ReadContext.java revision 4b82fba3ba46eb3f7169f9db9d3118e7d73c3682 
1/*
2 * [The "BSD licence"]
3 * Copyright (c) 2010 Ben Gruver (JesusFreke)
4 * All rights reserved.
5 *
6 * Redistribution and use in source and binary forms, with or without
7 * modification, are permitted provided that the following conditions
8 * are met:
9 * 1. Redistributions of source code must retain the above copyright
10 *    notice, this list of conditions and the following disclaimer.
11 * 2. Redistributions in binary form must reproduce the above copyright
12 *    notice, this list of conditions and the following disclaimer in the
13 *    documentation and/or other materials provided with the distribution.
14 * 3. The name of the author may not be used to endorse or promote products
15 *    derived from this software without specific prior written permission.
16 *
17 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
18 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
19 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
20 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
21 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
22 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
23 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
24 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
25 * INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
26 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
27 */
28
29package org.jf.dexlib;
30
31import org.jf.dexlib.Util.ExceptionWithContext;
32import org.jf.dexlib.Util.SparseArray;
33
34import java.util.List;
35
36
37/**
38 * This class stores context information that is only needed when reading in a dex file
39 * Namely, it handles "pre-creating" items when an item needs to resolve some other item
40 * that it references, and keeps track of those pre-created items, so the corresponding section
41 * for the pre-created items uses them, instead of creating new items
42 */
43public class ReadContext {
44    private SparseArray<TypeListItem> typeListItems = new SparseArray<TypeListItem>(0);
45    private SparseArray<AnnotationSetRefList> annotationSetRefLists = new SparseArray<AnnotationSetRefList>(0);
46    private SparseArray<AnnotationSetItem> annotationSetItems = new SparseArray<AnnotationSetItem>(0);
47    private SparseArray<ClassDataItem> classDataItems = new SparseArray<ClassDataItem>(0);
48    private SparseArray<CodeItem> codeItems = new SparseArray<CodeItem>(0);
49    private SparseArray<StringDataItem> stringDataItems = new SparseArray<StringDataItem>(0);
50    private SparseArray<DebugInfoItem> debugInfoItems = new SparseArray<DebugInfoItem>(0);
51    private SparseArray<AnnotationItem> annotationItems = new SparseArray<AnnotationItem>(0);
52    private SparseArray<EncodedArrayItem> encodedArrayItems = new SparseArray<EncodedArrayItem>(0);
53    private SparseArray<AnnotationDirectoryItem> annotationDirectoryItems = new SparseArray<AnnotationDirectoryItem>(0);
54
55    private SparseArray[] itemsByType = new SparseArray[] {
56            null, //string_id_item
57            null, //type_id_item
58            null, //proto_id_item
59            null, //field_id_item
60            null, //method_id_item
61            null, //class_def_item
62            typeListItems,
63            annotationSetRefLists,
64            annotationSetItems,
65            classDataItems,
66            codeItems,
67            stringDataItems,
68            debugInfoItems,
69            annotationItems,
70            encodedArrayItems,
71            annotationDirectoryItems,
72            null, //map_list
73            null //header_item
74    };
75
76
77    /**
78     * The section sizes that are passed in while reading HeaderItem/MapItem, via the
79     * addSection method.
80     */
81    private int[] sectionSizes = new int[18];
82
83    /**
84     * The section offsets that are passed in while reading MapItem/HeaderItem, via the
85     * addSection method.
86     */
87    private int[] sectionOffsets = new int[18];
88
89    /**
90     * Creates a new ReadContext instance.
91     */
92    public ReadContext() {
93        for (int i=0; i<18; i++) {
94            sectionSizes[i] = -1;
95            sectionOffsets[i] = -1;
96        }
97    }
98
99    /**
100     * Gets the offsetted item of the specified type for the given offset. This method does not support retrieving an
101     * optional item where a value of 0 indicates "not present". Use getOptionalOffsettedItemByOffset instead.
102     *
103     * @param itemType The type of item to get
104     * @param offset The offset of the item
105     * @return the offsetted item of the specified type at the specified offset
106     */
107    public Item getOffsettedItemByOffset(ItemType itemType, int offset) {
108        assert !itemType.isIndexedItem();
109
110        SparseArray<Item> sa = itemsByType[itemType.SectionIndex];
111        Item item = sa.get(offset);
112        if (item == null) {
113            throw new ExceptionWithContext(String.format("Could not find the %s item at offset %#x",
114                    itemType.TypeName, offset));
115        }
116        return item;
117    }
118
119    /**
120     * Gets the optional offsetted item of the specified type for the given offset
121     *
122     * @param itemType The type of item to get
123     * @param offset The offset of the item
124     * @return the offsetted item of the specified type at the specified offset, or null if the offset is 0
125     */
126    public Item getOptionalOffsettedItemByOffset(ItemType itemType, int offset) {
127        assert !itemType.isIndexedItem();
128
129        assert !itemType.isIndexedItem();
130
131        SparseArray<Item> sa = itemsByType[itemType.SectionIndex];
132        Item item = sa.get(offset);
133        if (item == null && offset != 0) {
134            throw new ExceptionWithContext(String.format("Could not find the %s item at offset %#x",
135                    itemType.TypeName, offset));
136        }
137        return item;
138    }
139
140    /**
141     * Adds the size and offset information for the given offset
142     * @param itemType the item type of the section
143     * @param sectionSize the size of the section
144     * @param sectionOffset the offset of the section
145     */
146    public void addSection(final ItemType itemType, int sectionSize, int sectionOffset) {
147        int storedSectionSize = sectionSizes[itemType.SectionIndex];
148        if (storedSectionSize == -1) {
149            sectionSizes[itemType.SectionIndex] = sectionSize;
150        } else {
151            if (storedSectionSize  != sectionSize) {
152                throw new RuntimeException("The section size in the header and map for item type "
153                        + itemType + " do not match");
154            }
155        }
156
157        int storedSectionOffset = sectionOffsets[itemType.SectionIndex];
158        if (storedSectionOffset == -1) {
159            sectionOffsets[itemType.SectionIndex] = sectionOffset;
160        } else {
161            if (storedSectionOffset != sectionOffset) {
162                throw new RuntimeException("The section offset in the header and map for item type "
163                        + itemType + " do not match");
164            }
165        }
166    }
167
168    /**
169     * Sets the items for the specified section. This should be called by an offsetted section
170     * after it is finished reading in all its items.
171     * @param itemType the item type of the section. This must be an offsetted item type
172     * @param items the full list of items in the section, ordered by offset
173     */
174    public void setItemsForSection(ItemType itemType, List<? extends Item> items) {
175        assert !itemType.isIndexedItem();
176
177        SparseArray<Item> sa = itemsByType[itemType.SectionIndex];
178
179        sa.ensureCapacity(items.size());
180        for (Item item: items) {
181            sa.append(item.getOffset(), item);
182        }
183    }
184
185    /**
186     * @param itemType the item type of the section
187     * @return the size of the given section as it was read in from the map item
188     */
189    public int getSectionSize(ItemType itemType) {
190        return sectionSizes[itemType.SectionIndex];
191    }
192
193    /**
194     * @param itemType the item type of the section
195     * @return the offset of the given section as it was read in from the map item
196     */
197    public int getSectionOffset(ItemType itemType) {
198        return sectionOffsets[itemType.SectionIndex];
199    }
200}
201