1 // Copyright 2017 The Chromium OS Authors. All rights reserved. 2 // Use of this source code is governed by a BSD-style license that can be 3 // found in the LICENSE file. 4 5 #include "bsdiff/diff_encoder.h" 6 7 #include <vector> 8 9 #include "bsdiff/logging.h" 10 11 namespace { 12 13 // The maximum positive number that we should encode. A number larger than this 14 // for unsigned fields will be interpreted as a negative value and thus a 15 // corrupt patch. 16 const uint64_t kMaxEncodedUint64Value = (1ULL << 63) - 1; 17 18 } // namespace 19 20 namespace bsdiff { 21 22 bool DiffEncoder::Init() { 23 return patch_->Init(new_size_); 24 } 25 26 bool DiffEncoder::AddControlEntry(const ControlEntry& entry) { 27 if (entry.diff_size > kMaxEncodedUint64Value) { 28 LOG(ERROR) << "Encoding value out of range " << entry.diff_size; 29 return false; 30 } 31 32 if (entry.extra_size > kMaxEncodedUint64Value) { 33 LOG(ERROR) << "Encoding value out of range " << entry.extra_size; 34 return false; 35 } 36 37 // entry.diff_size + entry.extra_size don't overflow in uint64_t since we 38 // checked the kMaxEncodedUint64Value limit before. 39 if (entry.diff_size + entry.extra_size > new_size_ - written_output_) { 40 LOG(ERROR) << "Wrote more output than the declared new_size"; 41 return false; 42 } 43 44 if (entry.diff_size > 0 && 45 (old_pos_ < 0 || 46 static_cast<uint64_t>(old_pos_) + entry.diff_size > old_size_)) { 47 LOG(ERROR) << "The pointer in the old stream [" << old_pos_ << ", " 48 << (static_cast<uint64_t>(old_pos_) + entry.diff_size) 49 << ") is out of bounds [0, " << old_size_ << ")"; 50 return false; 51 } 52 53 // Pass down the control entry. 54 if (!patch_->AddControlEntry(entry)) 55 return false; 56 57 // Generate the diff stream. 58 std::vector<uint8_t> diff(entry.diff_size); 59 for (uint64_t i = 0; i < entry.diff_size; ++i) { 60 diff[i] = new_buf_[written_output_ + i] - old_buf_[old_pos_ + i]; 61 } 62 if (!patch_->WriteDiffStream(diff.data(), diff.size())) { 63 LOG(ERROR) << "Writing " << diff.size() << " bytes to the diff stream"; 64 return false; 65 } 66 67 if (!patch_->WriteExtraStream(new_buf_ + written_output_ + entry.diff_size, 68 entry.extra_size)) { 69 LOG(ERROR) << "Writing " << entry.extra_size 70 << " bytes to the extra stream"; 71 return false; 72 } 73 74 old_pos_ += entry.diff_size + entry.offset_increment; 75 written_output_ += entry.diff_size + entry.extra_size; 76 77 return true; 78 } 79 80 bool DiffEncoder::Close() { 81 if (written_output_ != new_size_) { 82 LOG(ERROR) << "Close() called but not all the output was written"; 83 return false; 84 } 85 return patch_->Close(); 86 } 87 88 } // namespace bsdiff 89
