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/*
* Copyright (C) 2016 The Android Open Source Project
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
#include "androidfw/Chunk.h"
#include "android-base/logging.h"
namespace android {
Chunk ChunkIterator::Next() {
CHECK(len_ != 0) << "called Next() after last chunk";
const ResChunk_header* this_chunk = next_chunk_;
// We've already checked the values of this_chunk, so safely increment.
next_chunk_ = reinterpret_cast<const ResChunk_header*>(
reinterpret_cast<const uint8_t*>(this_chunk) + dtohl(this_chunk->size));
len_ -= dtohl(this_chunk->size);
if (len_ != 0) {
// Prepare the next chunk.
if (VerifyNextChunkNonFatal()) {
VerifyNextChunk();
}
}
return Chunk(this_chunk);
}
// TODO(b/111401637) remove this and have full resource file verification
// Returns false if there was an error.
bool ChunkIterator::VerifyNextChunkNonFatal() {
if (len_ < sizeof(ResChunk_header)) {
last_error_ = "not enough space for header";
last_error_was_fatal_ = false;
return false;
}
const size_t size = dtohl(next_chunk_->size);
if (size > len_) {
last_error_ = "chunk size is bigger than given data";
last_error_was_fatal_ = false;
return false;
}
return true;
}
// Returns false if there was an error.
bool ChunkIterator::VerifyNextChunk() {
const uintptr_t header_start = reinterpret_cast<uintptr_t>(next_chunk_);
// This data must be 4-byte aligned, since we directly
// access 32-bit words, which must be aligned on
// certain architectures.
if (header_start & 0x03) {
last_error_ = "header not aligned on 4-byte boundary";
return false;
}
if (len_ < sizeof(ResChunk_header)) {
last_error_ = "not enough space for header";
return false;
}
const size_t header_size = dtohs(next_chunk_->headerSize);
const size_t size = dtohl(next_chunk_->size);
if (header_size < sizeof(ResChunk_header)) {
last_error_ = "header size too small";
return false;
}
if (header_size > size) {
last_error_ = "header size is larger than entire chunk";
return false;
}
if (size > len_) {
last_error_ = "chunk size is bigger than given data";
return false;
}
if ((size | header_size) & 0x03) {
last_error_ = "header sizes are not aligned on 4-byte boundary";
return false;
}
return true;
}
} // namespace android
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