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
27namespace 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.
36class 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
70template <typename T, size_t MinSize = sizeof(T)>
71inline 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
78inline static const uint8_t* GetChunkData(const android::ResChunk_header* chunk) {
79  return reinterpret_cast<const uint8_t*>(chunk) + util::DeviceToHost16(chunk->headerSize);
80}
81
82inline 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
90inline bool ResChunkPullParser::IsGoodEvent(ResChunkPullParser::Event event) {
91  return event != Event::kEndDocument && event != Event::kBadDocument;
92}
93
94inline 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
101inline ResChunkPullParser::Event ResChunkPullParser::event() const {
102  return event_;
103}
104
105inline const std::string& ResChunkPullParser::error() const {
106  return error_;
107}
108
109inline 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