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// Copyright 2017 The Chromium OS Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
#include "bsdiff/diff_encoder.h"
#include <vector>
#include "bsdiff/logging.h"
namespace {
// The maximum positive number that we should encode. A number larger than this
// for unsigned fields will be interpreted as a negative value and thus a
// corrupt patch.
const uint64_t kMaxEncodedUint64Value = (1ULL << 63) - 1;
} // namespace
namespace bsdiff {
bool DiffEncoder::Init() {
return patch_->Init(new_size_);
}
bool DiffEncoder::AddControlEntry(const ControlEntry& entry) {
if (entry.diff_size > kMaxEncodedUint64Value) {
LOG(ERROR) << "Encoding value out of range " << entry.diff_size;
return false;
}
if (entry.extra_size > kMaxEncodedUint64Value) {
LOG(ERROR) << "Encoding value out of range " << entry.extra_size;
return false;
}
// entry.diff_size + entry.extra_size don't overflow in uint64_t since we
// checked the kMaxEncodedUint64Value limit before.
if (entry.diff_size + entry.extra_size > new_size_ - written_output_) {
LOG(ERROR) << "Wrote more output than the declared new_size";
return false;
}
if (entry.diff_size > 0 &&
(old_pos_ < 0 ||
static_cast<uint64_t>(old_pos_) + entry.diff_size > old_size_)) {
LOG(ERROR) << "The pointer in the old stream [" << old_pos_ << ", "
<< (static_cast<uint64_t>(old_pos_) + entry.diff_size)
<< ") is out of bounds [0, " << old_size_ << ")";
return false;
}
// Pass down the control entry.
if (!patch_->AddControlEntry(entry))
return false;
// Generate the diff stream.
std::vector<uint8_t> diff(entry.diff_size);
for (uint64_t i = 0; i < entry.diff_size; ++i) {
diff[i] = new_buf_[written_output_ + i] - old_buf_[old_pos_ + i];
}
if (!patch_->WriteDiffStream(diff.data(), diff.size())) {
LOG(ERROR) << "Writing " << diff.size() << " bytes to the diff stream";
return false;
}
if (!patch_->WriteExtraStream(new_buf_ + written_output_ + entry.diff_size,
entry.extra_size)) {
LOG(ERROR) << "Writing " << entry.extra_size
<< " bytes to the extra stream";
return false;
}
old_pos_ += entry.diff_size + entry.offset_increment;
written_output_ += entry.diff_size + entry.extra_size;
return true;
}
bool DiffEncoder::Close() {
if (written_output_ != new_size_) {
LOG(ERROR) << "Close() called but not all the output was written";
return false;
}
return patch_->Close();
}
} // namespace bsdiff
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