DexBackedField.java revision d1662b67fecaf835227aff3a136949a2358ccd4e 
1/*
2 * Copyright 2012, Google Inc.
3 * All rights reserved.
4 *
5 * Redistribution and use in source and binary forms, with or without
6 * modification, are permitted provided that the following conditions are
7 * met:
8 *
9 *     * Redistributions of source code must retain the above copyright
10 * notice, this list of conditions and the following disclaimer.
11 *     * Redistributions in binary form must reproduce the above
12 * copyright notice, this list of conditions and the following disclaimer
13 * in the documentation and/or other materials provided with the
14 * distribution.
15 *     * Neither the name of Google Inc. nor the names of its
16 * contributors may be used to endorse or promote products derived from
17 * this software without specific prior written permission.
18 *
19 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
20 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
21 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
22 * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
23 * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
24 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
25 * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
26 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
27 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
28 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
29 * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
30 */
31
32package org.jf.dexlib2.dexbacked;
33
34import org.jf.dexlib2.dexbacked.util.AnnotationsDirectory;
35import org.jf.dexlib2.dexbacked.util.StaticInitialValueIterator;
36import org.jf.dexlib2.iface.Field;
37import org.jf.dexlib2.iface.value.EncodedValue;
38
39import javax.annotation.Nonnull;
40import javax.annotation.Nullable;
41import java.util.List;
42
43public class DexBackedField implements Field {
44    @Nonnull public final DexBuffer dexBuf;
45
46    public final int accessFlags;
47    @Nullable public final EncodedValue initialValue;
48    public final int annotationSetOffset;
49
50    public final int fieldIndex;
51
52    private int fieldIdItemOffset;
53
54    // offsets for field_id_item
55    private static final int TYPE_OFFSET = 2;
56    private static final int NAME_OFFSET = 4;
57
58    public DexBackedField(@Nonnull DexReader reader,
59                          int previousFieldIndex,
60                          @Nonnull StaticInitialValueIterator staticInitialValueIterator,
61                          @Nonnull AnnotationsDirectory.AnnotationIterator annotationIterator) {
62        this.dexBuf = reader.getDexBuffer();
63
64        int fieldIndexDiff = reader.readSmallUleb128();
65        this.fieldIndex = fieldIndexDiff + previousFieldIndex;
66        this.accessFlags = reader.readSmallUleb128();
67
68        this.annotationSetOffset = annotationIterator.seekTo(fieldIndex);
69        this.initialValue = staticInitialValueIterator.getNextOrNull();
70    }
71
72    @Nonnull
73    @Override
74    public String getName() {
75        return dexBuf.getString(dexBuf.readSmallUint(getFieldIdItemOffset() + NAME_OFFSET));
76    }
77
78    @Nonnull
79    @Override
80    public String getType() {
81        return dexBuf.getType(dexBuf.readUshort(getFieldIdItemOffset() + TYPE_OFFSET));
82    }
83
84    @Override public int getAccessFlags() { return accessFlags; }
85    @Nullable @Override public EncodedValue getInitialValue() { return initialValue; }
86
87    @Nonnull
88    @Override
89    public List<? extends DexBackedAnnotation> getAnnotations() {
90        return AnnotationsDirectory.getAnnotations(dexBuf, annotationSetOffset);
91    }
92
93    /**
94     * Skips the reader over a single encoded_field structure.
95     * @param reader The {@code DexFileReader} to skip
96     * @param previousFieldIndex The field index of the previous field, or 0 if this is the first
97     * @return The field index of the field that was skipped
98     */
99    public static int skipEncodedField(@Nonnull DexReader reader, int previousFieldIndex) {
100        int idxDiff = reader.readSmallUleb128();
101        reader.skipUleb128();
102        return previousFieldIndex + idxDiff;
103    }
104
105    /**
106     * Skips the reader over the specified number of encoded_field structures
107     *
108     * @param reader The reader to skip
109     * @param count The number of encoded_field structures to skip over
110     */
111    public static void skipAllFields(@Nonnull DexReader reader, int count) {
112        for (int i=0; i<count; i++) {
113            reader.skipUleb128();
114            reader.skipUleb128();
115        }
116    }
117
118    private int getFieldIdItemOffset() {
119        if (fieldIdItemOffset == 0) {
120            fieldIdItemOffset = dexBuf.getFieldIdItemOffset(fieldIndex);
121        }
122        return fieldIdItemOffset;
123    }
124}
125