1 /*
 2  * Copyright (c) 2001, 2022, Oracle and/or its affiliates. All rights reserved.
 3  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
 4  *
 5  * This code is free software; you can redistribute it and/or modify it
 6  * under the terms of the GNU General Public License version 2 only, as
 7  * published by the Free Software Foundation.  Oracle designates this
 8  * particular file as subject to the "Classpath" exception as provided
 9  * by Oracle in the LICENSE file that accompanied this code.
10  *
11  * This code is distributed in the hope that it will be useful, but WITHOUT
12  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
13  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
14  * version 2 for more details (a copy is included in the LICENSE file that
15  * accompanied this code).
16  *
17  * You should have received a copy of the GNU General Public License version
18  * 2 along with this work; if not, write to the Free Software Foundation,
19  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
20  *
21  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
22  * or visit www.oracle.com if you need additional information or have any
23  * questions.
24  */
25 
26 package jdk.internal.reflect;
27 
28 import java.lang.reflect.Field;
29 import java.lang.reflect.Modifier;
30 
31 import jdk.internal.value.PrimitiveClass;
32 import jdk.internal.misc.Unsafe;
33 
34 /** Base class for jdk.internal.misc.Unsafe-based FieldAccessors. The
35     observation is that there are only nine types of fields from the
36     standpoint of reflection code: the eight primitive types and
37     Object. Using class Unsafe instead of generated bytecodes saves
38     memory and loading time for the dynamically-generated
39     FieldAccessors. */
40 
41 abstract class UnsafeFieldAccessorImpl extends FieldAccessorImpl {
42     static final Unsafe unsafe = Unsafe.getUnsafe();
43 
44     protected final long    fieldOffset;
45     protected final boolean isFinal;
46 
47     UnsafeFieldAccessorImpl(Field field) {
48         super(field);
49         int mods = field.getModifiers();
50         this.isFinal = Modifier.isFinal(mods);
51         if (Modifier.isStatic(mods))
52             fieldOffset = unsafe.staticFieldOffset(field);
53         else
54             fieldOffset = unsafe.objectFieldOffset(field);
55     }
56 
57     protected boolean isFlattened() {
58         return unsafe.isFlattened(field);
59     }
60 
61     protected boolean canBeNull() {
62         return !PrimitiveClass.isPrimitiveClass(field.getType()) ||
63                 PrimitiveClass.isPrimaryType(field.getType());
64     }
65 
66     protected Object checkValue(Object value) {
67         if (!canBeNull() && value == null)
68             throw new NullPointerException(field + " cannot be set to null");
69 
70         if (value != null) {
71             Class<?> type = value.getClass();
72             if (PrimitiveClass.isPrimitiveClass(type)) {
73                 type = PrimitiveClass.asValueType(type);
74             }
75             if (!field.getType().isInstance(value)) {
76                 throwSetIllegalArgumentException(value);
77             }
78         }
79         return value;
80     }
81 
82 }