1 /*
2 * Copyright (c) 2014, 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.tools.jlink.internal;
27
28 import java.nio.ByteBuffer;
29 import java.util.HashMap;
30 import jdk.internal.jimage.ImageStream;
31 import jdk.internal.jimage.ImageStrings;
32 import jdk.internal.jimage.ImageStringsReader;
33
34 class ImageStringsWriter implements ImageStrings {
35 private static final int NOT_FOUND = -1;
36 static final int EMPTY_OFFSET = 0;
37
38 private final HashMap<String, Integer> stringToOffsetMap;
39 private final ImageStream stream;
40
41 ImageStringsWriter() {
42 this.stringToOffsetMap = new HashMap<>();
43 this.stream = new ImageStream();
44
45 // Reserve 0 offset for empty string.
46 int offset = addString("");
47 if (offset != 0) {
48 throw new InternalError("Empty string not offset zero");
49 }
50
51 // Reserve 1 offset for frequently used ".class".
52 offset = addString("class");
53 if (offset != 1) {
54 throw new InternalError("'class' string not offset one");
55 }
56 }
57
58 private int addString(final String string) {
59 int offset = stream.getPosition();
60 byte[] bytes = ImageStringsReader.mutf8FromString(string);
61 stream.put(bytes, 0, bytes.length);
62 stream.put('\0');
63 stringToOffsetMap.put(string, offset);
64
65 return offset;
66 }
67
68 @Override
69 public int add(final String string) {
70 int offset = find(string);
71
72 return offset == NOT_FOUND ? addString(string) : offset;
73 }
74
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1 /*
2 * Copyright (c) 2014, 2025, 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.tools.jlink.internal;
27
28 import java.nio.ByteBuffer;
29 import java.util.HashMap;
30 import jdk.internal.jimage.ImageStream;
31 import jdk.internal.jimage.ImageStrings;
32 import jdk.internal.jimage.ImageStringsReader;
33
34 class ImageStringsWriter implements ImageStrings {
35 private static final int NOT_FOUND = -1;
36
37 private final HashMap<String, Integer> stringToOffsetMap;
38 private final ImageStream stream;
39
40 ImageStringsWriter() {
41 this.stringToOffsetMap = new HashMap<>();
42 this.stream = new ImageStream();
43
44 // Frequently used/special strings for which the offset is useful.
45 // New strings can be reserved after existing strings without having to
46 // change the jimage file version, but any change to existing entries
47 // requires the jimage file version to be increased at the same time.
48 reserveString("", ImageStrings.EMPTY_STRING_OFFSET);
49 reserveString("class", ImageStrings.CLASS_STRING_OFFSET);
50 reserveString("modules", ImageStrings.MODULES_STRING_OFFSET);
51 reserveString("packages", ImageStrings.PACKAGES_STRING_OFFSET);
52 }
53
54 private void reserveString(String value, int expectedOffset) {
55 int offset = addString(value);
56 if (offset != expectedOffset) {
57 throw new InternalError("Reserved string \"" + value + "\" not at expected offset " + expectedOffset + "[was " + offset + "]");
58 }
59 }
60
61 private int addString(final String string) {
62 int offset = stream.getPosition();
63 byte[] bytes = ImageStringsReader.mutf8FromString(string);
64 stream.put(bytes, 0, bytes.length);
65 stream.put('\0');
66 stringToOffsetMap.put(string, offset);
67
68 return offset;
69 }
70
71 @Override
72 public int add(final String string) {
73 int offset = find(string);
74
75 return offset == NOT_FOUND ? addString(string) : offset;
76 }
77
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