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 #include "ResChunkPullParser.h"
18 
19 #include <androidfw/ResourceTypes.h>
20 #include <cstddef>
21 
22 namespace aapt {
23 
24 using android::ResChunk_header;
25 
next()26 ResChunkPullParser::Event ResChunkPullParser::next() {
27     if (!isGoodEvent(mEvent)) {
28         return mEvent;
29     }
30 
31     if (mEvent == Event::StartDocument) {
32         mCurrentChunk = mData;
33     } else {
34         mCurrentChunk = reinterpret_cast<const ResChunk_header*>(
35                 reinterpret_cast<const char*>(mCurrentChunk) + mCurrentChunk->size);
36     }
37 
38     const std::ptrdiff_t diff = reinterpret_cast<const char*>(mCurrentChunk)
39             - reinterpret_cast<const char*>(mData);
40     assert(diff >= 0 && "diff is negative");
41     const size_t offset = static_cast<const size_t>(diff);
42 
43     if (offset == mLen) {
44         mCurrentChunk = nullptr;
45         return (mEvent = Event::EndDocument);
46     } else if (offset + sizeof(ResChunk_header) > mLen) {
47         mLastError = "chunk is past the end of the document";
48         mCurrentChunk = nullptr;
49         return (mEvent = Event::BadDocument);
50     }
51 
52     if (mCurrentChunk->headerSize < sizeof(ResChunk_header)) {
53         mLastError = "chunk has too small header";
54         mCurrentChunk = nullptr;
55         return (mEvent = Event::BadDocument);
56     } else if (mCurrentChunk->size < mCurrentChunk->headerSize) {
57         mLastError = "chunk's total size is smaller than header";
58         mCurrentChunk = nullptr;
59         return (mEvent = Event::BadDocument);
60     } else if (offset + mCurrentChunk->size > mLen) {
61         mLastError = "chunk's data extends past the end of the document";
62         mCurrentChunk = nullptr;
63         return (mEvent = Event::BadDocument);
64     }
65     return (mEvent = Event::Chunk);
66 }
67 
68 } // namespace aapt
69