8346657: Improve out of bounds exception messages for MemorySegments

src/java.base/share/classes/jdk/internal/foreign/AbstractMemorySegmentImpl.java

@@ -68,7 +68,7 @@
  * {@link MappedMemorySegmentImpl}.
  */
 public abstract sealed class AbstractMemorySegmentImpl
-        implements MemorySegment, SegmentAllocator, BiFunction<String, List<Number>, RuntimeException>
+        implements MemorySegment, SegmentAllocator
         permits HeapMemorySegmentImpl, NativeMemorySegmentImpl {
 
     static final JavaNioAccess NIO_ACCESS = SharedSecrets.getJavaNioAccess();
@@ -100,19 +100,19 @@ public boolean isReadOnly() {
 
     @Override
     public AbstractMemorySegmentImpl asSlice(long offset, long newSize) {
-        checkBounds(offset, newSize);
+        checkSliceBounds(offset, newSize);
         return asSliceNoCheck(offset, newSize);
     }
 
     @Override
     public AbstractMemorySegmentImpl asSlice(long offset) {
-        checkBounds(offset, 0);
+        checkSliceBounds(offset, 0);
         return asSliceNoCheck(offset, length - offset);
     }
 
     @Override
     public MemorySegment asSlice(long offset, long newSize, long byteAlignment) {
-        checkBounds(offset, newSize);
+        checkSliceBounds(offset, newSize);
         Utils.checkAlign(byteAlignment);
 
         if (!isAlignedForElement(offset, byteAlignment)) {
@@ -354,7 +354,7 @@ public void checkReadOnly(boolean readOnly) {
     @ForceInline
     public void checkAccess(long offset, long length, boolean readOnly) {
         checkReadOnly(readOnly);
-        checkBounds(offset, length);
+        checkAccessBounds(offset, length);
     }
 
     @ForceInline
@@ -398,20 +398,13 @@ private int checkArraySize(String typeName, int elemSize) {
     }
 
     @ForceInline
-    void checkBounds(long offset, long length) {
-        if (length > 0) {
-            Preconditions.checkIndex(offset, this.length - length + 1, this);
-        } else if (length < 0 || offset < 0 ||
-                offset > this.length - length) {
-            throw outOfBoundException(offset, length);
-        }
+    void checkSliceBounds(long offset, long length) {
+        Preconditions.checkFromIndexSize(offset, length, this.length, this::sliceOutOfBoundException);
     }
 
-    @Override
-    public RuntimeException apply(String s, List<Number> numbers) {
-        long offset = numbers.get(0).longValue();
-        long length = byteSize() - numbers.get(1).longValue() + 1;
-        return outOfBoundException(offset, length);
+    @ForceInline
+    void checkAccessBounds(long offset, long length) {
+        Preconditions.checkFromIndexSize(offset, length, this.length, this::accessOutOfBoundException);
     }
 
     @Override
@@ -429,9 +422,28 @@ public final MemorySessionImpl sessionImpl() {
         return scope;
     }
 
-    private IndexOutOfBoundsException outOfBoundException(long offset, long length) {
-        return new IndexOutOfBoundsException(String.format("Out of bound access on segment %s; new offset = %d; new length = %d",
-                        this, offset, length));
+    private IndexOutOfBoundsException sliceOutOfBoundException(String s, List<Number> numbers) {
+        return outOfBoundException(BoundPolicy.SLICE, numbers);
+    }
+
+    private IndexOutOfBoundsException accessOutOfBoundException(String s, List<Number> numbers) {
+        return outOfBoundException(BoundPolicy.ACCESS, numbers);
+    }
+
+    private IndexOutOfBoundsException outOfBoundException(BoundPolicy policy, List<Number> numbers) {
+        long offset = numbers.get(0).longValue();
+        long length = numbers.get(1).longValue();
+        long totalLength = numbers.get(2).longValue();
+
+        String msg = switch (policy) {
+            case BoundPolicy.SLICE  -> "attempting to get slice of length";
+            case BoundPolicy.ACCESS -> "attempting to access an element of length";
+        };
+
+        return new IndexOutOfBoundsException(String.format("Out of bound access on segment %s; " +
+                        "%s %d at offset %d " +
+                        "which is outside the valid range 0 <= offset+length < byteSize (=%d)",
+                this, msg, length, offset, totalLength));
     }
 
     static class SegmentSplitter implements Spliterator<MemorySegment> {
@@ -508,6 +520,10 @@ public int characteristics() {
         }
     }
 
+    private enum BoundPolicy {
+        SLICE, ACCESS
+    }
+
     // Object methods
 
     @Override

src/java.base/share/classes/jdk/internal/foreign/SegmentBulkOperations.java

@@ -194,7 +194,7 @@ public static void copy(AbstractMemorySegmentImpl src, long srcOffset,
     @ForceInline
     public static int contentHash(AbstractMemorySegmentImpl segment, long fromOffset, long toOffset) {
         final long length = toOffset - fromOffset;
-        segment.checkBounds(fromOffset, length);
+        segment.checkSliceBounds(fromOffset, length);
         if (length == 0) {
             // The state has to be checked explicitly for zero-length segments
             segment.scope.checkValidState();

src/java.base/share/classes/jdk/internal/foreign/StringSupport.java

@@ -145,7 +145,7 @@ public static int strlenByte(final AbstractMemorySegmentImpl segment,
                                  final long fromOffset,
                                  final long toOffset) {
         final long length = toOffset - fromOffset;
-        segment.checkBounds(fromOffset, length);
+        segment.checkSliceBounds(fromOffset, length);
         if (length < Byte.BYTES) {
             // There can be no null terminator present
             segment.scope.checkValidState();
@@ -179,7 +179,7 @@ public static int strlenShort(final AbstractMemorySegmentImpl segment,
                                   final long fromOffset,
                                   final long toOffset) {
         final long length = toOffset - fromOffset;
-        segment.checkBounds(fromOffset, length);
+        segment.checkSliceBounds(fromOffset, length);
         if (length < Short.BYTES) {
             // There can be no null terminator present
             segment.scope.checkValidState();
@@ -215,7 +215,7 @@ public static int strlenInt(final AbstractMemorySegmentImpl segment,
                                 final long fromOffset,
                                 final long toOffset) {
         final long length = toOffset - fromOffset;
-        segment.checkBounds(fromOffset, length);
+        segment.checkSliceBounds(fromOffset, length);
         if (length < Integer.BYTES) {
             // There can be no null terminator present
             segment.scope.checkValidState();

test/jdk/java/foreign/TestSegments.java

@@ -212,14 +212,32 @@ public void testSmallSegmentMin() {
     }
 
     @Test
-    public void testSegmentOOBMessage() {
+    public void testSegmentAccessOOBMessage() {
         try {
             var segment = Arena.global().allocate(10, 1);
             segment.getAtIndex(ValueLayout.JAVA_INT, 2);
+            fail("Expected IndexOutOfBoundsException was not thrown");
         } catch (IndexOutOfBoundsException ex) {
-            assertTrue(ex.getMessage().contains("Out of bound access"));
-            assertTrue(ex.getMessage().contains("offset = 8"));
-            assertTrue(ex.getMessage().contains("length = 4"));
+            assertTrue(ex.getMessage().startsWith("Out of bound access"));
+            assertTrue(ex.getMessage().endsWith("attempting to access an element of length 4 at offset 8 " +
+                    "which is outside the valid range 0 <= offset+length < byteSize (=10)"));
+        } catch (Exception ex) {
+            fail("Unexpected exception type thrown: " + ex);
+        }
+    }
+
+    @Test
+    public void testSegmentSliceOOBMessage() {
+        try {
+            var segment = Arena.global().allocate(10, 1);
+            var slice = segment.asSlice(8, 4);
+            fail("Expected IndexOutOfBoundsException was not thrown");
+        } catch (IndexOutOfBoundsException ex) {
+            assertTrue(ex.getMessage().startsWith("Out of bound access"));
+            assertTrue(ex.getMessage().endsWith("attempting to get slice of length 4 at offset 8 " +
+                    "which is outside the valid range 0 <= offset+length < byteSize (=10)"));
+        } catch (Exception ex) {
+            fail("Unexpected exception type thrown: " + ex);
         }
     }