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 "unflatten/ResChunkPullParser.h"
18 #include "util/Util.h"
19 
20 #include <androidfw/ResourceTypes.h>
21 #include <cstddef>
22 
23 namespace aapt {
24 
25 using android::ResChunk_header;
26 
next()27 ResChunkPullParser::Event ResChunkPullParser::next() {
28     if (!isGoodEvent(mEvent)) {
29         return mEvent;
30     }
31 
32     if (mEvent == Event::StartDocument) {
33         mCurrentChunk = mData;
34     } else {
35         mCurrentChunk = (const ResChunk_header*)
36                 (((const char*) mCurrentChunk) + util::deviceToHost32(mCurrentChunk->size));
37     }
38 
39     const std::ptrdiff_t diff = (const char*) mCurrentChunk - (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 (util::deviceToHost16(mCurrentChunk->headerSize) < sizeof(ResChunk_header)) {
53         mLastError = "chunk has too small header";
54         mCurrentChunk = nullptr;
55         return (mEvent = Event::BadDocument);
56     } else if (util::deviceToHost32(mCurrentChunk->size) <
57             util::deviceToHost16(mCurrentChunk->headerSize)) {
58         mLastError = "chunk's total size is smaller than header";
59         mCurrentChunk = nullptr;
60         return (mEvent = Event::BadDocument);
61     } else if (offset + util::deviceToHost32(mCurrentChunk->size) > mLen) {
62         mLastError = "chunk's data extends past the end of the document";
63         mCurrentChunk = nullptr;
64         return (mEvent = Event::BadDocument);
65     }
66     return (mEvent = Event::Chunk);
67 }
68 
69 } // namespace aapt
70