8259634: MemorySegment::asByteBuffer does not respect spatial bounds

Reviewed-by: alanb, chegar

src/java.base/share/classes/java/nio/Buffer.java

@@ -793,7 +793,7 @@ public ByteBuffer newMappedByteBuffer(UnmapperProxy unmapperProxy, long address,
 
                 @Override
                 public ByteBuffer newHeapByteBuffer(byte[] hb, int offset, int capacity, MemorySegmentProxy segment) {
-                    return new HeapByteBuffer(hb, offset, capacity, segment);
+                    return new HeapByteBuffer(hb, -1, 0, capacity, capacity, offset, segment);
                 }
 
                 @Override

test/jdk/java/foreign/TestByteBuffer.java

@@ -64,13 +64,15 @@
 import java.nio.file.StandardOpenOption;
 import java.util.ArrayList;
 import java.util.HashMap;
+import java.util.Iterator;
 import java.util.List;
 import java.util.Map;
 import java.util.function.BiConsumer;
 import java.util.function.BiFunction;
 import java.util.function.Consumer;
 import java.util.function.Function;
 import java.util.function.Predicate;
+import java.util.function.Supplier;
 import java.util.stream.Stream;
 
 import jdk.internal.foreign.HeapMemorySegmentImpl;
@@ -635,7 +637,8 @@ public void testIOOnClosedConfinedSegmentBuffer() throws IOException {
         }
     }
 
-    public void testIOOnClosedConfinedSegment() throws IOException {
+    @Test
+    public void testIOOnConfinedSegment() throws IOException {
         File tmp = File.createTempFile("tmp", "txt");
         tmp.deleteOnExit();
         try (FileChannel channel = FileChannel.open(tmp.toPath(), StandardOpenOption.WRITE)) {
@@ -648,6 +651,31 @@ public void testIOOnClosedConfinedSegment() throws IOException {
         }
     }
 
+    @Test(dataProvider="segments")
+    public void buffersAndArraysFromSlices(Supplier<MemorySegment> segmentSupplier) {
+        try (MemorySegment segment = segmentSupplier.get()) {
+            int newSize = 8;
+            var slice = segment.asSlice(4, newSize);
+
+            var bytes = slice.toByteArray();
+            assertEquals(newSize, bytes.length);
+
+            var buffer = slice.asByteBuffer();
+            // Fails for heap segments, but passes for native segments:
+            assertEquals(0, buffer.position());
+            assertEquals(newSize, buffer.limit());
+            assertEquals(newSize, buffer.capacity());
+        }
+    }
+
+    @DataProvider(name = "segments")
+    public static Object[][] segments() throws Throwable {
+        return new Object[][] {
+                { (Supplier<MemorySegment>) () -> MemorySegment.allocateNative(16) },
+                { (Supplier<MemorySegment>) () -> MemorySegment.ofArray(new byte[16]) }
+        };
+    }
+
     @DataProvider(name = "bufferOps")
     public static Object[][] bufferOps() throws Throwable {
         List<Object[]> args = new ArrayList<>();