Support for symlink detection.
+    static class JdkNioZipfsAccessImpl implements jdk.internal.access.JdkNioZipfsAccess {
+        public boolean isSymbolicLink(Path path) {
+            if (!(path instanceof ZipPath)) {
+                return false;
+            }
+
+            ZipPath zipPath = (ZipPath) path;
+            byte[] resolvedPath = zipPath.getResolvedPath();
+
+            return zipPath.zfs.isSymlink(resolvedPath);
+        }
+    }
+
+    // SapMachine 2026-04-14: Support for symlink detection.
+    static {
+        jdk.internal.access.SharedSecrets.setJdkNioZipfsAccess(new JdkNioZipfsAccessImpl());
+    }
+
     ZipPath(ZipFileSystem zfs, byte[] path) {
         this(zfs, path, false);
     }

test/jdk/sap/ZipfsUtilsTest.java

@@ -0,0 +1,55 @@
+/*
+ * Copyright (c) 2026 SAP SE. All rights reserved.
+ * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
+ *
+ * This code is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License version 2 only, as
+ * published by the Free Software Foundation.
+ *
+ * This code is distributed in the hope that it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
+ * version 2 for more details (a copy is included in the LICENSE file that
+ * accompanied this code).
+ *
+ * You should have received a copy of the GNU General Public License version
+ * 2 along with this work; if not, write to the Free Software Foundation,
+ * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
+ *
+ * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
+ * or visit www.oracle.com if you need additional information or have any
+ * questions.
+ *
+ */
+
+/**
+ * @test
+ * @summary Runs the test for com.sap.jdk.ext.util.ZipfsUtils.
+ *
+ * @run junit ZipfsUtilsTest
+ */
+
+import java.io.File;
+import java.net.URI;
+import java.nio.file.FileSystem;
+import java.nio.file.FileSystems;
+import java.util.Map;
+
+import com.sap.jdk.ext.util.ZipfsUtils;
+
+import org.junit.jupiter.api.Test;
+
+import static org.junit.jupiter.api.Assertions.assertFalse;
+import static org.junit.jupiter.api.Assertions.assertTrue;
+
+public class ZipfsUtilsTest {
+
+    @Test
+    public void basicTest() throws Exception {
+        File file = new File(System.getProperty("test.src", "."), "zip-with-symlink.zip");
+        URI uri = new URI("jar", file.toURI().toString(), null);
+        FileSystem fs = FileSystems.newFileSystem(uri, Map.of());
+        assertFalse(ZipfsUtils.isSymbolicLink(fs.getPath("file")));
+        assertTrue(ZipfsUtils.isSymbolicLink(fs.getPath("symlink")));
+    }
+}