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

@@ -35,12 +35,16 @@
  import java.nio.channels.FileChannel;
  import java.nio.file.Path;
  import java.nio.file.StandardOpenOption;
  import java.security.AccessController;
  import java.security.PrivilegedAction;
+ import java.util.NoSuchElementException;
  import java.util.Objects;
+ import java.util.Random;
  import java.util.stream.IntStream;
+ import java.util.stream.Stream;
+ 
  import jdk.internal.jimage.decompressor.Decompressor;
  
  /**
   * @implNote This class needs to maintain JDK 8 source compatibility.
   *

@@ -315,17 +319,66 @@
              return -1;
          }
      }
  
      public String[] getEntryNames() {
-         int[] attributeOffsets = new int[offsets.capacity()];
-         offsets.get(attributeOffsets);
-         return IntStream.of(attributeOffsets)
-                         .filter(o -> o != 0)
-                         .mapToObj(o -> ImageLocation.readFrom(this, o).getFullName())
-                         .sorted()
-                         .toArray(String[]::new);
+         return IntStream.range(0, offsets.capacity())
+                 .map(offsets::get)
+                 .filter(o -> o != 0)
+                 .mapToObj(o -> ImageLocation.readFrom(this, o).getFullName())
+                 .sorted()
+                 .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> getEntryNames(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) {
+                 if (!name.startsWith("/modules/") && !name.startsWith("/packages/")) {
+                     ImageLocation location = BasicImageReader.this.findLocation(name);
+                     if (location != null) {
+                         return location;
+                     }
+                 }
+                 throw new NoSuchElementException("No such resource entry: " + name);
+             }
+ 
+             @Override
+             public long getSize(String name) {
+                 return getResourceLocation(name).getUncompressedSize();
+             }
+ 
+             @Override
+             public byte[] getBytes(String name) {
+                 return BasicImageReader.this.getResource(getResourceLocation(name));
+             }
+         };
      }
  
      ImageLocation getLocation(int offset) {
          return ImageLocation.readFrom(this, offset);
      }