1 /* 2 * Copyright (C) 2016 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 "androidfw/Chunk.h" 18 19 #include "android-base/logging.h" 20 21 namespace android { 22 23 Chunk ChunkIterator::Next() { 24 CHECK(len_ != 0) << "called Next() after last chunk"; 25 26 const ResChunk_header* this_chunk = next_chunk_; 27 28 // We've already checked the values of this_chunk, so safely increment. 29 next_chunk_ = reinterpret_cast<const ResChunk_header*>( 30 reinterpret_cast<const uint8_t*>(this_chunk) + dtohl(this_chunk->size)); 31 len_ -= dtohl(this_chunk->size); 32 33 if (len_ != 0) { 34 // Prepare the next chunk. 35 VerifyNextChunk(); 36 } 37 return Chunk(this_chunk); 38 } 39 40 // Returns false if there was an error. 41 bool ChunkIterator::VerifyNextChunk() { 42 const uintptr_t header_start = reinterpret_cast<uintptr_t>(next_chunk_); 43 44 // This data must be 4-byte aligned, since we directly 45 // access 32-bit words, which must be aligned on 46 // certain architectures. 47 if (header_start & 0x03) { 48 last_error_ = "header not aligned on 4-byte boundary"; 49 return false; 50 } 51 52 if (len_ < sizeof(ResChunk_header)) { 53 last_error_ = "not enough space for header"; 54 return false; 55 } 56 57 const size_t header_size = dtohs(next_chunk_->headerSize); 58 const size_t size = dtohl(next_chunk_->size); 59 if (header_size < sizeof(ResChunk_header)) { 60 last_error_ = "header size too small"; 61 return false; 62 } 63 64 if (header_size > size) { 65 last_error_ = "header size is larger than entire chunk"; 66 return false; 67 } 68 69 if (size > len_) { 70 last_error_ = "chunk size is bigger than given data"; 71 return false; 72 } 73 74 if ((size | header_size) & 0x03) { 75 last_error_ = "header sizes are not aligned on 4-byte boundary"; 76 return false; 77 } 78 return true; 79 } 80 81 } // namespace android 82
