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
19#include <inttypes.h>
20#include <cstddef>
21
22#include "android-base/logging.h"
23#include "android-base/stringprintf.h"
24#include "androidfw/ResourceTypes.h"
25
26#include "util/Util.h"
27
28namespace aapt {
29
30using android::ResChunk_header;
31using android::base::StringPrintf;
32
33static std::string ChunkHeaderDump(const ResChunk_header* header) {
34  return StringPrintf("(type=%02" PRIx16 " header_size=%" PRIu16 " size=%" PRIu32 ")",
35                      util::DeviceToHost16(header->type), util::DeviceToHost16(header->headerSize),
36                      util::DeviceToHost32(header->size));
37}
38
39ResChunkPullParser::Event ResChunkPullParser::Next() {
40  if (!IsGoodEvent(event_)) {
41    return event_;
42  }
43
44  if (event_ == Event::kStartDocument) {
45    current_chunk_ = data_;
46  } else {
47    current_chunk_ =
48        (const ResChunk_header*)(((const char*)current_chunk_) +
49                                 util::DeviceToHost32(current_chunk_->size));
50  }
51
52  const std::ptrdiff_t diff = (const char*)current_chunk_ - (const char*)data_;
53  CHECK(diff >= 0) << "diff is negative";
54  const size_t offset = static_cast<const size_t>(diff);
55
56  if (offset == len_) {
57    current_chunk_ = nullptr;
58    return (event_ = Event::kEndDocument);
59  } else if (offset + sizeof(ResChunk_header) > len_) {
60    error_ = "chunk is past the end of the document";
61    current_chunk_ = nullptr;
62    return (event_ = Event::kBadDocument);
63  }
64
65  if (util::DeviceToHost16(current_chunk_->headerSize) < sizeof(ResChunk_header)) {
66    error_ = "chunk has too small header";
67    current_chunk_ = nullptr;
68    return (event_ = Event::kBadDocument);
69  } else if (util::DeviceToHost32(current_chunk_->size) <
70             util::DeviceToHost16(current_chunk_->headerSize)) {
71    error_ = "chunk's total size is smaller than header " + ChunkHeaderDump(current_chunk_);
72    current_chunk_ = nullptr;
73    return (event_ = Event::kBadDocument);
74  } else if (offset + util::DeviceToHost32(current_chunk_->size) > len_) {
75    error_ = "chunk's data extends past the end of the document " + ChunkHeaderDump(current_chunk_);
76    current_chunk_ = nullptr;
77    return (event_ = Event::kBadDocument);
78  }
79  return (event_ = Event::kChunk);
80}
81
82}  // namespace aapt
83