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
26package jdk.tools.jlink.internal;
27
28import java.nio.ByteBuffer;
29import java.util.HashMap;
30import jdk.internal.jimage.ImageStream;
31import jdk.internal.jimage.ImageStrings;
32import jdk.internal.jimage.ImageStringsReader;
33
34class 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
75    int find(final String string) {
76        Integer offset = stringToOffsetMap.get(string);
77
78        return offset != null ? offset : NOT_FOUND;
79    }
80
81    @Override
82    public String get(int offset) {
83        ByteBuffer buffer = stream.getBuffer();
84        int capacity = buffer.capacity();
85        if (offset < 0 || offset >= capacity) {
86            throw new InternalError("String buffer offset out of range");
87        }
88        int zero = NOT_FOUND;
89        for (int i = offset; i < capacity; i++) {
90            if (buffer.get(i) == '\0') {
91                zero = i;
92                break;
93            }
94        }
95        if (zero == NOT_FOUND) {
96            throw new InternalError("String zero terminator not found");
97        }
98        int length = zero - offset;
99        byte[] bytes = new byte[length];
100        int mark = buffer.position();
101        buffer.position(offset);
102        buffer.get(bytes);
103        buffer.position(mark);
104
105        return ImageStringsReader.stringFromMUTF8(bytes);
106    }
107
108    ImageStream getStream() {
109        return stream;
110    }
111
112    int getSize() {
113        return stream.getSize();
114    }
115
116    int getCount() {
117        return stringToOffsetMap.size();
118    }
119}
120