From b03880e33b0d9442a608c9ec911afbe863221bf2 Mon Sep 17 00:00:00 2001
From: Maurizio Cimadamore <mcimadamore@openjdk.org>
Date: Tue, 12 Jan 2021 17:09:05 +0000
Subject: [PATCH] 8259634: MemorySegment::asByteBuffer does not respect spatial
 bounds

Reviewed-by: alanb, chegar
---
 .../share/classes/java/nio/Buffer.java        |  2 +-
 test/jdk/java/foreign/TestByteBuffer.java     | 30 ++++++++++++++++++-
 2 files changed, 30 insertions(+), 2 deletions(-)

diff --git a/src/java.base/share/classes/java/nio/Buffer.java b/src/java.base/share/classes/java/nio/Buffer.java
index 8e286584b1f..0506078eed8 100644
--- a/src/java.base/share/classes/java/nio/Buffer.java
+++ b/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
diff --git a/test/jdk/java/foreign/TestByteBuffer.java b/test/jdk/java/foreign/TestByteBuffer.java
index a396ec48ec5..27d7a8a3e00 100644
--- a/test/jdk/java/foreign/TestByteBuffer.java
+++ b/test/jdk/java/foreign/TestByteBuffer.java
@@ -64,6 +64,7 @@
 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;
@@ -71,6 +72,7 @@
 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<>();