8368467: [lworld] Add new flag generation for jimage to support preview mode

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

@@ -442,13 +442,7 @@ public LocationType getType() {
             case ImageStrings.EMPTY_STRING_OFFSET:
                 // Only 2 choices, either the "/modules" or "/packages" root.
                 assert isRootDir() : "Invalid root directory: " + getFullName();
-
-                // Temporary logic to handle package root classification until new
-                // image reader code is committed which sets FLAGS_IS_PACKAGE_ROOT.
-                // Base name is "/packages" or "/modules" (NOT "packages" and "modules").
-                // TODO: Uncomment the FLAGS_IS_PACKAGE_ROOT test below.
-                // return (getFlags() & FLAGS_IS_PACKAGE_ROOT) != 0
-                return getBase().charAt(1) == 'p'
+                return (getFlags() & FLAGS_IS_PACKAGE_ROOT) != 0
                         ? LocationType.PACKAGES_ROOT
                         : LocationType.MODULES_ROOT;
             default:

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

@@ -52,11 +52,7 @@
  * to the jimage file provided by the shipped JDK by tools running on JDK 8.
  */
 public final class ModuleReference implements Comparable<ModuleReference> {
-    // The following flags are designed to be additive (hence "has-resources"
-    // rather than "is-empty", even though "isEmpty()" is whats in the API).
-    // API methods like "isEmpty()" and "hasPreviewVersion()" are designed to
-    // match the semantics of ImageLocation flags to avoid having business
-    // logic need to reason about two different flag regimes.
+    // The following flags are designed to be additive.
 
     /** If set, the associated module has resources (in normal or preview mode). */
     private static final int FLAGS_HAS_CONTENT = 0x1;
@@ -192,14 +188,7 @@ 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_HAS_NORMAL_VERSION | FLAGS_HAS_PREVIEW_VERSION);
-                    if (previewFlags == 0 || (previewFlags & testFlags) != 0) {
+                    if ((buffer.get(idx) & testFlags) != 0) {
                         return idx;
                     } else if (!includeNormal) {
                         // Preview entries are first in the offset buffer, so we

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

@@ -53,7 +53,7 @@ boolean resolve() {
     ENABLED() {
         @Override
         boolean resolve() {
-            return true;
+            return ENABLE_PREVIEW_MODE;
         }
     },
     /**
@@ -63,6 +63,9 @@ boolean resolve() {
     FOR_RUNTIME() {
         @Override
         boolean resolve() {
+            if (!ENABLE_PREVIEW_MODE) {
+                return false;
+            }
             // We want to call jdk.internal.misc.PreviewFeatures.isEnabled(), but
             // is not available in older JREs, so we must look to it reflectively.
             Class<?> clazz;
@@ -81,6 +84,15 @@ boolean resolve() {
         }
     };
 
+    // Temporary system property to disable preview patching and enable the new preview mode
+    // feature for testing/development. Once the preview mode feature is finished, the value
+    // will be always 'true' and this code, and all related dead-code can be removed.
+    private static final boolean DISABLE_PREVIEW_PATCHING_DEFAULT = false;
+    private static final boolean ENABLE_PREVIEW_MODE = Boolean.parseBoolean(
+            System.getProperty(
+                    "DISABLE_PREVIEW_PATCHING",
+                    Boolean.toString(DISABLE_PREVIEW_PATCHING_DEFAULT)));
+
     /**
      * Resolves whether preview mode should be enabled for an {@link ImageReader}.
      */

src/java.base/share/native/libjimage/imageFile.cpp

@@ -319,12 +319,7 @@ bool ImageFileReader::open() {
         !read_at((u1*)&_header, header_size, 0) ||
         _header.magic(_endian) != IMAGE_MAGIC ||
         _header.major_version(_endian) != MAJOR_VERSION ||
-        // Temporarily, we allow either version (1.1 or 1.0) of the file to
-        // be read so this code can be committed before image writing changes
-        // for preview mode. Preview mode changes do not modify any structure,
-        // so a 1.0 file will look like a jimage without any preview resources.
-        // TODO: Restore equality check for MINOR_VERSION.
-        _header.minor_version(_endian) > MINOR_VERSION) {
+        _header.minor_version(_endian) != MINOR_VERSION) {
         close();
         return false;
     }

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
@@ -76,10 +76,10 @@ 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++;
     }

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

@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2014, 2024, 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
@@ -49,6 +49,7 @@
 import java.util.stream.Collectors;
 import java.util.stream.Stream;
 
+import jdk.internal.jimage.ImageLocation;
 import jdk.tools.jlink.internal.Archive.Entry;
 import jdk.tools.jlink.internal.Archive.Entry.EntryType;
 import jdk.tools.jlink.internal.JRTArchive.ResourceFileEntry;
@@ -227,31 +228,8 @@ private static ResourcePool generateJImage(ResourcePoolManager allContent,
             DataOutputStream out,
             boolean generateRuntimeImage
     ) throws IOException {
-        ResourcePool resultResources;
-        try {
-            resultResources = pluginSupport.visitResources(allContent);
-            if (generateRuntimeImage) {
-                // Keep track of non-modules resources for linking from a run-time image
-                resultResources = addNonClassResourcesTrackFiles(resultResources,
-                                                                 writer);
-                // Generate the diff between the input resources from packaged
-                // modules in 'allContent' to the plugin- or otherwise
-                // generated-content in 'resultResources'
-                resultResources = addResourceDiffFiles(allContent.resourcePool(),
-                                                       resultResources,
-                                                       writer);
-            }
-        } catch (PluginException pe) {
-            if (JlinkTask.DEBUG) {
-                pe.printStackTrace();
-            }
-            throw pe;
-        } catch (Exception ex) {
-            if (JlinkTask.DEBUG) {
-                ex.printStackTrace();
-            }
-            throw new IOException(ex);
-        }
+        ResourcePool resultResources =
+                getResourcePool(allContent, writer, pluginSupport, generateRuntimeImage);
         Set<String> duplicates = new HashSet<>();
         long[] offset = new long[1];
 
@@ -282,8 +260,10 @@ private static ResourcePool generateJImage(ResourcePoolManager allContent,
                     offset[0] += onFileSize;
                     return;
                 }
+                int locFlags = ImageLocation.getFlags(
+                        res.path(), p -> resultResources.findEntry(p).isPresent());
                 duplicates.add(path);
-                writer.addLocation(path, offset[0], compressedSize, uncompressedSize);
+                writer.addLocation(path, offset[0], compressedSize, uncompressedSize, locFlags);
                 paths.add(path);
                 offset[0] += onFileSize;
             }
@@ -307,6 +287,40 @@ private static ResourcePool generateJImage(ResourcePoolManager allContent,
         return resultResources;
     }
 
+    private static ResourcePool getResourcePool(
+            ResourcePoolManager allContent,
+            BasicImageWriter writer,
+            ImagePluginStack pluginSupport,
+            boolean generateRuntimeImage)
+            throws IOException {
+        ResourcePool resultResources;
+        try {
+            resultResources = pluginSupport.visitResources(allContent);
+            if (generateRuntimeImage) {
+                // Keep track of non-modules resources for linking from a run-time image
+                resultResources = addNonClassResourcesTrackFiles(resultResources,
+                        writer);
+                // Generate the diff between the input resources from packaged
+                // modules in 'allContent' to the plugin- or otherwise
+                // generated-content in 'resultResources'
+                resultResources = addResourceDiffFiles(allContent.resourcePool(),
+                        resultResources,
+                        writer);
+            }
+        } catch (PluginException pe) {
+            if (JlinkTask.DEBUG) {
+                pe.printStackTrace();
+            }
+            throw pe;
+        } catch (Exception ex) {
+            if (JlinkTask.DEBUG) {
+                ex.printStackTrace();
+            }
+            throw new IOException(ex);
+        }
+        return resultResources;
+    }
+
     /**
      * Support for creating a runtime suitable for linking from the run-time
      * image.

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

@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2014, 2017, 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
@@ -54,8 +54,8 @@ private ImageLocationWriter addAttribute(int kind, String value) {
     }
 
     static ImageLocationWriter newLocation(String fullName,
-            ImageStringsWriter strings,
-            long contentOffset, long compressedSize, long uncompressedSize) {
+                                           ImageStringsWriter strings,
+                                           long contentOffset, long compressedSize, long uncompressedSize, int previewFlags) {
         String moduleName = "";
         String parentName = "";
         String baseName;
@@ -90,13 +90,14 @@ static ImageLocationWriter newLocation(String fullName,
         }
 
         return new ImageLocationWriter(strings)
-               .addAttribute(ATTRIBUTE_MODULE, moduleName)
-               .addAttribute(ATTRIBUTE_PARENT, parentName)
-               .addAttribute(ATTRIBUTE_BASE, baseName)
-               .addAttribute(ATTRIBUTE_EXTENSION, extensionName)
-               .addAttribute(ATTRIBUTE_OFFSET, contentOffset)
-               .addAttribute(ATTRIBUTE_COMPRESSED, compressedSize)
-               .addAttribute(ATTRIBUTE_UNCOMPRESSED, uncompressedSize);
+                .addAttribute(ATTRIBUTE_MODULE, moduleName)
+                .addAttribute(ATTRIBUTE_PARENT, parentName)
+                .addAttribute(ATTRIBUTE_BASE, baseName)
+                .addAttribute(ATTRIBUTE_EXTENSION, extensionName)
+                .addAttribute(ATTRIBUTE_OFFSET, contentOffset)
+                .addAttribute(ATTRIBUTE_COMPRESSED, compressedSize)
+                .addAttribute(ATTRIBUTE_UNCOMPRESSED, uncompressedSize)
+                .addAttribute(ATTRIBUTE_PREVIEW_FLAGS, previewFlags);
     }
 
     @Override