jimage writer changes to support preview mode.

src/java.base/share/classes/jdk/internal/jimage/ImageLocation.java

@@ -26,6 +26,7 @@
 package jdk.internal.jimage;
 
 import java.nio.ByteBuffer;
+import java.util.List;
 import java.util.Objects;
 import java.util.function.Predicate;
 
@@ -159,6 +160,29 @@ public static int getFlags(String name, Predicate<String> hasEntry) {
         }
     }
 
+     /**
+      * Helper function to calculate package flags for {@code "/packages/xxx"}
+      * directory entries.
+      *
+      * <p>Based on the module references, the flags are:
+      * <ul>
+      *     <li>{@code FLAGS_HAS_PREVIEW_VERSION} if <em>any</em> referenced
+      *     package has a preview version.
+      *     <li>{@code FLAGS_IS_PREVIEW_ONLY} if <em>all</em> referenced packages
+      *     are preview only.
+      * </ul>
+      *
+      * @return package flags for {@code "/packages/xxx"} directory entries.
+      */
+     public static int getPackageFlags(List<ModuleReference> moduleReferences) {
+        boolean hasPreviewVersion =
+                moduleReferences.stream().anyMatch(ModuleReference::hasPreviewVersion);
+        boolean isPreviewOnly =
+                moduleReferences.stream().allMatch(ModuleReference::isPreviewOnly);
+        return (hasPreviewVersion ? ImageLocation.FLAGS_HAS_PREVIEW_VERSION : 0)
+                | (isPreviewOnly ? ImageLocation.FLAGS_IS_PREVIEW_ONLY : 0);
+    }
+
     /**
      * Tests a non-preview image location's flags to see if it has preview
      * content associated with it.

src/java.base/share/classes/jdk/internal/jimage/ModuleReference.java

@@ -53,8 +53,7 @@ public final class ModuleReference implements Comparable<ModuleReference> {
     /** If set, this package exists in non-preview mode. */
     private static final int FLAGS_PKG_HAS_NORMAL_VERSION = 0x2;
     /** If set, the associated module has resources (in normal or preview mode). */
-    // TODO: Make this private again when image writer code is updated.
-    public static final int FLAGS_PKG_HAS_RESOURCES = 0x4;
+    private static final int FLAGS_PKG_HAS_RESOURCES = 0x4;
 
     /**
      * References are ordered with preview versions first which permits early
@@ -176,9 +175,9 @@ public static Iterator<Integer> readNameOffsets(
         if (bufferSize == 0 || (bufferSize & 0x1) != 0) {
             throw new IllegalArgumentException("Invalid buffer size");
         }
-        int testFlags = (includeNormal ? FLAGS_PKG_HAS_NORMAL_VERSION : 0)
+        int includeMask = (includeNormal ? FLAGS_PKG_HAS_NORMAL_VERSION : 0)
                 + (includePreview ? FLAGS_PKG_HAS_PREVIEW_VERSION : 0);
-        if (testFlags == 0) {
+        if (includeMask == 0) {
             throw new IllegalArgumentException("Invalid flags");
         }
 
@@ -188,14 +187,7 @@ public static Iterator<Integer> readNameOffsets(
             int nextIdx(int idx) {
                 for (; idx < bufferSize; idx += 2) {
                     // If any of the test flags are set, include this entry.
-
-                    // Temporarily allow for *neither* flag to be set. This is what would
-                    // be written by a 1.0 version of the jimage flag, and indicates a
-                    // normal resource without a preview version.
-                    // TODO: Remove the zero-check below once image writer code is updated.
-                    int previewFlags =
-                            buffer.get(idx) & (FLAGS_PKG_HAS_NORMAL_VERSION | FLAGS_PKG_HAS_PREVIEW_VERSION);
-                    if (previewFlags == 0 || (previewFlags & testFlags) != 0) {
+                    if ((buffer.get(idx) & includeMask) != 0) {
                         return idx;
                     } else if (!includeNormal) {
                         // Preview entries are first in the offset buffer, so we

src/jdk.jlink/share/classes/jdk/tools/jlink/internal/BasicImageWriter.java

@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2014, 2020, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2014, 2025, Oracle and/or its affiliates. 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
@@ -29,6 +29,7 @@
 import java.util.ArrayList;
 import java.util.List;
 import java.util.Objects;
+
 import jdk.internal.jimage.ImageHeader;
 import jdk.internal.jimage.ImageStream;
 import jdk.internal.jimage.ImageStringsReader;
@@ -76,10 +77,10 @@ public String getString(int offset) {
     }
 
     public void addLocation(String fullname, long contentOffset,
-            long compressedSize, long uncompressedSize) {
+                            long compressedSize, long uncompressedSize, int previewFlags) {
         ImageLocationWriter location =
                 ImageLocationWriter.newLocation(fullname, strings,
-                        contentOffset, compressedSize, uncompressedSize);
+                        contentOffset, compressedSize, uncompressedSize, previewFlags);
         input.add(location);
         length++;
     }
@@ -94,7 +95,7 @@ int getLocationsCount() {
 
     private void generatePerfectHash() {
         PerfectHashBuilder<ImageLocationWriter> builder =
-            new PerfectHashBuilder<>(
+                new PerfectHashBuilder<>(
                         PerfectHashBuilder.Entry.class,
                         PerfectHashBuilder.Bucket.class);