8371292: [lworld] Switch JLink to not use ImageReader API

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

@@ -37,8 +37,12 @@
 import java.nio.file.StandardOpenOption;
 import java.security.AccessController;
 import java.security.PrivilegedAction;
+import java.util.NoSuchElementException;
 import java.util.Objects;
+import java.util.function.Predicate;
 import java.util.stream.IntStream;
+import java.util.stream.Stream;
+
 import jdk.internal.jimage.decompressor.Decompressor;
 
 /**
@@ -326,6 +330,58 @@ public String[] getEntryNames() {
                         .toArray(String[]::new);
     }
 
+    /**
+     * Returns the "raw" API for accessing underlying jimage resource entries.
+     *
+     * <p>This is only meaningful for use by code dealing directly with jimage
+     * files, and cannot be used to reliably lookup resources used at runtime.
+     *
+     * <p>This API remains valid until the image reader from which it was
+     * obtained is closed.
+     */
+    // Package visible for use by ImageReader.
+    ResourceEntries getResourceEntries() {
+        return new ResourceEntries() {
+            @Override
+            public Stream<String> entryNamesIn(String module) {
+                if (module.isEmpty() || module.equals("modules") || module.equals("packages")) {
+                    throw new IllegalArgumentException("Invalid module name: " + module);
+                }
+                return IntStream.range(0, offsets.capacity())
+                        .map(offsets::get)
+                        .filter(offset -> offset != 0)
+                        // Reusing a location instance or getting the module
+                        // offset directly would save a lot of allocations here.
+                        .mapToObj(offset -> ImageLocation.readFrom(BasicImageReader.this, offset))
+                        // Reverse lookup of module offset would be faster here.
+                        .filter(loc -> module.equals(loc.getModule()))
+                        .map(ImageLocation::getFullName);
+            }
+
+            private ImageLocation getResourceLocation(String name) {
+                // Other types of invalid name just result in no entry being found.
+                if (name.startsWith("/modules/") || name.startsWith("/packages/")) {
+                    throw new IllegalArgumentException("Invalid entry name: " + name);
+                }
+                ImageLocation location = BasicImageReader.this.findLocation(name);
+                if (location == null) {
+                    throw new NoSuchElementException("No such resource entry: " + name);
+                }
+                return location;
+            }
+
+            @Override
+            public long sizeOf(String name) {
+                return getResourceLocation(name).getUncompressedSize();
+            }
+
+            @Override
+            public InputStream open(String name) {
+                return BasicImageReader.this.getResourceStream(getResourceLocation(name));
+            }
+        };
+    }
+
     ImageLocation getLocation(int offset) {
         return ImageLocation.readFrom(this, offset);
     }

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/ImageReader.java

@@ -230,6 +230,11 @@ public ByteBuffer getResourceBuffer(Node node) {
         return reader.getResourceBuffer(node.getLocation());
     }
 
+    // Package protected for use only by SystemImageReader.
+    ResourceEntries getResourceEntries() {
+        return reader.getResourceEntries();
+    }
+
     private static final class SharedImageReader extends BasicImageReader {
         // There are >30,000 nodes in a complete jimage tree, and even relatively
         // common tasks (e.g. starting up javac) load somewhere in the region of

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
@@ -118,7 +117,7 @@ public String name() {
      * under many modules, it only has resources in one.
      */
     public boolean hasResources() {
-        return ((flags & FLAGS_PKG_HAS_RESOURCES) != 0);
+        return (flags & FLAGS_PKG_HAS_RESOURCES) != 0;
     }
 
     /**
@@ -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/java.base/share/classes/jdk/internal/jimage/PreviewMode.java

@@ -56,6 +56,9 @@ public enum PreviewMode {
      * Resolves whether preview mode should be enabled for an {@link ImageReader}.
      */
     public boolean isPreviewModeEnabled() {
+        if (!ENABLE_PREVIEW_MODE) {
+            return false;
+        }
         // A switch, instead of an abstract method, saves 3 subclasses.
         switch (this) {
             case DISABLED:
@@ -83,4 +86,14 @@ public boolean isPreviewModeEnabled() {
                 throw new IllegalStateException("Invalid mode: " + this);
         }
     }
+    ;
+
+    // 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)));
 }

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

@@ -0,0 +1,41 @@
+package jdk.internal.jimage;
+
+import java.io.InputStream;
+import java.util.stream.Stream;
+
+/**
+ * Accesses the underlying resource entries in a jimage file.
+ *
+ * <p>This API is designed only for use by the jlink classes, which manipulate
+ * jimage files directly. For inspection of runtime resources, it is vital that
+ * {@code previewMode} is correctly observed, making this API unsuitable.
+ *
+ * <p>This API ignores the {@code previewMode} of the {@link ImageReader} from
+ * which it is obtained, and returns an unmapped view of entries (e.g. allowing
+ * for direct access of resources in the {@code META-INF/preview/...} namespace).
+ *
+ * <p>It disallows access to resource directories (i.e. {@code "/modules/..."}
+ * or packages (i.e. {@code "/packages/..."}.
+ */
+public interface ResourceEntries {
+    /**
+     * Returns the full entry names for all resources in the given module, in
+     * random order. Entry names will always be prefixed by the given module
+     * name (e.g. "/<module-name/...").
+     */
+    Stream<String> entryNamesIn(String module);
+
+    /**
+     * Returns the (uncompressed) size of a resource given its full entry name.
+     *
+     * @throws java.util.NoSuchElementException if the resource does not exist.
+     */
+    long sizeOf(String name);
+
+    /**
+     * Returns an {@link InputStream} for a resource given its full entry name.
+     *
+     * @throws java.util.NoSuchElementException if the resource does not exist.
+     */
+    InputStream open(String name);
+}

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

@@ -73,5 +73,15 @@ public static ImageReader get() {
         return SYSTEM_IMAGE_READER;
     }
 
+    /**
+     * Returns the "raw" API for accessing underlying jimage resource entries.
+     *
+     * <p>This is only meaningful for use by code dealing directly with jimage
+     * files, and cannot be used to reliably lookup resources used at runtime.
+     */
+    public static ResourceEntries getResourceEntries() {
+        return get().getResourceEntries();
+    }
+
     private SystemImageReader() {}
 }

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/Archive.java

@@ -24,6 +24,7 @@
  */
 package jdk.tools.jlink.internal;
 
+import java.io.Closeable;
 import java.io.IOException;
 import java.io.InputStream;
 import java.nio.file.Path;
@@ -34,7 +35,7 @@
  * An Archive of all content, classes, resources, configuration files, and
  * other, for a module.
  */
-public interface Archive {
+public interface Archive extends Closeable {
 
     /**
      * Entry is contained in an Archive
@@ -59,11 +60,12 @@ public static enum EntryType {
         private final String path;
 
         /**
-         * Constructs an entry of the given archive
-         * @param archive archive
-         * @param path
-         * @param name an entry name that does not contain the module name
-         * @param type
+         * Constructs an entry of the given archive.
+         *
+         * @param archive the archive in which this entry exists.
+         * @param path the complete path of the entry, including the module.
+         * @param name an entry name relative to its containing module.
+         * @param type the entry type.
          */
         public Entry(Archive archive, String path, String name, EntryType type) {
             this.archive = Objects.requireNonNull(archive);
@@ -72,10 +74,6 @@ public Entry(Archive archive, String path, String name, EntryType type) {
             this.type = Objects.requireNonNull(type);
         }
 
-        public final Archive archive() {
-            return archive;
-        }
-
         public final EntryType type() {
             return type;
         }
@@ -134,5 +132,6 @@ public String toString() {
     /*
      * Close the archive
      */
+    @Override
     void close() throws IOException;
 }