1 /*
2 * Copyright (c) 2000, 2018, 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.
8 *
9 * This code is distributed in the hope that it will be useful, but WITHOUT
10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
12 * version 2 for more details (a copy is included in the LICENSE file that
13 * accompanied this code).
14 *
15 * You should have received a copy of the GNU General Public License version
16 * 2 along with this work; if not, write to the Free Software Foundation,
17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
18 *
19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
20 * or visit www.oracle.com if you need additional information or have any
21 * questions.
22 *
23 */
24
25 package sun.jvm.hotspot.oops;
26
27 import java.io.*;
28 import java.util.*;
29 import sun.jvm.hotspot.debugger.*;
30 import sun.jvm.hotspot.runtime.*;
31 import sun.jvm.hotspot.types.*;
32 import sun.jvm.hotspot.utilities.*;
33
34 // A Symbol is a canonicalized string.
35 // All Symbols reside in global symbolTable.
36
37 public class Symbol extends VMObject {
38 static {
39 VM.registerVMInitializedObserver(new Observer() {
40 public void update(Observable o, Object data) {
41 initialize(VM.getVM().getTypeDataBase());
42 }
43 });
44 }
45
46 private static synchronized void initialize(TypeDataBase db) throws WrongTypeException {
47 Type type = db.lookupType("Symbol");
48 length = type.getCIntegerField("_length_and_refcount");
49 baseOffset = type.getField("_body").getOffset();
50 idHash = type.getCIntegerField("_identity_hash");
51 }
52
53 // Format:
54 // [header]
55 // [klass ]
56 // [length] byte size of uft8 string
57 // ..body..
58
59 public static Symbol create(Address addr) {
60 if (addr == null) {
61 return null;
62 }
63 return new Symbol(addr);
64 }
65
66 Symbol(Address addr) {
67 super(addr);
68 }
69
70 public boolean isSymbol() { return true; }
71
72 private static long baseOffset; // tells where the array part starts
73
74 // Fields
75 private static CIntegerField length;
76
77 // Accessors for declared fields
78 public long getLength() {
79 long i = length.getValue(this.addr);
80 return (i >> 16) & 0xffff;
81 }
82
83 public byte getByteAt(long index) {
84 return addr.getJByteAt(baseOffset + index);
85 }
86 // _identity_hash is a short
87 private static CIntegerField idHash;
88
89 public int identityHash() {
90 long addr_value = getAddress().asLongValue();
91 int addr_bits = (int)(addr_value >> (VM.getVM().getLogMinObjAlignmentInBytes() + 3));
92 int length = (int)getLength();
93 int byte0 = getByteAt(0);
94 int byte1 = getByteAt(1);
95 int id_hash = (int)(0xffff & idHash.getValue(this.addr));
96 return id_hash |
97 ((addr_bits ^ (length << 8) ^ ((byte0 << 8) | byte1)) << 16);
98 }
99
100 public boolean equals(byte[] modUTF8Chars) {
101 int l = (int) getLength();
102 if (l != modUTF8Chars.length) return false;
103 while (l-- > 0) {
104 if (modUTF8Chars[l] != getByteAt(l)) return false;
105 }
106 if (Assert.ASSERTS_ENABLED) {
107 Assert.that(l == -1, "we should be at the beginning");
108 }
109 return true;
110 }
111
112 public boolean equals(String string) {
113 return asString().equals(string);
114 }
115
116 public byte[] asByteArray() {
117 int length = (int) getLength();
118 byte [] result = new byte [length];
119 for (int index = 0; index < length; index++) {
120 result[index] = getByteAt(index);
121 }
122 return result;
123 }
124
125 public String asString() {
126 // Decode the byte array and return the string.
127 try {
128 return readModifiedUTF8(asByteArray());
129 } catch(Exception e) {
130 System.err.println(addr);
131 e.printStackTrace();
132 return null;
133 }
134 }
135
136 public boolean startsWith(String str) {
137 return asString().startsWith(str);
138 }
139
140 public void printValueOn(PrintStream tty) {
141 tty.print("#" + asString());
142 }
143
144 /** Note: this comparison is used for vtable sorting only; it
145 doesn't matter what order it defines, as long as it is a total,
146 time-invariant order Since Symbol* are in C_HEAP, their
147 relative order in memory never changes, so use address
148 comparison for speed. */
149 public long fastCompare(Symbol other) {
150 return addr.minus(other.addr);
151 }
152
153 private static String readModifiedUTF8(byte[] buf) throws IOException {
154 final int len = buf.length;
155 byte[] tmp = new byte[len + 2];
156 // write modified UTF-8 length as short in big endian
157 tmp[0] = (byte) ((len >>> 8) & 0xFF);
158 tmp[1] = (byte) ((len >>> 0) & 0xFF);
159 // copy the data
160 System.arraycopy(buf, 0, tmp, 2, len);
161 DataInputStream dis = new DataInputStream(new ByteArrayInputStream(tmp));
162 return dis.readUTF();
163 }
164 }