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_FORMAT_BINARY_RESCHUNKPULLPARSER_H
18 #define AAPT_FORMAT_BINARY_RESCHUNKPULLPARSER_H
19
20 #include <string>
21
22 #include "android-base/macros.h"
23 #include "androidfw/ResourceTypes.h"
24
25 #include "util/Util.h"
26
27 namespace aapt {
28
29 // A pull parser, modeled after XmlPullParser, that reads android::ResChunk_header structs from a
30 // block of data.
31 // An android::ResChunk_header specifies a type, headerSize, and size. The pull parser will verify
32 // that the chunk's size doesn't extend beyond the available data, and will iterate over each chunk
33 // in the given block of data.
34 // Processing nested chunks is done by creating a new ResChunkPullParser pointing to the data
35 // portion of a chunk.
36 class ResChunkPullParser {
37 public:
38 enum class Event {
39 kStartDocument,
40 kEndDocument,
41 kBadDocument,
42
43 kChunk,
44 };
45
46 // Returns false if the event is EndDocument or BadDocument.
47 static bool IsGoodEvent(Event event);
48
49 // Create a ResChunkPullParser to read android::ResChunk_headers from the memory pointed to by
50 // data, of len bytes.
51 ResChunkPullParser(const void* data, size_t len);
52
53 Event event() const;
54 const std::string& error() const;
55 const android::ResChunk_header* chunk() const;
56
57 // Move to the next android::ResChunk_header.
58 Event Next();
59
60 private:
61 DISALLOW_COPY_AND_ASSIGN(ResChunkPullParser);
62
63 Event event_;
64 const android::ResChunk_header* data_;
65 size_t len_;
66 const android::ResChunk_header* current_chunk_;
67 std::string error_;
68 };
69
70 template <typename T, size_t MinSize = sizeof(T)>
ConvertTo(const android::ResChunk_header * chunk)71 inline static const T* ConvertTo(const android::ResChunk_header* chunk) {
72 if (util::DeviceToHost16(chunk->headerSize) < MinSize) {
73 return nullptr;
74 }
75 return reinterpret_cast<const T*>(chunk);
76 }
77
GetChunkData(const android::ResChunk_header * chunk)78 inline static const uint8_t* GetChunkData(const android::ResChunk_header* chunk) {
79 return reinterpret_cast<const uint8_t*>(chunk) + util::DeviceToHost16(chunk->headerSize);
80 }
81
GetChunkDataLen(const android::ResChunk_header * chunk)82 inline static uint32_t GetChunkDataLen(const android::ResChunk_header* chunk) {
83 return util::DeviceToHost32(chunk->size) - util::DeviceToHost16(chunk->headerSize);
84 }
85
86 //
87 // Implementation
88 //
89
IsGoodEvent(ResChunkPullParser::Event event)90 inline bool ResChunkPullParser::IsGoodEvent(ResChunkPullParser::Event event) {
91 return event != Event::kEndDocument && event != Event::kBadDocument;
92 }
93
ResChunkPullParser(const void * data,size_t len)94 inline ResChunkPullParser::ResChunkPullParser(const void* data, size_t len)
95 : event_(Event::kStartDocument),
96 data_(reinterpret_cast<const android::ResChunk_header*>(data)),
97 len_(len),
98 current_chunk_(nullptr) {
99 }
100
event()101 inline ResChunkPullParser::Event ResChunkPullParser::event() const {
102 return event_;
103 }
104
error()105 inline const std::string& ResChunkPullParser::error() const {
106 return error_;
107 }
108
chunk()109 inline const android::ResChunk_header* ResChunkPullParser::chunk() const {
110 return current_chunk_;
111 }
112
113 } // namespace aapt
114
115 #endif // AAPT_FORMAT_BINARY_RESCHUNKPULLPARSER_H
116