1 /*
2 * Copyright (C) 2015 The Android Open Source Project
3 *
4 * Licensed under the Apache License, Version 2.0 (the "License");
5 * you may not use this file except in compliance with the License.
6 * You may obtain a copy of the License at
7 *
8 * http://www.apache.org/licenses/LICENSE-2.0
9 *
10 * Unless required by applicable law or agreed to in writing, software
11 * distributed under the License is distributed on an "AS IS" BASIS,
12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13 * See the License for the specific language governing permissions and
14 * limitations under the License.
15 */
16
17 #ifndef AAPT_RES_CHUNK_PULL_PARSER_H
18 #define AAPT_RES_CHUNK_PULL_PARSER_H
19
20 #include <androidfw/ResourceTypes.h>
21 #include <string>
22
23 namespace aapt {
24
25 /**
26 * A pull parser, modeled after XmlPullParser, that reads
27 * android::ResChunk_header structs from a block of data.
28 *
29 * An android::ResChunk_header specifies a type, headerSize,
30 * and size. The pull parser will verify that the chunk's size
31 * doesn't extend beyond the available data, and will iterate
32 * over each chunk in the given block of data.
33 *
34 * Processing nested chunks is done by creating a new ResChunkPullParser
35 * pointing to the data portion of a chunk.
36 */
37 class ResChunkPullParser {
38 public:
39 enum class Event {
40 StartDocument,
41 EndDocument,
42 BadDocument,
43
44 Chunk,
45 };
46
47 /**
48 * Returns false if the event is EndDocument or BadDocument.
49 */
50 static bool isGoodEvent(Event event);
51
52 /**
53 * Create a ResChunkPullParser to read android::ResChunk_headers
54 * from the memory pointed to by data, of len bytes.
55 */
56 ResChunkPullParser(const void* data, size_t len);
57
58 ResChunkPullParser(const ResChunkPullParser&) = delete;
59
60 Event getEvent() const;
61 const std::string& getLastError() const;
62 const android::ResChunk_header* getChunk() const;
63
64 /**
65 * Move to the next android::ResChunk_header.
66 */
67 Event next();
68
69 private:
70 Event mEvent;
71 const android::ResChunk_header* mData;
72 size_t mLen;
73 const android::ResChunk_header* mCurrentChunk;
74 std::string mLastError;
75 };
76
77 template <typename T>
convertTo(const android::ResChunk_header * chunk)78 inline static const T* convertTo(const android::ResChunk_header* chunk) {
79 if (chunk->headerSize < sizeof(T)) {
80 return nullptr;
81 }
82 return reinterpret_cast<const T*>(chunk);
83 }
84
getChunkData(const android::ResChunk_header & chunk)85 inline static const uint8_t* getChunkData(const android::ResChunk_header& chunk) {
86 return reinterpret_cast<const uint8_t*>(&chunk) + chunk.headerSize;
87 }
88
getChunkDataLen(const android::ResChunk_header & chunk)89 inline static size_t getChunkDataLen(const android::ResChunk_header& chunk) {
90 return chunk.size - chunk.headerSize;
91 }
92
93 //
94 // Implementation
95 //
96
isGoodEvent(ResChunkPullParser::Event event)97 inline bool ResChunkPullParser::isGoodEvent(ResChunkPullParser::Event event) {
98 return event != Event::EndDocument && event != Event::BadDocument;
99 }
100
ResChunkPullParser(const void * data,size_t len)101 inline ResChunkPullParser::ResChunkPullParser(const void* data, size_t len) :
102 mEvent(Event::StartDocument),
103 mData(reinterpret_cast<const android::ResChunk_header*>(data)),
104 mLen(len),
105 mCurrentChunk(nullptr) {
106 }
107
getEvent()108 inline ResChunkPullParser::Event ResChunkPullParser::getEvent() const {
109 return mEvent;
110 }
111
getLastError()112 inline const std::string& ResChunkPullParser::getLastError() const {
113 return mLastError;
114 }
115
getChunk()116 inline const android::ResChunk_header* ResChunkPullParser::getChunk() const {
117 return mCurrentChunk;
118 }
119
120 } // namespace aapt
121
122 #endif // AAPT_RES_CHUNK_PULL_PARSER_H
123