1 /*
 2  * Copyright (c) 2001, 2021, 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 import jdk.internal.misc.Unsafe;
31 
32 /** Base class for jdk.internal.misc.Unsafe-based FieldAccessors. The
33     observation is that there are only nine types of fields from the
34     standpoint of reflection code: the eight primitive types and
35     Object. Using class Unsafe instead of generated bytecodes saves
36     memory and loading time for the dynamically-generated
37     FieldAccessors. */
38 
39 abstract class UnsafeFieldAccessorImpl extends FieldAccessorImpl {
40     static final Unsafe unsafe = Unsafe.getUnsafe();
41 
42     protected final long    fieldOffset;
43     protected final boolean isFinal;
44 
45     UnsafeFieldAccessorImpl(Field field) {
46         super(field);
47         int mods = field.getModifiers();
48         this.isFinal = Modifier.isFinal(mods);
49         if (Modifier.isStatic(mods))
50             fieldOffset = unsafe.staticFieldOffset(field);
51         else
52             fieldOffset = unsafe.objectFieldOffset(field);
53     }
54 
55     protected boolean isFlattened() {
56         return unsafe.isFlattened(field);
57     }
58 
59     protected boolean canBeNull() {
60         return !field.getType().isPrimitiveClass() || field.getType().isPrimaryType();
61     }
62 
63     protected Object checkValue(Object value) {
64         if (!canBeNull() && value == null)
65             throw new NullPointerException(field + " cannot be set to null");
66 
67         if (value != null) {
68             Class<?> type = value.getClass();
69             if (type.isPrimitiveClass()) {
70                 type = type.asValueType();
71             }
72             if (!field.getType().isAssignableFrom(type)) {
73                 throwSetIllegalArgumentException(value);
74             }
75         }
76         return value;
77     }
78 
79 }