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 <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 /**
30 * A pull parser, modeled after XmlPullParser, that reads
31 * android::ResChunk_header structs from a block of data.
32 *
33 * An android::ResChunk_header specifies a type, headerSize,
34 * and size. The pull parser will verify that the chunk's size
35 * doesn't extend beyond the available data, and will iterate
36 * over each chunk in the given block of data.
37 *
38 * Processing nested chunks is done by creating a new ResChunkPullParser
39 * pointing to the data portion of a chunk.
40 */
41 class ResChunkPullParser {
42 public:
43 enum class Event {
44 kStartDocument,
45 kEndDocument,
46 kBadDocument,
47
48 kChunk,
49 };
50
51 /**
52 * Returns false if the event is EndDocument or BadDocument.
53 */
54 static bool IsGoodEvent(Event event);
55
56 /**
57 * Create a ResChunkPullParser to read android::ResChunk_headers
58 * from the memory pointed to by data, of len bytes.
59 */
60 ResChunkPullParser(const void* data, size_t len);
61
62 Event event() const;
63 const std::string& error() const;
64 const android::ResChunk_header* chunk() const;
65
66 /**
67 * Move to the next android::ResChunk_header.
68 */
69 Event Next();
70
71 private:
72 DISALLOW_COPY_AND_ASSIGN(ResChunkPullParser);
73
74 Event event_;
75 const android::ResChunk_header* data_;
76 size_t len_;
77 const android::ResChunk_header* current_chunk_;
78 std::string error_;
79 };
80
81 template <typename T, size_t MinSize = sizeof(T)>
ConvertTo(const android::ResChunk_header * chunk)82 inline static const T* ConvertTo(const android::ResChunk_header* chunk) {
83 if (util::DeviceToHost16(chunk->headerSize) < MinSize) {
84 return nullptr;
85 }
86 return reinterpret_cast<const T*>(chunk);
87 }
88
GetChunkData(const android::ResChunk_header * chunk)89 inline static const uint8_t* GetChunkData(
90 const android::ResChunk_header* chunk) {
91 return reinterpret_cast<const uint8_t*>(chunk) +
92 util::DeviceToHost16(chunk->headerSize);
93 }
94
GetChunkDataLen(const android::ResChunk_header * chunk)95 inline static uint32_t GetChunkDataLen(const android::ResChunk_header* chunk) {
96 return util::DeviceToHost32(chunk->size) -
97 util::DeviceToHost16(chunk->headerSize);
98 }
99
100 //
101 // Implementation
102 //
103
IsGoodEvent(ResChunkPullParser::Event event)104 inline bool ResChunkPullParser::IsGoodEvent(ResChunkPullParser::Event event) {
105 return event != Event::kEndDocument && event != Event::kBadDocument;
106 }
107
ResChunkPullParser(const void * data,size_t len)108 inline ResChunkPullParser::ResChunkPullParser(const void* data, size_t len)
109 : event_(Event::kStartDocument),
110 data_(reinterpret_cast<const android::ResChunk_header*>(data)),
111 len_(len),
112 current_chunk_(nullptr) {}
113
event()114 inline ResChunkPullParser::Event ResChunkPullParser::event() const {
115 return event_;
116 }
117
error()118 inline const std::string& ResChunkPullParser::error() const { return error_; }
119
chunk()120 inline const android::ResChunk_header* ResChunkPullParser::chunk() const {
121 return current_chunk_;
122 }
123
124 } // namespace aapt
125
126 #endif // AAPT_RES_CHUNK_PULL_PARSER_H
127